Hydrogen-bonding interactions, geometrical selectivity and spectroscopic properties of cobalt(III) complexes with unsymmetrical tridentate amine-amidato-phenolato type ligands
摘要:
Four cobalt(III) complexes with the formula of [Co(Ln)(2)] bearing tridentate amine-amidato-phenolato-type ligands (Ln: n = 1-4) were synthesized. All of the complexes were characterized by H-1 NMR spectroscopy and X-ray analysis. The geometrical selectivity was found to depend on the flexibility of the amine-amidato chelate in combination with the planar 2-oxybenzamido 6-membered chelate; that is, the amine-amidato 5-membered chelate took the mer-type geometry, and the 6-membered chelate took the fac-type geometry. In most of the mer-type complexes, intermolecular double hydrogen bonds via amidato(O) and amino group were selectively formed between their enantiomeric pairs of mononuclear complexes. In the case of two chiral ligands {L2(2) = 2-amino-1-(2-oxybenzamido) propane; L3(2) = trans-1-amino-2-(2-oxybenzamido)cyclohexane}, [Co(L3)(2)] showed diastereoselectivity while [Co(L2)(2)] did not. Furthermore, PPh4[Co(L1)(2)] (L1(2) = 2-amino-1-(2-oxybenzamido)-2-methylpropane) showed an apparent solvatochromic behavior in several solvents. Although the molecular structures of [Co(L2 or L3)(2)] are quite similar to that of [Co(L1)(2)] , these complexes did not exhibit such a solvatochromic behavior. (C) 2013 Elsevier B.V. All rights reserved.
Greatly Enhanced Fluorescence by Increasing the Structural Rigidity of an Imine: Enantioselective Recognition of 1,2-Cyclohexanediamine by a Chiral Aldehyde
作者:Yimang Xu、Shanshan Yu、Qi Chen、Xuemin Chen、Meng Xiao、Liming Chen、Xiaoqi Yu、Yong Xu、Lin Pu
DOI:10.1002/chem.201504686
日期:2016.4.18
sensitive fluorescenceenhancement sensor through incorporation of an additional hydrogen bonding unit to increase the structural rigidity of the reaction product of the aldehyde with the diamine. This new chiral aldehyde is synthesized in one step from the reaction of (S)‐3‐formylBINOL with salicyl chloride. When treated with trans‐1,2‐cyclohexanediamine in ethanol, it shows greatly enhanced fluorescence
A modular ligand macrocycle is composed from two phenolic groups linked to a cyclohexane bridge through an amide bond and an imine bond. The stability of the asymmetric linkers to metathesis permits a macrocyclic platform to be assembled from the condensation of two different phenolic groups in a single-step, high yield, reaction. The primary coordination sphere may be tuned with functional groups on one phenolic group. The other phenolic group may be modified with a scaffold possessing a proton transfer group. In this way, control over the secondary coordination sphere of the macrocycle is achieved. Manganese complexes of the amido-imine linked macrocycle catalytically epoxidizes 1,2-dihydronapthalene using sodium hypochlorite as the oxidant. The amido-imine macrocycles represent a new metal active site capable of supporting high oxidation states and attendant atom transfer chemistry while at the same time permitting control over the primary and secondary sphere of the metal center. (C) 2008 Elsevier Ltd. All rights reserved.