2,4,6-Tri(4-pyridyl)-1,3,5-triazine: Photoinduced Charge Separation and Photochromism in the Crystalline State.

2,4,6-Tri(4-pyridyl)-1,3,5-triazine (tpt) is a widely used ligand for functional coordination compounds. In this work, tpt has shown unprecedented photochromism in the crystalline state. Experimental and theoretical data has revealed that the photocoloration of tpt very likely originates from intramolecular charge separation and the formation of a triplet diradical product. This finding demonstrates a new simple, neutral photochromic molecule and endows the tpt molecule and related compounds with potential optical applications.