title: Mononuclear-dinuclear equilibrium of grafted copper complexes confined in the nanochannels of MCM-41 silica.
abstract: Following the structural concept of copper-containing proteins in which dinuclear copper centers are connected by hydroxide bridging ligands, a bidentate copper(II) complex has been incorporated into nano-confined MCM-41 silica by a multistep sequential grafting technique. Characterization by a combination of EPR spectroscopy, X-ray photoelectron spectroscopy (XPS), UV/Vis spectroscopy, IR spectroscopy , and solid-state (13)C and (29)Si cross-polarization magic-angle spinning (CP-MAS) NMR suggests that dinuclear Cu complexes are bridged by hydroxide and other counterions (chloride or perchlorate ions), similar to the situation for EPR-undetectable [Cu(II)···Cu(II)] dimer analogues in biological systems. More importantly, a dynamic mononuclear-dinuclear equilibrium between different coordination modes of copper is observed, which strongly depends on the nature of the counterions (Cl(-) or ClO(4)(-)) in the copper precursor and the pore size of the silica matrix (the so-called confinement effect). A proton-transfer mechanism within the hydrogen-bonding network is suggested to explain the dynamic nature of the dinuclear copper complex supported on the MCM-41 silica.
authors: Shanghai Key Laboratory of Green Chemistry and Chemical Processes, Department of Chemistry, East China Normal University, 3663 Zhongshan North Road, 200062, Shanghai, China. kzhang@chem.ecnu.edu.cn
authors: Kun
authors: K
authors: Zhang
authors: Koon-Fung
authors: KF
authors: Lam
authors: Belén
authors: B
authors: Albela
authors: Teng
authors: T
authors: Xue
authors: Lhoussain
authors: L
authors: Khrouz
authors: Qiong-Wei
authors: QW
authors: Hou
authors: En-Hui
authors: EH
authors: Yuan
authors: Ming-Yuan
authors: MY
authors: He
authors: Laurent
authors: L
authors: Bonneviot
mesh_terms: D002384:Catalysis; D003300:Copper / Q000737:chemistry*; D018360:Crystallography, X-Ray; D006860:Hydrogen Bonding; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D009942:Organometallic Compounds / Q000737:chemistry*; D056951:Photoelectron Spectroscopy; D011522:Protons; D012822:Silicon Dioxide / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet
chemical_list: C509968:MCM-41; D009942:Organometallic Compounds; D011522:Protons; D012822:Silicon Dioxide; D003300:Copper