Synthesis characterization and redox properties of antiaromatic expanded Isophlorins

Abstract

Macrocyclic oligothiophenes are attractive synthetic targets for their appealing -conjugation and as potential candidates for applications in organic electronics. The  framework also serves as model systems to explore the effect of  delocalization in large macrocycles. This thesis will describe the first one pot synthesis of macrocyclic oligothiophenes bearing 4n, (4n+2) and (4n+1) from commercially available precursors. The isolation of a free-radical with 25 electrons and its amphoteric behaviour has been discovered under ambient conditions. The details of characterizion in solution and solid states along with photo-physical properties and redox activity were discussed in detail. The ability of 4n macrocyclic systems (32 and 48) to undergo reversible two electron redox between antiaromatic and aromatic states has been explored for the first time. Both (32 and 48) undergo reversible oxidation to form 30 and 46 aromatic dication. Depending on the size of the macrocycle, the dicationic species were found to be either diamagnetic or paramagnetic in nature.