ICCAS OpenIR
Syntheses of new imidazole ligand series and evaluation of 1-, 2-and 4,5-imidazole substituent electronic and steric effects on N-donor strengths
Eseola, Abiodun O.1; Sun, Wen-Hua4,5; Li, Wen3; Woods, Joseph A. O.2
2010-12-15
Source PublicationJOURNAL OF MOLECULAR STRUCTURE
ISSN0022-2860
Volume984Issue:1-3Pages:117-124
AbstractA series of new imidazole based heterocycles (5-(4,5-diphenyl-1H-imidazol-2-yl)furan-2-yl)methyl acetate (Him-dp), (5-(1H-phenanthro(9,10-d]imidazol-2-yl)furan-2-yl)methyl acetate (HIm-pt), (5-(1H-imidazo(4,5-f][1,10]phenanthrolin-2-yl)furan-2-yl)methyl acetate (HIm-phen), 2-(2-nitrophenyl)-4,5-diphenyl-1H-imidazole (HIm-n), 1-methyl-2-(2-nitrophenyl)-4,5-diphenyl-1H-imidazole (MeIm-n), N-(2-(1-ethyl-4,5-diphenyl-1H-imidazol-2-yl)phenyl)benzamide (EtIm-ba) and 2,4-di-tertbutyl-6-(8-(1-ethyl-4,5-diphenyl-1H-imidazol-2-yl)-1,4-dihydroquinolin-2-yl)phenol (EtIm-q) were synthesized and studied for the dependence of their azole donor characteristics on substituent factors by means of experimentally determined ionization constant data (derived as pK(a)s), spectroscopic analyses and calculated properties of their OFT optimized molecular geometries performed at the B3LYP/6-311 + G* level. Results showed that the lowest donor strength recorded for HIm-pt (pK(a) = 2.67 +/- 0.07) could be traced to the extensive electronic conjugation of the azole pi-electrons with 4,5- and 2-substituents. On the other hand, the strongest imidazole donor strength in the series was obtained from EtIm-q (pK(a) = 4.61 +/- 0.04) for which the substituents possessed negligible pi-overlap with the azole ring. The experimental results and theoretical calculations lead to conclusions that effective conjugation between the imidazole ring and substituent aromatic groups is accountable for significant withdrawal of charge densities on the imidazole N-donor atom and vice versa. Furthermore, observed donor strengths in the series suggest that electronic inductive effects of the substituents provided lesser impact on donor strength modification of imidazole base and that alkylation of 1-imidazole position did not yield the anticipated push of electron density in favour of the N-donor atom. It is anticipated that the results should promote the understanding of azole-containing bio-macromolecular species and reactions as well as tuning and application of azole functions in molecular science. (C) 2010 Elsevier B.V. All rights reserved.
KeywordProtonation-deprotonation Substituent Effects Spectroscopy Dft Calculations
DOI10.1016/j.molstruc.2010.09.015
Indexed BySCI
Language英语
WOS IDWOS:000285659400015
PublisherELSEVIER SCIENCE BV
Citation statistics
Cited Times:6[WOS]   [WOS Record]     [Related Records in WOS]
Document Type期刊论文
Identifierhttp://ir.iccas.ac.cn/handle/121111/70692
Collection中国科学院化学研究所
Corresponding AuthorEseola, Abiodun O.
Affiliation1.Redeemers Univ, Dept Chem Sci, Redemption City, Ogun State, Nigeria
2.Univ Ibadan, Dept Chem, Ibadan, Nigeria
3.Chinese Acad Sci, Tech Inst Phys & Chem, Key Lab Photochem Convers & Optoelect Mat, Beijing 100190, Peoples R China
4.Chinese Acad Sci, Inst Chem, Key Lab Engn Plast, Beijing 100190, Peoples R China
5.Chinese Acad Sci, Inst Chem, Beijing Natl Lab Mol Sci, Beijing 100190, Peoples R China
Recommended Citation
GB/T 7714
Eseola, Abiodun O.,Sun, Wen-Hua,Li, Wen,et al. Syntheses of new imidazole ligand series and evaluation of 1-, 2-and 4,5-imidazole substituent electronic and steric effects on N-donor strengths[J]. JOURNAL OF MOLECULAR STRUCTURE,2010,984(1-3):117-124.
APA Eseola, Abiodun O.,Sun, Wen-Hua,Li, Wen,&Woods, Joseph A. O..(2010).Syntheses of new imidazole ligand series and evaluation of 1-, 2-and 4,5-imidazole substituent electronic and steric effects on N-donor strengths.JOURNAL OF MOLECULAR STRUCTURE,984(1-3),117-124.
MLA Eseola, Abiodun O.,et al."Syntheses of new imidazole ligand series and evaluation of 1-, 2-and 4,5-imidazole substituent electronic and steric effects on N-donor strengths".JOURNAL OF MOLECULAR STRUCTURE 984.1-3(2010):117-124.
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