Crystal structure and luminescence of 2,7-dimethylnaphthalene-1-carbonitrile

The title compound crystallizes in the monoclinic space group P21/c: Mr = 181.2; a = 7.119(1), b = 18.389(4), c = 7.5385(6) Å; β = 91.661(7)o; V = 986.4(5) Å3; and Z = 4. The purified material shows fluorescence similar to other naphthalene derivatives: monomer fluorescence (λmax 350-370 nm) in the solid state and in dilute solutions, and excimer fluorescence (λmax 421 nm) in concentrated solutions. Intense blue-green luminescence (λmax, 490 nm) is observed in some partially purified crystalline samples. This is attributed to phosphorescence from two isomeric bromodimethylnaphthalenecarbonitrile impurities detected by GC-MS analysis