Synthesis and sequential photochromism of thiophene-linked bis-pyrans

Novel bis[3H]-naphtho[2,1-b]pyrans 1a-1g and bis[2H]-naphtho[1,2-b]pyrans 2a-2g were prepared efficiently. Such thiophene-linked bispyrans display distinct color change under continuous UV irradiation with up to 110 am of bathochromic shift between the finally generated colored forms and initially generated forms. They also show high colorability, as well as good fatigue-resistance. (C) 2015 Elsevier Ltd. All rights reserved.