(C 14 H 14 N 2 )MCl 4 (M = Zn, Cd): two hybrid metal halides exhibiting strong second harmonic generation responses, large birefringence, and broadband photoluminescence

Two acentric (C 14 H 14 N 2 )MCl 4 (M = Zn, Cd) crystals were designed by combining planar π-conjugated (C 14 H 14 N 2 ) 2+ and [ZnCl 4 ] 2− /[CdCl 4 ] 2− groups. They show strong second-harmonic generation responses, large birefringence and broadband photoluminescence.