Lowest Triplet State in 1,4-Dinitronaphalene

The phosphorescence emission characteristics of 1, 4-dinitronaphthatene in some protic and nonprotic solvents at 77°K have been investigated and the lowest triplet state is assigned as 3ππ∗ in this molecule. The observed low phosphorescence intensity and the lifetime values have been attributed to the ‘proximity effect’.