Synthesis, Characterization, Electronic & Redox Properties of 28π, 42π and 56π Thia Porphyrinoids

Abstract

The thesis is entitled as “Synthesis, Characterization, Electronic & Redox Properties of 28π, 42π and 56π Thia Porphyrinoids”. These larger porphyrinoids have a greater number of heterocyclic units and meso positions in comparison to the parent porphyrin ring. The replacement of the pyrrole unit with thiophene/furan/selenophene results in core modification of these porphyrinoids. Therefore, expansion and modification of the ring affect the electronic and structural properties of these macrocycles. Higher analogues of isophlorins with distinct structural and photophysical characteristics have been accomplished by increasing the heterocyclic units in the core modified isophlorin. Herein, we attempted synthesis of thiophene based expanded isophlorins with antiaromatic 4nπ systems containing 28π and 56π electrons and aromatic (4n+2) π systems containing 42π electrons has been described. Apart from their synthesis, structural characterization by MALDI-TOF/TOF, High Resolution Mass Spectroscopy (HRMS) and 1H NMR, Redox Characterization through UV-Visible absorption studies, Cyclic Voltammetry and Spectroelectrochemistry and Computational Studies (AICD, NICS(0)) have been carried out for all the macrocycles. A reversible two electron oxidation carried out with Meerwein salt, [Et3O]+[SbCl6]- was observed for all the three macrocycles forming their corresponding dications. Furthermore, solid state analyses were carried out using Single Crystal X-ray diffractometer which revealed their molecular structures.