Azaindolizine proton cranes attached to 7-hydroxyquinoline and 3-hydroxypyridine: a comparative theoretical study

Abstract

New proton cranes based on 7-hydroxy-quinoline and 3-hydroxypyridine.

Photochromism of phenazine-2,3-diol derivatives through excited state intermolecular proton transfer based on keto–enol tautomerization

“…However, the ESIntraPT process requires the presence of intramolecular hydrogen bonding between proton donor and acceptor groups, that is, it is limited to molecules containing 5- or 6-membered ring hydrogen bonding structures, such as 3-hydroxyflavone, 7 2-hydroxybenzophenone, 8 and 2-(2′-hydroxyphenyl)benzothiazole (Scheme 1a). 9 On the other hand, the ESInterPT process has been found in molecules without 5- or 6-membered ring hydrogen bonding structures, including 3-hydroxy-2-naphthanilide, 10 lumazine, 11 anthracen-2-yl-3-phenylurea, 12 7-hydroxyquinoline, 13 7-azaindole, 14 and 2-hydroxyphenazine (Scheme 1b and c). 15 Among them, Ogawa et al revealed that 2-hydroxyphenazine exhibits photochromic properties by ESInterPT: 15 when a 2-methyltetrahydrofuran (2-MeTHF) solution containing 2-hydroxyphenazine was irradiated with UV light at 365 nm at 77 K, a new photoabsorption band appeared in the long-wavelength region ( ca.…”