Rod shaped oxovanadium(IV) Schiff base complexes: Synthesis, mesomorphism and influence of flexible alkoxy chain lengths
作者:Bishop Dev Gupta、Chitraniva Datta、Gobinda Das、Chira R. Bhattacharjee
DOI:10.1016/j.molstruc.2014.03.006
日期:2014.6
A series of oxovanadium(IV) complexes of bidentate [N,O] donor Schiff-base ligands of the type [VO(L)(2)], [L = N-(4-n-alkoxysalicylaldimine)-4 '-octadecyloxyaniline, n = 8, 10, 12, 14, 16 and 18] have been synthesized. The compounds were characterized by elemental analyses, Fourier transform infrared spectroscopy (FTIR), H-1, C-13 nuclear magnetic resonance (NMR), ultraviolet-visible spectroscopy (UV-Vis), and fast atom bombardment (FAB) mass spectrometry. The mesomorphic behavior of the compounds was studied by polarized optical microscopy (POM) and differential scanning calorimetry (DSC). The ligands and complexes are all thermally stable exhibiting smectic mesomorphism. The ligands 8-OR to 16-OR show SmC phase at,similar to 113-118 degrees C and an unidentified SmX phase reminiscent of soft crystal at similar to 77-91 degrees C whereas the complexes all showed SmA phases. Interestingly the complexes with C-10 and C-12 alkoxy chain length exhibited additionally SmC phases also. The melting points of the ligands linearly increases whereas mesophase to isotropic transition temperature decreases as a function of increasing carbon chain length of alkoxy arm while no trend was apparently noticeable for the complexes. (C) 2014 Elsevier B.V. All rights reserved.