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1 H NMR, IR and UV/VIS Spectroscopic Studies of Some Schiff Bases Derived from 2‐Aminobenzothiazole and 2‐Amino‐3‐Hydroxypyridine
Author(s) -
Issa Raafat M.,
Khedr Abdalla M.,
Rizk Helen
Publication year - 2008
Publication title -
journal of the chinese chemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.329
H-Index - 45
eISSN - 2192-6549
pISSN - 0009-4536
DOI - 10.1002/jccs.200800131
Subject(s) - chemistry , schiff base , absorption spectroscopy , proton nmr , benzaldehyde , nmr spectra database , infrared spectroscopy , carbon 13 nmr , molecular orbital , spectral line , crystallography , molecule , stereochemistry , organic chemistry , physics , quantum mechanics , astronomy , catalysis
By condensing 2‐aminobenzothiazole with 2‐hydroxy‐1‐naphthaldehyde, 2‐hydroxybenzaldehyde, 4‐methoxybenzaldehyde, 4‐hydroxybenzal‐dehyde, benzaldehyde and 4‐dimethylaminobenzaldehyde, and five Schiff bases Ia‐Ie are prepared. Also, two Schiff bases IIa and IIb are prepared by condensation of 2‐amino‐3‐hydroxypyridine with 2‐hydroxy‐1‐naphthaldehyde and 2‐hydroxybenzaldehyde. The 1 H NMR, IR and UV/Vis spectra of these seven Schiff bases are investigated. The signals of the 1 H NMR spectra as well as the important bands in the IR spectra are considered and discussed in relation to molecular structure. The UV/Vis absorption bands in ethanol are assigned to the corresponding electronic transitions and the electronic absorption spectra of Schiff bases Ib and IIb are studied in organic solvents of different polarities. The UV/Vis absorption spectra of 2‐amino‐3‐hydroxypyridine Schiff bases IIa and IIb are investigated in buffer solutions of different pH values containing 5% (v/v) methanol, and the results are utilized for the determination of pK a and ΔG * of the ionization of the phenolic OH‐groups. The fluorescence spectra of IIa and IIb are studied in organic solvents of different polarities. The obtained spectral results are confirmed by some molecular calculations using the atom super position and electron delocalization molecular orbital theory for the Schiff base IIb.