Piezoflurochromism and Aggregation Induced Emission Properties of 9, 10-bis (trisalkoxystyryl) Anthracene Derivatives

We report the synthesis of trisalkoxy substituted 9, 10-bis styrylanthracene derivatives (C8-ant and C12-ant) by Heck coupling with very good yield and their photophysical properties. Both C8-ant and C12-ant exhibit aggregation induced emission (AIE), mechnoflurochromism and thermochromism. Trisubstituted 9, 10-distyrylanthracene molecules having all the luminescent properties in a single molecule are first of its kind.     

Palladium(0)‐Catalyzed Single and Double Isonitrile Insertion: A Facile Synthesis of Benzofurans,Indoles, and Isatins

A palladium(0)‐catalyzed cascade process consisting of isonitrile insertion and α‐Csp³?H cross‐coupling can be achieved for the synthesis of benzofurans and indoles. The construction of isatins by a Pd‐catalyzed cascade reaction incorporating double isonitrile insertion, amination, and hydrolysis has also been achieved. The key features of this work include diverse heterocycle synthesis, phosphine‐ligand‐free reaction conditions, a one‐pot procedure, simple and commercially available starting materials, broad functional‐group compatibility, and moderate to good reaction yields.     

Parallel synthesis of bis-oxazole peptidomimetics

The parallel synthesis of bis-oxazole peptidomimetics starting from Boc-aminoacids and Serine-methyl ester is described. This work presents the synthesis of oxazole aminoacid building blocks in solution phase and their utilization for the solid phase peptide synthesis of a library of diverse bis-oxazole peptidomimetics in good overall yields.     

Electrical,structural and morphological characteristics of rapidly annealed Ni/Pd Schottky rectifiers on n‐type GaN

Schottky rectifiers are fabricated on n‐type GaN using Ni/Pd metallization scheme and its characteristics have been investigated by current‐voltage (I‐V), Capacitance‐Voltage (C‐V), X‐Ray Diffraction (XRD) and SIMS measurements as a function of annealing temperature. The calculated Schottky barrier height of the as‐deposited contact was found to be 0.60 eV (I‐V), 0.71 eV (C‐V) with an ideality factor of 1.44. However, the barrier height slightly increases after annealing at 300, 400 and 500 °C. On the basis of the experimental results, a high‐quality Schottky contact with barrier height and ideality factor of 0.81 eV (I‐V), 0.88 eV (C‐V) and 1.13 respectively, can be obtained after annealing at 600 °C for 1 min in a nitrogen atmosphere. Further, after annealing at 700 °C, it is found that the barrier height slightly decreased to 0.74 eV (I‐V) and 0.85 eV (C‐V). From the above observations, one can note that Ni/Pd Schottky contact exhibits excellent electrical properties after a rapid thermal annealing at 600 °C. According to the SIMS and XRD analysis, the formation of gallide phases at the Ni/Pd/n‐GaN interface could be the reason of the barrier height increase at elevated annealing temperatures. The Atomic Force Microscopy (AFM) results show that the overall surface morphology of Ni/Pd Schottky contacts on n‐GaN is fairly smooth. The above observations reveal that Ni/Pd Schottky metallization scheme was a good choice for the fabrication of high‐temperature and high‐power device applications. Copyright © 2010 John Wiley & Sons, Ltd.     

EPR,optical absorption,MIR and Raman spectral studies on libethenite mineral

Libethenite, a copper phosphate mineral originated from Congo is used in the present studies. Optical absorption spectrum is due to Cu(II), which is in rhombic distortion. Whereas EPR results show that Fe(III) and Mn(II) are also present in the mineral. MIR and Raman spectral features are attributed to phosphate fundamentals and lattices vibrations of CuO respectively. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Effect of iron scrap additives in stearic acid as PCM for thermal energy storage system

Journal of Thermal Analysis and Calorimetry - The thermal energy storage (TES) system is used to store the heat energy for longer periods and retrieve the heat energy as and when required....     

Parameters influencing the molecular weight of 3,6‐carbazole‐based D‐π‐A‐type copolymers

Condensation copolymerization reactions of carbazole 3,6‐diboronate with 4,7‐bis(5‐bromo‐2‐thienyl)‐2,1,3‐benzothiadiazole (DTBT) only produce low‐molecular‐weight donor (D)‐π‐acceptor (A) copolymers. High‐molecular‐weight copolymers for use in optoelectronic devices are necessary for achieving extended π‐conjugation and for controlling the copolymer processibility. To elucidate the cause of the persistently low molecular weight, we synthesized three 3,6‐carbazole‐based D‐A copolymers using copolymerizations of N‐9′‐heptadecanyl‐3,6‐carbazole with DTBT, N‐9′{2‐[2‐(2‐methoxy‐ethoxy)‐ethoxy]‐ethyl}‐3,‐6‐carbazole with DTBT, and N‐9′‐heptadecanyl‐3,6‐carbazole with alkyl‐substituted DTBT. We investigated several parameters for their influence on molecular copolymer weight, including the conformation of the chain during growth, the solubility of the monomers, and the dihedral angles between the donor and acceptor units. Size exclusion chromatography, UV–vis absorption spectroscopy, and computational studies revealed that the low molecular weights of 3,6‐carbazole‐based D‐A copolymers resulted from conjugation breaks and the resulting high coplanarity, which led to strong interactions between polymer chains. These interactions limited formation of high‐molecular‐weight‐copolymers during copolymerization. The strong intermolecular interactions of the 3,6‐carbazole moiety were exploited by incorporating 3,6‐carbazole units into poly[9′,9′‐dioctyl‐2,7‐flourene‐alt‐5,5‐(4′,7′‐di‐2‐thienyl‐2′,1′,3′‐benzothiadiazole)] prepared from 9′,9′‐dioctyl‐2,7‐flourene and DTBT. Interestingly, the number average molecular weight increased gradually with increasing 2,7‐fluorene monomer content but the number of conjugation breaks was a range of 6–7. The hole mobilities of the copolymers were studied for comparison purposes. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Biogenetic - Type Synthesis of 12,16 - Deoxyfuroscalarol

Cationic cyclization of a bicyclic furanosester-terpene precursor to a furoscalarane is reported.