N-hetero atomic effect on the photophysics of 2,2′-dipyridylketone

Emission characteristics of 2,2′-dipyridylketone (DPK) have been studied in the rigid glass matrices of ethanol (EtOH) and methyl cyclohexane (MCH) at 77 K. As in the case of the aromatic analogue benzophenone (BOP), DPK is found to exhibit only phosphorescence emission. Although both BOP and DPK have the lowest triplet states chiefly of nπ* nature, the presence of other triplet states in the neighbourhood of the lowest triplet one is found to play some significant roles in determining the photophysical properties of DPK, specially in the non-polar solvent (MCH). All the photophysical properties including the polarization characteristics have been explored in both the molecules. Experimental observations are corroborated with necessary quantum chemical calculations.