Synthesis, characterization and thermal studies of 1,3-bis(4-pyridyl) propane bridged dicobaloximes

Twelve different 1,3 bis(4-pyridyl) propane (dpyp)-bridged dicobaloximes of the type [RCo(dmgH)(2)](2)-mu-1,3-bis(4-pyridyl) propane where R = Me - octyl (1a-8a), decyl (9a), dodecyl (10a), tetradecyl (11a), 1-chlorohexyl (12a) have been synthesized from their corresponding aqua complexes. All the synthesized cobaloximes have been characterized by H-1, and C-13 Nuclear magnetic resonance (NMR) spectroscopy, elemental analysis, UV-visible (UV-Vis) and FT-IR spectroscopy. The X-ray structures of 2a and 8a are reported. Thermal stability of these complexes has been studied by thermogravimetric analysis (TGA) and differential thermal analysis (DTA). Differential scanning calorimetry (DSC) study reveals that there is a mesophase in these ligand-bridged dicobaloximes with higher alkyl chains. These dpyp-bridged complexes are significant due to the flexible spacer of dpyp in between two cobaltmetallobicycles which influence extensive intermolecular C-H center dot center dot center dot O interactions in the crystal packing diagram of the structures 2a and 8a. The mesophase formation for these complexes strongly depends on the length of the alkyl chain (axial R group). (C) 2016 Elsevier B.V. All rights reserved.