Synthesis and photochromic properties of new naphthopyrans

Two novel isomeric naphthopyrans substituted with phenyl (13-butyl-6,7-dimethoxy-3,3-bis(6-methoxybiphenyl-3-yl)-3,13-dihydrobenzo[h]indeno[2,1-f]chromen-13-ol) and 4-(naphthalen-1-yl)phenyl (13-butyl-6,7-dimethoxy-3,3-bis[6-methoxy-4'-(naphthalenyl)- biphenyl-3-yl]-3,13-dihydrobenzo[h]indeno[2,1-f]chromen-13-ol) moieties were synthesized. Their photochromism, electrochemical and fluorescent properties were investigated. They displayed faster color fading rate and larger fluorescence quantum yield than 13-butyl-6,7-dimethoxy-3,3-bis(4-methoxyphenyl)-3,13-dihydrobenzo[h]indeno[2,1-f]chromen-13-ol. Moreover, they showed excellent photochromic and fluorescent properties both in solution and in polymethylmethacrylate film. In addition, cyclic voltammetry tests showed that the aromatic substituents had a significant effect on the electrochemical behavior of the naphthopyran derivatives.