Co-reporter:Kalluvettukuzhy K. Neena;Pagidi Sudhakar;Kumbhar Dipak
Chemical Communications 2017 vol. 53(Issue 26) pp:3641-3644
Publication Date(Web):2017/03/28
DOI:10.1039/C6CC09717K
Herein we report the multifunctional characteristics such as aggregation induced emission (AIE), triboluminescence (TL), mechanofluorochromism and temperature sensing of molecular siblings 1 (10-(dimesitylboryl)phenothiazine) and 2 (10-(bis(2,6-dimethylphenyl)boryl)phenothiazine).
Co-reporter:Pagidi Sudhakar;Kalluvettukuzhy K. Neena
Journal of Materials Chemistry C 2017 vol. 5(Issue 26) pp:6537-6546
Publication Date(Web):2017/07/06
DOI:10.1039/C7TC01676J
Design, synthesis and structural characterization of borylated aryl amines, Mes2BAr {Ar = C6(CH3)4NR2 (1, 4); C6H4NR2 (2, 5); C6H3(NR2)2 (3, 6); R = H or CH3}, were reported. The intriguing optical signatures undoubtedly revealed their donor–acceptor characteristics and a bright tunable solid state emission is readily realized. The solid state luminescence characteristics of 1 and 3 were sensitive to mechanical stress with distinguishable emission color changes. Multiple strong intermolecular hydrogen bonds (N–H⋯N and N–H⋯π) accompanied by subtle conformational changes play a significant role in the piezochromic response. PXRD and FT-IR spectroscopic studies and insensitivity of substituted derivatives to mechanical stress support the above inference. Interestingly, compound 3 crystallized in two different polymorphic forms 3BP and 3GP, which showed distinct luminescence, i.e., green and blue color under UV light. Such changes are due to their distinct hydrogen-bond network assembly in the solid state. Quantum mechanical calculations were performed in order to corroborate the optical properties.
Co-reporter:Sanjoy Mukherjee and Pakkirisamy Thilagar
Journal of Materials Chemistry A 2016 vol. 4(Issue 14) pp:2647-2662
Publication Date(Web):08 Sep 2015
DOI:10.1039/C5TC02406D
Recent advancements of material science and its applications have been immensely influenced by the modern development of organic luminescent materials. Among all organic luminogens, boron containing compounds have already established their stature as one of the indispensable classes of luminescent dyes. Boron, in its various forms e.g. triarylboranes, borate dyes and boron clusters, has attracted considerable attention owing to its several unique and excellent photophysical features. In very recent times, beyond the realms of solution-state studies, luminescent boron-containing compounds have emerged as a large and versatile class of stimuli responsive materials. Based on several fundamental concepts of chemistry, researchers have come up with an admirable variety of boron-containing materials with AIE (aggregation-induced emission), mechano-responsive luminescence, thermoresponsive-luminescence as well as a number of purely organic phosphorescent materials and other standalone examples. The unique chemical as well as physical properties of boron-containing compounds are largely responsible for the development of such materials. In this review these new findings are brought together.
Co-reporter:Sanjoy Mukherjee and Pakkirisamy Thilagar
Chemical Communications 2016 vol. 52(Issue 6) pp:1070-1093
Publication Date(Web):26 Oct 2015
DOI:10.1039/C5CC08213G
In recent times, luminescent materials with tunable emission properties have found applications in almost all aspects of modern material sciences. Any discussion on the recent developments in luminescent materials would be incomplete if one does not account for the versatile photophysical features of boron containing compounds. Apart from triarylboranes and tetra-coordinate borate dyes, luminescent materials consisting of boron clusters have also found immense interest in recent times. Recent studies have unveiled the opportunities hidden within boranes, carboranes and metalloboranes, etc. as active constituents of luminescent materials. From simple illustrations of luminescence, to advanced applications in LASERs, OLEDs and bioimaging, etc., the unique features of such compounds and their promising versatility have already been established. In this review, recent revelations about the excellent photophysical properties of such materials are discussed.
Co-reporter:Samir Kumar Sarkar, George Rajendra Kumar and Pakkirisamy Thilagar
Chemical Communications 2016 vol. 52(Issue 22) pp:4175-4178
Publication Date(Web):11 Feb 2016
DOI:10.1039/C6CC00823B
The design and synthesis of two structurally close and complementarily fluorescent boron based molecular siblings 2 and 3 are reported. The luminescence properties of individual triads are modulated to complement each other by controlling the intramolecular energy transfer in 2 and 3. The binary mixture of 2 and 3 emits white-light.
Co-reporter:George Rajendra Kumar and Pakkirisamy Thilagar
Inorganic Chemistry 2016 Volume 55(Issue 23) pp:12220-12229
Publication Date(Web):November 21, 2016
DOI:10.1021/acs.inorgchem.6b01827
A new series of luminescent cyclometalated platinum complexes with triarylborane-functionalized acetylacetonate ligands is reported. The complexes exhibit solid state luminescence and phosphorescence under ambient conditions. The luminescence color can be tuned from green to red by varying the cyclometalating ligand [2-phenylpyridine (for 1 and 2), 2-thiophenylpyridine (for 3 and 4), 2-thianapthenylpyridine (for 5 and 6)]. The luminescence originates from mixed 3MLCT/3IL [MLCT, metal to ligand charge transfer; IL, intraligand] states of square planar platinum and borane moieties. The π spacer (phenyl or duryl) which connects the boryl and platinum entities has a significant role in determining the photoluminescence efficiency. The bulky duryl spacer in 2, 4, and 6 significantly reduces π–π stacking of the square planar platinum moiety in the solid state and provides a rigid backbone, thereby increasing their quantum yield significantly. The role of Lewis-acidic borane on the photoluminescence features is evaluated by fluoride binding experiments.
Co-reporter:Chinna Ayya Swamy P and Pakkirisamy Thilagar
Dalton Transactions 2016 vol. 45(Issue 11) pp:4688-4696
Publication Date(Web):25 Jan 2016
DOI:10.1039/C5DT02678D
Triarylborane-A2H2 (1) and triarylborane-Zn-A2H2 porphyrins (2) have been synthesized by acid catalyzed condensation of 4-dimesitylboryl-benzaldehyde and dipyrromethane under ambient conditions. Compounds 1 and 2 showed multiple emission bands upon excitation at the triarylborane dominated absorption region (350 nm). Detailed experimental and computational studies show that the multiple emission features of 1 and 2 arise as a result of a partial energy transfer from the donor (triarylborane) to the acceptor (porphyrin) moieties. Compounds 1 and 2 showed very high selectivities towards fluoride ions compared to other competing anions.
Co-reporter:Sanjoy Mukherjee and Pakkirisamy Thilagar
Chemical Communications 2015 vol. 51(Issue 55) pp:10988-11003
Publication Date(Web):19 May 2015
DOI:10.1039/C5CC03114A
Luminescent organic materials have attracted significant attention in recent times owing to their opportunities in various functional applications. Interestingly, unlike fluorescence, opportunities hidden within the phosphorescence properties of organic compounds have received considerably less attention even until last few years. It is only in the second decade of the 21st century, within a time span of less than last 5 years, that the concepts and prospects of organic compounds as phosphorescent materials have evolved rapidly. The previously perceived limitations of organic compounds as phosphorescent materials have been overcome and several molecules have been designed using old and new concepts, such as heavy atom effects, matrix assisted isolation, hydrogen bonding and halogen bonding, thereby gaining access to a significant number of materials with efficient phosphorescent features. In addition, significant improvements have been made in the development of RTP (room temperature phosphorescent) materials, which can be used under ambient conditions. In this review, we bring together the vastly different approaches developed by various researchers to understand and appreciate this recent revolution in organic luminescent materials.
Co-reporter:George Rajendra Kumar, Samir Kumar Sarkar and Pakkirisamy Thilagar
Physical Chemistry Chemical Physics 2015 vol. 17(Issue 45) pp:30424-30432
Publication Date(Web):12 Oct 2015
DOI:10.1039/C5CP05378A
Three new triarylborane conjugated dicyanovinyl chromophores (Mes2B–π–donor–DCV); donor: N-methyldiphenylamine (1) and triphenylamine (2 and 3 [with two BMes2 substitutions]) of type A–D–A (acceptor–donor–acceptor) are reported. Compounds 1–3 exhibit intense charge transfer (CT) absorption bands in the visible region. These absorption peaks are combination CT bands of the amine donor to both the BMes2 and DCV units. This inference was supported by theoretical studies. Compound 1 shows weak fluorescence compared to 2 and 3. The discrimination of fluoride and cyanide ions is essential in the case of triarylborane (TAB) based anion sensors as a similar response is given towards both the anions. Anion binding studies of 1, 2 and 3 showed that fluoride ions bind selectively to the boron centre and block the corresponding CT transition (donor to BMes2) leaving the other CT transition to be red shifted. On the other hand, cyanide ions bind with both the receptor sites and stop both the CT transition processes and hence a different colorimetric response was noted. The binding of F−/CN− induces colour changes in the visible region of the electronic spectra of 2 and 3, which allows for the naked-eye detection of F− and CN− ions. The anion binding mechanisms are established using NMR titration experiments.
Co-reporter:Chinna Ayya Swamy P;Ragam N. Priyanka;Sanjoy Mukherjee
European Journal of Inorganic Chemistry 2015 Volume 2015( Issue 13) pp:2338-2344
Publication Date(Web):
DOI:10.1002/ejic.201500089
Abstract
A new triarylborane–aza-BODIPY conjugate is reported. The compound consists of two blue emissive dimesitylarylborane moieties and a near-infrared (NIR) emissive aza-BOIDPY core and shows panchromatic absorption spanning approximately 300–800 nm. DFT computational studies suggest limited electronic communication between the individual fluorophore units. Hence, the partial energy transfer from blue fluorophore triarylborane to NIR chromophore aza-BODIPY unit leads to a broad dual-emissive feature covering a large part of visible and NIR region. Furthermore, the broadband emissive compound can act as a selective sensor for fluoride anion as a result of fluorescence quenching response in both visible and NIR spectral regions.
Co-reporter:Sanjoy Mukherjee and Pakkirisamy Thilagar
RSC Advances 2015 vol. 5(Issue 4) pp:2706-2714
Publication Date(Web):01 Dec 2014
DOI:10.1039/C4RA12071J
Random changes in the alkyl substitution patterns of fluorescent dyes, e.g. BODIPYs, are often accompanied by significant changes in their photophysical properties. To understand such alterations in properties in closely related molecular systems, a comparative DFT (density functional theory) computational investigation was performed in order to comprehend the effects of alkyl substitution in controlling the structural and electronic nature of BODIPY dyes. In this context, a systematic strategy was utilized, considering all possible outcomes of constitutionally-isomeric molecules to understand the alkyl groups’ effects on the BODIPY molecules. Four different computational methods {i.e. B3LYP/6-31G(d); B3LYP/6-311++G(d,p); wb97xd/6-311++G(d,p) and mpw1pw91/6-311++G(d,p)} were employed to rationalize the agreement of the trends associated with the molecular properties. In line with experimental observations, it was found that alkyl substituents in BODIPY dyes situated at 3/5-positions effectively participate in stabilization as well as planarization of such molecules. Screening of all the possible isomeric molecular systems was used to understand the individual properties and overall effects of the typical alkyl substituents in controlling several basic properties of such BODIPY molecules.
Co-reporter:Dr. Chinna Ayya SwamyP ;Dr. Pakkirisamy Thilagar
Chemistry - A European Journal 2015 Volume 21( Issue 24) pp:8874-8882
Publication Date(Web):
DOI:10.1002/chem.201500727
Abstract
Synthesis and crystal structures of three porphyrin-based polyfunctional Lewis acids 1–3 are reported. Intermolecular HgCl⋅⋅⋅HgCl (linear and μ-type) interactions in the solid state of the peripherally ArHgCl-decorated compound 3 lead to a fascinating 3D supramolecular architecture. Compound 3 shows a selective fluorescence quenching response to picric acid and discriminates other nitroaromatic-based explosives. For the first time, an electron-deficient polyfunctional Lewis acid is shown to be useful for the selective detection and discrimination of nitroaromatic explosives. The Stern–Volmer quenching constant and detection limits of compound 3 for picric acid are the best among the reported small-molecular receptors for nitroaromatic explosives. The electronic structure, Lewis acidity, and selective sensing characteristics of 3 are well corroborated by DFT calculations.
Co-reporter:SANJOY MUKHERJEE
Journal of Chemical Sciences 2015 Volume 127( Issue 2) pp:241-255
Publication Date(Web):2015 February
DOI:10.1007/s12039-015-0783-4
The interaction of a Lewis acid with a Lewis base results in the formation of a Lewis acid–base adduct. Understanding Lewis acids and bases is central to conceptualizing chemical interactions and constitutes a major portion of metal–ligand chemistry. Sterically encumbered/constrained Lewis pairs cannot form acid–base adducts, but such ‘Frustrated Lewis Pairs’ (FLPs), with their unquenched electronic demands can be elegantly used to simultaneously react with a third species, resulting in unusual reactivity of small molecules. Such unusual reactions, explored only in the last few years, have found several applications, e.g., heterolytic splitting of H2, activation of small molecules (CO2, N2O, etc.). FLPs have opened new opportunities in synthetic chemistry, covering organic, main group as well as transition metal chemistry. The design strategies adopted for FLP systems and their unique reactivity are discussed here.
Co-reporter:P. Chinna Ayya Swamy, Sanjoy Mukherjee, and Pakkirisamy Thilagar
Analytical Chemistry 2014 Volume 86(Issue 7) pp:3616
Publication Date(Web):February 26, 2014
DOI:10.1021/ac500230p
Peripherally triarylborane decorated porphyrin (2) and its Zn(II) complex (3) have been synthesized. Compound 3 contains of two different Lewis acidic binding sites (Zn(II) and boron center). Unlike all previously known triarylborane based sensors, the optical responses of 3 toward fluoride and cyanide are distinctively different, thus enabling the discrimination of these two interfering anions. Metalloporphyrin 3 shows a multiple channel fluorogenic response toward fluoride and cyanide and also a selective visual colorimetric response toward cyanide. By comparison with model systems and from detailed photophysical studies on 2 and 3, we conclude that the preferential binding of fluoride occurs at the peripheral borane moieties resulting in the cessation of the EET (electronic energy transfer) process from borane to porphyrin core and with negligible negetive cooperative effects. On the other hand, cyanide binding occurs at the Zn(II) core leading to drastic changes in its absorption behavior which can be followed by the naked eye. Such changes are not observed when the boryl substituent is absent (e.g., Zn-TPP and TPP). Compounds 2 and 3 were also found to be capable of extracting fluoride from aqueous medium.
Co-reporter:Chinna Ayya Swamy P and Pakkirisamy Thilagar
Inorganic Chemistry 2014 Volume 53(Issue 6) pp:2776-2786
Publication Date(Web):March 4, 2014
DOI:10.1021/ic402898n
Facile synthesis of triad 3 and tetrad 4 incorporating −B(Mes)2 (Mes = mesityl (2,4,6-trimethylphenyl)), boron dipyrromethene (BODIPY), and triphenylamine is reported. Introduction of two dissimilar acceptors (triarylborane and BODIPY) on a single donor resulted in two distinct intramolecular charge transfer processes (amine-to-borane and amine-to-BODIPY). The absorption and emission properties of the new triad and tetrad are highly dependent on individual building units. The nature of electronic communication among the individual fluorophore units has been comprehensively investigated and compared with building units. Compounds 3 and 4 showed chromogenic and fluorogenic responses for small anions such as fluoride and cyanide.
Co-reporter:Chinna Ayya Swamy P, Sanjoy Mukherjee, and Pakkirisamy Thilagar
Inorganic Chemistry 2014 Volume 53(Issue 10) pp:4813-4823
Publication Date(Web):May 6, 2014
DOI:10.1021/ic402470a
Co-reporter:Samir Kumar Sarkar, Sanjoy Mukherjee, and Pakkirisamy Thilagar
Inorganic Chemistry 2014 Volume 53(Issue 5) pp:2343-2345
Publication Date(Web):February 13, 2014
DOI:10.1021/ic402441w
The design and synthesis of a new tri- and tetracoordinate boron conjugate is reported. The conjugate shows broad near-IR emission (∼625–850 nm) and is found to be a selective colorimetric and ratiometric sensor for fluoride ions.
Co-reporter:George Rajendra Kumar and Pakkirisamy Thilagar
Dalton Transactions 2014 vol. 43(Issue 10) pp:3871-3879
Publication Date(Web):28 Nov 2013
DOI:10.1039/C3DT52768A
A facile synthetic route for a new class of organoborane compounds (Mes)2B-arene-acacH and (Mes)2B-arene-acacBF2 (Mes = mesityl and arene = C6H4 or C6Me4) is reported. The new dyads exhibit intriguing photophysical properties. A small structural change in spacer connecting the two chromophores leads to fine tuning of photophysical properties. The dyad containing 2,3,5,6-tetramethyl phenyl spacer acts as a selective “turn-on” chemodosimetric sensor for cyanide ion. Steric crowding around the boron centre significantly alters anion binding events. From NMR titration studies it is established that fluoride and cyanide follow different binding mechanisms which lead to intriguing optical properties in the reported probes.
Co-reporter:Sanjoy Mukherjee and Pakkirisamy Thilagar
Physical Chemistry Chemical Physics 2014 vol. 16(Issue 38) pp:20866-20877
Publication Date(Web):22 Aug 2014
DOI:10.1039/C4CP02071E
An investigation of a series of seven angular “V” shaped NPIs (1–7) is presented. The effect of substitution of these structurally similar NPIs on their photophysical properties in the solution-state and the solid-state is presented and discussed in light of experimental and computational findings. Compounds 1–7 show negligible to intensely strong emission yields in their solid-state depending on the nature of substituents appended to the oxoaryl moiety. The solution and solid-state properties of the compounds can be directly correlated with their structural rigidity, nature of substituents and intermolecular interactions. The versatile solid-state structures of the NPI siblings are deeply affected by the pendant substituents. All of the NPIs (1–7) show antiparallel dimeric π–π stacking interactions in their solid-state which can further extend in a parallel, alternate, orthogonal or lateral fashion depending on the steric and electronic nature of the C-4′ substituents. Structural investigations including Hirshfeld surface analysis methods reveal that where strongly interacting systems show weak to moderate emission in their condensed states, weakly interacting systems show strong emission yields under the same conditions. The nature of packing and extended structures also affects the emission colors of the NPIs in their solid-states. Furthermore, DFT computational studies were utilized to understand the molecular and cumulative electronic behaviors of the NPIs. The comprehensive studies provide insight into the condensed-state luminescence of aggregation-prone small molecules like NPIs and help to correlate the structure–property relationships.
Co-reporter:George Rajendra Kumar and Pakkirisamy Thilagar
Dalton Transactions 2014 vol. 43(Issue 19) pp:7200-7207
Publication Date(Web):14 Feb 2014
DOI:10.1039/C3DT53638F
Two new dicyanovinyl (DCV) functionalized triarylboranes (Mes2B-π-spacer-DCV, for 1: π-spacer = C6H4, for 2: π-spacer = 2,3,5,6-tetramethyl-phenyl) are reported. The molecular structures of 1 and 2 are similar except for the spacer which connects the boryl and DCV units. This small structural perturbation induces drastic changes in the optical properties of 1 and 2. Compound 2 shows weak dual fluorescence emission in nonpolar solvents and a stronger emission in polar solvents. Compound 1 is weakly fluorescent in polar environments but shows an intense single luminescence peak in less polar environments. Compound 1 exhibits a turn-off fluorescence response for both fluoride and cyanide: in contrast, 2 shows a turn on fluorescence response for both anions with different fluorescence signatures. The NMR titration studies reveal that for compound 2, fluoride binds to the boron centre and cyanide binds to the DCV unit. For compound 1, the fluoride ion binds to the boron center, whereas the CN− binds to both the Ar3B and DCV units.
Co-reporter:Chinna Ayya Swamy P., Ragam N. Priyanka and Pakkirisamy Thilagar
Dalton Transactions 2014 vol. 43(Issue 10) pp:4067-4075
Publication Date(Web):02 Dec 2013
DOI:10.1039/C3DT52565A
The synthesis and optical properties of four new triarylborane–dipyrromethane (TAB–DPM) conjugates (3a–d) containing dual binding sites (hydrogen bond donor and Lewis acid) have been reported. The new compounds exhibit a selective fluorogenic response towards the F− ion. The NMR titrations show that the anions bind to the TAB–DPM conjugates via the Lewis acidic triarylborane centre in preference to the hydrogen bond donor (dipyrromethane) units.
Co-reporter:Sanjoy Mukherjee, Pakkirisamy Thilagar
Dyes and Pigments 2014 110() pp: 2-27
Publication Date(Web):
DOI:10.1016/j.dyepig.2014.05.031
Co-reporter:Sanjoy Mukherjee ;Dr. Pakkirisamy Thilagar
Chemistry - A European Journal 2014 Volume 20( Issue 26) pp:8012-8023
Publication Date(Web):
DOI:10.1002/chem.201304694
Abstract
Systematic structural perturbation has been used to fine-tune and understand the luminescence properties of three new 1,8-naphthalimides (NPIs) in solution and aggregates. The NPIs show blue emission in the solution state and their fluorescence quantum yields are dependent upon their molecular rigidity. In concentrated solutions of the NPIs, intermolecular interactions were found to quench the fluorescence due to the formation of excimers. In contrast, upon aggregation (in THF/H2O mixtures), the NPIs show aggregation-induced emission enhancement (AIEE). The NPIs also show moderately high solid-state emission quantum yields (ca. 10–12.7 %). The AIEE behaviour of the NPIs depends on their molecular rigidity and the nature of their intermolecular interactions. The NPIs 1–3 show different extents of intermolecular (π–π and CH⋅⋅⋅O) interactions in their solid-state crystal structures depending on their substituents. Detailed photophysical, computational and structural investigations suggest that an optimal balance of structural flexibility and intermolecular communication is necessary for achieving AIEE characteristics in these NPIs.
Co-reporter:Sanjoy Mukherjee ;Dr. Pakkirisamy Thilagar
Chemistry - A European Journal 2014 Volume 20( Issue 29) pp:9052-9062
Publication Date(Web):
DOI:10.1002/chem.201305049
Abstract
Three new NPI–BODIPY dyads 1–3 (NPI=1,8-naphthalimide, BODIPY=boron-dipyrromethene) were synthesized, characterized, and studied. The NPI and BODIPY moieties in these dyads are electronically separated by oxoaryl bridges, and the compounds only differ structurally with respect to methyl substituents on the BODIPY fluorophore. The NPI and BODIPY moieties retain their optical features in molecular dyads 1–3. Dyads 1–3 show dual emission in solution originating from the two separate fluorescent units. The variations of the dual emission in these compounds are controlled by the structural flexibilities of the systems. Dyads 1–3, depending on their molecular flexibilities, show considerably different spectral shapes and dissimilar intensity ratios of the two emission bands. The dyads also show significant aggregation-induced emission switching (AIES) on formation of nano-aggregates in THF/H2O with changes in emission color from green to red. Whereas the flexible and aggregation-prone compound 1 shows AIES, rigid systems with less favorable intermolecular interactions (i.e., 2 and 3) show aggregation-induced quenching of emission. Correlations of the emission intensity and structural flexibility were found to be reversed in solution and aggregated states. Photophysical and structural investigations suggested that intermolecular interactions (e.g., π–π stacking) play a major role in controlling the emission of these compounds in the aggregated state.
Co-reporter:Chinna Ayya Swamy P, Sanjoy Mukherjee and Pakkirisamy Thilagar
Journal of Materials Chemistry A 2013 vol. 1(Issue 31) pp:4691-4698
Publication Date(Web):30 May 2013
DOI:10.1039/C3TC30632A
A series of new BODIPYs (4–9) with bulky meso-trimethylsilylphenyl substitution were synthesized. The effect of the substituent's position on the emission properties of the BODIPYs was investigated in detail both in solution and solid state. The new BODIPYs exhibit emission in single crystals and in thin films. The logical increment of steric crowding in the compounds resulted in a periodic change in their conformational flexibility as evident from their 19F NMR spectra, which in turn led to an increase of fluorescence in solution, thin films and single crystals.
Co-reporter:Samir Kumar Sarkar and Pakkirisamy Thilagar
Chemical Communications 2013 vol. 49(Issue 76) pp:8558-8560
Publication Date(Web):29 Jul 2013
DOI:10.1039/C3CC42979B
The structure and photophysical properties of a new triad (borane–bithiophene–BODIPY) 1 have been investigated. Triad 1 exhibits unprecedented tricolour emission when excited at the borane centred high energy absorption band and also acts as a selective fluorescent and colorimetric sensor for fluoride ions with ratiometric response. The experimental results are supported by computational studies.
Co-reporter:Chinna Ayya Swamy P, Sanjoy Mukherjee and Pakkirisamy Thilagar
Chemical Communications 2013 vol. 49(Issue 10) pp:993-995
Publication Date(Web):10 Dec 2012
DOI:10.1039/C2CC38352G
Facile synthesis of two new dimesitylboryl appended BODIPYs is reported. The two dyads have similar fluorescent chromophores but differ in their molecular conformations. They exhibit dual fluorescence, intramolecular energy transfer between boryl and BODIPY chromophores and different fluorescence responses (emission enhancement and quenching) upon fluoride binding.
Co-reporter:Sanjoy Mukherjee and Pakkirisamy Thilagar
Chemical Communications 2013 vol. 49(Issue 66) pp:7292-7294
Publication Date(Web):21 Jun 2013
DOI:10.1039/C3CC43351J
Four “V” shaped 1,8-naphthalimides (1–4) have been synthesized and their fluorescence quantum-yields correlated to their molecular flexibility. The correlation was used for detection of Hg(II) via a chemodosimetric approach. 4 was found to be an AIE active molecule with the formation of fluorescent nanoaggregates.
Co-reporter:PAGIDI SUDHAKAR
Journal of Chemical Sciences 2013 Volume 125( Issue 1) pp:41-49
Publication Date(Web):2013 January
DOI:10.1007/s12039-012-0356-8
Optically active Lewis acids and Lewis pairs were synthesized and characterized by multinuclear NMR, UV/Vis spectroscopy and elemental analysis. Optical rotation measurements were carried out and the absolute configuration of the new chiral molecules confirmed by single crystal X-ray diffraction.
Co-reporter:Pagidi Sudhakar, Sanjoy Mukherjee, and Pakkirisamy Thilagar
Organometallics 2013 Volume 32(Issue 10) pp:3129-3133
Publication Date(Web):May 3, 2013
DOI:10.1021/om301197f
The structure and photophysical properties of two known borylanilines, 4-(dimesitylboryl)aniline (1) and 4-(dimesitylboryl)-3,5-dimethylaniline (2), have been investigated. 1 and 2 have similar donor and acceptor centers but differ in their molecular conformations. Compounds 1 and 2 have been structurally characterized, and they exhibit a rare form of intermolecular N–H- - -π electrostatic interactions. The structure and photophysical properties of 1 and 2 are discussed in the context of computational results.
Co-reporter:Pakkirisamy Thilagar, Pagidi Sudhakar, P. Chinna Ayya Swamy, Sanjoy Mukherjee
Inorganica Chimica Acta 2012 390() pp: 163-166
Publication Date(Web):
DOI:10.1016/j.ica.2012.03.016
Co-reporter:V. Chandrasekhar, P. Thilagar, and A. Steiner
Crystal Growth & Design 2011 Volume 11(Issue 5) pp:1446-1449
Publication Date(Web):April 12, 2011
DOI:10.1021/cg2001927
The reaction of [n-BuSn(O)OH]n and 9-hydroxy-9-fluorenecarboxylic acid in the presence of p-X-C6H4-OH (X = F, Br) afforded hydroxyl-rich hexameric organostannoxane prismanes. The crystal structures of these prismanes reveal guest-assisted supramolecular structures. Self-assembly of these compounds on a mica surface affords organooxotin nanotubules.
Co-reporter:Sanjoy Mukherjee and Pakkirisamy Thilagar
Chemical Communications 2016 - vol. 52(Issue 6) pp:NaN1093-1093
Publication Date(Web):2015/10/26
DOI:10.1039/C5CC08213G
In recent times, luminescent materials with tunable emission properties have found applications in almost all aspects of modern material sciences. Any discussion on the recent developments in luminescent materials would be incomplete if one does not account for the versatile photophysical features of boron containing compounds. Apart from triarylboranes and tetra-coordinate borate dyes, luminescent materials consisting of boron clusters have also found immense interest in recent times. Recent studies have unveiled the opportunities hidden within boranes, carboranes and metalloboranes, etc. as active constituents of luminescent materials. From simple illustrations of luminescence, to advanced applications in LASERs, OLEDs and bioimaging, etc., the unique features of such compounds and their promising versatility have already been established. In this review, recent revelations about the excellent photophysical properties of such materials are discussed.
Co-reporter:Sanjoy Mukherjee and Pakkirisamy Thilagar
Chemical Communications 2013 - vol. 49(Issue 66) pp:NaN7294-7294
Publication Date(Web):2013/06/21
DOI:10.1039/C3CC43351J
Four “V” shaped 1,8-naphthalimides (1–4) have been synthesized and their fluorescence quantum-yields correlated to their molecular flexibility. The correlation was used for detection of Hg(II) via a chemodosimetric approach. 4 was found to be an AIE active molecule with the formation of fluorescent nanoaggregates.
Co-reporter:George Rajendra Kumar and Pakkirisamy Thilagar
Dalton Transactions 2014 - vol. 43(Issue 10) pp:NaN3879-3879
Publication Date(Web):2013/11/28
DOI:10.1039/C3DT52768A
A facile synthetic route for a new class of organoborane compounds (Mes)2B-arene-acacH and (Mes)2B-arene-acacBF2 (Mes = mesityl and arene = C6H4 or C6Me4) is reported. The new dyads exhibit intriguing photophysical properties. A small structural change in spacer connecting the two chromophores leads to fine tuning of photophysical properties. The dyad containing 2,3,5,6-tetramethyl phenyl spacer acts as a selective “turn-on” chemodosimetric sensor for cyanide ion. Steric crowding around the boron centre significantly alters anion binding events. From NMR titration studies it is established that fluoride and cyanide follow different binding mechanisms which lead to intriguing optical properties in the reported probes.
Co-reporter:George Rajendra Kumar and Pakkirisamy Thilagar
Dalton Transactions 2014 - vol. 43(Issue 19) pp:NaN7207-7207
Publication Date(Web):2014/02/14
DOI:10.1039/C3DT53638F
Two new dicyanovinyl (DCV) functionalized triarylboranes (Mes2B-π-spacer-DCV, for 1: π-spacer = C6H4, for 2: π-spacer = 2,3,5,6-tetramethyl-phenyl) are reported. The molecular structures of 1 and 2 are similar except for the spacer which connects the boryl and DCV units. This small structural perturbation induces drastic changes in the optical properties of 1 and 2. Compound 2 shows weak dual fluorescence emission in nonpolar solvents and a stronger emission in polar solvents. Compound 1 is weakly fluorescent in polar environments but shows an intense single luminescence peak in less polar environments. Compound 1 exhibits a turn-off fluorescence response for both fluoride and cyanide: in contrast, 2 shows a turn on fluorescence response for both anions with different fluorescence signatures. The NMR titration studies reveal that for compound 2, fluoride binds to the boron centre and cyanide binds to the DCV unit. For compound 1, the fluoride ion binds to the boron center, whereas the CN− binds to both the Ar3B and DCV units.
Co-reporter:Sanjoy Mukherjee and Pakkirisamy Thilagar
Physical Chemistry Chemical Physics 2014 - vol. 16(Issue 38) pp:NaN20877-20877
Publication Date(Web):2014/08/22
DOI:10.1039/C4CP02071E
An investigation of a series of seven angular “V” shaped NPIs (1–7) is presented. The effect of substitution of these structurally similar NPIs on their photophysical properties in the solution-state and the solid-state is presented and discussed in light of experimental and computational findings. Compounds 1–7 show negligible to intensely strong emission yields in their solid-state depending on the nature of substituents appended to the oxoaryl moiety. The solution and solid-state properties of the compounds can be directly correlated with their structural rigidity, nature of substituents and intermolecular interactions. The versatile solid-state structures of the NPI siblings are deeply affected by the pendant substituents. All of the NPIs (1–7) show antiparallel dimeric π–π stacking interactions in their solid-state which can further extend in a parallel, alternate, orthogonal or lateral fashion depending on the steric and electronic nature of the C-4′ substituents. Structural investigations including Hirshfeld surface analysis methods reveal that where strongly interacting systems show weak to moderate emission in their condensed states, weakly interacting systems show strong emission yields under the same conditions. The nature of packing and extended structures also affects the emission colors of the NPIs in their solid-states. Furthermore, DFT computational studies were utilized to understand the molecular and cumulative electronic behaviors of the NPIs. The comprehensive studies provide insight into the condensed-state luminescence of aggregation-prone small molecules like NPIs and help to correlate the structure–property relationships.
Co-reporter:George Rajendra Kumar, Samir Kumar Sarkar and Pakkirisamy Thilagar
Physical Chemistry Chemical Physics 2015 - vol. 17(Issue 45) pp:NaN30432-30432
Publication Date(Web):2015/10/12
DOI:10.1039/C5CP05378A
Three new triarylborane conjugated dicyanovinyl chromophores (Mes2B–π–donor–DCV); donor: N-methyldiphenylamine (1) and triphenylamine (2 and 3 [with two BMes2 substitutions]) of type A–D–A (acceptor–donor–acceptor) are reported. Compounds 1–3 exhibit intense charge transfer (CT) absorption bands in the visible region. These absorption peaks are combination CT bands of the amine donor to both the BMes2 and DCV units. This inference was supported by theoretical studies. Compound 1 shows weak fluorescence compared to 2 and 3. The discrimination of fluoride and cyanide ions is essential in the case of triarylborane (TAB) based anion sensors as a similar response is given towards both the anions. Anion binding studies of 1, 2 and 3 showed that fluoride ions bind selectively to the boron centre and block the corresponding CT transition (donor to BMes2) leaving the other CT transition to be red shifted. On the other hand, cyanide ions bind with both the receptor sites and stop both the CT transition processes and hence a different colorimetric response was noted. The binding of F−/CN− induces colour changes in the visible region of the electronic spectra of 2 and 3, which allows for the naked-eye detection of F− and CN− ions. The anion binding mechanisms are established using NMR titration experiments.
Co-reporter:Chinna Ayya Swamy P, Sanjoy Mukherjee and Pakkirisamy Thilagar
Journal of Materials Chemistry A 2013 - vol. 1(Issue 31) pp:NaN4698-4698
Publication Date(Web):2013/05/30
DOI:10.1039/C3TC30632A
A series of new BODIPYs (4–9) with bulky meso-trimethylsilylphenyl substitution were synthesized. The effect of the substituent's position on the emission properties of the BODIPYs was investigated in detail both in solution and solid state. The new BODIPYs exhibit emission in single crystals and in thin films. The logical increment of steric crowding in the compounds resulted in a periodic change in their conformational flexibility as evident from their 19F NMR spectra, which in turn led to an increase of fluorescence in solution, thin films and single crystals.
Co-reporter:Sanjoy Mukherjee and Pakkirisamy Thilagar
Journal of Materials Chemistry A 2016 - vol. 4(Issue 14) pp:NaN2662-2662
Publication Date(Web):2015/09/08
DOI:10.1039/C5TC02406D
Recent advancements of material science and its applications have been immensely influenced by the modern development of organic luminescent materials. Among all organic luminogens, boron containing compounds have already established their stature as one of the indispensable classes of luminescent dyes. Boron, in its various forms e.g. triarylboranes, borate dyes and boron clusters, has attracted considerable attention owing to its several unique and excellent photophysical features. In very recent times, beyond the realms of solution-state studies, luminescent boron-containing compounds have emerged as a large and versatile class of stimuli responsive materials. Based on several fundamental concepts of chemistry, researchers have come up with an admirable variety of boron-containing materials with AIE (aggregation-induced emission), mechano-responsive luminescence, thermoresponsive-luminescence as well as a number of purely organic phosphorescent materials and other standalone examples. The unique chemical as well as physical properties of boron-containing compounds are largely responsible for the development of such materials. In this review these new findings are brought together.
Co-reporter:Chinna Ayya Swamy P., Ragam N. Priyanka and Pakkirisamy Thilagar
Dalton Transactions 2014 - vol. 43(Issue 10) pp:NaN4075-4075
Publication Date(Web):2013/12/02
DOI:10.1039/C3DT52565A
The synthesis and optical properties of four new triarylborane–dipyrromethane (TAB–DPM) conjugates (3a–d) containing dual binding sites (hydrogen bond donor and Lewis acid) have been reported. The new compounds exhibit a selective fluorogenic response towards the F− ion. The NMR titrations show that the anions bind to the TAB–DPM conjugates via the Lewis acidic triarylborane centre in preference to the hydrogen bond donor (dipyrromethane) units.
Co-reporter:Samir Kumar Sarkar and Pakkirisamy Thilagar
Chemical Communications 2013 - vol. 49(Issue 76) pp:NaN8560-8560
Publication Date(Web):2013/07/29
DOI:10.1039/C3CC42979B
The structure and photophysical properties of a new triad (borane–bithiophene–BODIPY) 1 have been investigated. Triad 1 exhibits unprecedented tricolour emission when excited at the borane centred high energy absorption band and also acts as a selective fluorescent and colorimetric sensor for fluoride ions with ratiometric response. The experimental results are supported by computational studies.
Co-reporter:Chinna Ayya Swamy P, Sanjoy Mukherjee and Pakkirisamy Thilagar
Chemical Communications 2013 - vol. 49(Issue 10) pp:NaN995-995
Publication Date(Web):2012/12/10
DOI:10.1039/C2CC38352G
Facile synthesis of two new dimesitylboryl appended BODIPYs is reported. The two dyads have similar fluorescent chromophores but differ in their molecular conformations. They exhibit dual fluorescence, intramolecular energy transfer between boryl and BODIPY chromophores and different fluorescence responses (emission enhancement and quenching) upon fluoride binding.
Co-reporter:Sanjoy Mukherjee and Pakkirisamy Thilagar
Chemical Communications 2015 - vol. 51(Issue 55) pp:NaN11003-11003
Publication Date(Web):2015/05/19
DOI:10.1039/C5CC03114A
Luminescent organic materials have attracted significant attention in recent times owing to their opportunities in various functional applications. Interestingly, unlike fluorescence, opportunities hidden within the phosphorescence properties of organic compounds have received considerably less attention even until last few years. It is only in the second decade of the 21st century, within a time span of less than last 5 years, that the concepts and prospects of organic compounds as phosphorescent materials have evolved rapidly. The previously perceived limitations of organic compounds as phosphorescent materials have been overcome and several molecules have been designed using old and new concepts, such as heavy atom effects, matrix assisted isolation, hydrogen bonding and halogen bonding, thereby gaining access to a significant number of materials with efficient phosphorescent features. In addition, significant improvements have been made in the development of RTP (room temperature phosphorescent) materials, which can be used under ambient conditions. In this review, we bring together the vastly different approaches developed by various researchers to understand and appreciate this recent revolution in organic luminescent materials.
Co-reporter:Samir Kumar Sarkar, George Rajendra Kumar and Pakkirisamy Thilagar
Chemical Communications 2016 - vol. 52(Issue 22) pp:NaN4178-4178
Publication Date(Web):2016/02/11
DOI:10.1039/C6CC00823B
The design and synthesis of two structurally close and complementarily fluorescent boron based molecular siblings 2 and 3 are reported. The luminescence properties of individual triads are modulated to complement each other by controlling the intramolecular energy transfer in 2 and 3. The binary mixture of 2 and 3 emits white-light.
Co-reporter:Kalluvettukuzhy K. Neena, Pagidi Sudhakar, Kumbhar Dipak and Pakkirisamy Thilagar
Chemical Communications 2017 - vol. 53(Issue 26) pp:NaN3644-3644
Publication Date(Web):2016/12/16
DOI:10.1039/C6CC09717K
Herein we report the multifunctional characteristics such as aggregation induced emission (AIE), triboluminescence (TL), mechanofluorochromism and temperature sensing of molecular siblings 1 (10-(dimesitylboryl)phenothiazine) and 2 (10-(bis(2,6-dimethylphenyl)boryl)phenothiazine).
Co-reporter:Pagidi Sudhakar, Kalluvettukuzhy K. Neena and Pakkirisamy Thilagar
Journal of Materials Chemistry A 2017 - vol. 5(Issue 26) pp:NaN6546-6546
Publication Date(Web):2017/05/26
DOI:10.1039/C7TC01676J
Design, synthesis and structural characterization of borylated aryl amines, Mes2BAr {Ar = C6(CH3)4NR2 (1, 4); C6H4NR2 (2, 5); C6H3(NR2)2 (3, 6); R = H or CH3}, were reported. The intriguing optical signatures undoubtedly revealed their donor–acceptor characteristics and a bright tunable solid state emission is readily realized. The solid state luminescence characteristics of 1 and 3 were sensitive to mechanical stress with distinguishable emission color changes. Multiple strong intermolecular hydrogen bonds (N–H⋯N and N–H⋯π) accompanied by subtle conformational changes play a significant role in the piezochromic response. PXRD and FT-IR spectroscopic studies and insensitivity of substituted derivatives to mechanical stress support the above inference. Interestingly, compound 3 crystallized in two different polymorphic forms 3BP and 3GP, which showed distinct luminescence, i.e., green and blue color under UV light. Such changes are due to their distinct hydrogen-bond network assembly in the solid state. Quantum mechanical calculations were performed in order to corroborate the optical properties.
Co-reporter:Chinna Ayya Swamy P and Pakkirisamy Thilagar
Dalton Transactions 2016 - vol. 45(Issue 11) pp:NaN4696-4696
Publication Date(Web):2016/01/25
DOI:10.1039/C5DT02678D
Triarylborane-A2H2 (1) and triarylborane-Zn-A2H2 porphyrins (2) have been synthesized by acid catalyzed condensation of 4-dimesitylboryl-benzaldehyde and dipyrromethane under ambient conditions. Compounds 1 and 2 showed multiple emission bands upon excitation at the triarylborane dominated absorption region (350 nm). Detailed experimental and computational studies show that the multiple emission features of 1 and 2 arise as a result of a partial energy transfer from the donor (triarylborane) to the acceptor (porphyrin) moieties. Compounds 1 and 2 showed very high selectivities towards fluoride ions compared to other competing anions.
Co-reporter:Kalluvettukuzhy K. Neena and Pakkirisamy Thilagar
Journal of Materials Chemistry A 2016 - vol. 4(Issue 48) pp:NaN11473-11473
Publication Date(Web):2016/11/07
DOI:10.1039/C6TC04470K
Replacing homodiatomic CC in polyaryl systems with an isoelectronic heterodiatomic B–N unit is a powerful strategy for the rational design and construction of novel materials with versatile properties. Herein, we uncover for the first time the intriguing aggregation induced emission (AIE) properties of four tetra-arylaminoboranes (TAAB) 1–4 in which the CC fragment of the tetra-arylethene molecule is replaced by the isoelectronic B–N unit. The dipole of these compounds was fine-tuned by judiciously employing amine donor(s) on the aryl groups attached to nitrogen. The optical properties are intriguing and are greatly influenced by the number of amine donor(s) on the B–N fragment. Compounds 1–4 are weakly emissive in dilute solutions, but are strongly emissive in the aggregated/condensed state. Compounds with strong amine donor(s) on the B–N fragment exhibit reversible mechanofluorochromism. The luminescent nano-aggregates of 1–4 were explored for the detection of nitroaromatic compounds. The experimental observations are supported by detailed computational studies.
