Synthesis and NMR spectral studies of multidentate N and S heterocycles, 1,3,5-tris(N-methylbenzimidazolyl)benzene, 1,3,5-tris(benzimidazolyl)benzene,1,3,5-tris(benzothiazolyl) benzene, 2,2'-bipyridine 3,3'-bis(benzothiazolyl)benzene and 1,2,4,5-tetrakis(benzothiazolyl) benzene have been carried out. 2D (1)H-(1)H PFG-COSY as well as (1)H-(13)C single and multiple bond correlated (2D GRASP-HSQC and GRASP-HMBC) experiments have been employed to characterize the compounds. 1D NOE experiments have been useful in understanding the structure of 1,3,5-tris(N-methylenzimidazolyl)benzene.

Free radical-induced oxidation reactions of glucosamine naphthalene acetic acid (GNaa) and naphthalene acetic acid (Naa) have been studied using pulse radiolysis. GNaa was synthesized by covalently attaching Naa on glucosamine. Hydroxyl adduct (from the reaction of hydroxyl radicals ( • OH) at the naphthalene ring) was identified as the major transient intermediate (suggesting that the • OH reaction is on the naphthalene ring) and is characterized by its absorption maxima of 340 and 400 nm. Both GNaa and Naa undergo similar reaction pattern. The bimolecular rate constants determined for the reactions are 4.8 × 10 9 and 8.9 × 10 9 dm 3 mol À1 s À1 for GNaa and Naa respectively. The mechanism of reaction of • OH with GNaa was further confirmed using steady-state method. Radical cation of GNaa was detected as an intermediate during the reaction of sulfate radical (SO 4•À ) with GNaa (k 2 = 4.52 × 10 9 dm 3 mol À1 s À1 ). This radical cation transforms to a • OH adduct at higher pH. The radical cation of GNaa is comparatively long lived, and a cyclic transition state by neighboring group participation accounts for its stability. The oxy radical anion (O •À ) reacts with GNaa (k 2 = 1.12 × 10 9 dm 3 mol À1 s À1 ) mainly by one-electron transfer mechanism. The reduction potential values of Naa and GNaa were determined using cyclic voltammetric technique, and these are 1.39 V versus NHE for Naa and 1.60 V versus NHE for GNaa.

a b s t r a c t a r t i c l e i n f oIn the present study, we demonstrate the self transformation of aqueous cadmium acetate into CdCO 3 nanowires through hydrothermal reaction. The reaction temperature and the volume ratio of water to ethanol were found to be crucial for the formation of CdCO 3 nanowires. The nanowires are of single crystal in nature having width ∼ 17-30 nm as observed from selected area electron diffraction (SAED) pattern and transmission electron microscopic (TEM) results. The major weight loss found in thermogravimetric analysis (TGA) corresponds to the formation of CdO and CO 2 . The powder X-ray diffraction (PXRD) patterns of CdCO 3 and CdO are respectively indexed to pure rhombohedral and cubic phases. The photoluminescence (PL) spectrum of CdO exhibits an emission peak at 483 nm due to the transition between the valence and conduction bands.

] (X = Cl, Br, I). Elemental analysis, IR and 1 H nuclear magnetic resonance (NMR) chemical shifts supported the binuclear nature of the complexes. Cyclometallation was detected by conventional 13 C NMR spectra that showed a doublet around ∼190 ppm. Cyclometallation was also detected by gradient-enhanced heteronuclear multiple bond correlation (g-HMBC) experiment that showed cross-peaks between the cyclometallated carbon and the central benzene ring protons of 1-3. Cyclometallation was substantiated by two-dimensional 1 H-1 H correlated experiments (gradiant-correlation spectroscopy and rotating frame Overhauser effect spectroscopy) and 1 H-13 C single bond correlated two-dimensional NMR experiments (gradient-enhanced heteronuclear single quantum coherence). The 1 H-15 N g-HMBC experiment suggested the coordination of the heterocycles to the metal ion via tertiary nitrogen.