Extended viologen compounds with photochromism, photoresponsive luminescence and ultrahigh quenching efficiency

Two coordination polymers, {[Cd(m-TTzPA)Br 2 ]·H 2 O} n and {[Zn(m-TTzPA)Br 2 ]·H 2 O} n , were synthesized based on (m-H 2 TTzPA)(HSO 3 ) 2 . All compounds show photochromic behaviors and have obvious fluorescence quenching behaviors upon irradiation.