Synthesis, optical and thermal behaviour of palladium(II) complexes with 4-(4-alkoxy-2-hydroxybenzylideneamino)azobenzene

Abstract

A series of new Pd(II) complexes derived from the reaction of palladium acetate with 4-(4-alkoxy-2-hydroxybenzylideneamino)azobenzene having the flexible terminal chain of OC n H 2n+1 , in which n are even numbers ranging from 8 to 16, has been successfully synthesized. The physical measurement and spectroscopic techniques (FTIR and 1 H-NMR) reveal that the Pd(II) complexes possess the Pd-N and Pd-O coordination modes in which the central Pd(II) adopts square-planar geometry. The observation under the polarized light shows that all the ligands and Pd(II) complexes exhibit enantiotropic mesophases. The ligands with n-octyloxy and n-decyloxy flexible chains exhibit the nematic (N) and smectic A (SmA) phases whilst the Pd(II) complexes show exclusive SmA phase. The SmA phase observed in Pd(II) complexes can be supported by the presence of focal conic fan-shaped texture with the presence of curved lines which are prominent during the cooling process. On the other hand, the comparison studies show that Pd(II) complexes possess exceptional higher phase transition temperatures as compared to the corresponding Cu(II) and Ni(II) complexes.

Spherical Compound Micelles with Lamellar Stripes Self‐Assembled from Star Liquid Crystalline Diblock Copolymers in Solution

“…The mesophase was also identified by POM observation. When cooling to around 110 °C, batonnet textures appeared, indicating a smectic A phase, [31][32][33][34][35] as shown in Figure 3a, which is similar with that of linear block copolymer PEO-b-PMA(Az). [36] Figure 3b shows the WAXD patterns of 3PEO 22 -b-PMA(Az) 62 annealed at 98 °C and 110 °C, respectively .…”