Photoisomerization of azobenzenes isolated in cryogenic matrices

摘要: 2,2′-Dihydroxyazobenzene (DAB), 2,2′-azotoluene (AT) and azobenzene (AB) were isolated in argon xenon matrices their molecular structures photochemical transformations characterized by infrared spectroscopy theoretical calculations. All these compounds can adopt the E Z isomeric forms around central CNNC moiety, which be enriched several conformational tautomeric modifications for DAB AT. A number of AT identified first time. For DAB, azo-enol isomer with two intramolecular six-membered quasi-rings formed via OH⋯N hydrogen bonds was found after deposition. Irradiation UV light generated a different form H-bonded five-membered quasi-rings. Phototransformation shown to reversible could interconverted irradiation at wavelengths. The isomerization between constitutes direct experimental observation an → azobenzene-type molecules. Further form(s) bearing both OH NH groups. AT, isomers CH3 groups forming five/six-membered azo group observed as-deposited matrices. that converted back E-AB deposited matrix phototransformations (contrary what previously reported where only conversion occurred). AB photoisomerization becomes more pronounced elevated temperatures, thus indicating effects responsible hindering are essentially due steric restrictions. channels discussed terms small-amplitude pedal motion.