Synthesis, structure and photophysical properties of NIR aza-BODIPYs with -F/-N-3/NH2 groups at 1,7-positions

摘要

With 4-fluorostyrene as the starting material, symmetric/asymmetric fluorine-containing aza-difluor-oboradiaza-s-indacenes (aza-BODIPYs) 3-6 at 1/7-position were successfully prepared. NaN3 undertook nucleophilic aromatic substitution via replacement of F atoms of 4 to form the N-3/NH2-containing aza-BODIPYs 9 and 10. The solid-state structure of aza-BODIPY 4 was confirmed by single crystal X-ray analysis, the F-Cph bond distance of which was found to be shorter than those of the reported fluoride. These aza-BODIPYs absorb and emit in the NIR region. Surprisingly, although the withdrawing group was introduced at 1/7 positions of 3-6, the effect of the fluorine atoms to the photophysical properties is trifling. However, 9 and 10 with N-3/NH2 groups resulted in a remarkable bathochromic shift. Aza-BODIPY 10 could be also used as a turn-on fluorescent probe for pH value. Moreover, the main photo physical data are well supported and explained by cLR-PCM(CHCI3)-M06-2X/6-311 + G(2d,p)/SOS-CIS(D) calculations. (C) 2016 Elsevier Ltd. All rights reserved.