Co-reporter:Linlin Hao, Masoom Kartik Desai, Peng Wang, and Suresh Valiyaveettil
ACS Sustainable Chemistry & Engineering May 1, 2017 Volume 5(Issue 5) pp:3742-3742
Publication Date(Web):April 2, 2017
DOI:10.1021/acssuschemeng.6b02152
Renewable adsorbents are interesting for water purification owing to easy access and presence of multiple functional groups for extraction of pollutants. The biowaste, ghee residue from the milk industry was washed to remove fat contents, coated with polyethylenimine (PEI) and Fe(III) ions (Prot-PEI-Fe) was synthesized for the successive adsorption of As(V), Cu(II) and P(V) ions from spiked water samples. The pretreated ghee residue was characterized using FTIR, SEM, ζ-potential and elemental analysis. Batch mode experiments and kinetic regression results showed that the adsorption processes of As(V) and P(V) anions were more accurately described by a pseudo-second-order model, whereas the adsorption of Cu(II) ions followed a pseudo-first-order model. The maximum adsorption capacities estimated by Langmuir model for As(V), Cu(II) and P(V) ions were 45.1, 80.7 and 21.7 mg/g, respectively. The successive adsorptions of As(V), Cu(II) and P(V) ions were achieved through electrostatic attraction, which was demonstrated by the changes in ζ-potentials of the adsorbent after each experiment. The dynamic column adsorption behavior of the adsorbent was described by Thomas model. The simulated results showed good agreement between the theoretical values (q0) generated by using Thomas model and the experimental values (qexp). The results presented in this paper could be used for developing new adsorbent from the renewable waste materials for water purification.Keywords: Adsorbent; Arsenic pollution; Biowaste; Ghee residue protein; Heavy metal ions; Successive Adsorption;
Co-reporter:Deepa Sriramulu;Shuvan Prashant Turaga;Andrew Anthony Bettiol
RSC Advances (2011-Present) 2017 vol. 7(Issue 52) pp:32692-32702
Publication Date(Web):2017/06/23
DOI:10.1039/C7RA05036D
Controlling the assembly of molecules in thin films is essential for developing functional materials for sensitive and smart coatings. Highly oriented heterogeneous and optically anisotropic 2D silica films were prepared at the liquid–liquid interface using octadecylsilane and perylenesilane as starting materials. The film formation involved the organization of molecules assisted by van der Waals interactions and network formation from silica polymerization. All films were fully characterized using a wide range of instruments. Wetting behavior of the thin film was established using contact angle measurement. The octadecylsilica (O-Si) film showed a water contact angle of ∼107° on the hydrophobic side and ∼70° on the hydrophilic side. The films prepared from perylenesilane (P-Si) and mixtures of perylenesilane and octadecylsilane (POx-Si) through hydrolysis, were fully characterized and showed higher contact angle than the O-Si films. As expected, an increase in the concentration of octadecylsilane in POx-Si film led to the disruption of the π–π stacking of perylene groups, followed by changes in optical properties of the film, which were established using spectroscopic techniques. Such bifunctional anisotropic films can be used for creating interesting functional coatings on different substrates.
Co-reporter:Choong Ping Sen, Vanga Devendar Goud, Rekha Goswami Shrestha, Lok Kumar Shrestha, Katsuhiko Ariga and Suresh Valiyaveettil
Polymer Chemistry 2016 vol. 7(Issue 25) pp:4213-4225
Publication Date(Web):26 May 2016
DOI:10.1039/C6PY00847J
A series of A2B3 and A2B4 type hyperbranched polymers (HP1–HP3) based on 4,4′-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) was synthesized via Sonogashira cross coupling polymerization reactions. The target polymers were fully characterized with molecular weights (Mn) of 10000 to 25000 g mol−1 and were soluble in common organic solvents. The polymers showed red shifts in absorption maxima (570 nm to 630 nm) in the solution state compared to that of BODIPY monomers (540 nm). Particularly, the absorption studies done in solution suggest strong interactions between HP2 and toluene with observed red shifts in absorption maxima (20 nm) and emission maxima (11 nm) when the solvent was changed from chloroform to toluene for the optical measurements. All polymers were coated on quartz crystal microbalance (QCM) electrodes for sensing organic vapors. Among all polymers tested, HP2 showed high sensitivity towards benzene and toluene vapors. In addition, the hyperbranched polymer HP2 has higher sensitivity for toluene over benzene compared to linear BODIPY copolymers. Such sensitive polymers are useful for the development of potential sensors for aromatic molecules.
Co-reporter:Deepa Sriramulu, Suresh Valiyaveettil
Dyes and Pigments 2016 Volume 134() pp:306-314
Publication Date(Web):November 2016
DOI:10.1016/j.dyepig.2016.07.028
•Perylene derivatives used as fluorescent probe for sensing amines in solution.•Detailed photophysical studies carried out to study perylene-amine interaction.•Fluorescence quenching observed due to photoinduced electron transfer process.•PDI showed selectivity in sensing amines compared to PMI derivative.•Stern-Volmer plot was used to understand emission quenching mechanism.Amines play an important role in many physiological processes in living organisms. The present study explores the use of perylene diimide (PDI) and perylene monoimide (PMI) for the detection of common amines in solution. A systematic investigation using primary, secondary and tertiary amines as electron donors and perylene derivatives as electron acceptors is carried out in solution to understand the molecular interactions. Results from steady-state luminescence spectroscopy suggested that the PDI and PMI interact with the amine derivatives in the excited state, which led to photoinduced electron transfer and fluorescence quenching. Stern-Volmer plots were used to understand the quenching behavior of perylene derivatives in presence of various amines. The bimolecular rate constants of the dynamic quenching have been deduced for PDI, the values are in the range of 1.8 × 109 M−1s−1 for primary amines, 8 × 109 M−1s−1 for tertiary amines and 2.2 × 1010 M−1s−1 for aniline. Similar quenching rate constants for primary, secondary and tertiary amines were also observed for PMI. PDI showed higher selectivity for bulky hydrophobic amines over linear primary amines in solution. Such interactions could be investigated further to understand the response of perylene based sensors for amines.
Co-reporter:M.G. Murali, Xingzhu Wang, Qing Wang, Suresh Valiyaveettil
Dyes and Pigments 2016 Volume 134() pp:375-381
Publication Date(Web):November 2016
DOI:10.1016/j.dyepig.2016.07.017
•New A–D–π–D–A type organic dyes with two end-anchoring groups are reported.•Optical, electrochemical and photovoltaic properties are described.•The DSSCs from MA-2 dye showed a power conversion efficiency of 6.87%.•Multi(donor-anchor) concept is beneficial for improving the device performance.Two new bent A–D–π–D–A type organic dyes (MA-1 and MA-2) consisting of carbazole and phenothiazine moieties as electron donors with 2,1,3-benzothiadiazole as a π-linker with two end-anchoring groups are designed, synthesized and tested in DSSCs. The photophysical and electrochemical properties of the dyes are investigated in detail. Incorporation of phenothiazine unit in MA-2 resulted in high HOMO level (0.62 V vs. NHE), with a red shift in absorption maxima and broadening of the absorption spectrum. Under standard global AM 1.5 solar conditions, the MA-2 sensitized solar cells exhibited a short circuit photocurrent density of 13.1 mA cm−2, an open-circuit voltage of 0.73 V, a fill factor of 0.72, corresponding to an overall conversion efficiency of 6.87%. Such design and development of molecular dyes are useful for improving the overall efficiency of DSSCs.
Co-reporter:M. G. Murali, Xingzhu Wang, Qing Wang and Suresh Valiyaveettil
RSC Advances 2016 vol. 6(Issue 63) pp:57872-57879
Publication Date(Web):08 Jun 2016
DOI:10.1039/C6RA10881D
A series of ruthenium complexes (MC-1–MC-3), incorporated with carbazole, fluorene and phenothiazine units with dipyrido[3,2-a:2′,3′-c]phenazine are synthesized, characterized and their optical, electrochemical and photovoltaic properties are investigated. The observed differences in light-harvesting ability of the sensitizers are associated with the electron donor strength of the ancillary ligand used for preparing complexes. The dye-sensitized solar cell fabricated from complex MC-1 exhibited a power conversion efficiency of 6.18%. It is demonstrated that new molecular design and increase in molar absorption coefficient of the sensitizer improved the device performance.
Co-reporter:Roshan DSouza, Deepa Sriramulu and Suresh Valiyaveettil
RSC Advances 2016 vol. 6(Issue 29) pp:24508-24517
Publication Date(Web):24 Feb 2016
DOI:10.1039/C5RA27108H
Polyurea (PU) films are interesting owing to the high mechanical properties and wide range of applications. Here we report an interfacial synthesis of a PU thin film at the liquid–liquid interface using the reaction between diisocyanate and polyamines. Three amines – polyethylenimine (PEI), diethylenetriamine (DETA) and tris(2-aminoethyl)amine (TREN) were dissolved in the aqueous phase separately and allowed to react with an organic solution of hexamethylene diisocyanate (HMDI) at the liquid–liquid interface. The structure and morphologies of the films were established using spectroscopic and microscopic techniques. Smooth PU films were obtained from the reaction of HMDI with PEI, whereas films with holes and tubules were obtained from small molecular amines such as DETA and TREN. Such observations are explained based on the differences in solubility, reactivity of the reagents and molecular size dependant diffusion across the film. The effect of the changes in concentration of reactants and time of reaction on film thickness and transport of organic dye molecules through the film were investigated. PEI gave a smooth defect-free film of PU, whereas small molecular amines upon reaction with HMDI gave films with significant number of defects. To demonstrate the accessibility of functional groups on the film, adsorption of fluorescent dyes on the film surface was investigated. From the UV-Vis spectroscopic measurements, it is clear that acidic molecules adsorb on the surface of the films and the corresponding esters are not extracted efficiently by the film. In summary, the synthesis and characterization of PU films from multiple amines, and the transport of small molecules and adsorption of dyes on the surface of the films were established.
Co-reporter:Ashok Keerthi, Ming Hui Chua, Thuang Yuan Timothy Chan, Yeru Liu, Qing Wang and Suresh Valiyaveettil
RSC Advances 2016 vol. 6(Issue 57) pp:51807-51815
Publication Date(Web):23 May 2016
DOI:10.1039/C6RA08530J
Multi-donor incorporated organic dyes were designed and synthesized and their structure–property relationship was investigated in dye-sensitized solar cells (DSCs). Five N,N-disubstituted aniline donor groups along with carbazole and thiophene secondary donors were combined into the (D)n–π–A design with cyanoacrylic acid as the acceptor. The dyes showed broad absorption bands with absorption maxima in the range of 470–485 nm and optical band gap around 1.94–2.37 eV. Our results indicate that incorporation of bulky groups and bent-type architecture helps to improve the performance of DSCs.
Co-reporter:Ramakrishna Mallampati, Li Xuanjun, Avner Adin, and Suresh Valiyaveettil
ACS Sustainable Chemistry & Engineering 2015 Volume 3(Issue 6) pp:1117
Publication Date(Web):April 8, 2015
DOI:10.1021/acssuschemeng.5b00207
Removal of heavy metal ions and dissolved organic compounds present in wastewater is a challenge for many countries owing to high cost of existing technologies and continued increase in water consumption. In this study, three natural materials, avocado, hamimelon and dragon fruit peels, were selected and used as simple and renewable adsorbents for water purification. The presence of surface functional groups such as −CO2H, −OH and morphologies of the peels were characterized using spectroscopic and electron microscopic techniques, respectively. All peals were effective toward removing dyes and toxic metal ions from water. The extraction capacity of peels increased with extraction time and a plateau was reached at equilibrium. Dragon fruit peels showed highest extraction efficiency toward alcian blue (71.85 mg/g) and methylene blue (62.58 mg/g). Hamimelon peels and avaocado peels showed moderate extraction capacity for Pb2+ (7.89 mg/g, 9.82 mg/g) and Ni2+ (9.45 mg/g, 4.93 mg/g) cations. The Langmuir isotherm model was useful to explain the adsorption process, dominated by electrostatic interaction between adsorbent and adsorbates, indicating a monolayer adsorption at the binding sites on the surface of the peels. However, the adsorption model for methylene blue and neutral red is still a matter of conjecture. The adsorbents can be regenerated at acidic pH and could reuse for a few cycles.Keywords: Adsorption; Bioadsorbents; Biopeels; Extraction; Pollutants; Water purification;
Co-reporter:Choong Ping Sen and Suresh Valiyaveettil
RSC Advances 2015 vol. 5(Issue 127) pp:105435-105445
Publication Date(Web):07 Dec 2015
DOI:10.1039/C5RA21089E
Oligothiophenes are used in many applications owing to their easy accessibility in high purity, tunable electron density, high chemical stability and desired processability in solution and in the solid state. In this work, a series of soluble branched oligothiophenes have been synthesized and fully characterized. The target molecules (SCT-1 to SCT-4) are soluble in common organic solvents. Full characterization of optical and electrochemical properties indicated that the extended π-conjugation led to red-shifts in the absorption maximum (λmax) from 360 nm (SCT-1) to 440 nm (SCT-4). Fluorescence quantum yields were in the range of 6–45% for the SCTs. The observed properties of the target molecules are better than the corresponding linear oligothiophenes. Electron deficient Hg(II) cations interact with electron rich SCT-4 to form a charge-transfer complex which led to significant quenching of photoluminescence in solution. Moreover, an electron deficient molecule, 7,7,8,8-tetracyanoquinodimethane (TCNQ), also interacts with electron rich SCTs to form a TCNQ dianion (TCNQ2−). Such conjugated optical materials could be used for developing potential applications in the near future.
Co-reporter:Daisy Setyono and Suresh Valiyaveettil
RSC Advances 2015 vol. 5(Issue 101) pp:83286-83294
Publication Date(Web):24 Sep 2015
DOI:10.1039/C5RA10609E
Enhanced usage of metal nanoparticles (NPs) in chemical industry and consumer products is causing undesirable environmental pollution, toxicity, and damage to the ecosystem. New methods are needed to remove such emerging pollutants from the environment. In this paper, we report the synthesis and characterization of polyethylenimine coated porous ethyl cellulose microcapsules and show potential application in the extraction of dissolved citrate or PVP-capped Ag NPs and Au NPs from water. The high surface area of the capsules and affinity of amine functional groups towards metal nanoparticles are used to enhance the extraction efficiency. Kinetics, isotherm models, and pH studies were used to understand the observed extraction efficiency of capsules. The capsules showed interesting Langmuir adsorption capacities of 270 mg g−1 for Ag-citrate, 208 mg g−1 for Ag-PVP, 116 mg g−1 for Au-citrate, and 50 mg g−1 for Au-PVP nanoparticles. We have also developed a simple method to detect metal nanoparticles via modification of the microcapsule with fluorescein isothiocyanate. Overall, our results demonstrate that the porous PEI-crosslinked microcapsules are useful for the extraction of Ag NPs and Au NPs from contaminated water. They can also be modified for the detection of metallic NPs at a ppb level concentration.
Co-reporter:Roshan Dsouza and Suresh Valiyaveettil
RSC Advances 2015 vol. 5(Issue 41) pp:32862-32871
Publication Date(Web):02 Apr 2015
DOI:10.1039/C5RA01675D
Polymer microparticles have been used in catalysis, sensing, environmental and biomedical applications. In this paper, the synthesis and characterization of amine functionalized polymer microparticles or aminoparticles via copolymerisation of glycidyl methacrylate and styrene monomers are reported. The surface of the microspheres was grafted with different amines – ethylenediamine, hexamethylenediamine, xylylenediamine and n-butylamine to increase the number and types of amino groups on the surface. The amine content on the microsphere surface was estimated and compared using elemental analyses and volumetric titration method. The fully characterized aminoparticles were used for the extraction of heavy metal ions and emerging pollutants such as gold and silver nanoparticles from aqueous solutions. The effect of contact time and concentrations of adsorbates on the extraction efficiency of pollutants, adsorption kinetics and isotherms were studied in detail. The extraction efficiencies of the synthesized particles were proportional to the surface amine content and surface charges of the particles. Such particles will be useful towards developing novel column materials for analytical separations.
Co-reporter:Ramakrishna Mallampati and Suresh Valiyaveettil
RSC Advances 2015 vol. 5(Issue 15) pp:11023-11028
Publication Date(Web):09 Jan 2015
DOI:10.1039/C4RA14292F
Presence of nanosized contaminants such as engineered gold (Au), silver (Ag) nanoparticles and graphene oxide (GO) in many commercial products are creating environmental concerns owing to their high toxicity. Removal of such nanomaterials (NMs) from water using current technologies is not very efficient owing to the small size and shapes of such pollutants. Here we explore a fast method for the extraction of NMs from aqueous solutions based on in situ co-precipitation of calcium carbonate particles. Removal efficiency was estimated using batch adsorption studies. The co-precipitation method entraps and removes the nanomaterials in a fast and efficient manner to purify water. Microscopic observation and spectrophotometric analyses indicated the extraction and incorporation of NMs into the calcium carbonate precipitate. Complete removal (99%) of metal nanoparticles and graphene oxide was observed within 10 min during the co-precipitation and settling of the solids. This method is efficient to remove nanopollutants from water at low concentration (ppm) levels. Co-precipitation, a simple and scalable purification method using nontoxic material can be scaled up to treat contaminated industrial effluents.
Co-reporter:Vanga Devendar Goud, Roshan DSouza and Suresh Valiyaveettil
RSC Advances 2015 vol. 5(Issue 59) pp:47647-47658
Publication Date(Web):20 May 2015
DOI:10.1039/C5RA04155D
Amine functionalised polymers are not widely used in applications owing to increased reactivity, sensitivity to air and moisture, low stability and processing difficulties. Here, we report a convergent strategy for the synthesis of four stable and processable amphiphilic amine functionalized polymers, poly(N-triazolepropyl phenyl aniline-co-styrene) P1, poly(N-triazoleoctyl phenyl aniline-co-styrene) P2, poly(N-triazolexylyl phenyl aniline-co-styrene) P3, and poly(N-aminopropylphenyl pyridine-co-styrene) P4, using click reaction. Full structural characterization and properties of the polymers are established using different spectroscopic and physicochemical methods. All the polymers were soluble in common organic solvents and insoluble in water. Porous films and spherical particles were obtained via drop-casting the solutions of copolymers in chloroform or in N,N-dimethylformamide, respectively, on glass substrates. The synthesized polyamines were used for the liquid–liquid and solid–liquid extraction of metal nanoparticles, organic dyes and heavy metal ions from water. All the polymers showed significant extraction efficiencies towards metal nanoparticles (20–45 mg g−1) and organic dyes (25–70 mg g−1) dissolved in water. Such synthetic polyamines can be used as potential adsorbents for water purification.
Co-reporter:Choong Ping Sen;Dr. Rekha Goswami Shrestha;Dr. Lok Kumar Shrestha;Dr. Katsuhiko Ariga;Dr. Suresh Valiyaveettil
Chemistry - A European Journal 2015 Volume 21( Issue 48) pp:17344-17354
Publication Date(Web):
DOI:10.1002/chem.201502939
Abstract
Conjugated polymers with strong photophysical properties are used in many applications. A homopolymer (P1) and five new low band gap copolymers based on 4,4′-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) and acceptors 3,6-dithienyldiketopyrrolopyrrole (P2), phthalimide (P3), benzotriazole (P4), 4,7-dithienyl[1,2,3]triazolo[4,5g]quinoxaline (P5), and 2,5-dithienylthieno[3,4-b]pyrazine (P6) were prepared by means of Sonogashira polymerization. The characterization of polymers by using 1H NMR, absorption, and emission spectroscopy is discussed. All polymers with high molecular weights (Mn) of 16 000 to 89 000 g mol−1 showed absorption maxima in the deep-red region (λ=630–760 nm) in solution and exhibited significant redshifts (up to 70 nm) in thin films. Polymers P2, P5, and P6 showed narrow optical band gaps of 1.38, 1.35, and 1.38 eV, respectively, which are significantly lower than that of P1 (1.63 eV). The HOMO and LUMO energy levels of the polymers were calculated by using cyclic voltammetry measurements. The LUMO energy levels of BODIPY-based alternating copolymers were independent of the acceptors; this suggests that the major factor that tunes the LUMO energy levels of the polymers could be the BODIPY core. All polymers showed selective and reproducible detection of volatile organic solvents, such as toluene and benzene, which could be used for developing sensors.
Co-reporter:Daisy Setyono and Suresh Valiyaveettil
ACS Sustainable Chemistry & Engineering 2014 Volume 2(Issue 12) pp:2722
Publication Date(Web):November 13, 2014
DOI:10.1021/sc500458x
Environmentally friendly and cost-effective adsorbent materials for arsenic extraction are needed for removing pollutants from groundwater. Here, lanthanum or zirconium oxide nanoparticle-incorporated sawdust was used for the removal of arsenic anions from water. The chemically modified sawdust was fully characterized and used for extraction of arsenic from water. The influences of ionic strength, pH, and interfering ionic pollutants toward the extraction efficiency of arsenic anions were investigated to understand the mechanism. ZrO2-sawdust showed extraction capacities of 29 and 12 mg/g for arsenite and arsenate anions, respectively, while La2O3-sawdust extracted arsenite (22 mg/g) and arsenate (28 mg/g) anions efficiently. Desorption studies were performed on surface-modified sawdust to check the recyclability. La2O3-sawdust can be fully regenerated with no change in arsenic removal efficiency, while ZrO2-sawdust retains ∼50% of its adsorption efficiency. Such modified renewable bioadsorbents are useful for developing environmentally friendly materials for water purification.Keywords: Adsorption; Arsenic; Glutamic acid; Isotherms; Kinetics; Lanthanum; Sawdust; Zirconium
Co-reporter:Jitendra Kumar, Ramakrishna Mallampati, Avner Adin, and Suresh Valiyaveettil
ACS Sustainable Chemistry & Engineering 2014 Volume 2(Issue 12) pp:2675
Publication Date(Web):October 22, 2014
DOI:10.1021/sc5004242
Increased use of nanomaterials in commercial products will lead to environmental contamination in the near future. So far, limited adsorbents are available for the removal of such emerging pollutants from water. The objective of this work was to synthesize functionalized carbon nanospheres (C-spheres) for the removal of emerging nanopollutants from water and to study the mechanisms involved. C-spheres were prepared using hydrothermal carbonization of glucose. Post-modification with polyethylenimine (PEI) generated amine-coated C-spheres, followed by protonation using diluted acid solution. The surface functional groups and morphologies of the C-spheres were characterized using infrared spectroscopy and field emission scanning electron microscopy, respectively. The C-spheres were used for the extraction of citrate-capped gold and silver nanoparticles from water. The equilibrium adsorption data was interpreted using Langmuir and Freundlich isotherms, and the adsorption mechanism was investigated using kinetic studies. Our data suggest that the adsorption of nanoparticles on modified C-spheres followed pseudo-second-order kinetics, and adsorption can be best explained by the Langmuir adsorption model. The observed results suggest that the developed material shows enhanced extraction capacities (102 mg/g for AuNPs and 135 mg/g for AgNPs). Further, the NP-adsorbed C-spheres were evaluated for the catalytic reduction of p-nitrophenol to demonstrate the activity of adsorbed NPs.Keywords: Adsorption; Carbon sphere; Hydrothermal; Nanoparticles; p-NP reduction; Water treatment
Co-reporter:Ramakrishna Mallampati and Suresh Valiyaveettil
ACS Sustainable Chemistry & Engineering 2014 Volume 2(Issue 4) pp:855
Publication Date(Web):January 13, 2014
DOI:10.1021/sc4004899
Heterogeneous catalysts are used in many industrial processes. Here, we report a simple method for a template-assisted synthesis of nanoparticle catalysts and for testing their catalytic efficiency toward two model organic reactions. Eggshell membrane (ESM) reduced metal cations to metal atoms, stabilized the nanoparticles, and was used as a supporting material for the nanoparticles. The gold and silver nanoparticles were characterized using UV–vis spectroscopy, FESEM, XRD, and XPS studies. As a proof of concept, the resultant membrane-supported nanoparticles were used as a heterogeneous catalyst for the reduction of p-nitrophenol and synthesis of propargylamine. High recyclability of the reactions indicates that nanoparticles are strongly attached to the eggshell membrane surface. Easy synthesis, high catalytic activity, and recyclability make these catalysts interesting for further studies.Keywords: A3 coupling; Catalyst; Eggshell membrane; Reduction; Template;
Co-reporter:Brahatheeswaran Dhandayuthapani, Ramakrishna Mallampati, Deepa Sriramulu, Roshan Fredrick Dsouza, and Suresh Valiyaveettil
ACS Sustainable Chemistry & Engineering 2014 Volume 2(Issue 4) pp:1014
Publication Date(Web):February 12, 2014
DOI:10.1021/sc500003k
Recent developments in nanotechnology led to the incorporation of many nanomaterials into consumer products. Disposal of such products will lead to potential contamination of the environment. Nanomaterials are emerging contaminants in water and show significant toxicity to living systems. Considering the diversity in structure and properties, removal of nanopollutants from water warrants novel methods and materials. The objective of this study was to prepare PVA/gluten hybrid nanofibers, which are nontoxic and biodegradable adsorbents for the extraction of nanopollutants from water. Surface morphology, elemental composition, and functional groups on the fiber surface were established using microscopic and spectroscopic techniques. Influence of analytical factors such as experimental pH, time, and concentration of the pollutants toward establishing the efficiency of extraction were quantified using UV–vis spectroscopy. Nanofiber mats with 5 wt % gluten exhibited high extraction efficiency of 99% toward citrate-capped silver (Ag) and gold (Au) nanoparticles with a maximum adsorptive capacity of 31.84 mg/g for Ag NPs and 36.54 mg/g for AuNPs. The kinetic and equilibrium adsorption data were interpreted using Freundlich and Langmuir isotherm models, and a potential adsorption mechanism was suggested. The adsorption kinetics showed a pseudo-second-order model for the extraction of nanoparticles. The prepared PVA/gluten hybrid nanofibers can be utilized as an efficient low-cost adsorbents for removal and recovery of metal nanoparticles from the aqueous environment.Keywords: Environmental; Gluten; Nanofiber; Nanoparticle; PVA
Co-reporter:Devendar Goud Vanga, Mithun Santra, Ashok Keerthi and Suresh Valiyaveettil
Organic & Biomolecular Chemistry 2014 vol. 12(Issue 40) pp:7914-7918
Publication Date(Web):28 Aug 2014
DOI:10.1039/C4OB01509F
A few pyrene-based fluorescent compounds were synthesized using Pd/Cu-catalyzed cross-coupling reaction. Photophysical properties of the π-conjugated pyrene derivatives were studied and the results indicate materials with high quantum efficiency and high extinction coefficient. No π stacking was observed in the crystal lattice. The molecules described here may be useful in developing sensors or imaging agents.
Co-reporter:Daisy Setyono and Suresh Valiyaveettil
RSC Advances 2014 vol. 4(Issue 95) pp:53365-53373
Publication Date(Web):09 Oct 2014
DOI:10.1039/C4RA09030F
Arsenic contamination in ground water is a major problem in various countries, and causes serious health issues, such as cancer and skin diseases. Among the many different methods of arsenic removal, extraction using functional adsorbents has been employed owing to its low cost, simplicity, and fast regeneration. In this paper, preparation and characterization of mixed metal oxide loaded polycaprolactone microcapsules and their application as adsorbents for both As(III) and As(V) from water is demonstrated. The presence of CeO2 nanoparticles on microcapsules enhance the affinity towards As(III), while magnetic Fe3O4 nanoparticles help to bind As(V) and facilitate the removal of capsules from the medium under an applied magnetic field. Polyvinylpyrrolidone was used as a surface modifier to prepare microcapsules with high surface roughness and large surface area. Efficient removal of As(III) and As(V) can be achieved using the modified microcapsules within 15 minutes. The arsenic extraction was insensitive to changes in pH within a range of 3–11. The microcapsules were recycled using 1 M NaOH solution and reused 3 times without losing significant extraction efficiency. The microcapsules showed a maximum Langmuir adsorption capacity of 32 and 28 mg g−1 for As(III) and As(V), respectively. In summary, our metal oxide incorporated polycaprolactone microcapsules can be used as efficient and readily removable adsorbents for arsenic removal from ground water.
Co-reporter:Ziyauddin S. Qureshi;Roshan DSouza;Ramakrishna Mallampati
Journal of Applied Polymer Science 2014 Volume 131( Issue 20) pp:
Publication Date(Web):
DOI:10.1002/app.40943
ABSTRACT
Polyamines are rare in literature owing to increased reactivity, sensitivity to air and moisture, low stability, and processing difficulties. Here, we report the synthesis and characterization of highly processable polyamines and use them for the removal of dissolved metallic nanoparticles from water. Three amphiphilic block polyamines such as poly(N-aminoethyl acrylamide-b-styrene), poly(N-aminopropyl acrylamide-b-styrene), and poly(N-aminoxylyl acrylamide-b-styrene) have been synthesized using atom transfer radical polymerization of ethyl acrylate and styrene followed by aminolysis of the acrylic block. The polymerization and properties of the polymers are studied using different physicochemical techniques. Surface morphology of films prepared from these block copolymers by dissolving in different solvents such as chloroform, tetrahydrofuran and N,N-dimethylformamide, and drop-casting polymers on a glass substrate show interesting porous films and spherical nanostructures. In addition, the amine-functionalized block copolymers have been used for the removal of nanoparticles from water and show high extraction efficiency toward silver (Ag) and gold (Au) nanoparticles. All three amine-functionalized block copolymers show higher extraction capacities (Qe) toward Au NPs (50–109 mg g−1) and Ag NPs (99–117 mg g−1). Our approach allows us to make amine-functionalized block copolymers which are stable in air and can be easily processed in nonpolar solvents. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40943.
Co-reporter:Satyana Barik
Journal of Polymer Science Part A: Polymer Chemistry 2014 Volume 52( Issue 15) pp:2217-2227
Publication Date(Web):
DOI:10.1002/pola.27234
ABSTRACT
A facile synthetic strategy for preparing hydroxylated polymethacrylate amphiphilic block copolymers (PCzMMA-b-PBMMA, PFlMMA-b-PBMMA) incorporated with primary and secondary hydroxyl groups and electroactive moieties along the polymer backbone is reported. Full characterization, structure-property relationship and self-assembly of these polymers are discussed. Due to interplay of hydrophobic/hydrophilic interactions, PCzMMA-b-PBMMA formed a layered lattice and PFlMMA-b-PBMMA showed a vesicular morphology. Electropolymerization of the electroactive units led to the formation of cross-conjugated polymer network in solution and in thin films. The network structure was characterized with a range of spectroscopic techniques. Such highly processable polymers may be of interest to applications in which a conducting amphiphilic films with strong adhesion to various substrates are required. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 2217–2227
Co-reporter:Ramakrishna Mallampati and Suresh Valiyaveettil
ACS Applied Materials & Interfaces 2013 Volume 5(Issue 10) pp:4443
Publication Date(Web):May 1, 2013
DOI:10.1021/am400901e
The presence of anions such as chromate, arsenate, and arsenite in drinking water is a major health concern in many parts of the world due to their high toxicity. Removal of such anions from water using low cost biomass is an efficient and affordable treatment process. Owing to the easy availability and biodegradability, we chose to use apple peel as a substrate for our investigations. Zirconium cations were immobilized onto the apple peel surface and used for the extraction of anions. Zirconium loaded apple peels were used to extract anions such as phosphate, arsenate, arsenite, and chromate ions from aqueous solutions. The presence of Zr cations on the apple peel surface was characterized using XPS. The modified adsorbent was characterized using SEM, EDS, and FT-IR. Zr treated apple peels showed efficient adsorption toward AsO2– (15.64 mg/g), AsO43– (15.68 mg/g), Cr2O72– (25.28 mg/g), and PO43– (20.35 mg/g) anions. The adsorption and desorption studies revealed the adsorption mechanism involves electrostatic interactions. Anion removal efficiency was estimated by batch adsorption studies. Adsorption kinetic parameters for all anions at different concentrations were described using pseudo-first-order and pseudo-second-order rate equations. Langumir and Freundlich isotherms were used to validate our adsorption data. Arsenate and chromate anions were strongly adsorbed at the pH range from 2 to 6, while arsenite was extracted efficiently between pH 9 and 10. Overall, the Zr immobilized apple peel is an efficient adsorbent for common anionic pollutants.Keywords: adsorption; anions; apple peel; isotherms; kinetics;
Co-reporter:Narahari Mahanta, Yiwei Teow and Suresh Valiyaveettil
Biomaterials Science 2013 vol. 1(Issue 5) pp:519-527
Publication Date(Web):25 Feb 2013
DOI:10.1039/C3BM00167A
Hydrogels are three dimensional scaffolds of hydrophilic polymers with inter-connected water channels. In this investigation, an interesting approach for the fabrication of a highly viscoelastic hydrogel derived from a polyvinyl alcohol (PVA) based macromer is reported. PVA was crosslinked using Fe3+ ions under basic conditions to obtain a stable hydrogel with a highly porous network structure. The swelling ratio of the designed hydrogels was evaluated and correlated to the network structure of the metal coordinated crosslinked macromers. Compressive modulus and dynamic viscoelastic measurements were carried out using a dynamic mechanical analyzer and no significant changes in storage modulus were observed by increasing the temperature up to 45 °C. A creep study revealed that the elastic recovery was enhanced with an increase in the degree of crosslinking. The effect of crosslinking influenced properties such as the glass transition, melting point and melting enthalpy of the crosslinked network. The cytocompatibility of the gels was studied using human lung fibroblasts (IMR-90) and no toxic effects or significant cell attachments were observed on the surface of the gel after 5 days. The designed hydrogels may be useful for biomedical procedures which require highly viscoelastic, biocompatible, thermally and mechanically stable biomaterials.
Co-reporter:Ashok Keerthi, Deepa Sriramulu, Yeru Liu, Chan Thuang Yuan Timothy, Qing Wang, Suresh Valiyaveettil
Dyes and Pigments 2013 Volume 99(Issue 3) pp:787-797
Publication Date(Web):December 2013
DOI:10.1016/j.dyepig.2013.07.002
•Designed and synthesized six new dyes with the carbazole moiety.•Investigated the structure–property relationships and photovoltaic performances.•Theoretical calculations were carried out to support experimental results.•The dye structure with low alteration strongly affected the performances of DSSCs.•The performances of DSSCs were significantly changed with alkoxy-2-ethylhexyl substitution on the carbazole dyes.Herein we report design, synthesis, characterization and application of a series of molecules with D-π-A structures that contain a push-pull-pull with substituted carbazole as the electron donor and cyanoacrylic acid as the electron acceptor bridged by a benzothiadiazole fragment. Theoretical, electrochemical and photophysical properties of the target molecules with respect to the chemical nature and position of substituent on the carbazole moiety were investigated in detail. The substituents on carbazole changed the solubility, packing and orientation of molecules on the TiO2 surface of DSSCs. The dye sensitized solar cell performances of the molecules were studied and compared with respect to the position and substituent.
Co-reporter:Narahari Mahanta and Suresh Valiyaveettil
RSC Advances 2013 vol. 3(Issue 8) pp:2776-2783
Publication Date(Web):21 Dec 2012
DOI:10.1039/C2RA22768A
Arsenic is a potent contaminant in waterways across the world. In this investigation, Fe3+ ion immobilized poly(vinyl alcohol) (PVA) nanofibers were used for the removal of arsenic (As) from water. Nanofiber mats were prepared from a PVA/Fe3+ mixture using an electrospinning technique and cross-linked in a desiccator saturated with ammonia vapour. The fibers showed a smooth surface morphology and were 600–800 nm in diameter. An increase in the glass transition temperature along with a lowering of the melting peak enthalpy with an increase in the concentration of Fe3+ ions was observed. The nanofibers extracted As(III) and As(V) compounds from spiked aqueous solutions. The maximum capacity of the nanofibers for arsenic removal was found to be 67 mg g−1 for As(III) and 36 mg g−1 for As(V). The effect of pH on the adsorption behavior was compared for both acidic and basic conditions. The effect of coexisting anions such as silicate ions on the adsorption behavior showed significant interference, whereas humic acid had no significant effect on the adsorption behavior. The FTIR and XPS spectroscopic analyses demonstrated that arsenic ions were adsorbed on the sorbent surface. Hence, these modified PVA nanofibers are efficient for removing arsenic from water and may be used for water purification.
Co-reporter:Wang Chunyan and Suresh Valiyaveettil
RSC Advances 2013 vol. 3(Issue 34) pp:14329-14338
Publication Date(Web):16 May 2013
DOI:10.1039/C3RA41346B
Metal nanoparticles are used in a wide range of commercial products such as cosmetics, food packaging and household detergents. Owing to interesting antimicrobial properties, silver nanoparticles (Ag NPs) are commonly used in many commercial products. Recently, green approaches using plant extracts at room temperature have been developed for the synthesis of Ag NPs. Here we explored a one-pot approach, which combines capping, reducing agents and templates in one bioextract for synthesizing water soluble Ag NPs. Ginger, coffee and mint extracts were used for the synthesis of water soluble Ag NPs. The as-synthesized nanostructures were characterized using transmission electron microscopy and UV-Vis spectroscopy. The toxicity of Ag NPs with different capping agents was studied using hepatocellular liver carcinoma cells (HepG2) and human cervical cancer cells (HeLa). The level of toxicity was evaluated using changes in cell morphology, cell viability and oxidative stress studies. Ag NPs caused a decrease in the amount of ATP in cells while plant extracts alone did not have significant effect on the amount of ATP. It is interesting to note that bioextract capped Ag NPs do not increase but decrease production of reactive oxygen species (ROS) in a dose dependent manner, which could mostly be attributed to the antioxidant activity of biocapping agents on the surface of nanoparticles. Ag–mint, Ag–ginger and Ag–coffee NPs treatment caused cell cycle arrest in the G2/M phase and Ag–mint NPs exposure resulted in cell cycle arrest in the sub G1 stage. Annexin-V propidium iodide staining showed a large amount of apoptosis in Ag–mint NPs treated cells. A possible mechanism of toxicity of Ag NPs resulted from interruption of ATP synthesis, which further caused DNA damage and cell death through apoptosis. A complete elimination of toxicity, especially at higher concentrations of Ag NPs has not yet been achieved.
Co-reporter:Narahari Mahanta, Wai Ying Leong and Suresh Valiyaveettil
Journal of Materials Chemistry A 2012 vol. 22(Issue 5) pp:1985-1993
Publication Date(Web):07 Dec 2011
DOI:10.1039/C1JM15018A
The increased use of nanoparticles in various commercial products enhances the contamination of nanomaterials in the environment which may cause serious health concern in the near future. To address this problem, new methods need to be developed for removal of nanomaterials from the environment. In this report, we explored the removal of nanoparticles from water using cellulosic nanofibers extracted from a renewable source such as sugarcane bagasse. The nanofibers were coated with chitosan to introduce additional functional groups on the surface. The designed cellulosic nanofibers showed high extraction efficiency (80–90%) towards silver (Ag) and gold (Au) nanoparticles. The maximum adsorption efficiency (Qt) towards citrate and polyvinylpyrrolidone (PVP) capped Ag-nanoparticles using chitosan coated cellulose nanofibers was 13.1 mg g−1. Similarly, Qt values for citrate and PVP capped Au-nanoparticles were 17.9 mg g−1 and 17.4 mg g−1, respectively. The adsorption of nanoparticles onto the nanofibers was confirmed using scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDX). Even though we used spiked solutions for the current study, it is expected that such low cost, highly abundant nanofibers may be used for setting up a large-scale nanoparticle removal system for water purification.
Co-reporter:Narahari Mahanta and Suresh Valiyaveettil
RSC Advances 2012 vol. 2(Issue 30) pp:11389-11396
Publication Date(Web):26 Sep 2012
DOI:10.1039/C2RA20637D
Ultra-fine nanofiber mats of cellulosic polymer and polyvinyl alcohol (PVA) containing silver (Ag) nanoparticles were fabricated using the electrospinning technique. Polymers with hydroxyl groups on the backbone such as PVA, PVA/dextran and PVA/methyl cellulose were chosen for this study. All polymers showed the ability to reduce silver nitrate (AgNO3) to Ag-nanoparticles. To make crosslinkable networks of the water soluble polymers, the photo-crosslinkable glycidyl methacrylate moiety was attached to the hydroxyl groups of the designed macromers. AgNO3 and cytocompatible initiator (IRGACURE 2959) were added to the methacrylated polymeric solution mixture before electrospinning. The fiber morphology of the resultant nanofiber was characterised using scanning electron microscopy (SEM) and an average diameter in the range of 300 to 500 nm was observed. The resultant nanofibers containing Ag-ions and initiators were crosslinked under photoirradiation at a wavelength of 365 nm for 6 h and heated at 100 °C for 6 h for complete reduction of Ag-ions into Ag-nanoparticles. Transmission electron microscopy (TEM) analysis revealed that the Ag-nanoparticles with an average diameter of 10 to 20 nm were uniformly distributed throughout the nanofibers and its presence was confirmed using X-ray diffraction analysis. The effect of Ag-nanoparticles on the microcrystalline structure of the polymer was studied by thermal and mechanical properties analysis. The biocompatibility of the methacrylated macromers was investigated using human lung fibroblasts (IMR-90) and no cytotoxic effects were found after 4 days of incubation. The antimicrobial activity of the PVA nanofiber containing Ag-nanoparticles was tested against Escherichia coli. The nanofiber containing Ag-nanoparticles may have potential applications in biomedical devices which will be explored in the near future.
Co-reporter:Ramakrishna Mallampati and Suresh Valiyaveettil
RSC Advances 2012 vol. 2(Issue 26) pp:9914-9920
Publication Date(Web):10 Sep 2012
DOI:10.1039/C2RA21108D
Heavy metal ions and dissolved organic compounds in waste water are known to adversely affect human health, aquatic life and the overall ecosystem. Many hazardous pollutants need to be removed from drinking water; however, such technologies are not accessible for economically disadvantaged people around the world. Naturally abundant tomato peels or other biomembranes are used as an efficient biomaterial to remove toxic metal ions and organic pollutants from aqueous solution. The functional groups and morphologies of the tomato peels were characterized using FT-IR and FESEM, respectively. Factors such as pH, nature and amount of adsorbent used for extraction were studied to establish the optimum conditions. The maximum adsorption capacity was observed at different pH values for different pollutants. The equilibrium adsorption data were interpreted by using Freundlich and Langmuir isotherms and the adsorption mechanism was investigated by kinetic studies. Results showed that tomato peels have good potential as an efficient adsorbent to remove various pollutants from water.
Co-reporter:Ashok Keerthi;Yeru Liu;Dr. Qing Wang; Suresh Valiyaveettil
Chemistry - A European Journal 2012 Volume 18( Issue 37) pp:11669-11676
Publication Date(Web):
DOI:10.1002/chem.201201196
Abstract
Perylene monoimide (PMI) was brominated to give tetra- and tribrominated molecules, which underwent a Suzuki coupling reaction with 4-(diphenylamino)phenylboronic acid to give PMI derivatives. The photophysical and electrochemical properties of the synthesized compounds were investigated, and theoretical calculations were performed. Single crystals of tetrasubstituted PMI were grown and studied in detail. The structure–property relationships were examined to reveal the effect of the position and number of substituents on the perylene core unit. All molecules showed a broad absorption up to 750 nm. Corresponding anhydrides of PMIs were used for fabrication of dye-sensitized solar cells. The molecule with four triphenylamine units on perylene monoanhydride showed the highest power conversion efficiency.
Co-reporter:Ashok Keerthi and Suresh Valiyaveettil
The Journal of Physical Chemistry B 2012 Volume 116(Issue 15) pp:4603-4614
Publication Date(Web):March 22, 2012
DOI:10.1021/jp210736x
A series of conjugation extended donor–acceptor 1,6- and 1,7-regiomers of perylenediimide were synthesized, separated, and characterized. The photophysical, electrochemical, and thermal properties of these compounds were investigated and compared. The absorption spectra of 1,6-substituted PDI showed blue shift as compared to its 1,7-substituted PDI. At the same time, the emission spectrum showed no significant differences among the regiomers. Both 1,6- and 1,7-regiomers were thermally stable up to 450 °C and showed different melting and crystallization transitions. The electrochemical studies did not show significant differences in oxidation and redox potentials owing to similar HOMO/LUMO gap of 1,6- and 1,7-regiomers, which is also supported by theoretical calculations. Comparison of properties of a series of 1,6- or 1,7-substituted PDIs showed significant differences. Such regiomerically pure compounds can offer certain advantages in applications, which are currently being investigated.
Co-reporter:Narahari Mahanta and Suresh Valiyaveettil
Nanoscale 2011 vol. 3(Issue 11) pp:4625-4631
Publication Date(Web):09 Sep 2011
DOI:10.1039/C1NR10739A
Contamination of water from nanomaterials will be an emerging problem in the future due to incorporation of nanomaterials in many commercial products and improper disposal of waste materials. In this report, electrospun polyvinyl alcohol nanofibers (PVA NFs) with diameters ranging between 300 and 500 nm were used for the extraction of nanosized contaminants from the aqueous environment. To obtain the best extraction efficiency, surface hydroxyl groups of PVA NFs were chemically modified with functional groups, such as thiols and amines. Two model nanoparticles (silver and gold) dissolved in water were used for adsorption studies. Depending on the nature of the surface functionalities, the fibers showed unique ability to adsorb nanoparticles. The extraction studies revealed that the amine and thiol modified PVA NFs showed 90% extraction efficiency for both silver and gold nanoparticles. The thiol and amine functionalized PVA NFs showed maximum adsorption capacities (Qt) towards Au NPs, which were around 79–84 mg g−1. Similarly for Ag NP extraction, amine functionalized PVA NFs showed a value for Qt at 56 mg g−1. Our results highlight that functionalized nanofibers have high extraction efficiency for dissolved nanoparticles in water and can be used for removal of the nanocontaminants from the aqueous environment.
Co-reporter:Sajini Vadukumpully, Jhinuk Gupta, Yongping Zhang, Guo Qin Xu and Suresh Valiyaveettil
Nanoscale 2011 vol. 3(Issue 1) pp:303-308
Publication Date(Web):04 Nov 2010
DOI:10.1039/C0NR00547A
A facile and simple approach for the covalent functionalization of surfactant wrapped graphene sheets is described. The approach involves functionalization of dispersible graphene sheets with various alkylazides and 11-azidoundecanoic acid proved the best azide for enhanced dispersibility. The functionalization was confirmed by infrared spectroscopy and scanning tunneling microscopy. The free carboxylic acid groups can bind to gold nanoparticles, which were introduced as markers for the reactive sites. The interaction between gold nanoparticles and the graphene sheets was followed by UV-vis spectroscopy. The gold nanoparticle-graphene composite was characterized by transmission electron microscopy and atomic force microscopy, demonstrating the uniform distribution of gold nanoparticles all over the surface. Our results open the possibility to control the functionalization on graphene in the construction of composite nanomaterials.
Co-reporter:Yiwei Teow, P. V. Asharani, M. Prakash Hande and Suresh Valiyaveettil
Chemical Communications 2011 vol. 47(Issue 25) pp:7025-7038
Publication Date(Web):11 Apr 2011
DOI:10.1039/C0CC05271J
Many engineered nanomaterials (NMs) are being synthesized and explored for potential use in consumer and medical products. Already, nanoparticles (NPs) of titanium dioxide (TiO2), zinc oxide (ZnO), silver (Ag) and other metals or their oxides are present in commercial products such as sunscreens, cosmetics, wound dressings, surgical tools, detergents, automotive paints and tires. More recent and advanced FDA-approved use of NMs includes quantum dots (QDs) in live cell imaging, zirconium oxides in bone replacement and prosthetic devices and nanocarriers in drug delivery. The benefits from nanotechnology are aplenty, comprising antimicrobial activities, scratch- and water-resistance, long-lasting shine, improved processor speeds and better display resolution, to name a few. While developers of these products often focus on the exciting beneficial aspects of their products, safety and toxicity issues are often not discussed in detail. Long-term effects such as chronic exposure and environmental pollution are even less documented. Along with widespread manufacture and use of NMs, concerns for occupational hazards, proper handling, disposal, storage, shipping and clean up are expected to rise. This review focus on the possible biological impact of engineered NPs, serving as a reminder that nanomaterials can become a double-edged sword if not properly handled.
Co-reporter:Ganapathy Balaji, Tejaswini S. Kale, Ashok Keerthi, Andrea M. Della Pelle, S. Thayumanavan, and Suresh Valiyaveettil
Organic Letters 2011 Volume 13(Issue 1) pp:18-21
Publication Date(Web):November 30, 2010
DOI:10.1021/ol1023486
Perylenediimide−pentathiophene systems with varied architecture of thiophene units were synthesized. The photophysical, electrochemical, and charge transport behavior of the synthesized compounds were studied. Both molecules showed a low band gap of ∼1.4 eV. Surprisingly, the molecule with pentathiophene attached via β-position to the PDI unit upon annealing showed a predominant hole mobility of 1 × 10−4 cm2 V−1 s−1 whereas the compound with branched pentathiophene attached via β-position showed an electron mobility of 9.8 × 10−7 cm2 V−1 s−1. This suggests that charge transport properties can be tuned by simply varying the architecture of pentathiophene units.
Co-reporter:Sajini Vadukumpully, Jinu Paul, Narahari Mahanta, Suresh Valiyaveettil
Carbon 2011 Volume 49(Issue 1) pp:198-205
Publication Date(Web):January 2011
DOI:10.1016/j.carbon.2010.09.004
The fabrication and characterization of ultrathin composite films of surfactant-wrapped graphene nanoflakes and poly(vinyl chloride) is described. Free-standing composite thin films were prepared by a simple solution blending, drop casting and annealing route. A significant enhancement in the mechanical properties of pure poly(vinyl chloride) films was obtained with a 2 wt.% loading of graphene, such as a 58% increase in Young’s modulus and an almost 130% improvement of tensile strength. Thermal analysis of the composite films showed an increase in the glass transition temperature of the polymer, which confirms their enhanced thermal stability. The composite films had very low percolation threshold of 0.6 vol.% and showed a maximum electrical conductivity of 0.058 S/cm at 6.47 vol.% of the graphene loading.Graphical abstractResearch highlights► CTAB stabilized graphene sheets act as reinforcing filler for Poly (vinyl chloride). ► Graphene/PVC thin films with very low level loading of graphene exhibited high thermal and mechanical stability. ► The composite films had very low percolation threshold and high conductivity.
Co-reporter:Sajini Vadukumpully, Chanbasha Basheer, Cheng Suh Jeng, Suresh Valiyaveettil
Journal of Chromatography A 2011 Volume 1218(Issue 23) pp:3581-3587
Publication Date(Web):10 June 2011
DOI:10.1016/j.chroma.2011.04.003
The isolation and characterization of carbon nanofibers from soot obtained by burning natural oil is reported. The fibers were extracted from the soot with tetrahydrofuran followed by sonication. The carbon nanofibers were mixed with poly(vinyl alcohol) and electrospun to get the nanofiber mat. The extraction ability of electrospun nanofibers for the separation and preconcentration of aromatic compounds such as 3-nitroaniline, 4-chloroaniline, 4-bromoaniline and 3,4-dichloroaniline were tested and efficiently evaluated using high performance liquid chromatography. Under optimized conditions, the method showed good linearity in a range of 0.5–50 μg L−1 with correlation coefficient ranging from 0.989 to 0.998. High precision of the extraction with RSD values of 4.5–5.8% and low LOD value in a range of 0.009–0.081 μg L−1 for all aniline compounds were achieved. The proposed microextraction method offers advantages such as easy operation, high recovery, fast extraction, minimal use of organic solvent and elimination of tedious solvent evaporation and reconstitution steps.
Co-reporter:P. V. Asharani;Swaminathan Sethu;Sajini Vadukumpully;Shaoping Zhong;Chwee Teck Lim;M. Prakash He
Advanced Functional Materials 2010 Volume 20( Issue 8) pp:
Publication Date(Web):
DOI:10.1002/adfm.201090030
Co-reporter:P. V. Asharani;Swaminathan Sethu;Sajini Vadukumpully;Shaoping Zhong;Chwee Teck Lim;M. Prakash He
Advanced Functional Materials 2010 Volume 20( Issue 8) pp:1233-1242
Publication Date(Web):
DOI:10.1002/adfm.200901846
Abstract
Human erythrocytes or red blood cells (RBCs), which constitute 99% of blood cells, perform an important function of oxygen transport and can be exposed to nanoparticles (NPs) entering into the human body during therapeutical applications involving such NPs. Hence, the haemocompatibility of the Ag, Au, and Pt NPs on human RBCs is investigated. The parameters monitored include haemolysis, haemagglutination, erythrocyte sedimentation rate, membrane topography, and lipid peroxidation. The findings suggest that platinum and gold NPs are haemocompatible compared to Ag NPs. Erythrocytes exhibit significant lysis, haemagglutination, membrane damage, detrimental morphological variation, and cytoskeletal distortions following exposure to Ag NPs at a concentration of 100 µg mL−1. Exposure of Ag+ to RBCs shows no lysis or deterioration, implying that the observed toxicity is solely due to NPs. The haemolyzed erythrocyte fraction has the ability to induce DNA damage in nucleated cells. Additionally, multiple pits and depressions are observed on RBC membrane following exposure to Ag NPs (50 µg mL−1 onwards). Hence, it is apparent that Ag NPs exhibit toxicity on RBCs and on other cells that are exposed to NP-mediated haemolyzed fractions.
Co-reporter:Yiwei Teow and Suresh Valiyaveettil
Nanoscale 2010 vol. 2(Issue 12) pp:2607-2613
Publication Date(Web):11 Oct 2010
DOI:10.1039/C0NR00204F
Interaction of nanoparticles with human cells is an interesting topic for understanding toxicity and developing potential drug candidates. Water soluble platinum nanoparticles were synthesized via reduction of hexachloroplatinic acid using sodium borohydride in the presence of capping agents. The bioactivity of folic acid and poly(vinyl pyrrolidone) capped platinum nanoparticles (Pt-nps) has been investigated using commercially available cell lines. In the cell viability experiments, PVP-capped nanoparticles were found to be less toxic (>80% viability), whereas, folic acid-capped platinum nanoparticles showed a reduced viability down to 24% after 72 h of exposure at a concentration of 100 μg ml−1 for MCF7 breast cancer cells. Such toxicity, combined with the possibility to incorporate functional organic molecules as capping agents, can be used for developing new drug candidates.
Co-reporter:Ganapathy Balaji, Dazril Izrar Phua, Wong Low Shim and Suresh Valiyaveettil
Organic Letters 2010 Volume 12(Issue 2) pp:232-235
Publication Date(Web):December 9, 2009
DOI:10.1021/ol902528b
Indole-fused dithieno[3,2-b:2′,3′-d]pyrrole-based unsymmetrical and extended heteroacenes were synthesized and characterized. Solid-state structures were examined using single-crystal X-ray diffraction to understand their packing behavior. The optical and electrochemical properties of these new heteroacenes are also described in detail.
Co-reporter:Jhinuk Gupta, Sajini Vadukumpully, Suresh Valiyaveettil
Polymer 2010 Volume 51(Issue 22) pp:5078-5086
Publication Date(Web):15 October 2010
DOI:10.1016/j.polymer.2010.09.012
A series of fluorescent conjugated polymers, poly(pyreneethynylene)s, have been designed and synthesized to investigate the effect of shape of polymer backbone on physical properties. Polymers with linear and kinked backbone were synthesized using 1,6- and 1,8-disubstituted pyrene. The target copolymers were designed to incorporate various spacer units, such as, alkoxyphenyl, carbazole and fluorene on the polymer backbone. Characterization of the target compounds was achieved by NMR, IR, GPC and MALDI-TOF mass spectrometry. Detailed investigation on their optical, electrochemical and thermal properties revealed significant contribution of the geometry of polymer backbone towards physical properties. Kinked backbone of cisoid-polymers was found to result in lower optical band gap, less negative EHOMO and higher thermal stability as compared to their linear analogues, most probably due to the coiling of polymer chains. Comparison of the physical properties of the polymers with those of the model compounds suggested similar extent of conjugation through 1,6- and 1,8-position of pyrene.
Co-reporter:V. Sivamurugan, K. Kazlauskas, S. Jursenas, A. Gruodis, J. Simokaitiene, J. V. Grazulevicius and S. Valiyaveettil
The Journal of Physical Chemistry B 2010 Volume 114(Issue 5) pp:1782-1789
Publication Date(Web):January 20, 2010
DOI:10.1021/jp907697f
A series of perylenediimide-based small molecules (PDI1−PDI5) containing electron-deficient groups in the bay region were synthesized and characterized. The PDI derivatives were found to be capable of forming molecular glasses with glass transition temperatures ranging from 50 to 102 °C. Detailed investigations of the optical properties of the synthesized derivatives were performed and compared with those obtained from quantum chemical calculations. Optimized molecular structures of the PDI derivatives exhibited core-twisting by 16° and torsional angle between the bay substituent and the perylene core in the range of 60−72°. The PDI derivatives exhibited absorption maxima in the range of 2.27−2.36 eV and emission maxima in the range of 2.10−2.28 eV. The impact of the bay substituents on the emission, fluorescence quantum yield, and lifetimes in solutions and thin films was established. The red shift of emission maxima (from 2.282 to 2.095 eV) observed for various PDIs in solutions was accompanied by significant reduction in the emission quantum yield (from 0.73 to 0.44) and corresponding increase of the fluorescence lifetime (from 4.5 to 6.8 ns). This was in agreement with quantum chemical calculations indicating decrease of the radiative relaxation rate due to reduction of the oscillator strength and remarkable decrease of the torsional activation barrier. The spectral properties of the wet-casted perylenediimide films featuring different bay substituents were also studied. The variation in the emission peak (of 0.25 eV) and the considerable increase of the Stokes shift (of 0.4 eV) are explained in terms of the formation of the amorphous state. The influence of the bay substituents on the thermal and spectral properties of the films are discussed.
Co-reporter:Ganapathy Balaji, Manoj Parameswaran, Tan Mein Jin, Chellappan Vijila, Zhu Furong and Suresh Valiyaveettil
The Journal of Physical Chemistry C 2010 Volume 114(Issue 10) pp:4628-4635
Publication Date(Web):February 19, 2010
DOI:10.1021/jp909064n
A new series of dithieno[3,2-b:2′,3′-d]pyrrole-incorporated oligomers was synthesized and characterized. The crystal structure, crystal packing, optical properties, electrochemical properties, and time-of-flight mobilities were investigated in detail. The oligomers are highly fluorescent in both solution and the solid state. The solution-state quantum yield of these new compounds ranged from 52 to 75%. Band gaps of these oligomers were found to be in the range of 2.5−2.8 eV. The surface morphology of the film was also characterized by atomic force microscopy. The material was found to be hole-transporting with a mobility on the order of 10−6 cm2/(V s).
Co-reporter:Sivamurugan Vajiravelu, Lygaitis Ramunas, Gražulevičius Juozas Vidas, Gaidelis Valentas, Jankauskas Vygintas and Suresh Valiyaveettil
Journal of Materials Chemistry A 2009 vol. 19(Issue 24) pp:4268-4275
Publication Date(Web):15 May 2009
DOI:10.1039/B901847F
Electron donating substituents such as 3,4,5-trimethoxy phenyl (PDI1), thiophene (PDI2), 6-methoxy naphthyl (PDI3), 5-hexyl dithiophene (PDI4) and thioanthrenyl (PDI5) moieties incorporated at the bay region of N,N′-dodecylperylene diimide (PDI) derivatives have been synthesized and characterised. The absorption maxima of PDI1–5 showed a bathochromic shift with considerable peak broadening and merging of vibronic fine structure as compared to that of PDI. The photoinduced intramolecular charge transfer (ICT) from electron donating substituents to the perylene-acceptor has been observed from fluorescence self-quenching. The molecules are stable up to 400 °C and amorphous in nature. The cyclic voltammetry results revealed that the oxidation potential can be tuned by the electron donating capacity of the substituents and the dithiophene-attached perylene derivative (PDI4) showed a very low band gap of 1.57 eV. The electron transporting properties have been studied using xerographic time-of-flight method and the highest electron mobility reached up to 4.4 × 10−4 cm2V−1 s−1 at 6.4 × 105 V cm−1 for 1,7-di(3,4,5-trimethoxyphenyl)perylene diimide (PDI1) under ambient conditions.
Co-reporter:Ganapathy Balaji and Suresh Valiyaveettil
Organic Letters 2009 Volume 11(Issue 15) pp:3358-3361
Publication Date(Web):July 2, 2009
DOI:10.1021/ol901133m
Symmetrical and unsymmetrical heteroacenes containing thiophene and pyrrole rings were synthesized. The unsymmetrical heteroacene was synthesized in two steps involving an unexpected palladium catalyzed amination of alkyl or aryl amines with benzo[b]thiophene followed by a copper catalyzed coupling. The symmetrical heteroacene was obtained by a palladium catalyzed amination reaction and also by a copper catalyzed amidation reaction. The crystal structure, photophysical and electrochemical properties of symmetrical and unsymmetrical heteroacenes are described.
Co-reporter:Ganapathy Balaji, Wong Low Shim, Manoj Parameswaran and Suresh Valiyaveettil
Organic Letters 2009 Volume 11(Issue 19) pp:4450-4453
Publication Date(Web):September 8, 2009
DOI:10.1021/ol901806q
Indolo[2,3-a]carbazole-based heteroacenes containing thiadiazole units were synthesized. Compounds showed a sandwich herringbone packing in solid state with improved stability. The change in photophysical and electrochemical properties upon incorporation of an acceptor moiety (benzothiadazole) in a fused ring system was studied. The unsubstituted compound was electropolymerized to yield a stable polymer.
Co-reporter:Sajini Vadukumpully, Jinu Paul, Suresh Valiyaveettil
Carbon 2009 Volume 47(Issue 14) pp:3288-3294
Publication Date(Web):November 2009
DOI:10.1016/j.carbon.2009.07.049
A simple and effective method for the preparation of a few layered graphene nanoflakes directly from graphite has been successfully demonstrated. Mild ultrasonication of highly ordered pyrolytic graphite, in presence of a cationic surfactant cetyltrimethylammonium bromide and acetic acid yielded graphene nanoflakes, which formed a stable colloidal suspension in organic solvent such as N,N-dimethyl formamide. Scanning and transmission electron microscopic analyses showed that the dispersed phase consist of mainly few layered graphene nanoflakes. Average thickness of the flakes was found to be ∼1.18 nm. Energy dispersive X-ray analysis indicated the absence of graphene oxide. Field emission measurements for the nanoflakes showed a turn on voltage of 7.5 V/μm and emission current densities of 0.15 mA/cm2.
Co-reporter:Manoj Parameswaran, Ganapathy Balaji, Tan Mein Jin, Chellappan Vijila, Sajini Vadukumpully, Zhu Furong, Suresh Valiyaveettil
Organic Electronics 2009 10(8) pp: 1534-1540
Publication Date(Web):
DOI:10.1016/j.orgel.2009.08.022
Co-reporter:Hairong Li, Suresh Valiyaveettil
Tetrahedron Letters 2009 50(38) pp: 5311-5314
Publication Date(Web):
DOI:10.1016/j.tetlet.2009.06.119
Co-reporter:P. V. AshaRani, Grace Low Kah Mun, Manoor Prakash Hande and Suresh Valiyaveettil
ACS Nano 2009 Volume 3(Issue 2) pp:279
Publication Date(Web):December 30, 2008
DOI:10.1021/nn800596w
Silver nanoparticles (Ag-np) are being used increasingly in wound dressings, catheters, and various household products due to their antimicrobial activity. The toxicity of starch-coated silver nanoparticles was studied using normal human lung fibroblast cells (IMR-90) and human glioblastoma cells (U251). The toxicity was evaluated using changes in cell morphology, cell viability, metabolic activity, and oxidative stress. Ag-np reduced ATP content of the cell caused damage to mitochondria and increased production of reactive oxygen species (ROS) in a dose-dependent manner. DNA damage, as measured by single cell gel electrophoresis (SCGE) and cytokinesis blocked micronucleus assay (CBMN), was also dose-dependent and more prominent in the cancer cells. The nanoparticle treatment caused cell cycle arrest in G2/M phase possibly due to repair of damaged DNA. Annexin-V propidium iodide (PI) staining showed no massive apoptosis or necrosis. The transmission electron microscopic (TEM) analysis indicated the presence of Ag-np inside the mitochondria and nucleus, implicating their direct involvement in the mitochondrial toxicity and DNA damage. A possible mechanism of toxicity is proposed which involves disruption of the mitochondrial respiratory chain by Ag-np leading to production of ROS and interruption of ATP synthesis, which in turn cause DNA damage. It is anticipated that DNA damage is augmented by deposition, followed by interactions of Ag-np to the DNA leading to cell cycle arrest in the G2/M phase. The higher sensitivity of U251 cells and their arrest in G2/M phase could be explored further for evaluating the potential use of Ag-np in cancer therapy.Keywords: cell cycle arrest; cytotoxicity; DNA damage; genotoxicity; micronucleus; silver nanoparticle
Co-reporter:Muhammad Hanafiah Nurmawati;Parayil Kumaran Ajikumar;Ravindranath Renu
Advanced Functional Materials 2008 Volume 18( Issue 20) pp:3213-3218
Publication Date(Web):
DOI:10.1002/adfm.200800396
Abstract
Fabrication of two and three-dimensional nanostructures requires the development of new methodologies for the assembly of molecular/macromolecular objects on substrates in predetermined arrangements. Templated self-assembly approach is a powerful strategy for the creation of materials from assembly of molecular components or nanoparticles. The present study describes the development of a facile, template directed self-assembly of (metal/organic) nanomaterials into periodic micro- and nanostructures. The positioning and the organization of nanomaterials into spatially well-defined arrays were achieved using an amphiphilic conjugated polymer-aided, self-organization process. Arrays of honeycomb patterns formed from conjugated C12PPPOH film with homogenous distribution of metal/organic nanomaterials. Our approach offers a straightforward and inexpensive method of preparation for hybrid thin films without environmentally controlled chambers or sophisticated instruments as compared to multistep micro-fabrication techniques.
Co-reporter:Muhammad Hanafiah Nurmawati, Parayil Kumaran Ajikumar, Lili Amanda Heng, Hairong Li and Suresh Valiyaveettil
Chemical Communications 2008 (Issue 40) pp:4945-4947
Publication Date(Web):30 Aug 2008
DOI:10.1039/B808689C
Formation and characterization of nanocrystallite spheres from a hybrid of functionalized cross-conjugated poly(p-phenylene) and C60 are reported.
Co-reporter:Satyananda Barik and Suresh Valiyaveettil
Macromolecules 2008 Volume 41(Issue 17) pp:6376-6386
Publication Date(Web):August 8, 2008
DOI:10.1021/ma8008349
The methacrylic copolymers incorporated with electroactive groups such as thiophene, carbazole, and fluorene moieties on the side chain were synthesized. Our approach consists of incorporating multiple electroactive functional groups onto a polymer backbone that can be used to develop functional materials. All copolymers were characterized, and a systematic structure−property relationship study was established. The structure and morphology of supramolecular self-assembly of copolymers were studied using transmission electron microscopy, wide-angle X-ray diffraction, and atomic force microscopy. Polymers can be patterned using an atomic force microscope, and nanosized lines or dots can be drawn on the polymer films. Polymer nanotubes obtained through self-assembly can be further stabilized by electropolymerization of the side chains.
Co-reporter:Hairong Li, Manoj Parameswaran, Muhammad Hanafiah Nurmawati, Qinghua Xu and Suresh Valiyaveettil
Macromolecules 2008 Volume 41(Issue 22) pp:8473-8482
Publication Date(Web):October 23, 2008
DOI:10.1021/ma801506c
A series of cross-conjugated polyarenes were synthesized and fully characterized. The polymers were soluble in common organic solvents and showed good thermal stability. Powder XRD showed ordered structures for all polymers and significant shift in the emission maxima with increasing concentration, indicating strong aggregation of polymer chains in solution. Solvatochromism studies showed blue shifts of absorption and fluorescence maxima in toluene as compared to the values in THF, suggesting that polymers tend to aggregation less or solvated more in toluene. A large two-photon absorption (TPA) cross section was observed for all polymers due to the unique molecular architectures. Fluorescence lifetime studies revealed that aggregation induced fast decay kinetics. Self-assembled helical nanofibers and nanorings were observed when casted films from polymer solutions. HRTEM and XRD investigation of the thin films revealed nanocrystalline structures of the polymers.
Co-reporter:Muhammad Hanafiah Nurmawati, Parayil Kumaran Ajikumar, Ravindranath Renu, Chorng Haur Sow and Suresh Valiyaveettil
ACS Nano 2008 Volume 2(Issue 7) pp:1429
Publication Date(Web):June 25, 2008
DOI:10.1021/nn8001664
Molecular level alignment of components and optimum morphology of hybrid materials are of great interest in many applications. Morphology control has been extensively used as a direct tool in the evaluation of interactions and assemblies of components in thin films. It is believed that preparation method and composition are powerful tools to direct the morphology, particularly in self-assembled systems such as fullerene-based hybrid materials. The present report outlines a synergistic self-assembly of fullerenes (C60) and functionalized poly (p-phenylene) (PPP) to develop nanofibers with high aspect ratios. Nanostructured PPP−C60 hybrids were prepared by direct casting of the dilute solution on solid substrates and on water under ambient conditions. The formation of whiskers with high aspect ratio and investigation of interesting photophysical properties are discussed. An amphiphilic PPP was used as a template for preparing nanohybrids of C60 at ambient temperature and conditions.Keywords: amphiphilic poly(p-phenylene)s; fullerene; light-emitting polymers; nanostructured whiskers; self-assembly
Co-reporter:S. Sindhu;S. Jegadesan;L. Hairong;P. K. Ajikumar;M. Vetrichelvan;S. Valiyaveettil
Advanced Functional Materials 2007 Volume 17(Issue 10) pp:
Publication Date(Web):5 JUN 2007
DOI:10.1002/adfm.200600547
Nature employs specialized macromolecules to produce highly complex structures and understanding the role of these macromolecules allows us to develop novel materials with interesting properties. Herein, we report the role of modified conjugated polymers in the nucleation, growth, and morphology of calcium carbonate (CaCO3) crystals. In situ incorporation of sulfonated poly(p-phenylene) (s(PPP)) into a highly oriented calcium carbonate matrix is investigated along with the synthesis and patterning of luminescent CaCO3–PPP hybrid materials. Functionalized PPP with polar and nonpolar groups are used as additives in the mineralization medium. The polymer (P1) with polar groups give iso-oriented calcite crystals, whereas PPP with an additional alkyl chain (P2) results in vaterite crystals. The crystallization mechanism can be explained based on self-assembly and aggregation of polymers in an aqueous environment. Such light-emitting hybrid composites with tunable optical properties are excellent candidates for optoelectronics and biological applications.
Co-reporter:Chanbasha Basheer, Muthalagu Vetrichelvan, Suresh Valiyaveettil, Hian Kee Lee
Journal of Chromatography A 2007 Volume 1139(Issue 2) pp:157-164
Publication Date(Web):19 January 2007
DOI:10.1016/j.chroma.2006.11.008
Porous polypropylene hollow fiber membrane coated with a conjugated polymer was used as an on-site sampling device for the extraction of polychlorinated biphenyls and polybrominated biphenyl ethers from coastal sea water samples. The coated hollow fiber membrane was placed in a vial containing the sample, and the target compounds extracted via manual shaking of the vials at the site of sample collection. For each extraction, two fibers were used. After extraction, the fibers with the adsorbed analytes were brought back to the laboratory for further processing. Care was taken to preserve the integrity of the analytes and to avoid contamination during transport; after extraction, the fibers were carefully removed and placed in air-tight crimper vials which were stored in an ice-box. The analytes were desorbed by solvent in the laboratory and analyses were carried out using gas chromatography/mass spectrometry. This method was highly reproducible with relative standard deviations in the range of 1–9%. Recoveries from spiked water samples ranged from 83% to 98%. Low limits of detections between 0.04 and 0.21 ng l−1 were achieved. The extraction efficiency was compared with solid-phase microextraction.
Co-reporter:Subramanyam Gayathri;Rajamani Lakshminarayanan;James C. Weaver;Daniel E. Morse ;R. Manjunatha Kini
Chemistry - A European Journal 2007 Volume 13(Issue 11) pp:
Publication Date(Web):5 JAN 2007
DOI:10.1002/chem.200600825
The mechanisms of formation of biogenic magnesium-rich calcite remain an enigma. Here we present ultrastructural and compositional details of ossicles from the seastar Pisaster giganteus (Echinodermata, Asteroidea). Powder X-ray diffraction, infrared spectroscopy and elemental analyses confirm that the ossicles are composed of magnesium-rich calcite, whilst also containing about 0.01 % (w/w) of soluble organic matrix (SOM) as an intracrystalline component. Amino acid analysis and N-terminal sequencing revealed that this mixture of intracrystalline macromolecules consists predominantly of glycine-rich polypeptides. In vitro calcium carbonate precipitation experiments indicate that the SOM accelerates the conversion of amorphous calcium carbonate (ACC) into its final crystalline product. From this observation and from the discovery of ACC in other closely related taxa, it is suggested that substitution of magnesium into the calcite lattice through a transient precursor phase may be a universal phenomenon prevalent across the phylum echinodermata.
Co-reporter:M. H. Nurmawati;R. Renu;P. K. Ajikumar;S. Sindhu;F. C. Cheong;C. H. Sow;S. Valiyaveettil
Advanced Functional Materials 2006 Volume 16(Issue 18) pp:
Publication Date(Web):3 NOV 2006
DOI:10.1002/adfm.200600362
Micro- and nanostructuring of conjugated polymers are of critical importance in the fabrication of molecular electronic devices as well as photonic and bandgap materials. The present report delineates the single-step self-organization of highly ordered structures of functionalized poly(p-phenylene)s without the aid of either a controlled environment or expensive fabrication methodologies. Microporous films of these polymers, with a honeycomb pattern, were prepared by direct spreading of the dilute polymer solution on various substrates, such as glass, quartz, silicon wafer, indium tin oxide, gold-coated mica, and water, under ambient conditions. The polymeric film obtained from C12PPPOH comprises highly periodic, defect-free structures with blue-light-emitting properties. It is expected that such microstructured, conjugated polymeric films will have interesting applications in photonic and optoelectronic devices. The ability of the polymer to template the facile micropatterning of nanomaterials gives rise to hybrid films with very good spatial dispersion of the carbon nanotubes.
Co-reporter:S. Jegadesan;R. C. Advincula;S. Valiyaveettil
Advanced Materials 2005 Volume 17(Issue 10) pp:
Publication Date(Web):24 MAR 2005
DOI:10.1002/adma.200401388
Electrochemical nanolithography is used to fabricate conducting nanopatterns by selective oxidative crosslinking of poly(vinylcarbazole) (PVK; see Figure). The stable patterns have line thicknesses of 30–150 nm and heights of 4 nm, depending on the bias voltage and writing speed. The technique is simple, low-cost, and operates in ambient conditions.
Co-reporter:Chanbasha Basheer, Sindhu Swaminathan, Hian Kee Lee and Suresh Valiyaveettil
Chemical Communications 2005 (Issue 3) pp:409-410
Publication Date(Web):01 Dec 2004
DOI:10.1039/B414429E
An efficient oxidation of glucose to gluconic acid was performed using a porous gold(0) catalyst in a low-cost microreactor designed from Pyrex glass capillary tubing; compared with the conventional synthesis procedure this novel approach of using a capillary-microreactor offers a convenient and highly efficient means to optimise reaction conditions and catalytic activities.
Co-reporter:Balasubramaniam Venkataramanan, Zu Ning, Jagadese J. Vittal and Suresh Valiyaveettil
CrystEngComm 2005 vol. 7(Issue 16) pp:108-112
Publication Date(Web):24 Jan 2005
DOI:10.1039/B417663D
Self-assembly of the molecular complexes of O-alkoxy isophthalic acid (5-C12 and 4-C12) with 4,4′-bipyridine (bipy) in the crystal lattice is described. Complexes 5-C12ISA·bipy and 4-C12ISA·bipy exhibit 3-D supramolecular structures through and interplay of H-bonding, alkyl chain interdigitation, π⋯π and C–H⋯π interactions. The former forms a unique triple helix which further assembles into a 2D network stabilized via
π⋯π stacking interactions. The latter forms hydrogen bonded supramolecular sheets.
Co-reporter:Shaowen Liao;Choi Pheng Soo;Huanwen Ye
Polymer International 2005 Volume 54(Issue 4) pp:
Publication Date(Web):7 JAN 2005
DOI:10.1002/pi.1713
A series of novel fluorophore-rich polymers has been synthesized with the aim of developing radiation-sensitive materials as electron-beam resists. The polymers were characterized using FTIR and NMR spectroscopy, and gel permeation chromatography, differential scanning calorimetry and thermogravimetric analysis measurements. These polymers showed strong absorbance in the region of 330–380 nm, and can be patterned by an electron-beam in their pure form or mixed with other components. All polymers also generated intense emission in the range 510–565 nm when irradiated by a laser source operating at a wavelength of 488 nm. The sensitivity of the polymeric fluorescence label as an electron-beam resist was also discussed. Moreover, through immobilization of the fluorophores onto a polymer backbone, we managed to avoid the crystallization of fluorophores inside the polymer film. Copyright © 2005 Society of Chemical Industry
Co-reporter:Parayil Kumaran Ajikumar, Bee Jin Michelle Low, Suresh Valiyaveettil
Surface and Coatings Technology 2005 Volume 198(1–3) pp:227-230
Publication Date(Web):1 August 2005
DOI:10.1016/j.surfcoat.2004.10.028
The emerging science of nanobiotechnology relies on the observation that, through evolution, nature has produced highly complex nanostructures using macromolecules, especially nucleic acids, polysaccharides and proteins. Understanding the molecular mechanism of how these macromolecules interact to produce nanostructures is the key to the biomimetic materials design and synthesis. Calcium carbonate (CaCO3)-based biominerals such as nacre of mollusk shells have complex and hierarchal architectures on submicrometer length scales. The fabrication of such composite materials with control over the shape and properties can be achieved by adopting the natural process of template-driven biomineralization. Our strategy is to obtain nanostructured thin films of CaCO3 by tuning the chemical structures of organic matrices. Herein, we report the fabrication of functional thin films of aragonite, vaterite and calcite by a template-driven mineralization of calcium carbonate over a functionalized natural scaffold such as demineralized eggshell membrane. The functionalized templates were generated by the pre-adsorption of various soluble polymers such as polyaspartic acid (PAsp), polyglutamic acid (PGlu) and aspartic acid incorporated polyacrylic acid (PA-Asp). These biocompatible calcium carbonate coatings might be useful for tissue engineering applications and also for fundamental studies of cell–matrix interactions.
Co-reporter:Monique Martina, Gayathri Subramanyam, James C. Weaver, Dietmar W. Hutmacher, Daniel E. Morse, Suresh Valiyaveettil
Biomaterials 2005 Volume 26(Issue 28) pp:5609-5616
Publication Date(Web):October 2005
DOI:10.1016/j.biomaterials.2005.02.011
Calcareous skeletal elements (ossicles) isolated from the seastar, Pisaster giganteus, were characterized and tested as potential biocompatible substrates for cellular attachment. These ossicles have a remarkably robust open-framework architecture with an interconnected network of ca. 10 μm diameter pores. Scanning electron and confocal microscopy was used to characterize the cell-substrate interaction. Cell culturing experiments revealed that the cells firmly attach to the ossicle surface, forming cell aggregates of several layers thick. The anchored cells extended to form ‘bridges’ between the openings in the bicontinuous framework and the degree of coverage increased as culture time progressed. Osteoblasts grown on the ossicles were found to be viable up to 32 days after initial seeding, as proven by assaying with AlamarBlue™ and FDA/PI staining indicating the ossicle's potential as an alternative highly effective tissue scaffold. Given the limitation in availability of this natural material, the results presented here should be seen as offering guidelines for future development of synthetic materials with physical and chemical properties strongly conducive to bone repair and restoration.
Co-reporter:Muthalagu Vetrichelvan Dr.
Chemistry - A European Journal 2005 Volume 11(Issue 20) pp:
Publication Date(Web):23 JUN 2005
DOI:10.1002/chem.200500078
We report on the synthesis and characterization of a series of asymmetrically functionalized amphiphilic polymers with alternating π-donor units (e.g., substituted benzene) and π-acceptor units (e.g., pyridine) along the polymer backbone. The purpose of our present work involves incorporation of functional groups along the main chain to form intrachain hydrogen bonds, which promote planarization of the polymer backbone, and to fine-tune the optical properties. The structure–property relationship of polymers P 1–P 6 was investigated by means of analytical methods, such as FTIR spectroscopy, 1H and 13C NMR spectroscopy, UV/Vis spectroscopy, fluorescence spectroscopy, gel permeation chromatography, thermogravimetric analysis, cyclic voltammetry, and X-ray powder diffraction. All polymers were soluble in common organic solvents, and the optical and fluorescence spectra of the polymers showed significant changes according to the formation (P 4, P 5) or absence (P 6) of intramolecular hydrogen bonding along the polymer backbone. Moreover, the 2,6- or 3,5-linkage of the pyridine rings in P 5 and P 6, respectively, reduced the conjugation along the polymer backbone and this is reflected in their optical properties. The optical properties of the polymers were influenced by the addition of acid (P 1–P 6), base (P 4–P 6), and metal ions (e.g., Cu2+, Fe3+, Ag+, Ni2+, Pd2+, Mn2+, Zn2+, Mg2+, and Pr3+). Such polymers could be used in various applications, including sensors and stimuli-responsive displays.
Co-reporter:Parayil Kumaran Ajikumar Dr.;Subramanian Vivekanan Dr.;Rajamani Lakshminarayanan Dr.;Seetharama D. S. Jois Dr.;R. Manjunatha Kini
Angewandte Chemie 2005 Volume 117(Issue 34) pp:
Publication Date(Web):1 AUG 2005
DOI:10.1002/ange.200500261
Vorbild Eierschale: Mithilfe von Designer-Peptiden lassen sich die Struktur-Aktivitäts-Beziehungen von Eierschalen-Matrixproteinen entschlüsseln. Die Anordnung von Dubletts aus geladenen Aminosäureresten im Peptid und dessen Selbstorganisationscharakteristika spielen eine zentrale Rolle bei der biomimetischen Zusammenlagerung von polykristallinen Calcitkristallaggregaten (siehe Bild) nach dem Vorbild des durch das Eierschalen-Matrixprotein Ansocalcin ausgelösten Prozesses.
Co-reporter:Parayil Kumaran Ajikumar Dr.;Subramanian Vivekanan Dr.;Rajamani Lakshminarayanan Dr.;Seetharama D. S. Jois Dr.;R. Manjunatha Kini
Angewandte Chemie International Edition 2005 Volume 44(Issue 34) pp:
Publication Date(Web):1 AUG 2005
DOI:10.1002/anie.200500261
An eggshell finish: Designed peptides can be used as a tool to unravel the structure–activity relationships of eggshell matrix proteins. The ordered arrangement of doublets of charged residues on the peptide and its self-assembling characteristics play a key role in the biomimetic nucleation of polycrystalline calcite crystal aggregates (see picture), which models that initiated by the goose eggshell matrix protein, ansocalcin.
Co-reporter:Balasubramaniam Venkataramanan, Mohamed-Abubakar Saifudin, Vittal Jagadese J. and Valiyaveettil Suresh
CrystEngComm 2004 vol. 6(Issue 49) pp:284-289
Publication Date(Web):20 Aug 2004
DOI:10.1039/B408208G
Solid state self-assembly of methacrylamides (1–3) with intermolecular N–H⋯O and C–H⋯O hydrogen bonds are discussed. Interesting structures in the crystal lattice of 1 and 2 are ascribed to the aromatic surfaces that are orthogonal and twisted to each other along the hydrogen bonded chains. In addition, an interconnected network of face-to-face (π⋯π) and edge-to-face (C–H⋯π) interactions have been observed which are cooperative in nature. Compound 3 showed a staggered packing of adamantane groups along the H-bonded chains. In all three structures, the self-assembly was facilitated by strong hydrogen bonding, π⋯π interactions and packing forces involving bulky groups.
Co-reporter:Ailong Fan, Suresh Valiyaveettil and Jagadese J. Vittal
CrystEngComm 2003 vol. 5(Issue 6) pp:38-41
Publication Date(Web):16 Jan 2003
DOI:10.1039/B210303F
The solid state self-assembly of 5-alkoxyisophthalamides (1 and 2) shows monohelical structures formed through an interplay of intermolecular hydrogen bonds, interdigitation of alkyl chains, a large head-to-tail volume ratio and 1,3,5-functionalization of the central benzene ring.
Co-reporter:Wenmiao Shu and Suresh Valiyaveettil
Chemical Communications 2002 (Issue 13) pp:1350-1351
Publication Date(Web):27 May 2002
DOI:10.1039/B201742C
Two novel disc-shaped compounds (1, 2) with strong intramolecular hydrogen bonds were prepared and characterized; compound 2 showed a thermotropic mesophase as characterised by polarized optical microscopy, DSC and X-ray diffraction studies.
Co-reporter:Rong Liu, Suresh Valiyaveettil, Kum-Fun Mok, Jagadese J. Vittal and Angelia Kar Min Hoong
CrystEngComm 2002 vol. 4(Issue 95) pp:574-579
Publication Date(Web):06 Nov 2002
DOI:10.1039/B206055H
Solid-state self-assembly of 1,4-bis(2-carboxybenzyloxy)benzene and its stoichiometric complexes with diamines such as 4,4′-bipyrydyl and 1,2-bis(4-pyridyl)ethylene are described with complete structural details. Carboxylic acid dimer formation and O–H⋯N-type hydrogen bonds were the major hydrogen bonding motifs in the crystal lattice. A wave-type topology was observed for the hydrogen bonded chains.
Co-reporter:Suresh Valiyaveettil;R. Manjunatha Kini;Rajamani Lakshminarayanan
PNAS 2002 Volume 99 (Issue 8 ) pp:5155-5159
Publication Date(Web):2002-04-16
DOI:10.1073/pnas.072658899
The role of proteins in biomineralization and the mechanism of eggshell formation are not well understood. We have isolated
and purified the major protein, ansocalcin from goose eggshell matrix. The amino acid sequence study indicates that ansocalcin
is homologous to the chicken eggshell protein, ovocleidin 17, and C-type lectins. Ansocalcin nucleates polycrystalline aggregates
of calcite crystals in in vitro mineralization experiments. The polycrystalline aggregates obtained at higher concentration of ansocalcin appears to be similar
to the crystals observed at the mamillary layer of the eggshell.
Co-reporter:Ailong Fan, Hon Kah Hong, Suresh Valiyaveettil, Jagadese J Vittal
Journal of Supramolecular Chemistry 2002 Volume 2(1–3) pp:247-254
Publication Date(Web):January–June 2002
DOI:10.1016/S1472-7862(03)00079-0
A neutral urea incorporated anion receptor 1 with a tripodal pseudocavity was synthesized in good yield. The influence of preorganization and rigidity of the receptors towards anion recognition was evaluated using rigid (1) and flexible (2) receptors. Binding affinities were investigated using 1H NMR and luminescence titration methods. Receptor 1 showed high binding affinities with 1:1 stoichiometry for carboxylate anions in polar solvents. No binding was observed with small anions, presumably due to the large cavity and the rigidity of the receptor.A new anion receptor with high binding affinities to carboxylate anions is reported with full details on synthesis, characterization and the binding studies. The obtained results are explained based on the rigidity and preorganization of the receptor.
Co-reporter:Rong Liu, Kum-Fun Mok and Suresh Valiyaveettil
New Journal of Chemistry 2001 vol. 25(Issue 7) pp:890-892
Publication Date(Web):14 Jun 2001
DOI:10.1039/B102098F
1,3,5-Benzenetricarboxylic acid (trimesic acid, TMA) was cocrystallized with 0.5 equiv. of 1,3,5-trihydroxybenzene (phloroglucinol, THB) to generate a close-packed non-interpenetrating planar mosaic motif. Both O–H···O and C–H···O hydrogen bonds were observed in the crystal lattice. Each THB molecule is hydrogen bonded to six adjacent TMA molecules to form a
planar rosette-shaped structure, which constitutes the repeating units of a layer-type lattice.
Co-reporter:Choong Ping Sen, Suresh Valiyaveettil
European Polymer Journal (February 2017) Volume 87() pp:
Publication Date(Web):February 2017
DOI:10.1016/j.eurpolymj.2016.12.015
•Conjugated polyphenols with trihydroxybenzene side groups are reported.•The structure-property relationships of conjugated polyphenols are investigated.•Polyphenol structures can be fine-tuned for selective sensing of metal ions.•P1(OH)n showed high binding constant (Ksv = 3.73 x 105 M−1) for zinc ions.Conjugated polymers with ion sensing groups have been synthesized and characterized for developing sensors for toxic and explosive chemicals in different media. In this study, three conjugated polyphenols (P1(OH)n–P3(OH)n) were synthesized using Sonogashira polymerization and structure-property relationships were established. The target conjugated polyphenols exhibited blue-shifts in absorption (up to 50 nm) and emission (up to 15 nm) maxima in THF, and red-shifts in absorption (up to 45 nm) and emission (up to 17 nm) maxima in DMF of the target polyphenols as compared to those of protected polymers (P1–P3). This is attributed to the disruption of polymer conformation owing to the formation of interchain hydrogen bonds between the trihydroxybenzene groups along the polymer backbone. P1(OH)n showed strong interactions with Zn2+ ions with a red-shift in emission maximum from 475 nm to 535 nm and a high binding constant (Ksv = 3.73 × 105 M−1). In contrast, P2(OH)n and P3(OH)n exhibited smaller changes in emission maximum upon addition of Zn2+ ions (Ksv = 0.69 × 105 M−1 for P2(OH)n and 0.32 × 105 M−1 for P3(OH)n). The understanding of the structure-property relationships of such polymers helps to develop metal ion sensors with better selectivity and sensitivity in the future.
Co-reporter:Deepa Sriramulu, Shuvan Prashant Turaga, Ang Xin Yi, Andrew Anthony Bettiol and Suresh Valiyaveettil
Journal of Materials Chemistry A 2016 - vol. 4(Issue 47) pp:NaN11197-11197
Publication Date(Web):2016/11/16
DOI:10.1039/C6TC03677E
Luminescent inorganic nanoparticles are interesting owing to their high stability and photophysical characteristics. In this study, luminescent ZnO–SiO2 nanoparticles (ZnOSiO2-X NPs, X = 1, 2, 3, 4) were designed and synthesized using the reverse microemulsion method. Here ZnO quantum dots are encapsulated and homogeneously distributed inside the silica matrix of ZnOSiO2-X NPs. The structural and optical properties of the nanoparticles were fully established using a variety of techniques. High-resolution TEM micrographs and electron diffraction data confirmed the presence of ZnO quantum dots inside silica nanoparticles. The ZnOSiO2-X NPs gave intense blue-white luminescence and the intensity varied with changes in the composition of the particles. In addition to fluorescence emission, these particles showed phosphorescence emission in solution and in the solid state. As a proof of concept, UV active invisible printing was demonstrated by using a ZnOSiO2/PDMS mixture in inkjet printing and mechanical stamping. The prepared stable luminescent NPs can be used for applications such as bioimaging, ink-jet printing or stamping in nanoelectronics.
Co-reporter:Sivamurugan Vajiravelu, Lygaitis Ramunas, Gražulevičius Juozas Vidas, Gaidelis Valentas, Jankauskas Vygintas and Suresh Valiyaveettil
Journal of Materials Chemistry A 2009 - vol. 19(Issue 24) pp:NaN4275-4275
Publication Date(Web):2009/05/15
DOI:10.1039/B901847F
Electron donating substituents such as 3,4,5-trimethoxy phenyl (PDI1), thiophene (PDI2), 6-methoxy naphthyl (PDI3), 5-hexyl dithiophene (PDI4) and thioanthrenyl (PDI5) moieties incorporated at the bay region of N,N′-dodecylperylene diimide (PDI) derivatives have been synthesized and characterised. The absorption maxima of PDI1–5 showed a bathochromic shift with considerable peak broadening and merging of vibronic fine structure as compared to that of PDI. The photoinduced intramolecular charge transfer (ICT) from electron donating substituents to the perylene-acceptor has been observed from fluorescence self-quenching. The molecules are stable up to 400 °C and amorphous in nature. The cyclic voltammetry results revealed that the oxidation potential can be tuned by the electron donating capacity of the substituents and the dithiophene-attached perylene derivative (PDI4) showed a very low band gap of 1.57 eV. The electron transporting properties have been studied using xerographic time-of-flight method and the highest electron mobility reached up to 4.4 × 10−4 cm2V−1 s−1 at 6.4 × 105 V cm−1 for 1,7-di(3,4,5-trimethoxyphenyl)perylene diimide (PDI1) under ambient conditions.
Co-reporter:Muhammad Hanafiah Nurmawati, Parayil Kumaran Ajikumar, Lili Amanda Heng, Hairong Li and Suresh Valiyaveettil
Chemical Communications 2008(Issue 40) pp:NaN4947-4947
Publication Date(Web):2008/08/30
DOI:10.1039/B808689C
Formation and characterization of nanocrystallite spheres from a hybrid of functionalized cross-conjugated poly(p-phenylene) and C60 are reported.
Co-reporter:Narahari Mahanta, Yiwei Teow and Suresh Valiyaveettil
Biomaterials Science (2013-Present) 2013 - vol. 1(Issue 5) pp:NaN527-527
Publication Date(Web):2013/02/25
DOI:10.1039/C3BM00167A
Hydrogels are three dimensional scaffolds of hydrophilic polymers with inter-connected water channels. In this investigation, an interesting approach for the fabrication of a highly viscoelastic hydrogel derived from a polyvinyl alcohol (PVA) based macromer is reported. PVA was crosslinked using Fe3+ ions under basic conditions to obtain a stable hydrogel with a highly porous network structure. The swelling ratio of the designed hydrogels was evaluated and correlated to the network structure of the metal coordinated crosslinked macromers. Compressive modulus and dynamic viscoelastic measurements were carried out using a dynamic mechanical analyzer and no significant changes in storage modulus were observed by increasing the temperature up to 45 °C. A creep study revealed that the elastic recovery was enhanced with an increase in the degree of crosslinking. The effect of crosslinking influenced properties such as the glass transition, melting point and melting enthalpy of the crosslinked network. The cytocompatibility of the gels was studied using human lung fibroblasts (IMR-90) and no toxic effects or significant cell attachments were observed on the surface of the gel after 5 days. The designed hydrogels may be useful for biomedical procedures which require highly viscoelastic, biocompatible, thermally and mechanically stable biomaterials.
Co-reporter:Narahari Mahanta, Wai Ying Leong and Suresh Valiyaveettil
Journal of Materials Chemistry A 2012 - vol. 22(Issue 5) pp:NaN1993-1993
Publication Date(Web):2011/12/07
DOI:10.1039/C1JM15018A
The increased use of nanoparticles in various commercial products enhances the contamination of nanomaterials in the environment which may cause serious health concern in the near future. To address this problem, new methods need to be developed for removal of nanomaterials from the environment. In this report, we explored the removal of nanoparticles from water using cellulosic nanofibers extracted from a renewable source such as sugarcane bagasse. The nanofibers were coated with chitosan to introduce additional functional groups on the surface. The designed cellulosic nanofibers showed high extraction efficiency (80–90%) towards silver (Ag) and gold (Au) nanoparticles. The maximum adsorption efficiency (Qt) towards citrate and polyvinylpyrrolidone (PVP) capped Ag-nanoparticles using chitosan coated cellulose nanofibers was 13.1 mg g−1. Similarly, Qt values for citrate and PVP capped Au-nanoparticles were 17.9 mg g−1 and 17.4 mg g−1, respectively. The adsorption of nanoparticles onto the nanofibers was confirmed using scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDX). Even though we used spiked solutions for the current study, it is expected that such low cost, highly abundant nanofibers may be used for setting up a large-scale nanoparticle removal system for water purification.
Co-reporter:Yiwei Teow, P. V. Asharani, M. Prakash Hande and Suresh Valiyaveettil
Chemical Communications 2011 - vol. 47(Issue 25) pp:NaN7038-7038
Publication Date(Web):2011/04/11
DOI:10.1039/C0CC05271J
Many engineered nanomaterials (NMs) are being synthesized and explored for potential use in consumer and medical products. Already, nanoparticles (NPs) of titanium dioxide (TiO2), zinc oxide (ZnO), silver (Ag) and other metals or their oxides are present in commercial products such as sunscreens, cosmetics, wound dressings, surgical tools, detergents, automotive paints and tires. More recent and advanced FDA-approved use of NMs includes quantum dots (QDs) in live cell imaging, zirconium oxides in bone replacement and prosthetic devices and nanocarriers in drug delivery. The benefits from nanotechnology are aplenty, comprising antimicrobial activities, scratch- and water-resistance, long-lasting shine, improved processor speeds and better display resolution, to name a few. While developers of these products often focus on the exciting beneficial aspects of their products, safety and toxicity issues are often not discussed in detail. Long-term effects such as chronic exposure and environmental pollution are even less documented. Along with widespread manufacture and use of NMs, concerns for occupational hazards, proper handling, disposal, storage, shipping and clean up are expected to rise. This review focus on the possible biological impact of engineered NPs, serving as a reminder that nanomaterials can become a double-edged sword if not properly handled.
Co-reporter:Devendar Goud Vanga, Mithun Santra, Ashok Keerthi and Suresh Valiyaveettil
Organic & Biomolecular Chemistry 2014 - vol. 12(Issue 40) pp:NaN7918-7918
Publication Date(Web):2014/08/28
DOI:10.1039/C4OB01509F
A few pyrene-based fluorescent compounds were synthesized using Pd/Cu-catalyzed cross-coupling reaction. Photophysical properties of the π-conjugated pyrene derivatives were studied and the results indicate materials with high quantum efficiency and high extinction coefficient. No π stacking was observed in the crystal lattice. The molecules described here may be useful in developing sensors or imaging agents.
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![Benzaldehyde, 4-[(2-ethylhexyl)oxy]-](http://img.cochemist.com/ccimg/119700/119630-71-6_b.png)
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![[1,1':4',1'':3'',1''':4''',1''''-QUINQUEPHENYL]-5''-CARBOXYLIC ACID, 2''-HYDROXY-](http://img.cochemist.com/ccimg/799300/799297-51-1_b.png)
![[1,1':4',1''-TERPHENYL]-2',3,3''-TRIOL, 5'-(DODECYLOXY)-](http://img.cochemist.com/ccimg/865000/864910-71-4.png)
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![BENZENEMETHANOL, 3,4,5-TRIS[(2,2-DIMETHYL-1,3-DIOXOLAN-4-YL)METHOXY]-](http://img.cochemist.com/ccimg/862400/862396-27-8.png)
![BENZENEMETHANOL, 3,4,5-TRIS[(2,2-DIMETHYL-1,3-DIOXOLAN-4-YL)METHOXY]-](http://img.cochemist.com/ccimg/862400/862396-27-8_b.png)
![1,2-Ethanedione, 1,2-bis[4-[(2-ethylhexyl)oxy]phenyl]-](/data/chemimg/2977400/150149-11-4.png)
![1,2-Ethanedione, 1,2-bis[4-[(2-ethylhexyl)oxy]phenyl]-](/data/chemimg/2977400/150149-11-4_b.png)
![Dipyrido[3,2-a:2',3'-c]phenazine](/data/chemimg/1778900/19535-47-8.png)
![Dipyrido[3,2-a:2',3'-c]phenazine](/data/chemimg/1778900/19535-47-8_b.png)
![[2,2':5',2''-Terthiophene]-3',4'-diamine](http://img.cochemist.com/ccimg/185700/185691-91-2.png)
![[2,2':5',2''-Terthiophene]-3',4'-diamine](http://img.cochemist.com/ccimg/185700/185691-91-2_b.png)
![Benzo[b]thiophen-3-amine](http://img.cochemist.com/ccimg/17500/17402-82-3.png)
![Benzo[b]thiophen-3-amine](http://img.cochemist.com/ccimg/17500/17402-82-3_b.png)
![1,3-Bis([1,1'-biphenyl]-4-yloxy)-2-propanol](http://img.cochemist.com/ccimg/22900/22820-60-6.png)
![1,3-Bis([1,1'-biphenyl]-4-yloxy)-2-propanol](http://img.cochemist.com/ccimg/22900/22820-60-6_b.png)
![Benzoic acid, 2,2'-[1,4-phenylenebis(oxymethylene)]bis-, dimethyl ester](http://img.cochemist.com/ccimg/501000/500904-59-6.png)
![Benzoic acid, 2,2'-[1,4-phenylenebis(oxymethylene)]bis-, dimethyl ester](http://img.cochemist.com/ccimg/501000/500904-59-6_b.png)
![Benzoic acid, 2,2'-[1,4-phenylenebis(oxymethylene)]bis-](http://img.cochemist.com/ccimg/501000/500904-56-3.png)
![Benzoic acid, 2,2'-[1,4-phenylenebis(oxymethylene)]bis-](http://img.cochemist.com/ccimg/501000/500904-56-3_b.png)
![Benzoic acid, 2,2'-[1,4-phenylenebis(oxymethylene)]bis-, compd. with4,4'-(1E)-1,2-ethenediylbis[pyridine] (1:1)](http://img.cochemist.com/ccimg/501000/500904-58-5.png)
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](http://img.cochemist.com/ccimg/27000/26913-06-4.png)
](http://img.cochemist.com/ccimg/27000/26913-06-4_b.png)
![Poly[imino[(1S)-1-(carboxymethyl)-2-oxo-1,2-ethanediyl]]](http://img.cochemist.com/ccimg/26100/26063-13-8.png)
![Poly[imino[(1S)-1-(carboxymethyl)-2-oxo-1,2-ethanediyl]]](http://img.cochemist.com/ccimg/26100/26063-13-8_b.png)
![Poly[oxy(1-oxo-1,6-hexanediyl)]](http://img.cochemist.com/ccimg/25300/25248-42-4.png)
![Poly[oxy(1-oxo-1,6-hexanediyl)]](http://img.cochemist.com/ccimg/25300/25248-42-4_b.png)
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![Silane, [(4-ethenylphenyl)ethynyl]trimethyl-](http://img.cochemist.com/ccimg/135100/135005-24-2_b.png)
![Benzaldehyde,4-[2-(diethylamino)ethoxy]-](http://img.cochemist.com/ccimg/15200/15182-94-2.png)
![Benzaldehyde,4-[2-(diethylamino)ethoxy]-](http://img.cochemist.com/ccimg/15200/15182-94-2_b.png)
![1,3,2-Dioxaborolane, 2-(5'-hexyl[2,2'-bithiophen]-5-yl)-4,4,5,5-tetramethyl-](/data/chemimg/86100/579503-59-6.png)
![1,3,2-Dioxaborolane, 2-(5'-hexyl[2,2'-bithiophen]-5-yl)-4,4,5,5-tetramethyl-](/data/chemimg/86100/579503-59-6_b.png)
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