Synthesis, characterization and X-ray crystallographic structural study of copper(II) and nickel(II) complexes of the 2-quinoline carboxaldehyde Schiff base of S-methyldithiocarbazate (Hqaldsme)

Complexes of general formulae, [Cu(qaldsme)(X)(CH3OH)(n)] and [Ni(qaldsme)(2)] (.) 0.5CH(3)CN (qaldsme = anionic form of the 2-quinoline carboxaldehyde Schiff base of S-methyldithiocarbazate; X = NCS-, I-, NO3-; n = 0 or 1) have been synthesized and characterized by magnetic and spectroscopic techniques. X-ray crystal structure determination of [Cu(qaldsme)(ONO2)(CH3OH)] (1), [Cu(qaldsme)(NCS)](2) (2) and [Ni(qaldsme)(2)] (.) 0.5CH(3)CN (4) shows that the nitrato-complex of copper (1) is monomeric and five-coordinate and the thiocyanato-complex (2) has a novel thiolate sulfur-bridged dimeric structure in which each of the copper(II) ions adopts a five-coordinate, approximately square-pyramidal geometry, with a CuN3S2 coordination kernel. The nickel(II) complex (3) has a distorted octahedral geometry with meridional dispositions of the two uninegatively charged tridentate NNS ligands. In all these complexes, the Schiff bases are coordinated in their iminothiolate forms via the quinoline nitrogen atom, the azomethine nitrogen atom and the thiolate sulfur atom. (c) 2006 Elsevier Ltd. All rights reserved

A three orders of magnitude increase in nonlinear optical response by external electric field on Cryptand[2.2.2] (C222) based alkaline earthides

A new series of alkaline earthides based on Cryptand [2.2.2] (C222) containing nine complexes is designed by carefully placing alkali metals and alkaline earth metals inside and outside the C222 complexant, respectively i.e., M1(C222)M2 (M1 = Li, Na, K; M2 = Be, Mg, Ca). The designed complexes are reasonably stable both electronically and thermodynamically, as revealed through their vertical ionization potentials (VIPs) and interaction energies, respectively. Moreover, the true alkaline earthide nature of the complexes is confirmed through NBO and FMO analyses showing the negative charges and HOMOs over the alkaline earth metals, respectively. The further validity of true earthide characteristic is represented graphically by the spectra of partial density of states (PDOS). HOMO-LUMO gaps of the compounds are also very small (from 2.23 to 2.83 eV) when compared with pure cage's (C222) H-L gap i.e., 5.63 eV. All these features award these complexes with very small values of transition energies (ΔE) ranging from 0.68 to 2.06 eV ultimately resulting in remarkably high hyperpolarizability values up to 2.7 × 105 au (for Na+(C222)Mg−). Furthermore, applying external electric field (EEF) on the complexes enhances hyperpolarizability further. A remarkable increase of 1000 folds has been seen when hyperpolarizability of K+(C222)Ca− is calculated after EEF application i.e., from 8.79 × 104 au to 2.48 × 107 au; when subjected to 0.001 au external electric field