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 (Ni2-1)/fullerene host–guest ensembles. Both absorption and fluorescence studies reveal that Ni2-1 undergoes efficient complexation with both C60 and C70 in toluene medium. In the fluorescence study, remarkable enhancement of the fluorescence intensity of Ni2-1 was observed by the addition of C60, while normal quenching of fluorescence occurred in case of C70. From the fluorescence and UV–vis studies, the binding constants of Ni2-1 with C60 and C70 were determined to be ∼1.7 × 104 and ∼2.7 × 104 dm3 mol−1, respectively. Ab initio theoretical calculations reveal that C70/Ni2-1 complex favor end-on orientation of C70 rather than side-on approach.