Photoisomerizations of the photochromic anil salicylidene-1-naphthylamine in 3-methylpentane
- Stephan, J.S.
- Mordziński, Andrzej
- Rodríguez, C.Ríos
- Grellmann, K.H.
ISSN: 0009-2614, 1873-4448
Datum der Publikation: 1994
Ausgabe: 229
Nummer: 4-5
Seiten: 541-550
Art: Artikel
Andere Publikationen in: Chemical Physics Letters
Zusammenfassung
The results of a nanosecond flash-photolysis study with solutions of salicylidene-1-naphthyl-amine (SN) in 3-methylpentane (3MP) at ambient and at low temperatures are reported. Besides a newly discovered triplet state, two photochromic transients (PCTs) are formed after excited state intramolecular proton-transfer (ESIPT) has taken place. Above 140 K the formation of a quinoid trans-keto tautomer (1Ktr) prevails. At 100 K a second PCT is observed in steady-state experiments which we tentatively assign to a twisted conformer of the keto form of SN. The transient 1Ktr re-enolizes in dry 3MP by second-order double proton-transfer; in the presence of 10−4 M methanol the re-enolization of 1Ktr is proton catalyzed and the lifetime of 1Ktr is shortened by more than two orders of magnitude. The properties of the flexible SN are compared with two other rotationally hindered ‘ESIPT molecules’.
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