Reversal of the Intramolecular Charge Transfer in p-Dimethylaminobenzanilides by Amido Anilino Substitution
摘要:
p-Dimethylaminobenzanilides with a para or meta substituent at the amido anilino moiety were designed to generate a series of dual fluorescent molecules of variable electron acceptors. Ab initio calculations indicated that the anilino substitution did not lead to an obvious change in the ground-state structures of the fluorophores, and the H-1 NMR signal of the amido -NH proton was found to experience a linear downfield shift with increasing a of the substitutent, supporting the fact that the amido anilino moiety was indeed varied comparably by the substitution. The intramolecular charge transfer dual fluorescence was indeed observed in solvents over a large polarity range from the nonpolar cyclohexane (CHX) through diethyl ether (DEE) and tetrahydrofuran (THF) to highly polar acetonitrile (ACN). It was found that the CT emission shifted to the blue with increasing electron-withdrawing ability of the amido anilino substituent up to a Hammett constant sigma of ca. +0.39 and to the red at higher sigma. The solvent polarity variation did not change the sigma value at which the CT emission shift direction reverses. Similar variation profiles were also observed with the CT to LE emission intensity ratio and the total fluorescence quantum yield. It was concluded that the CT direction in p-dimethylaminobenzanilides was reversed by the amido,anilino substitution, and the CT occurs from amido anilino to benzoyl moiety at low sigma, whereas at high sigma, the CT switches to that from dimethylamino to the benzanilide moiety, which was also supported from the Hartree-Fock calculations. This finding provides an alternative method based on substitutent effect for identifying the charge-transfer direction in multiple charge-transfer systems. The results suggested that the anilino group could be a much stronger electron donor than an aliphatic amino group, which would be of use in designing electron donor substituted molecules. In both cases the dependences of the CT emission energy against sigma of the substituent at the amido aniline phenyl ring were found to be much stronger than that in the ester counterparts of p-dimethylaminobenzanilides. This interesting sigma dependence in the CT emission would be of significance in developing new fluorescent sensors based on electron donor/acceptor variations in p-dimethylaminobenzanilides.
<scp>Iron‐Catalyzed</scp> Amide Bond Formation from Carboxylic Acids and Isocyanates<sup>†</sup>
作者:Lingjian Zi、Jing Zhang
DOI:10.1002/cjoc.202300396
日期:2023.12
We describe an iron-catalyzed amidebondformation from readily available carboxylic acids and isocyanates. This method utilizes an abundant and biocompatible iron catalyst and easily accessible starting materials, generates CO2 as the only byproduct, and features broad substrate scopes with good functional group compatibility. Therefore, it provides a cost-effective and practical protocol to access
[EN] N-PHENYL-BENZAMIDES PROVIDING PROTECTION FROM THE HARMFUL EFFECTS OF ULTRAVIOLET LIGHT
申请人:——
公开号:WO1992019208A1
公开(公告)日:1992-11-12
[EN] N-phenyl-benzamides may be used as sun filters or sun screens for UV-A, UV-B and UV-AB in cosmetic and medical compositions, or as agents for protecting foodstuffs and materials from deterioration by ultraviolet light. [FR] Les N-phényl-benzamides peuvent être utilisés comme filtres solaires, écrans solaires UV-A, UV-B et UV-AB dans les préparations cosmétiques et médicales. Les N-phényl-benzamides peuvent être des agents de protection des denrées alimentaires et des matériaux contre les dégradations provoquées par la lumière ultra-violette.
[EN] USE OF HEMATOPOIETIC GROWTH FACTOR MIMETICS<br/>[FR] UTILISATION DE MIMÉTIQUES D'UN FACTEUR DE CROISSANCE HÉMATOPOÏÉTIQUE
申请人:LIGAND PHARM INC
公开号:WO2012068406A2
公开(公告)日:2012-05-24
The present invention relates to uses of small molecule mimetics of hematopoietic growth factors. In particular the present invention relates to uses of small molecule mimetics of erythropoietin.