PICOSECOND FLUORESCENCE AND 2-STEP LIF STUDIES OF THE EXCITED-STATE PROTON-TRANS

2020-04-05 20:41:18

ME bonded HQ fluorescence KANAZAWA

责任者: NAKAGAWA, T;KOHTANI, S;ITOH, M 单位: KANAZAWA UNIV,GRAD SCH,DEPT PHYS & CHEM BIODYNAM,KANAZAWA,ISHIKAWA 920,JAPAN.;KANAZAWA UNIV,FAC PHARMACEUT SCI,KANAZAWA,ISHIKAWA 920,JAPAN. 来源出处: JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, v 117, AUG 2 1995, p 7952- 7957 摘要: The methanol solutions of 7-hydroxyquinoline (7-HQ) and 6-methyl-substituted 7-HQ (6-Me-7-HQ) exhibit UV (lambda(max) 370-390 nm) and large Stokes shifted (lambda(max) 510-520 nm) fluorescence spectra. The former and latter were ascribed to the normal (1:1 and 1:2 H-bonded complexes) and tautomer fluorescence spectra. Picosecond fluorescence and nanosecond/picosecond two-step LIF demonstrated that the tautomer fluorescence was generated by the excited-state proton transfer (ESPT) in the 1:2 H-bonded complexes of these compounds. The methanol solution of 7-hydroxy-8-methylquinoline (8-Me-7-HQ) shows a considerably broad UV fluorescence (lambda(max) similar to 400 nm) without the tautomer fluorescence. Concentration dependence (methanol/hexane) of absorption spectra and pK(a) determination of these compounds indicated that 7-HQ and 6-Me-7-HQ probably form 1:2 H-bonded complexes leading to the ESPT, while 8-Me-7-HQ forms only 1:1 H-bonded complex exhibiting no significant ESPT. Taking account of the steric factor of the 6- and 8-methyl groups, the cis conformation of the 7-OH group and the ring nitrogen atom seems to be required for 1:2 H-bonded complex formation leading to the ESPT in alcohol solutions of 7-HQ and its methyl-substituted compounds. 关键词: CORTICOTROPIN-RELEASING FACTOR; PHORBOL ESTERS; DEXAMETHASONE; FORSKOLIN; SECRETION; SYNTHESIS; RADIOIMMUNOASSAY FORSKOLIN; SECRETION; SYNTHESIS; RADIOIMMUNOASSAY; 2-STEP LASER-EXCITATION; TIME-RESOLVED FLUORESCENCE; TRANSIENT ABSORPTION; GROUND-STATE; TRIPLET-STATES; 3-HYDROXYFLAVONE; ABSORPTION; GROUND-STATE; TRIPLET-STATES; 3-HYDROXYFLAVONE; 7-AZAINDOLE; 2-NAPHTHYL-3-HYDROXYCHROMONES; 7-QUINOLINOL; RELAXATION 7-AZAINDOLE; 2-NAPHTHYL-3-HYDROXYCHROMONES; 7-QUINOLINOL; RELAXATION