Structural investigation towards understanding photo isomerization and photo induced mechanical Effects in second sphere coordination complexes of nitropentaamminecobalt iii cation

Abstract

The present thesis work represents detailed synthesis and characterization of several complexes based on nitropentaammine cobalt (III) cation stabilized by organic/Inorganic counter anions. Around twenty new compounds were synthesised out of which ten compounds show only isomerization behaviour, five compounds show both isomerization and photo-mechanical effect and the rest of the complexes do not show any stimuli-responsive behaviour. Further, a few selected complexes were used to prepare several crystal-polymer composite films using the solution casting technique where the polymers used such as PVA, PVDF, Agarose etc. The composite films were further characterized by using AFM, nanoindentation, thermal analysis and many other analytical methods. Most of the composite films show good actuation properties under different stimuli such as light/heat. Only a few crystals and their composite films show thermo-mechanical behaviour under heating. To gain more insight of the photo/ thermomechanical effect and molecular level understanding, cavity, Hirshfeld analysis as well as theoretical studies were performed using DFT analysis and the results were quite interesting. As a future outlook, we aim to see hybrid composite films in combination with piezoelectric materials where the compound can be used for energy harvesting and new material development applications. newline