2,2,4,6-Tetraaryl-2H-benzo[h]chromenes: The influence of electronic communication between aryl substituents on their photochromism

A series of photochromic 2,2,4,6-tetraaryl-2 H -benzo[ h ]chromenes have been efficiently synthesised by two complementary strategies employing the condensation 1,1,3-triarylprop-2-yn-1-ols with 4-substituted 1-naphthols and Suzuki cross-coupling chemistry. The novel 1,1,3-triarylpropynols were readily obtained either addition an arylacetylide to requisite benzophenones or a Sonogashira coupling halobenzene preformed 1,1-diarylprop-2-yn-1-ol. tetraarylbenzochromenes which possessed strong electron withdrawing aryl moiety at C-4 exhibited good room temperature photochromism. combination donating group C-6 resulted in generation photomerocyanine absorption bands visible region electromagnetic spectrum, rather than one broad band when was only weakly donating. Remarkably inverting electronic nature groups inhibition photochromism instead led fluorescence. TD-DFT calculations used rationalise shift from • succinctly strategies. most efficient route employed reaction arylboronic acids 6-bromo-2,2,4-triaryl-2 ]chromenes. Photochromism observed for donor C-6. Inverting switched off favour