Organic small-molecule-based devices with multilevel electroresistive memory behaviors have attracted more and more attentions due to their super-high data-storage density. However, up to now, only ternary memory molecules have been reported, and ternary storage devices may not be compatible with the binary computing systems perfectly. In this work, a donor–acceptor structured molecule containing three electron acceptors is rationally designed and the field-induced charge-transfer processes can occur from the donors. Organic quaternary memory devices based on this molecule are successfully demonstrated for the first time. The switching threshold voltages of the memory device are –2.04, –2.73, and –3.96 V, and the current ratio of the “0,” “1,” “2,” and “3” states is 1:10^1.78:10^3.47:10^5.36, which indicate a low possibility of read and write errors. The results represent a further step in organic high-density data-storage devices and will inspire the further study in this field.

Advanced materials with intelligent switchable surfaces that can respond to external stimuli have encouraging application in oil/water separation and oil clean-up. Herein, a facile method has been demonstrated to prepare a robust and superhydrophobic sponge by integrating the melamine-formaldehyde (MF) sponge with light-responsive spiropyran derivative via a radical copolymerization process, which shows the light-controllable oil absorption and desorption property under light illumination. The key chemistry is that the MF sponge is first modified with vinyl for the copolymerization via a facile solution-immersion process. Afterward, light-responsive spiropyran methacrylate monomers are copolymerized with vinyl-modified MF sponges to fabricate polymer-MF sponge composites (denoted as SP-MF sponge), resulting in the wettability conversion from amphiphilic to superhydrophobic with a water contact angle of 155.5°. The superhydrophobic MF sponge shows excellent selectivity and high absorption capacity for a range of oils and organic solvents from 70 to 154 times its own weight. More importantly, since the hydrophobic polymer of the SP-MF sponge can be converted to hydrophilic under UV illumination, the wettability of SP-MF sponge will change to hydrophilic, resulting in the light-controlled oil desorption process. These findings offer a new responsive absorbent material and a new approach for oil recovery.

Organic resistive memory devices have been considered as potential candidates for next-generation, non-volatile memories. As prerequisites for real applications such memory devices would need to attain a high storage density, low power consumption, and, especially, long-term stability. Although extensive research has been carried out these issues have thus far not been resolved in a satisfactory manner. In this work, two phenothiazine-cored, cyano-substituted diphenylethene derivatives with trifluoromethyl and nitro-groups (PTZ-CF₃ and PTZ-NO₂) are presented and the performance of electroresistive memory devices based on these two molecules is investigated. Both molecules can realize ternary memory data storage with ternary device yields as high as 70%. In addition, PTZ-CF₃-based devices exhibit a long-term stability (up to three months), lower operating voltage (−1.01/−2.42 V), and higher ON/OFF ratios (>10⁴ and 10³) compared to those based on PTZ-NO₂. Such superior performance can be attributed to the introduced trifluoromethyl group, which leads to a better solubility, film-forming ability, and hydrophobicity. These results may serve as a guide to improve the performance and promote the development of organic memories.

One of the most pervasive environmental issues is water contaminated with oil or organic solvents; this global challenge calls for emerging materials that could effectively separate oil or organic solvents from water. Here, such a material is presented by integrating 3D porous graphene foam (GF) with a smart pH-responsive surface, showing switchable superoleophilic and superoleophobic properties in response to the medium pH. The key chemistry applied in this study is to modify the 3D porous GF with an amphiphilic copolymer containing a block of poly(2-vinylpyridine) and polyhexadecyl acrylate (P2VP-b-PHA), resulting in a smart GF (ss-GF) with an either superoleophilic or superoleophobic surface at different medium pH. The as-designed ss-GF can effectively absorb oil or organic solvents from the aqueous media by using its superoleophilic surface at pH of 7.0, and it can also completely release the adsorbates when the pH is switched to 3.0 (and the surface of ss-GF is therefore shifted to superoleophobic); with a continuous operation of many cycles (e.g., >10). Furthermore, the as-designed ss-GF shows superior absorption capacity for oil and organic solvent, with a high capacity of ≈196 times of the weight relative to that of the pristine ss-GF. The present work suggests encouraging applications of the ss-GF to water–oil and water–organic solvent separation.

For the organic memory device with vertically arranged electrodes, controlling the film-packing to achieve highly oriented crystallite arrangement is critical but challenging for obtaining the satisfied performance. Here, the effect of backbone planarity on the crystallite orientation is studied. Two diketopyrrolopyrrole-based small molecules (NI₂PDPP and NI₂FDPP) are synthesized with increasing planarity by furan substitution for phenyl rings. Upon thin-film analysis by atomic force microscopy, X-ray diffraction, and grazing-incidence small-angle X-ray scattering, the orientations of these crystallites are demonstrated to be well controlled through tailoring molecular planarity. The highly planar NI₂FDPP in film prefers out-of-plane crystallite orientation with respect to the substrate normal while the nonplanar NI₂PDPP displays less ordered packing with a broad orientation distribution relative to the substrate. As a result, NI₂FDPP-based memory device exhibits superior multilevel performance. More importantly, the oriented crystallite arrangement favors uniformity in NI₂FDPP thin film, thus, the device displays higher reproducibility of memory effects. This study provides an effective synthetic strategy for designing multilevel memory materials with favorable crystallite orientation.

A new atom-transfer radical polymerization (ATRP) initiator 4-[1-(2-dodecyl-1,3-dioxo-2,3-dihydro-1H-benzo[de]isoquinolin-6-yl)-3-(4-nitrophenyl)-4,5-dihydro-1H-pyrazol-5-yl]phenyl 2-bromo-2-methylpropanoate (IN) as an electron acceptor (A) and a monomer 2-(9H-carbazole-9-yl)-ethyl methacrylate (MCz) as an electron donor (D) were simultaneously introduced into two different D–A polymer systems by using the end-functionalizing or blending method. The mass percentage of IN in the end-functionalized polymer PMCz-IN and the mixed polymer composite PMCz+IN were both controlled at approximately 1.0 wt %. The optical, electrochemical, and surface morphology properties of the two polymeric films prepared by means of spin-coating technology were comparatively investigated. Sandwich devices based on PMCz-IN and PMCz+IN demonstrated nonvolatile write-once-read-many-times memory (WORM) and volatile static random access memory (SRAM) characteristics, respectively, which were further verified by the Kelvin probe force microscopy (KPFM) measurements. The proposed memory mechanism could be attributed to the formation of a stable charge-transfer (CT) complex for PMCz-IN and an unstable CT complex for PMCz+IN. Furthermore, the different distribution of IN in the two polymeric films might be the main reason for the stability of the CT complex.

Three small organic molecules that contained a phenothiazine backbone and triphenylamine (TPA), carbazole (CZ), or anthracene (AN) as a terminal electron donor were synthesized and fabricated in ITO/organic film/Al sandwiched memory devices. The influence of the extent of conjugation in the three molecules on the performance of their corresponding devices was investigated and the results showed that all of the fabricated devices exhibited nonvolatile ternary WORM character, whilst the switch threshold voltages decreased on moving from TPA to CZ and AN, which is promising for low-power-consumption data storage. These results revealed that tailoring the extent of conjugation in the terminal electron donor in the D–A molecules could effectively optimize the device performance, in particular the switch-threshold voltage, which could be instructive for the design of low-energy-consumption memory materials.

In this study, two structural isomers α-PBT and β-PBT, which only differ in the phenyl substituent position on the quinoline chromophore, have been designed and successfully synthesized. The influences of substituent position on the film morphology and the storage performance of the devices were investigated. Both molecules employed in the memory devices exhibited same nonvolatile binary (write-once-read-many-times; WORM) characteristics, but the switch threshold voltage (Vth) of the β-PBT-based device was clearly lower than that of the α-PBT-based device. Simulation results demonstrate that the variation of the phenyl substituent position led to different intermolecular stacking styles and thus to varied grain sizes for each film morphology. This work illustrates that altering the phenyl substituent position on the molecular backbone could improve the quality of the film morphology and reduce power consumption, which is good for the rational design of future advanced organic memory devices (OMDs).

Four 1,8-naphthalimide hydrazone molecules with different electron-donating groups have been applied in the study of linear and nonlinear optical (NLO) properties. These compounds showed strong green emission in solution. Their NLO properties such as two-photon absorption (TPA) behavior with femtosecond laser pulses ca. 800 nm and excited-state absorption (ESA) behavior with nanosecond laser pulses at 532 nm were investigated. Compound 4 presented the largest two-photon cross section (550 GM) among them due to two factors: the conjugated length of compound 4 is the longest and the electron-donating ability of compound 4 is the strongest. Different from TPA behavior, compound 2 showed the best nonlinear absorption properties at 532 nm and its nonlinear absorption coefficient and third-order nonlinear optical susceptibilities χ⁽³⁾ were up to 1.41×10⁻¹⁰ MKS and 4.65×10⁻¹² esu, respectively. Through the modification of the structure, the nonlinear optical properties of these compounds at different wavelengths (532 and 800 nm) were well tuned. The great broad-band nonlinear optical properties indicate hydrazones are good candidates for organic nonlinear optical absorption materials.

4-(3-(4-(Dimethylamino)phenyl)acryloyl)phenyl-2-bromo-2-methylpropanoate (APPBr) was used for the heterogeneous atom transfer radical polymerization (ATRP) of styrene (St) with copper(I) bromide/N,N,N′,N′′,N′′-pentamethyldiethylenetriamine (PMDETA) catalytic system. The functional end group was characterized via UV-Vis and ¹H NMR spectra. The polymerization showed a first-order kinetic characteristic and each of the obtained polymers had well-controlled molecular weight and relatively low polydispersity index (PDI). Furthermore, the obtained end-functionalized polystyrene (PS) in solution showed strong green-light emission which is further affected by mixing different metal cations. In particular, the fluorescent intensity of the polymer was decreased in the presence of Ag⁺, Cu²⁺ and Fe³⁺.

This paper is focused on investigation of coordination polymers constructed by Cu(II) and rigid pyridyl ligands, such as 4,4′-bipyridyl-1,2,4-triazole (Hpytz) and 1,10-phenanthroline (phen) from a mononuclear precursor [Cu(DMF)₄(NCS)₂] (1). As expected, the complex was self-assembled with phen to form a 1D double-stranded chain of [Cu(phen)(µ-SCN)₂]_∞ (2), with Hpytz to form 1D zigzag chain of [Cu₂(µ-Hpytz)₂(NCS)₂(DMF)₂(µ-SCN)₂]_∞ (3) in which thiocyanate anion linked the Cu-µ-Hpytz-Cu chain into an infinite 2D network via weak Cu···S interaction. To treat 3 with the bridged anion dca, a novel 3D framework [Cu(µ-Hpytz)(µ-dca)(µ-SCN)] _∞ (4) was obtained in which Cu-µ-Hpytz-Cu chain is preserved and both thiocyanate anion and dicyanamide (dca) act as bridging ligands. In addition, complex 3 was applied as a metal catalyst in polymerization of MMA in aqueous solution at room temperature.

We report the synthesis of two imidazole-based small molecules with different planarity of terminal aromatic rings and their application in memory devices with a sandwich configuration. The optical, electric, and the on-based device performances were systematically investigated. Surprisingly, the device based on BT-PMZ exhibited volatile static random access memory (SRAM) behavior, whereas that based on BT-BMZ showed nonvolatile write-once-read-many-times (WORM) behavior. Further studies on the film morphology and the molecular electronic structure were carried out to investigate the underlying mechanism for the large difference in their performance. Moreover, the performance of the device that incorporates a LiF buffer layer (5 nm) embedded at the interface between the BT-BMZ active layer and the Al top electrode as well as that of the device with a cold-deposited top electrode of mercury droplet was further investigated. At that point a dramatic change in memory performance of the devices from the WORM to SRAM type was observed. The intrinsic volatile SRAM performance for the two molecules results from the moderate electron-withdrawing strength of the acceptor moieties and thus weak trapping of the charge carriers.

In the presence or absence of water, a Schiff-base compound, 4-amino-3-(2-(2-hydroxybenzylidene)hydrazinyl)-1H-1,2,4-triazole-5(4H)-thione (HATT), forms different crystalline states (HATT, HATT⋅2 H₂O, and a lamellar structure, m-HATT⋅n H₂O), which show different luminescence emission properties. Herein, we investigate the emission of HATT and the role of water molecules. A water molecule, which acts as both a hydrogen-bond acceptor and -donor, enlarges the distance between adjacent HATT molecules and hinders non-radiative decay pathways.

Multifunctional theranostic systems with good biocompatibility, strong clinical imaging capability, and target specificity are the desired features of future medicine. Here, the design of a theranostic nanocomposite capable of simultaneous targeting and imaging of the cancer cells is presented. It releases its drug payload by a controlled release mechanism. The nanocomposite contains luminescent gold nanocluster (L-AuNC) photostable and biocompatible diagnostic probes conjugated to a folic acid (FA)-modified pH-responsive amphiphilic polymeric system for controlled drug release. The nanocomposite uses a core-satellite structure to encapsulate hydrophobic drugs and releases the drug payload in mildly acidic endosomal/lysosomal compartments by the action of the pH-labile linkages in the polymer. In vivo studies show the selective accumulation of the FA-conjugated nanocomposite in tumor tissues by folate-receptor-mediated endocytosis. These findings demonstrate the potential of the nanocomposite as a nontoxic, folate-targeting, pH-responsive drug carrier that is useful for the early detection and therapy of folate-overexpressing cancerous cells.

A phenoxazinium-based chemosensor (1) bearing di(2-picolyl)amine unit was successfully synthesized. The result shows that it is a red-emitting and full water-soluble chemosensor for the selective detection of Cu²⁺ in pure water. The fluorescence on-off mechanism was studied by ab initio calculations. To confirm the suitability of 1 for biological applications, it was employed in the fluorescence detection of the intracellular Cu²⁺ with cultured KB cells. The results indicated that 1 had good membrane permeability and could be useful for the fluorescence microscopic imaging.

Two colorimetric probes based on oxazine-thione 1a and 1b for the detection of Hg²⁺ were designed and synthesized. The probe 1a exhibits about a 70-fold enhancement in fluorescence and a color change after the addition of Hg²⁺ in acetonitrile/wate solvent. 1a was also highly selective to Hg²⁺ over other metal ions. Furthermore, DFT/TDDFT calculations were taken to explain the OFF-ON emission response.

A new amphiphilic copolymer (copoly-(MR-BMA-HEA-MAA), PRBHM) containing multihydroxyl segments was designed and synthesized for application in drug carrier. PRBHM can be dissolved in water to form aggregates directly with a critical aggregate concentration (CAC) of 0.0138 mg mL⁻¹. The chains of PRBHM can be collapsed into hydrophobic globules when pH decreases from neutral to slightly acid condition (pH = 5.0–7.0) in water. Since the hydrophilic hydroxyl group is independent on pH, PRBHM can keep stable both in neutral and slightly acid aqueous solutions. The hydrophobic small molecules such as 5-(4-(4-vinylbenzyloxy) phenyl)-4,5-dihydro-1,3-diphenyl-1H-pyrazole (PY) can be loaded into PRBHM aggregates via ultrasonic treatment in water, and can be internalized into BEL-7402 cancer cells. The cytotoxicity determination also indicates the good biocompatibility of PRBHM in potential application as a drug carrier. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

A novel ultrathin platinum nanowire with uniform length and a diameter of 1.5 nm was synthesized by acidic etching of FePt nanowire in methanol. This nanowire was characterized by high-resolution transmission electron microscopy (HRTEM). X-ray diffraction (XRD) data indicated that the main plane is (111). The ability of this nanowire to catalyze the heterogeneous hydrogenation of nitroaromatics to give the corresponding amines has been investigated. The catalyst showed satisfactory activity in various solvents under mild conditions and showed excellent stability. The catalytic performance was also evaluated in the one-pot reduction of nitroaromatics and amidation with carboxylic acids under a hydrogen atmosphere at 100 °C. These methods for the hydrogenation of nitroaromatics and the direct amidation of nitroaromatics with carboxylic acids are simple, economical, and environmentally benign, and have practical advantages for the synthesis of amines and amides without the production of toxic byproducts.

Traditionally important in the pharmaceutical, agrochemical, and synthetic dye industries, CN coupling has proved useful for the preparation of a number of valuable organic compounds. Here, a new method for the direct one-pot reductive CN coupling from carbonyl and aromatic nitro compounds is described. Employing ultrathin platinum nanowires as the catalyst and hydrogen as the reducing agent, N-alkylamines were achieved in high yields. Debenzylation products were not detected after prolonged reaction times. Time-dependent analysis, ReactIR spectroscopy and DFT calculations revealed that the CN coupling proceeded through a different mechanism than traditional “reductive amination.” N-Alkylamines were directly obtained by intermolecular dehydration over platinum nanowires under a hydrogen atmosphere, instead of intramolecular water elimination and imine hydrogenation.

Iron oxide coated platinum nanowires (Pt@Fe₂O₃ NWs) with a diameter of 2.8 nm have been prepared by the oxygen oxidation of FePt NWs in oleylamine. These “cable”-like NWs were characterised by transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and X-ray absorption fine structure analysis. These Pt@Fe₂O₃ NWs were used as “non-support” heterogeneous catalysts in oxidation of olefins and alcohols. The results revealed that it is an active and highly selective catalyst. Styrene derivatives were tested with molecular oxygen as the sole oxidant, with benzaldehyde successfully obtained from styrene in an absolute yield of 31 %, whereas the use of tert-butyl hydroperoxide as the sole oxidant in the oxidation of alcohols led to yields of more than 80 % of the corresponding ketone or aldehyde. This unsupported catalyst was found to be more active (TOF=96.5 h⁻¹) than other reported Fe₂O₃ nanoparticle catalysts and could be recycled multiple times without any notable decrease in activity. Our findings will extend the use of such nanomaterial catalysts to new catalytic systems.

Poly(o-methyl-acrylamideyl-benzoic acid)-ZnS (P(o-MAABA)-ZnS) nanocomposites have been prepared and characterized. The resultant P(o-MAABA)-ZnS nanocomposites in solution show two emissions in the purple-light area (370 nm) and in the blue-light area (425 nm), which are assigned to the polymer and ZnS nanoparticles, respectively. The coordination between the polymer and Zn²⁺ and the surface chemical composition has been studied by Infrared spectroscopy and X-ray photoelectron spectroscopy (XPS). The particle size of ZnS nanoparticles was homogeneous and the average size was 3.8 nm, which were characterized by UV absorption spectrum and X-ray Diffraction. The P(o-MAABA)-ZnS composites displays good film formability and the films also show two emissions in 370 and 425 nm. After doped with Tb³⁺, there was effective energy transfer from ZnS nanoparticles to Tb³⁺. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Nanocomposites comprised of poly(3-alkyl thiophenes) (P3ATs)/semiconductor nanoparticles exhibited excellent photoelectricity performance because of contributions from both the P3ATs and the semiconductor nanoparticles. In this article, poly(3-decylthiophene) (P3DT) was synthesized and P3DT/CdS nanocomposites were prepared using an in-situ method. The CdS nanoparticles exhibited strong quantum effect on the photoluminescence (PL) properties of P3DT/CdS and the nanocomposites exhibit an enhanced PL and red-shifted emission with increasing CdS content. The PL quenched at CdS-to-3DT ratio at 0.35 mol%. The charge-transfer process between P3DT and CdS particles is discussed. P3DT/CdS composites also exhibit excellent nonlinear optical (NLO) properties. The third-order NLO coefficient of P3DT/CdS (χ⁽³⁾ = −4.62 × 10⁻¹² esu) is higher than that of P3DT. The P3DT/CdS nanocomposites have potential optical applications. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers

Polystyrene incorporating carboxylate group as α-end was synthesized by using initiator 4-chloromethyl benzoic acid via atom transfer radical polymerization. Its ω-chlorine end-group was transformed by cumic acid, diethyl malonate, and thiol, respectively, to form end-functionalized telechelic polystyrenes. These PSts with different functionalized ω-end group (PSt1, PSt2, and PSt3) were obtained and characterized by H NMR and TGA. This type of end-functionalized telechelic polymers can further act as polymeric ligands to form polymeric metal complexes. In this study, PSt1 with carboxylate group at each end was allowed to react with Eu(DBM)₂Cl·2H₂O to afford a new polymeric complex PSt1-Eu(III) showing significant red-light emission. Moreover, the film of PSt1-Eu shows similar emission pattern with its DMF solution. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008