Photophysical, photostability, and ROS generation properties of new trifluoromethylated quinoline-phenol Schiff bases

A new series of ten examples of Schiff bases, namely (E)-2-(((2-alkyl(aryl/heteroaryl)-4-(trifluoromethyl)quinolin-6-yl)imino)methyl)phenols 3, was easily synthesized with yields of up to 91% from the reactions involving a series of 2-(R-substituted) 6-amino-4-(trifluoromethyl)quinolines 1 and 4(5)-R(1)-substituted salicylaldehydes 2 – in which alkyl/aryl/heteroaryl for 2-R-substituents are Me, Ph, 4-MeC(6)H(4), 4-FC(6)H(4), 4-NO(2)C(6)H(4), and 2-furyl, and R(1)-substituents are 5-NEt(2), 5-OCH(3), 4-Br, and 4-NO(2). Complementarily, the Schiff bases showed low to good quantum fluorescence yield values in CHCl(3) (Φ(f) = 0.12–0.80), DMSO (Φ(f) = 0.20–0.75) and MeOH (Φ(f) = 0.13–0.85). Higher values of Stokes shifts (SS) were observed in more polar solvents (DMSO; 65–150 nm and MeOH; 65–130 nm) than in CHCl(3) (59–85 nm). Compounds 3 presented good stability under white-LED irradiation conditions and moderate ROS generation properties were observed.