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SPECTROSCOPIC STUDIES ON A RETINYLIDENE‐IMINE‐TETRAFLUOROBORATE
Author(s) -
Baran Jan,
Ilczyszyn Marek,
Ratajczak Henryk,
Baron MarieHélène,
PiartGoypiron Annie,
Ratovelomanaicole,
Zine Hassan,
Sandorfy Camille
Publication year - 1995
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1995.tb09161.x
Subject(s) - anharmonicity , tetrafluoroborate , imine , protonation , chemistry , hydrogen bond , spectral line , photochemistry , overtone , schiff base , crystallography , ion , molecule , physics , organic chemistry , ionic liquid , quantum mechanics , astronomy , catalysis
— N ‐retinylidene‐butyl‐l‐aminium tetrafluoroborate (NRBH+BF 4 ‐ ) was used to determine the frequencies of the free (non‐hydrogen‐bonded) v (N+‐H) and v (C=NH+) vibrations and their anharmon‐icity constants. For this purpose the Fourier‐transform IR and near‐IR (overtone) spectra were recorded. The visible‐UV spectra were also taken. The results locate the free v (N+‐H) band at about 3250 ± 50 cm ‐1 ; the vibration has normal anharmonicity while v (C=NH+) is very nearly harmonic. The UV and IR spectra show that the Schiff base is protonated, but that the proton is only very weakly hydrogen‐bonded to the anion. Therefore, in this respect, NRBH+BF 4 ‐ is a good model for the hydrogen‐bonding environment of the region around the nitrogen of rhodopsin chromophores.