Two New Three-dimensional Supramolecular Complexes with 5-Carboxyl-1-carboxymethyl-2-oxidopyridinium: Syntheses and Crystal Structures

Two new supramolecular complexes [MnL(H2O) 4](1) and [ZnL(H2O) 5]·0.25H2O(2) (H2L = 5-carboxy-1-carboxymethyl-2-oxidopyridinium) have been synthesized and structurally characterized by elemental analysis,IR and X-ray single-crystal structure determination. Complex 1 crystallizes in the monoclinic system,space group P21/n with a = 5.1537(2) ,b = 21.2008(9) ,c = 10.9727(4) ,β = 99.182(2) °,V = 1183.54(8) 3,C8H13MnNO9,Mr = 322.13,Dc = 1.808,Z = 4,F(000) = 660,μ = 1.160,R = 0.0372 and wR = 0.0750 for 2217 observed reflections(I > 2σ(I)) . Complex 2 crystallizes in the triclinic system,space group P1 with a = 7.730(2) ,b = 8.030(2) ,c = 11.400(2) ,α = 104.27(3) ,β = 92.93(3) ,γ = 102.67(3) °,V = 664.9(2) 3,C8H15.5ZnNO10.25,Mr = 355.08,Dc = 1.774,Z = 2,F(000) = 365,μ = 1.899,R = 0.0243 and wR = 0.0695 for 2759 observed reflections(I > 2σ(I)) . Their thermal properties have been studied.     

Collective behaviour of climate indices in the North Pacific air-sea system and its potential relationships with decadal climate changes

A climate network of six climate indices of the North Pacific air-sea system is constructed during the period of 1948-2009.In order to find out the inherent relationship between the intrinsic mechanism of climate index network and the important climate shift,the synchronization behaviour and the coupling behaviour of these indices are investigated.Results indicate that climate network synchronization happened around the beginning of the 1960s,in the middle of the 1970s and at the beginnings of the 1990s and the 2000s separately.These synchronization states were always followed by the decrease of the coupling coefficient.Each synchronization of the network was well associated with the abrupt phase or trend changes of annually accumulated abnormal values of North Pacific sea-surface temperature and 500-hPa height,among which the one that happened in the middle of the 1970s is the most noticeable climate shift.We can also obtain this mysterious shift from the first mode of the empirical orthogonal function of six indices.That is to say,abrupt climate shift in North Pacific air-sea system is not only shown by the phase or trend changes of climate indices,but also might be indicated by the synchronizing and the coupling of climate indices.Furthermore,at the turning point of 1975,there are also abrupt correlation changes in the yearly mode of spatial degree distribution of the sea surface temperature and 500-hPa height in the region of the North Pacific,which further proves the probability of climate index synchronization and coupling shift in air-sea systems.     

超临界水中醋酸锌水解反应的分子动力学模拟

氧化锌(ZnO)是一种重要的化工原料, 超临界水热合成法制备纳米ZnO的第一步是锌盐与碱或水发生水解反应生成Zn(OH)₂, 后者接着脱水生成ZnO. 以Zn(CH₃COO)₂为原料, 直接和超临界水(SCW)反应能够制备纳米级的ZnO颗粒, 但对反应机理的探讨较少. 本研究利用分子动力学模拟超临界条件下Zn(CH₃COO)₂水解反应过程中的结构和能量变化, 发现Zn(CH₃COO)₂在SCW中容易聚集成无定形的团簇, 1个Zn²⁺平均和5个CH₃COO^-和1个H₂O配位, 形成6配位的八面体结构. 处于Zn(CH₃COO)₂团簇和SCW界面的Zn²⁺能够和更多的H₂O配位. 水解反应后系统的势能降低, 同时伴随Zn(CH₃COO)₂团簇结构的改变. 反应产物OH^-分布在Zn(CH₃COO)₂团簇内部, 富集Zn²⁺, 而CH₃COOH则分布在SCW中. 本文的工作为超临界水热合成的反应过程提供了基本的理论依据.