Diversified Photo/Electronic Functions Based on a Simple Chalcone Skeleton: Effects of Substitution Pattern and Molecular Packing

Structurally simple chalcone derivatives 1-2 are prepared and their diversified emission behaviors are deeply investigated. Two polymorphs (1G:lambda(em) = 536 nm, Phi(f) = 0.08, tau = 1.81 ns; 1O:lambda(em) = 573 nm, Phi(f) = 0.19, tau = 10.82 ns) with distinctively different emission behaviors are constructed by finely controlling the crystallization conditions of compound 1. 1G exhibits typical amplified spontaneous emission while 1O shows an interesting blue shift under smashing process (1O-S: lambda(em) = 562 nm, Phi(f) = 0.23, tau = 6.42 ns), which is ascribed to their different molecular packing structures and intermolecular interactions. Notably, simply introducing a fluorine substituent effectively endows the crystal with red emission (crystal 2: lambda(em) = 598 nm, Phi(f) = 0.16, tau = 18.77 ns). Thus multicolor emissions including green, yellow, orange, and red emissions are obtained based on this simple chalcone skeleton.