A 12 V Substrate-Integrated PbO2-Activated Carbon Asymmetric Hybrid Ultracapacitor with Silica-Gel-Based Inorganic-Polymer Electrolyte

A 12 V Substrate-Integrated PbO2-Activated Carbon hybrid ultracapacitor (SI-PbO2-AC HUCs) with silica-gel sulfuric acid electrolyte is developed and performance tested. The performance of the silica-gel based hybrid ultracapacitor is compared with flooded and AGM-based HUCs. These HUCs comprise substrate-integrated PbO2 (SI-PbO2) as positive electrodes and high surface-area activated carbon with dense graphite-sheet substrate as negative electrodes. 12 V SI-PbO2-AC HUCs with flooded, AGM and gel electrolytes are found to have capacitance values of 308 F, 184 F, and 269 F at C-rate and can be pulse charged and discharged for 100,000 cycles with only a nominal decrease in their capacitance values. The best performance is exhibited by gel-electrolyte HUCs.

Advanced multifunctional inorganic nanostructured oxides for controlled release and sensing

ADVANCED MULTIFUNCTIONAL INORGANIC NANOSTRUCTURED OXIDES FOR CONTROLLED RELEASE AND SENSING. We demonstrate here certain examples of multifunctional nanostructured oxidematerials for biotechnological and environmental applications.Various in-house synthesized homogeneous nanostructured viz.mesoporous and nanotubes silica and titania have been employed for controlled drug delivery and electrochemical biosensing applications. Confinement of macromolecules such as proteins studied via electrochemical, thermal and spectroscopic methods showed no detrimental effect on native protein structure and function, thus suggesting effective utility of oxide nanostructures as bio-encapsulators. Multi-functionalitywas demonstrated via employing similar nanostructures for sensing organic water pollutants e.g. textile dyes.

Fluorescent Tris-Imidazolium Sensors for Picric Acid Explosive

Two new anthracene-functionalized fluorescent tris-imidazolium salts have been synthesized, characterized, and proven to be selective sensors for picric acid, which is a common constituent of many powerful explosives. Theoretical studies revealed an unusual ground-state electron transfer from picrate anion to the sensor molecules.

YGa1-xMnxO3: A novel purple inorganic pigment

A purple inorganic pigment, YGa1-xMnxO3 (0 < x <= 0.10), based on hexagonal YGaO3 is reported here. The metastable series of oxides were prepared by a sol-gel technique where the dried gels, obtained from aqueous solutions of metal nitrate-citric acid mixtures, were calcined for a short duration in a preheated furnace around 850 degrees C. The purple colour of the oxides arises from the specific trigonal bipyramidal ligand field around Mn-III in a YGaO3 host. Other hexagonal RGaO3 hosts for R = Lu, Tm and Ho substituted with Mn-III also produce similar purple coloured materials.

Polyvinylbutyral based hybrid organic/inorganic films as a moisture barrier material

Flexible and thermally stable, freestanding hybrid organic/inorganic based polymer-composite films have been fabricated using a simple solution casting method. Polyvinylbutyral and amine functionalized mesoporous silica were used to synthesize the composite. An additional polyol-''tripentaerythritol''-component was also used to increase the -OH group content in the composite matrix. The moisture permeability of the composites was investigated by following a calcium degradation test protocol. This showed a reduction in the moisture permeability with the increase in functionalized silica loadings in the matrix. A reduction in permeability was observed for the composites as compared to the neat polymer film. The thermal and mechanical properties of these composites were also investigated by various techniques like thermogravimetric analysis, differential scanning calorimetry, tensile experiments, and dynamic mechanical analysis. It was observed that these properties detonate with the increase in the functionalized silica content and hence an optimized loading is required in order to retain critical properties. This deterioration is due to the aggregation of the fillers in the matrix. Furthermore, the films were used to encapsulate P3HT (poly 3 hexyl thiophene) based organic Schottky structured diodes, and the diode characteristics under accelerated aging conditions were studied. The weathered diodes, encapsulated with composite film showed an improvement in the lifetime as compared to neat polymer film. The initial investigation of these films suggests that they can be used as a moisture barrier layer for organic electronics encapsulation application.

Exploring the color of transition metal ions in irregular coordination geometries: new colored inorganic oxides based on the spiroffite structure, Zn2-xMxTe3O8 (M = Co, Ni, Cu)

We describe the synthesis, crystal structures, and optical absorption spectra of transition metal substituted spiroffite derivatives, Zn2-xMxTe3O8 (M-II = Co, Ni, Cu; 0 < x <= 1.0). The oxides are readily synthesized by solid state reaction of stoichiometric mixtures of the constituent binaries at 620 degrees C. Reitveld refinement of the crystal structures from powder X-ray diffraction (XRD) data shows that the Zn/MO6 octahedra are strongly distorted, as in the parent Zn2Te3O8 structure, consisting of five relatively short Zn/M-II-O bonds (1.898-2.236 angstrom) and one longer Zn/M-II-O bond (2.356-2.519 angstrom). We have interpreted the unique colors and the optical absorption/diffuse reflectance spectra of Zn2-xMxTe3O8 in the visible, in terms of the observed/irregular coordination geometry of the Zn/M-II-O chromophores. We could not however prepare the fully substituted M2Te3O8 (M-II = Co, Ni, Cu) by the direct solid state reaction method. Density Functional Theory (DFT) modeling of the electronic structure of both the parent and the transition metal substituted derivatives provides new insights into the bonding and the role of transition metals toward the origin of color in these materials. We believe that transition metal substituted spiroffites Zn2-xMxTe3O8 reported here suggest new directions for the development of colored inorganic materials/pigments featuring irregular/distorted oxygen coordination polyhedra around transition metal ions.

New solid forms of the anti-HIV drug etravirine: salts, cocrystals, and solubility

Thirteen new solid forms of etravirine were realized in the process of polymorph and cocrystal/salt screening to improve the solubility of this anti-HIV drug. One anhydrous form, five salts (hydrochloride, mesylate, sulfate, besylate, and tosylate), two cocrystals (with adipic acid and 1,3,5-benzenetricarboxylic acid), and five solvates (formic acid, acetic acid, acetonitrile, and 2:1 and 1:1 methanolates) were obtained. The conformational flexibility of etravirine suggests that it can adopt four different conformations, and among these, two are sterically favorable. However, in all 13 solid forms, the active pharmaceutical ingredient (API) was found to adopt just one conformation. Due to the poor aqueous solubility of the API, the solubilities of the salts and cocrystals were measured in a 50% ethanol water mixture at neutral pH. Compared to the salts, the cocrystals were found to be stable and showed an improvement in solubility with time. All the salts were dissociated within an hour, except the tosylate, which showed 50% phase transformation after 1 h of the slurry experiment. A structure property relationship was examined to analyze the solubility behavior of the solid forms.

Synthon transferability probed with IR spectroscopy: cytosine salts as models for salts of lamivudine

Co-crystal screening of the anti-HIV drug lamivudine was carried out with dicarboxylic acids as co-formers, and three of the resulting crystalline solids, two salts and a co-crystal, were studied with SCXRD, PXRD and FTIR spectroscopy. Salts of cytosine, a molecule that incorporates critical structural features of lamivudine, with the same co-formers, were taken as model systems for IR spectroscopic studies of the synthons in the salts of lamivudine. It is shown that different systems with the same synthon show very similar spectral signatures in the regions corresponding to the synthon absorptions. This reveals again the modular nature of the supramolecular synthon.

Stable Crystalline Salts of Haloperidol: A Highly Water-Soluble Mesylate Salt

Haloperidol, an antipsychotic drug, was screened for new solid crystalline phases using high throughput crystallization in pursuit of solubility improvement. Due to the highly basic nature of the API, all the solid forms with acids were obtained in the form of salts. Eleven crystalline salts in the form of oxalate (1:1), benzoate (1:1), salicylate (1:1 and 1:2), 4-hydroxybenzoate (1:1), 4-hydroxybenzoate ethyl acetate solvate (1:1:1), 3,4-dihydroxybenzoate (1:1), 3,5-dihydroxybenzoate (1:1), mesylate (1:1), besylate (1:1), and tosylate (1:1) salt were achieved. There is an insertion of carboxylate or sulfonate anion into the hydrogen bonding pattern of haloperidol. The salts with the aliphatic carboxylic acids were found to be more prone to form salt hydrates compared with aromatic carboxylate salts. All the salts were subjected to solubility measurement in water at neutral pH. There was no direct correlation observed between the solubility of the salt and its coformer. All the salts are stable at room temperature as well as after 24 h slurry experiment except the oxalate salt, which showed an unusual phase transformation from its hydrated form to the anhydrous form. A structureproperty relationship was examined to analyze the solubility behavior of the solid forms.

Seeded-growth, nanocrystal-fusion, ion-exchange and inorganic-ligand mediated formation of semiconductor-based colloidal heterostructured nanocrystals

This article highlights different synthetic strategies for the preparation of colloidal heterostructured nanocrystals, where at least one component of the constituent nanostructure is a semiconductor. Growth of shell material on a core nanocrystal acting as a seed for heterogeneous nucleation of the shell has been discussed. This seeded-growth technique, being one of the most heavily explored mechanisms, has already been discussed in many other excellent review articles. However, here our discussion has been focused differently based on composition (semiconductor@semiconductor, magnet@semiconductor, metal@semiconductor and vice versa), shape anisotropy of the shell growth, and synthetic methodology such as one-step vs. multi-step. The relatively less explored strategy of preparing heterostructures via colloidal sintering of different nanostructures, known as nanocrystal-fusion, has been reviewed here. The ion-exchange strategy, which has recently attracted huge research interest, where compositional tuning of nanocrystals can be achieved by exchanging either the cation or anion of a nanocrystal, has also been discussed. Specifically, controlled partial ion exchange has been critically reviewed as a viable synthetic strategy for the fabrication of heterostructures. Notably, we have also included the very recent methodology of utilizing inorganic ligands for the fabrication of heterostructured colloidal nanocrystals. This unique strategy of inorganic ligands has appeared as a new frontier for the synthesis of heterostructures and is reviewed in detail here for the first time. In all these cases, recent developments have been discussed with greater detail to add upon the existing reviews on this broad topic of semiconductor-based colloidal heterostructured nanocrystals.

Nanocomposite Based Organic-Inorganic Cu3BiS3 High Sensitive Hybrid Photonic Devices

We report the synthesis and application Cu3BiS3 nanorods in infrared photodectection. Cu3BiS3 nano rods were characterized structurally, optically and electrically. The detailed IR photodectection properties in terms of photo response were demonstrated with IA lamp and 1064 nm laser illuminations. The rapid photocurrent time constants followed by the slower components, resulting due to the defect states. The photo detecting properties for different concentrations of nanorods blended with the conjugate polymer devices were demonstrated. Further the photocurrent was enhanced to threefold increase from 3.47 x 10(-7) A to 2.37 x 10(-3) A at 1 V for 10 mg nanorods embedded in the polymer device. Responsivity of hybrid device was enhanced from 0.0158 NW to 102 NW. The detailed trap assisted space charge transport properties were studied considering the different regimes. Hence Cu3BiS3 can be a promising candidate in the nano switchable near IA photodetectors.

Salts of hexamethylenetetramine with organic acids: Enhanced anomeric interactions with a lowering of molecular symmetry revealed by crystal structures

The hexamethylenetetramine (HMT) framework displays interesting stereoelectronic interactions of the anomeric type. In the highly symmetrical parent system, the nitrogen centres act as both donors and acceptors. Protonation lowers symmetry and also leads to an enhancement of the anomeric interaction around the protonated centre. X-ray diffraction crystal structures of four derivatives of HMT - with succinic, (DL)-malic, phthalic and 4-hydroxybenzoic acids - reveal significant trends. (The first three form well-defined salts, 4-hydroxybenzoic acid forming a co-crystalline compound.) Each molecular structure is essentially characterised by a major anomeric interaction involving the protonated centre as acceptor. In two cases (succinic and 4-hydroxybenzoic), secondary protonation leads to a weaker anomeric interaction site that apparently competes with the dominant one. Bond length changes indicate that the anomeric interaction decreases as malic > phthalic > succinic > 4-hydroxybenzoic, which correlates with the degree of proton transfer to the nitrogen centre. Along with other bond length and angle changes, the results offer insight into the applicability of the antiperiplanar lone pair hypothesis (ALPH) in a rigid system. (C) 2014 Elsevier B.V. All rights reserved.

Salts of hexamethylenetetramine with organic acids: Enhanced anomeric interactions with a lowering of molecular symmetry revealed by crystal structures

The hexamethylenetetramine (HMT) framework displays interesting stereoelectronic interactions of the anomeric type. In the highly symmetrical parent system, the nitrogen centres act as both donors and acceptors. Protonation lowers symmetry and also leads to an enhancement of the anomeric interaction around the protonated centre. X-ray diffraction crystal structures of four derivatives of HMT - with succinic, (DL)-malic, phthalic and 4-hydroxybenzoic acids - reveal significant trends. (The first three form well-defined salts, 4-hydroxybenzoic acid forming a co-crystalline compound.) Each molecular structure is essentially characterised by a major anomeric interaction involving the protonated centre as acceptor. In two cases (succinic and 4-hydroxybenzoic), secondary protonation leads to a weaker anomeric interaction site that apparently competes with the dominant one. Bond length changes indicate that the anomeric interaction decreases as malic > phthalic > succinic > 4-hydroxybenzoic, which correlates with the degree of proton transfer to the nitrogen centre. Along with other bond length and angle changes, the results offer insight into the applicability of the antiperiplanar lone pair hypothesis (ALPH) in a rigid system. (C) 2014 Elsevier B.V. All rights reserved.

Differential Cocrystallization Behavior of Isomeric Pyridine Carboxamides toward Antitubercular Drug Pyrazinoic Acid

Pyrazinoic acid, the active form of the antitubercular pro-drug Pyrazinamide, is an amphiprotic molecule containing carboxylic acid and pyridine groups and therefore can form both salts and cocrystals with relevant partner molecules. Cocrystallization of pyrazinoic acid with isomeric pyridine carboxamide series resulted in a dimorphic mixed-ionic complex with isonicotinamide and in eutectics with nicotinamide and picolinamide, respectively. It is observed that with alteration of the carboxamide position, steric and electrostatic compatibility issues between molecules of the combination emerge and affect intermolecular interactions and supramolecular growth, thus leading to either cocrystal or eutectic for different pyrazinoic acid-pyridine carboxamide combinations. Intermolecular interaction energy calculations have been performed to understand the role of underlying energetics on the formation of cocrystal/eutectic in different combinations. On the other hand, two molecular salts with piperazine and cytosine and a gallic acid cocrystal of the drug were obtained, and their X-ray crystal structures were also determined in this work.