Photophysical properties of a novel Ni(II)-diporphyrin in presence of fullerenes: Insights from experimental and theoretical studies

The present paper highlights the photophysical aspects of the topologically new Ni(II)-diporphyrin (Ni-2-1)/fullerene host-guest ensembles. Both absorption and fluorescence studies reveal that Ni-2-1 undergoes efficient complexation with both C-60 and C-70 in toluene medium. In the fluorescence study, remarkable enhancement of the fluorescence intensity of Ni-2-1 was observed by the addition of C-60, while normal quenching of fluorescence occurred in case of C-70. From the fluorescence and UV-vis studies, the binding constants of Ni-2-1 with C-60 and C-70 were determined to be similar to 1.7 x 10(4) and similar to 2.7 x 10(4) dm(3) mol(-1), respectively. Ab initio theoretical calculations reveal that C-70/Ni-2-1 complex favor end-on orientation of C-70 rather than side-on approach. (C) 2007 Elsevier B.V. All rights reserved.