Novel 5-(Benzo[b]thiophen-3-yl)pyridine-3-carbaldehyde (BTPA) Functionalization Framework For Modulating Fullerene Electronics

Through a cycloaddition reaction, fullerene (C-60) was derivatized with a novel organic compound 5-(benzo[b]thiophen-3-yl) pyridine-3-carbaldehyde to form the processable and stable 3-(benzo[b]thiophene-3yl)-5-fullero-1-methylpyrrolidinepyridine (BTFP) compound. BTFP exhibits close similarities to phenyl-C61- butyric-acid-methyl-ester (PCBM) in terms of first reduction potential values (-0.62 and -0.61 V vs. Ag/AgCl, for BTFP and PCBM, respectively) and lowest occupied molecular orbital (LUMO) energy level values (3.93 eV in both cases). In chloroform, BTFP exhibits a bathochromic shift in the lambda(max) of BTFP (lambda(max), BTFP=290 nm and lambda(max), PCBM=260 nm), owing to the grafted benzo[ b] thiophene-3-yl) pyridine moiety. Despite the similarity in LUMO (3.93 eV) energy values, BTFP and PCBM differ in their luminescence-quenching ability. The bathochromic shift in the lambda(max) of BTFP (relative to PCMB) is likely to contribute to improved light absorption of a suitable donor for photovoltaic applications.