Nanostructured barbed wire architecturing of organic conducting material blends by electrospinning

In this study, fibers of barbed wire structure were obtained by electrospinning blend of organic conducting crystalline material and polyethylene oxide. Thermal and structural characterization of the blend fibers has been carried out to study the fiber characteristics. An increase in crystallinity in the electrospun fibers was observed and was attributed to both electrospinning process as well as addition of organic conducting crystalline material. A mechanism for the formation of this barbed wire structure has also been proposed. (C) 2012 American Institute of Physics. [doi:10.1063/1.3673620]

C-H functionalization of tertiary amines by cross dehydrogenative coupling reactions: solvent-free synthesis of alpha-aminonitriles and beta-nitroamines under aerobic condition

A solvent-free synthesis of alpha-aminonitriles and beta-nitroamines by oxidative cross-dehydrogenative coupling under aerobic condition is reported. A catalytic amount of molybdenum(VI) acetylacetonoate was found to catalyze cyanation of tertiary amines to form alpha-aminonitriles, whereas vanadium pentoxide was found to promote aza-Henry reaction to furnish beta-nitroamines. Both of these environmentally benign reactions are performed in the absence of solvents using molecular oxygen as an oxidant.

Evidence of aggregation induced emission enhancement and keto-enol-tautomerism in a gallic acid derived salicylideneaniline gel

A novel salicylideneaniline type fluorescent organogelator based on a 3,4,5-(tri-dodecyloxy)benzoyl group immobilizes aromatic solvents. The resulting gels show enhancement in emission and thermochromic/non-photochromic behaviour during sol-to-gel transition.

Charge transfer complex states in diketopyrrolopyrrole polymers and fullerene blends: Implications for organic solar cell efficiency

The spectral photocurrent characteristics of two donor-acceptor diketopyrrolopyrrole (DPP)-based copolymers (PDPP-BBT and TDPP-BBT) blended with a fullerene derivative [6,6]-phenyl C-61-butyric acid methyl ester (PCBM) were studied using Fourier-transform photocurrent spectroscopy (FTPS) and monochromatic photocurrent (PC) method. PDPP-BBT: PCBM shows the onset of the lowest charge transfer complex (CTC) state at 1.42 eV, whereas TDPP-BBT: PCBM shows no evidence of the formation of a midgap CTC state. The FTPS and PC spectra of P3HT:PCBM are also compared. The larger singlet state energy difference of TDPP-BBT and PCBM compared to PDPP-BBT/P3HT and PCBM obliterates the formation of a midgap CTC state resulting in an enhanced photovoltaic efficiency over PDPP-BBT: PCBM. (C) 2011 American Institute of Physics. [doi:10.1063/1.3670043]

Evaluation of the role of disordered organic fluorine in crystal packing: insights from halogen substituted benzanilides

The determination of the crystal and molecular structures of a large number of compounds containing the C(sp(2))-F bond has been investigated in detail in halogenated benzanilides and also in liquids, namely the fluorinated amines. It has been observed that when the fluorine atom is present in the ortho or meta position with respect to the amide functionality in benzanilides or the amino group in fluorinated amines which are liquids at room temperature, the fluorine atom exhibits positional disorder. This is associated with changes in patterns of intermolecular interactions which affect crystal packing. Furthermore, the presence of a fluorine atom on the benzanilide framework, in the presence of a heavier halogen (chloro, bromo and iodo), meta or ortho to the amide group does not eliminate the disorder associated with these molecules. In this article, we highlight the salient features present in halogenated compounds exhibiting disorder in the position of organic fluorine with concomitant changes in crystal packing. This feature is also compared with related compounds exhibiting similarity in electronic features, namely positional disorder.

Biodegradation of some organic reagents from mineral process effluents

The utility of a soil microbe, namely Bacillus polymyxa, in the removal of organic reagents such as dodecylamine, ether diamine, isopropyl xanthate and sodium oleate from aqueous solutions is demonstrated. Time-bound removal of the above organic reagents from an alkaline solution was investigated under different experimental conditions during bacterial growth and in the presence of metabolites by frequent monitoring of residual concentrations as a function of time, reagent concentration and cell density. The stages and mechanisms in the biodegradation process were monitored through UV-visible and FTIR spectroscopy. Surface chemistry of the bacterial cells as well as the biosorption tendency for various organics were also established through electrokinetic and adsorption density measurements. Both the cationic amines were found to be biosorbed followed by their degradation through bacterial metabolism. The presence of the organic reagents promoted bacterial growth through effective bacterial utilization of nitrogen and carbon from the organics. Under optimal conditions, complete degradation and bioremoval of all the organics could be achieved.

Dithienylcyclopentadienone derivative-co-benzothiadiazole: An alternating copolymer for organic photovoltaics

Alternating copolymer of 7,9-di(thiophen-2-yl)-8H-cyclopenta[a]acenaphthylen-8-one-co-benzothia diazole was synthesized by palladium(0) catalyzed Stille coupling reaction. This solution processable copolymer shows an excellent thermal stability and has a broad absorption range from 300 to 800 nm with a band gap of about 1.51 eV. High LUMO energy level and low band gap of the synthesized copolymers suggest that, this copolymer will be a suitable donor material for use in an organic photovoltaic device. Photovoltaic devices were fabricated from the blend of copolymer and phenyl-C61-butyric acid methyl ester as the active material. (C) 2011 Elsevier By. All rights reserved.

Intra-molecular hydrogen bonding with organic fluorine in the solution state: Deriving evidence by a two dimensional NMR experiment

The direct evidence for the existence of intra-molecular C-F center dot center dot center dot H-N hydrogen bond in organofluorine molecules, in the liquid state, is derived using NMR spectroscopy by the detection of long range interactions among fluorine, nitrogen and hydrogen atoms. The present study reports the determination of the relative signs and magnitudes of through space and through bond couplings to draw unambiguous evidence on the existence of weak molecular interactions involving organic fluorine. It is a simple, easy to implement, N-15 natural abundant two dimensional heteronuclear N-15-H-1 double quantum-single quantum correlation experiment. The existence of intra-molecular hydrogen bond is conclusively established in the investigated molecules. (C) 2011 Elsevier B.V. All rights reserved.

First-Principles Study of the Effect of Organic Ligands on the Crystal Structure of CdS Nanoparticles

We show with the aid of first-principles electronic structure calculations that suitable choice of the capping ligands may be an important control parameter for crystal structure engineering of nanoparticles. Our calculations on CdS nanocrystals reveal that the binding energy of model trioctylphosphine molecules on the (001) facets of zincblende nanocrystals is larger compared to that on wurtzite facets. Similarly, the binding energy of model cis-oleic acid is found to be dominant for the (10 (1) over bar0) facets of wurtzite structure. As a consequence, trioctylphosphine as a capping agent stabilizes the zincblende structure while cis-oleic acid stabilizes the wurtzite phase by influencing the surface energy, which has a sizable contribution to the energetics of a nanocrystal. Our detailed analysis suggests that the binding of molecules on the nanocrystalline facets depends on the surface topology of the facets, the coordination of the surface atoms where the capping molecule is likely to attach, and the conformation of the capping molecule.

Acenaphtho[1,2-b]quinoxaline based low band gap copolymers for organic thin film transistor applications

We report the synthesis of a novel class of low band gap copolymers based on anacenaphtho[1,2-b]quinoxaline core and oligothiophene derivatives acting as the acceptor and the donor moieties, respectively. The optical properties of the copolymers were characterized by ultraviolet-visible spectroscopy while the electrochemical properties were determined by cyclic voltammetry. The band gap of these polymers was found to be in the range 1.8-2.0 eV as calculated from the optical absorption band edge. X-ray diffraction measurements show weak pi-pi stacking interactions between the polymer chains. The hole mobility of the copolymers was evaluated using field-effect transistor measurements yielding values in the range 10(-5)-10(-3) cm(2)/Vs.

Synthesis, Structure, and Magnetic Properties of a New Eight-Connected Metal-Organic Framework (MOF) based on Co-4 Clusters

A hydrothermal reaction of cobalt nitrate, 4,4'-oxybis(benzoic acid) (OBA), 1,2,4-triazole, and NaOH gave rise to a deep purple colored compound Co-4(triazolate)(2)(OBA)(3)], I, possessing Co-4 clusters. The Co-4 clusters are connected together through the tirazolate moieties forming a two-dimensional layer that closely resembles the TiS2 layer. The layers are pillared by the OBA units forming the three-dimensional structure. To the best of our knowledge, this is the first observation of a pillared TiS2 layer in a metal-organic framework compound. Magnetic studies in the temperature range 1.8-300 K indicate strong antiferromagetic interactions for Co-4 clusters. The structure as well as the magnetic behavior of the present compound has been compared with the previously reported related compound Co-2(mu 3-OH)(mu(2)-H2O)(pyrazine)(OBA)(OBAH)] prepared using pyrazine as the linker between the Co-4 clusters.