张献明
论文题目：系列含氮氧配体的功能配(聚)合物的水热合成、结构、性质和机理研究
作者简介：张献明，男，1972年07月出生，1999年09月师从于中山大学陈小明教授，于2002年06月获博士学位。
摘
要
第一章 前言
主要介绍了以下几个方面的研究进展和本课题的选题意义
（一）Gillard机理及争论进展
氮杂环配体2,2¢-联吡啶、邻菲咯啉及其衍生物的过渡金属配合物在配位化学的发展中占有核心的位置。但是，在这些配合物实验数据中有相当大的比例是反常的。这些反常现象涉及动力学、稳定性和反应性等方面，从传统的分子观点很难解释。为了解释这些反常现象，Gillard借用了有机的氮杂环化学上的共价水的思想，在1975年的《配位化学评论》上提出了Gillard机理。该机理的核心部分是，吡啶氮杂环配体配位于金属离子产生的效应类似于吡啶氮的季铵化，增加了吡啶的2-和4-位碳的正电性，使吡啶类配体容易发生水加成反应生成共价水。不幸的是，该机理一提出就立刻遭到一些保守的配位化学家的猛烈的评击，Serpone甚至用到“神话”(myth)这样的词来评论该机理。于是以Gillard和Serpone为代表的双方针对该机理展开了一场持久激烈的争论。双方争论的焦点是金属离子的极化效应和反馈效应的贡献的相对大小。极化效应将活化氢氧根对吡啶类配体的亲核进攻，反馈效应将去活化氢氧根对吡啶配体的亲核进攻。由于争论双方的依据都是各种光谱和动力学的数据，没有直接的分子（晶体）结构证据，所以没有任何一方能说服对方。本章这部分的结尾指出：要最终证明Gillard机理在设计实验时必须选用邻菲咯啉、2,2¢-联吡啶或吡啶这类在水溶液中本身是惰性（不能自发与氢氧根发生加成反应）的配体，产物要用X射线单晶结构分析证明这些配位的氮杂环配体在水中a-碳上发生了羟基化形成2-羟基-1,10-菲咯啉、6-羟基-2,2¢-联吡啶或2-羟基-吡啶。
（二）微孔的类分子筛研究进展
这部分介绍了微孔的类分子筛化合物，特别是Yaghi等利用刚性和热稳性本身比较好的芳香多酸和多碱配体和金属离子(或金属氧簇)作为建筑单元发展的的第三代类分子筛，即：金属—有机框架。这一代类分子筛的孔穴是非常大的（纳米数量级），热稳性和Langmuir表面积方面也更接近于分子筛。
（三） 配位化合物的水热合成进展
水热法被广泛地用来制备各种配位化合物的晶体，与传统的蒸发溶剂、扩散和溶胶–凝胶生长晶体的方法相比，它是在较高的温度和压力下进行的。因此，水热反应中常伴随着一些在通常条件下不能进行的有机反应，形成新的配体。我们分类介绍了，水热条件下合成的含无机的同多或杂多酸配体、联吡啶、 有机多酸、 吡啶羧酸和混合酸碱配体的配位化合物。
（四）水热条件下配体反应和机理研究
总结了以往在水热条件下观察到的几类配体反应： （1）吡啶腈、醛和酯在醇和水混合溶液中水解成吡啶羧酸；（2）磺基取代羧基反应；（3）邻菲啰啉的脱氢的聚合：（4）甲醇被氧化偶合生成草酸：（5）间苯二甲酸的羟基化反应。
（五）选题意义
正如Constable 所说，Gillard机理是非常重要的，因为它不仅能成功地解释了含氮杂环配体的配位化合物在水溶液中的反常现象，更重要的在于，它将两个明显不同的领域（配位化学和有机杂环化学）相联系起来了。如果该机理是正确的话，它极有可能成为这两个领域之间的一个桥梁。另一方面，Gillard机理是建立在吡啶配位于金属离子产生的效应类似于吡啶氮的季铵化这样一个假设的前题下的，因而该机理的正确性就不可避免地受到质疑。事实上，从Gillard机理的提出到现在的近三十年时间里，针对该机理的正确性的争论就从未停止过。针对这个机理的评论性文章就有三篇，除此之外，在Constable在《金属和配体的反应性》等专著中占有大量的篇幅讨论该机理及争论进展。另外，本课题选择的微孔的类分子筛、多钒酸和手性的金属配合物的研究都是当今国际和国内无机化学的前沿领域。
第二章 含羟基化的联吡啶类配体的多核銅配合物的合成、表征、机理与性质研究
在水热条件下，用邻菲咯啉和铜盐反应合成了二核铜配合物[CuI2(ophen)2] (ophen = 2-羟基-1,10-邻菲咯啉)的三个超分子异构体，这三个超分子异构分子中Cu…Cu距离是2.68 Å，存在弱的Cu(I)-Cu(I)成键作用。配合物[CuI2(ophen)2]的三种超分子异构体中有C–H···O 氢键, 芳环的 p-p堆积作用和分子间的Cu···Cu 作用三种不同的超分子作用力，它们的相对贡献的不同导致形成不同的超分子的异构体。配合物[CuI2(ophen)2]具有Cu(I)-Cu(I)成键作用引发的光致发光特性。
在水热条件下，用邻菲咯啉（或-2,2’-联吡啶）、二羧酸和铜盐反应合成了三个含羟基化的联吡啶类配体（2-羟基-1,10-邻菲咯啉或6-羟基-2,2¢-联吡啶）的四核Cu(I,II)配合物[Cu4(ophen)4(tp)]、[Cu4(obpy)4(tp)] 和[Cu4(obpy)4(dpdc)]×2H2O （obpy =6-羟基-2,2¢-联吡啶；tp =对苯二甲酸； dpdc =联苯对二酸）。三个四核混合价铜化合物具有相似的分子结构，它们由一对[Cu2(ophen)2]+ 或 [Cu2(obpy)2]+ 碎片和一个架桥的二羧酸配体组成中性的四核的哑铃型结构。配合物[Cu4(ophen)4(tp)]的磁化率数据表明每一个Cu2 单元的有效磁距是1.73 玻尔磁子，证实每个Cu2 单元有一个未成对的电子，价键计算显示每个铜的化合价是1.5价，说明它们是自旋离域的混合价铜化合物。三个四核铜化合物中，Cu…Cu距离都非常短，约2.40-2.44 Å，含有生物化学上重要的CuI–CuII键。控制的实验表明二核的[CuI2(ophen)2]是四核的混合价铜(I,II)配合物[Cu4(ophen)4(tp)]的中间体；
本章所涉及的配合物的水热合成过程中，配体邻菲咯啉转化为2-羟基-1,10-邻菲咯啉，2,2¢-联吡啶转化成6-羟基-2,2¢-联吡啶，这与前言部分提到的长期争论的Gillard机理的核心部分完全一致，第一次从结构上证明了长期争论的Gillard机理的核心部分(即“共价水”的形成)。此外，这些多核铜配合物的形成机理，其形成过程涉及羟基与铜(II)的配位、脱a-氢和分子内的电子转移，为进一步澄清铜(II)盐催化氧化醇的机理提供了新的依据。
第三章 微孔的类分子筛的合成、表征和性质
选用不同的配体，从不同的设计原理合成了四个微孔的类分子筛化合物，并初步探讨了这些化合物的孔穴大小、热稳定性和离子交换等特性。化合物[Co3(OH)2(2,4-pdc)2]是一个由吡啶-2,4-二甲酸“十”字形连接无机钴氧链而形成的含一维的大的通道的有机—无机杂化三维框架。扣除原子范德华半径之后，通道尺寸为 7 ´ 7 Å，有效孔穴体积是晶体总体积的 43.7%，热稳定性为270 °C，孔穴尺寸和比表面等方面都接近于目前使用的大孔分子筛；化合物[Zn(2,2¢-bpy)(tp)]是由一维的链通过C–H···O氢键连接子和p-p堆积作用构筑的有大的通道 (13 ´ 7 Å)的化合物，孔穴体积是晶体总体积的40.7%，热稳定性为310 oC，在客体分子去除后能够保持框架的完整性；混合价铜(I,II)化合物[Cu3(4,4¢-bpy)(2,4-pdc)2] 是由[Cu(4,4¢-bpy)]+n链通过[Cu(II)(2,4-pdc)2]2+ “配合物配体”连接成的二维的波浪形的(6,3)层状结构。“配合物配体”作为(6,3)的网连接物，其效应是相当于延长了桥连配体的长度，产生了大小为18 ´ 16 Å 的孔穴(已扣除了范德华半径)。同时，又使得波浪形的二维层有相当高的波动幅度，使得一个二维层可以和更多的独立层相穿插，导致第一个五重平形穿插的 (6,3) 网。这个化合物中五重穿插并没有占据所有可利用的孔穴，而是留了17%的通道体积。微孔的化合物[VIVO(dod)2]X2是双波浪的(4,4)拓朴结构的层，相邻的层以错位的方式堆积，产生了中等尺寸的通道，它是第一个非簇的四价钒的配位聚合物。
第四章 钒氧化物的固态配位化合物的合成和表征
多钒酸离子可以作为配体配位于其它过渡金属离子，形成簇状、一维、二维或三维结构的固态化合物。本章以邻菲咯啉为有机配体在水热条件下合成了固态两个钒氧配位化合物[{Co(phen)2}2V6O17]和[{Cu(phen)2}4V10O29]。[{Co(phen)2}2V6O17]结构是一维的阶梯状的链，由[Co(phen)2]2+配合物碎片和新型的{V6O17}n4n-链组成，阴离子的{V6O17}n4n-钒酸盐链是新颖的多钒酸物种，由四钒酸簇V4O124- 和二钒酸簇V2O74-通过共用氧原子连接而成的。[{Cu(phen)2}4V10O29]是一个十四核的异金属簇，V10O298- 簇是由两个V4O124- 簇和一个 V2O74-簇通过共用氧原子而成的。本章的介绍的新型{V6O17}n4n-链和V10O298-簇属首次发现，它们的结构暗示了它们与四核的V4O124-和二核的V2O74-簇有密切的联系。
第五章 磷酸钒氧化物的固态配合物的合成、表征和性质研究
本章介绍了三个层状的含联吡啶或邻菲咯啉配体的磷酸钒氧化物的固态配位化合物。化合物[{Cu(phen)}2(VVO2)2VIVO2(H2O)(PO4)2]与Zubieta报导的[{Cu(phen)}2(VVO2)3(OH)(PO4)2]同结构，这两化合物代表了相对少见的全部V(V)和V(V)/V(IV) 混合价类似物；化合物[Zn(phen)Zn(VO)(PO4)2] 是由阴离子的[Zn(VO)(PO4)2]2-层和阳离子的配合物碎片 [Zn(phen)]2+组成的二维层状结构。锌原子不仅以ZnO4四面体形式构筑无机的Zn/V/P/O层，而且以[Zn(phen)]2+的形式装饰无机Zn/V/P/O层，具有双重功能；化合物[V4O7(2,2¢-bpy)2(HPO4)2]是一个由2,2’-联吡啶直接配位于钒原子构筑成的具有(4,6,8)拓朴结构的化合物，与化合物[V3O7(phen)]有相关的拓朴学。
第六章 功能手性配合物的合成、表征和性质
以吡啶-2,5-二甲酸配体与钴(II)或镍(II)反应合成了 (6,3)拓朴结构的非中心对称的配位聚合物[M(2,5-pdc)(H2O)2]×H2O (M = Co, Ni)，具有二维层状结构，在层内含有手性的孔穴。以混合的4-羟基-间苯二甲酸和2,2’-联吡啶合成了由三核簇单元构筑的配位聚合物[M3(2,2’-bpy)3(oip)2(H2O)] ×4H2O (M = Zn, Co)，具有二维的（4,4）拓朴结构，在层内有手性孔穴（ 5.5 ´ 6.0 Å）。无色透明的锌配合物，是良好的非线性光学材料的候选物。
关键词： Gillard机理 类分子筛 水热法 配位化合物
Abstract
Chapter I. Introduction
The chapter introduces the related research progress and the meaning of the research topic.
(I) Progress of Gillard mechanism and its argument
The chelate ligands 2,2¢-bipyridine (bpy), 1,10-phenanthroline (phen) and their substituted derivatives have played an important role in the development of coordination chemistry and there are increasing so-called “anomalies” in the reaction of metal complexes of bpy and phen. The anomalies involve kinetics, stability and reactivity, etc., and it is difficult to explain them with traditional molecular term. To rationalize the anomalous properties of the complexes such as [M(bpy)3]n+ and [M(phen)3]n+, Gillard borrowed the idea of ‘covalent hydrates’ from organic literature and proposed an interesting Gillard mechanism in Coordination Chemistry Reviews. The core of the Gillard mechanism is that the coordination of pyridine N-heterocycle to a metal ion has an effect similar to quaternization of pyridine nitrogen which increases the positive charge of carbon adjacent to nitrogen and thus will activate nucleophilic attack of a hydroxide ion on coordinated heterocyclic ligand to form covalent hydrate. Unfortunately, some conservative chemists seriously questioned the Gillard mechanism and Serpone used “myth” to comment the mechanism. Thus there has been heated and long-term argument on the correctness of the Gillard mechanism. The focus of the argument is the polarization effect and feedback effect of metal ions as well as their relative contribution. The polarization effect will activate the nucleophilic attack of a hydroxide ion on coordinated heterocyclic ligands; the feedback effect will deactivate the nucleophilic attack of a hydroxide ion on coordinated heterocyclic ligands. The Gillard mechanism became a long-term argument because all evidences from both sides of argument came from spectral and kinetic data (no structural evidence of covalent hydrate). According to the core of the Gillard mechanism and the argument focus, we point out at the end of this part that if one wants to final verify the Gillard mechanism, he must choose 2,2¢-bipyridine, 1,10-phenanthroline or pyridine ligand which does not spontaneously react with hydroxide ion. Furthermore, the hydroxylated product (6-hydroxyl-2,2¢-bipyridine, 2-hydroxyl-1,10-phenanthroline or 2-hydroxy-pyrdine) should be characterized by X-ray single crystal structural analysis.
(II) Progress on microporous zeolite-like compounds
This part introduce microporous zeolite compounds, especially the zeolite-like compounds which were developed by Yaghi et al by using thermally stable aromatic polyacid (or polybase) and metal ions (or metal clusters) as second building unit. These zeolite-like compounds have large pore, good thermal stability and Langmuir surface.
(III) Progress on hydrothermal syntheses of complexes
Hydrothermal method has been widely used to prepare complex crystals, and compared with traditional crystal growth methods such as evaporation, diffusion and sol-gel method, it is performed under higher temperature and pressure. Thus, it is often accompanied by some organic ligand reaction which is difficult to conduct under general condition. This part we introduce complexes synthesized by hydrothermal method containing inorganic polyacid, bipyrindine, organic polyacid, pyridine-carboyxlate, and mixed polyacid and polybase ligands.
(IV) Ligand reaction and mechanism under hydrothermal condition
Several types of ligand reactions observed under hydrothermal condition were summed up: (1) hydrolysis of pyridine nitrile, aldehyde and ester in mixed water and alcohol into pyridine-carboxylate; (2) replacement of carboxylate group with sulfonic group; (3) coupling of phenanthroline by dehydrogen; (4) oxidative coupling of methanol into oxalic acid; (5) hydroxylation of isophthalate.
(V) Significance of the research topic
As said by Constable: the Gillard mechanism is very important because it can rationalize the anomalies of the N-heterocyclic complexes in aqueous solution. Equivalently important, it links two remarkable different fields (coordination chemistry and organic N-heterocyclic chemistry) together. If the Gillard mechanism is correct, it will possibly be a bridge between coordination chemistry and organic N-heterocyclic chemistry. One the other hand, the Gillard mechanism is built upon the hypothetical prerequisite of coordination of pyridine to metal ion having similar effect to quaternization of nitrogen, and thus it will unavoidably be questioned. In fact, there has been the argument on the Gillard mechanism over the past nearly thirty years. Three review articles on the Gillard mechanism were published. Besides, it takes a number of pages talking about the Gillard mechanism in the book “Reactivity of Metal Ions and Ligands” edited by Constable.
Chapter II syntheses, characterizations, mechanisms and properties of polynuclear copper complexes with hydroxylated bipyridine-like ligands
Hydrothermal reaction of copper(II) salt and 1,10-phenanthroline resulted in dinuclear [Cu2(ophen)2] (ophen = 2-hydroxy-1,10-phenanthroline). The dinuclear [Cu2(ophen)2] were isolated in three supramolecular isomers，and the Cu…Cu distances in the three isomers are ca. 2.68 Å，indicating there are weak Cu(I)-Cu(I) bonding interactions. There are C–H···O hydrogen bonds, p-p stacking interaction and intermolecular Cu···Cu interaction in the three isomers. The dinuclear [CuI2(ophen)2] shows interesting photoluminescent properties supported by copper(I)-copper(I) interactions.
Hydrothermal reaction of copper(II) salt, 1,10-phenanthroline (or 2,2¢-bipyridine) and dicarboxylate resulted in three tetranuclear copper(I,II) complexes [Cu4(ophen)4(tp)], [Cu4(obpy)4(tp)] and [Cu4(obpy)4(dpdc)]×2H2O (ophen = 2-hydroxy-1,10-phenanthroline, obpy = 6-hydroxy-2,2¢-bipyridine). The three tetranuclear copper complexes are structurally analogous and they all consist of a pair of [Cu2(ophen)2]+ or [Cu2(obpy)2]+ fragments bridged by a deprotonated dicarboxylate into dumbbell-shaped, neutral, tetranuclear molecules. The temperature-dependent magnetic susceptibility shows an effective magnetic moment of 1.73 mB per Cu2 unit at 200 K is consistent with one unpaired electron per dimer. The valence sum calculation reveals the valence state of per copper is 1.5, indicating they are delocalized mixed-valence copper(I,II) complexes. The Cu…Cu distances in the three tetranuclear complexes are in the range of 2.40-2.44 Å, indicating there are copper(I)-copper(II) bond. The controlled experment shows dinuclear [Cu2(ophen)2] is the intermediate for tetranuclear [Cu4(ophen)4(tp)].
The hydroxylation of 1,10-phenanthroline or 2,2¢-bipyridine ligand leading to 2-hydroxy-1,10-phenanthroline or 6-hydroxy-2,2¢-bipyridine in these copper complexes provides first structural supports for the long-term argued Gillard mechanism. The formation mechanisms of these copper complexes involve coordination of hydroxyl to copper(II) ion, removal of a-hydrogen and intra-molecular electron transfer which show similarities to the so far known main steps in the catalytic oxidation of alcohol by copper(II) salt to aldehydes or ketones, and thus the work is helpful to understand the precise mechanism of catalytic oxidation of alcohol.
Chapter III synthesis, characterization and properties of microporous zeolite-like compounds
Four microporous zeolite-like compounds were synthesized from different designing principle and different ligands, and the channel size, thermal stability and ion-exchange properties were also investigated. Compound [Co3(OH)2(2,4-pdc)2] is a 3-D organic-inorganic hybrid framework with 1-D large channels in which the water molecules are filled. The free dimensions (7 ´ 7 Å) of these channels occupy as large as 43.7% of the crystal volume, being comparable with those of most open zeolites (47% to 50%), such as the faujasite, paulingite, and zeolite A families. The thermal stability of [Co3(OH)2(2,4-pdc)2] is at least 270 °C. [Zn(2,2¢-bpy)(tp)] is a 3-D framework featuring 1-D large channels constructed from 1-D chains via C–H···O synthons and p-p stacking interactions and its framework can be retained in the absence of guest molecules. The free dimensions (13 ´ 7 Å) of these channels produced after calcinations occupy as large as 40.7% of the crystal volume. Mixed-valence complex [Cu3(4,4¢-bpy)(2,4-pdc)2] is constructed by [CuII(pydc)2]2– ‘metal complex ligand’ linking [CuI(4,4¢-bpy)]nn+ zigzag chains to generate a 2-D wave-like (6,3) brick-wall array. The [CuII(pydc)2]2– as connector prolong space which resultes in large void (18 ´ 16 Å) within the layer. Besides, it makes one independent layer interpenetrate with more layers generating first five-fold interpenetrating (6,3) net. The five-fold interpenetration of 2-D (6,3) networks does not occupy all voids formed by one independent 2-D network but leaves 1-D channels occupying 17% of the crystal volume. Compound [VO(dod)2]X2 is double wave-like two-dimensional layer, and adjacent layers stack in a staggered fashion giving medium size channel. [VO(dod)2]X2 is the first non-cluster vanadium(IV) coordination polymer with partial ion-exchange properties.
Chapter IV syntheses and characterization of solid state compounds of vanadium oxide
The coordination of polyvanadate anions to metal ions can form cluster-like, chain-like, layered or three-dimensional framework (solid state coordination compound). Two novel solid state coordination complexes of vanadium oxides, namely [{Co(phen)2}2V6O17] and [{Cu(phen)2}4V10O29], were hydrothermally synthesized and structurally characterized. [{Co(phen)2}2V6O17] has stepped chain-like structure constructed by [Co(phen)2]2+ fragments and the unprecedented {V6O17}n4n-chain which can be viewed as oxygen-sharing linking of V4O124- and V2O74- clusters. [{Cu(phen)2}4V10O29] comprises discrete V10O298- cluster with four [Cu(phen)2]2+ fragments covalently attached and V10O298-cluster can be viewed as oxygen-sharing linking of two V4O124- and one V2O74- clusters. Both {V6O17}n4n- chain and V10O298- cluster were firstly found, and their structures indicate they have close relevance to V4O124- and V2O74- clusters.
Chapter V syntheses, characterizations and properties of solid state compounds of phosphate vanadium oxides
Three layered solid-state coordination complexes of phosphate vanadium oxides were synthesized and structurally characterized. [{Cu(phen)}2(VVO2)2VIVO2(H2O)-(PO4)2] is isostructural to fully oxidized [{Cu(phen)}2(VVO2)3(OH)(PO4)2] reported by Zubieta, and the two compounds represent relatively rare examples of all V(V) and V(V)/V(IV) mixed-valence analogues in the solid state. [Zn(phen)Zn(VO)(PO4)2] consists of anionic mixed zinc-vanadium phosphate layers [Zn(VO)(PO4)2]2– in pairs attached by cationic [Zn(phen)]2+ complex fragments. The zinc atoms play unique dual functions, that is, not only in the form of ZnO4 constructing inorganic Zn/V/P/O layer but also in the form of [Zn(phen)]2 decorating inorganic layer. Compound [V4O7(2,2¢-bpy)2(HPO4)2] is a rare solid-state coordination complex of phosphate oxovanadium with the 2,2¢-bipy ligands directly coordinated to vanadium atoms, showing (4,6,8) net topologically related to [V3O7(phen)].
Chapter VI Syntheses, characterizations and properties of chiral complexes
Hydrothermal reaction of pyridine-2,5-dicarboxylate and M(II) salt resulted in coordination polymer [M(2,5-pdc)(H2O)2]×H2O (M =Co, Ni) which crystallize in a chiral space group and has a layered structure with chiral void. Hydrothemal reaction of 4-hydroxy-isophthalate, 2,2’-bipy and M(II) salt results in [M3(2,2’-bpy)3(oip)2(H2O)]×4H2O (M = Zn, Co) which has a layered (4,4) topological structure constructed by trinuclear metal cluster units and crystallizes in a chiral space group. Colorless [Zn(2,5-pdc)(H2O)2]×H2O and [Zn3(2,2’-bpy)3(oip)2(H2O)] ×4H2O can be good candidates for NLO materials.
Keyword: Gillard mechanism, microporous zeolite-like compound, hydrothermal, complex
