Showing papers by "Cunyuan Zhao published in 2011"
TL;DR: Detailed comparison of the geometric and electronic structure for the HpPNP cleavage reaction mechanisms in the presence/absence of catalyst revealed that the catalyst significantly altered the determining-step transition state to become far more associative or tight, that is, bond formation to the nucleophile was remarkably more advanced than leaving group bond fission in the catalyzed mechanism.
Abstract: Density functional theory (DFT) calculations were used to study the mechanism for the cleavage reaction of the RNA analogue HpPNP (HpPNP = 2-hydroxypropyl-4-nitrophenyl phosphate) catalyzed by the dinuclear Zn(II) complex of 1,3-bis(1,4,7-triazacyclonon-1-yl)-2-hydroxypropane (Zn2(L2O)). We present a binding mode in which each terminal phosphoryl oxygen atom binds to one zinc center, respectively, and the nucleophilic 2-hydroxypropyl group coordinates to one of the zinc ions, while the hydroxide from deprotonation of a water molecule coordinates to the other zinc ion. Our calculations found a concerted mechanism for the HpPNP cleavage with a 16.5 kcal/mol reaction barrier. An alternative proposed stepwise mechanism through a pentavalent oxyphosphorane dianion reaction intermediate for the HpPNP cleavage was found to be less feasible with a significantly higher energy barrier. In this stepwise mechanism, the deprotonation of the nucleophilic 2-hydroxypropyl group is accompanied with nucleophilic attack in ...
56 citations
TL;DR: A surprisingly low pK(a) for a Cu(II) bridging water was found in the presented complex, Cu(2)L, resulting in 3 orders of magnitude higher phosphodiesterase activity on BNPP than Zn( 2)L at typical lysosomal pH (~5.0).
28 citations
TL;DR: In this article, the influencing effect of different transition metal ions on the coordination geometries and structural architectures of metal-organic complexes with the same ligand was explored, and 10 new coordination compounds of a monobranched tripodal ligand N-[N′-(carboxymethyl)benzimidazol-2-ylmethyl]-N,N, N-bis(benzinimidaxylmethyl)amine (HAcNTB), namely, [Co6(AcNTB)6]·6ClO4·2CH
Abstract: To explore the influencing effect of different transition metal ions on the coordination geometries and structural architectures of metal–organic complexes with the same ligand, 10 new coordination compounds of a monobranched tripodal ligand N-[N′-(carboxymethyl)benzimidazol-2-ylmethyl]-N,N-bis(benzimidazol-2-ylmethyl)amine (HAcNTB), namely, [Co6(AcNTB)6]·6ClO4·36H2O (Co-ClO4), [Co6(AcNTB)6]·6BF4·9H2O·3CHCl3 (Co-BF4), [Zn6(AcNTB)6]·6ClO4·2CHCl3·15H2O (Zn-ClO4), [Zn6(AcNTB)6]·6BF4·52H2O (Zn-BF4), [Ni2(AcNTB)2(H2O)2]·2ClO4·2CH3OH·2H2O (Ni-ClO4), [Ni2(AcNTB)2(H2O)2]·2BF4·4CH3OH (Ni-BF4), {[Mn(AcNTB)(CH3OH)]·ClO4·H2O}n (Mn-ClO4), {[Mn(AcNTB)(CH3OH)]·BF4·H2O}n (Mn-BF4), {[Cd(AcNTB)(CH3OH)]·ClO4·H2O}n] (Cd-ClO4), {[Cd(AcNTB)(CH3OH)]·BF4·H2O}n (Cd-BF4) have been synthesized and characterized by elemental analyses, IR spectroscopy, powder X-ray diffraction, and single-crystal X-ray diffraction. In isomorphous complexes Co-ClO4, Co-BF4, Zn-ClO4, and Zn-BF4, the metal centers (Zn2+ and Co2+) are five-coordinated in...
22 citations
TL;DR: In this article, the structural, energetic and electronic properties of organometallic MCp 2 @SWCNT are obtained from DFT method, and the authors verify that such encapsulation is non-covalent functionalization, and examined binding energies and charge transfers of MCp2 @(16, 0) SWCNT systems.
15 citations