Towards the Synthesis of Poly(Azafulleroid)S: Main Chain Fullerene Oligomers for Organic Photovoltaic Devices

For the first time, imino chemistry is explored for the synthesis of main chain fullerene oligomers and low-molecular-weight polymers. Oligo(aziridinofullerene)s and low-molecular-weight poly(aziridinofullerene)s (PAFs) are prepared by 1,3-dipolar cycloadditions of bis(azidoalkyl) comonomers to C-60. The effect of the steric bulk of the comonomer is studied and it is found that PAF solubilities and molecular weights are increased with longer comonomer side-chains. Initial and promising photovoltaic characterizations show commensurate improvements in properties. Interestingly, the PAFs exhibit lowest unoccupied molecular orbitals close to those of phenyl-C-61-butyric acid methyl ester. Routine characterizations are correlated with DFT/B3LYP/6-31G(d) to understand structural and electronic behaviours. It is expected that higher molecular weights may be obtained through comonomer variations and that this novel methodology will open a route to interesting materials for optoelectronics. (C) 2017 Society of Chemical Industry