Synthesis and spectral-luminescence properties of 2,7-diaminobenzopyrylium tetrafluoroborates

2,7-Diaminobenzopyrylium Dyes Are Live-Cell Mitochondrial Stains

“…Inspired by the structural relationship between compounds 4 / 5 and 6 / 7 , we considered 2,7-diaminobenzopyrylium (DAB) structures exemplified by the tetraethyl derivative 8 ; this is the “coumarin-sized” analog of Rhodamine B ( 9 ). Although iminocoumarins have received some attention as dyes and indicators, the cationic 2,7-diaminobenzopyrylium fluorophore scaffold is essentially unexplored, with a lone report in the Soviet chemistry literature from 1989 …”

“…Although iminocoumarins have received some attention as dyes 15 and indicators, 16 the cationic 2,7-diaminobenzopyrylium fluorophore scaffold is essentially unexplored, with a lone report in the Soviet chemistry literature from 1989. 17 We began our investigation by synthesizing the known tetraethyl DAB dye 8 starting from Coumarin 1 (6, Scheme 1a). 17 Treatment with Et 3 OBF 4 generates a 2-ethoxychromenylium intermediate that reacts with diethylamine to give 8, which we obtained in 41% yield.…”

“…17 We began our investigation by synthesizing the known tetraethyl DAB dye 8 starting from Coumarin 1 (6, Scheme 1a). 17 Treatment with Et 3 OBF 4 generates a 2-ethoxychromenylium intermediate that reacts with diethylamine to give 8, which we obtained in 41% yield. Based on the success of this simple synthetic protocol, we prepared additional DAB dyes.…”