【作者】 张倩；

【导师】 江云宝；

【作者基本信息】 厦门大学 ， 分析化学， 2017， 博士

【摘要】 20世纪80年代以来,金配位化学得到了广泛而深入的研究,并推动了亲金属相互作用概念的提出和发展。当两个闭壳层金属离子(如Au+、Ag+和Cu+等)间距小于其范德华半径之和时,二者之间非但没有相互排斥,反而表现出相互吸引作用,此相互作用被称为亲金属相互作用(metallophilic interactions)或金属-金属相互作用。早在对相关金属配合物的研究过程中已发现,金属-金属相互作用可诱导基于LMMCT的发光,其配合物可发展成为具有独特光物理性质的材料。近年来,亲金属相互作用作为一种非共价弱相互作用,已广泛应用于超分子化学领域,可用于构建功能化的超分子聚集体。本实验室通过硫醇配体RSH与Ag(I)的原位反应,构建基于Ag(I)…Ag(I)相互作用的Ag(I)-SR超分子配位聚合物,在分子离子识别与传感以及超分子凝胶材料等方面取得了成功。本论文在实验室长期研究的基础上,对该领域作了进一步的延伸,设计合成一系列硫醇配体,通过与Ag(I)的配位作用,拓展其于分子识别与传感、双重手性超分子及其手性调控、超分子手性凝胶以及构建新型能量转移模式等方面的研究。论文分五章,主要包括以下内容:第一章,首先概述亲金属相互作用的产生及作用机理,简要介绍了Ag(I)…Ag(Ⅰ)相互作用的种类,列举了从结构和光谱方面判断Ag(I)…Ag(I)相互作用存在的实验依据,最后详述亲金属相互作用在分子离子识别与传感、超分子自组装以及发光材料等方面的应用。第二章主要介绍非手性超分子聚合物Ag(I)-MPBA对糖的手性识别及传感。以识别糖分子为设计目标,我们尝试在硫醇配体上衍生硼酸基团,该基团可以与糖分子上的顺式邻二醇以硼酸酯的作用模式可逆结合。配体MPBA的巯基与Ag(I)具有强配位作用,二者通过原位反应,在Ag(I)…Ag(I)相互作用下形成以Ag(I)-MPBA为结构重复单元、以银链为骨架的非手性聚合物链,该聚合物链上负载了大量的硼酸,以作为糖的结合位点,即以非共价弱相互作用构建多硼酸位点的超分子聚集体。单糖是具有手性的,通过与硼酸结合,客体糖分子的手性可以传递至聚合物链上,并在超分子的层面上加以放大,诱导非手性的Ag(I)-MPBA配位聚合物成为手性组装体。不同糖的手性性质不同,因此可以通过诱导的超分子手性信号对糖客体进行手性识别,提高检测糖的灵敏度。其中葡萄糖可以与硼酸1:2特异性结合,虽然硼酸与果糖的结合常数远高于其他糖类,但是本体系可以表现出对葡萄糖有最高的响应灵敏度和信号强度,对果糖却几乎没有信号响应。第三章在现有的单手性配体半胱氨酸(Cys)的基础上,引入第二个手性氨基酸(苯丙氨酸),探究双重手性因素调控下的手性传递和组装体谱学性质。同手性二肽LLFC与异手性二肽DLFC相比,分子组成上的区别仅表现为苯丙氨酸残基构型不同,但是通过核磁可以看到半胱氨酸巯基部分的化学环境已受干扰。因此,同/异手性二肽配位聚合物Ag(Ⅰ)-FC的光谱性质存在差异也是可以预见的。此外,将该部分研究拓展至对不同手性源的讨论,通过对一系列二肽Ac-AAx-CysOEt的研究,我们发现该体系具有识别外源氨基酸的潜在应用价值。第四章在第三章N-乙酰基-苯丙氨酸-半胱氨酸乙酯(AFC)二肽的基础上对氨基换用Boc保护,增强了其疏水作用,与Ag(Ⅰ)配位络合后,同/异手性Ag(Ⅰ)-BFC聚合物均可在超分子层面上表现出明显的手性差异。除此之外,在体系内的氢键作用、疏水作用、苯环间π-π堆积等弱相互作用协同调控下,以Ag(Ⅰ)…Ag(Ⅰ)相互作用为骨架的链状Ag(Ⅰ)-BFC聚合物可以快速固定乙醇溶剂,形成热稳定性较高的金属有机凝胶。同手性超分子凝胶Ag(Ⅰ)-LLBFC呈无色透明状,异手性凝胶Ag(Ⅰ)-DLBFC呈浅黄色,颜色的差异可能与聚合物Ag-Ag间距相关,且卤素离子的加入可以引起Ag(Ⅰ)-DLBFC凝胶的颜色变化。虽然I-对两种凝胶均有破坏作用,但是结构更有序的Ag(Ⅰ)-LLBFC凝胶再生能力明显较弱,该性质受到了聚合物结构差异的影响。第五章构建了实现荧光共振能量转移(FRET)的新模式。实现共振能量转移要求给体发射和受体吸收光谱有较好的重叠、能量给体和受体间距小于10 nm以及具有合适的偶极矩方位。针对以上条件,我们筛选合适的能量转移对荧光团,并分别在其结构上衍生巯基,给体和受体分散在溶液中时需尽可能避免FRET产生,而在Ag+加入后伴随着Ag(Ⅰ)-SR配位聚合物的形成,Ag(Ⅰ)…Ag(Ⅰ)相互作用拉近了能量给体和受体之间的距离,从而构建了 Ag(Ⅰ)…Ag(Ⅰ)相互作用诱导的共振能量转移模式。更多还原

【Abstract】 Since 1980s,scholars have studied gold chemistry extensively and deeply,promoting the development of metallophilic interactions.Two closed-shell metal cations(such as Au+,Ag+ and Cu+)tend to have attractive interactions rather than repulsion when their distance are smaller than the sum of the van der Waals radii,as is the so-called metallophilic interaction(metal…metal interaction).During the research of related metal complexes,it has been found that luminescence,assigned to ligand-to-metal charge transfer transition modified by the metallophilic interaction(LMMCT),is usually induced,which makes it possible that the complexes can be developed into materials that are with unique photophysical properties.In recent years,metallophilic interaction,which has been widely used in the field of supramolecular chemistry as a non-covalent interaction,is employed to construct functional systems.Jiang’s group has built up Ag(I)-SR coordination polymers as platforms for molecular sensing systems and supramolecular hydrogels facilitated by argentophilic interactions,based on in situ reaction of thiol-based ligands and Ag(I).Further investigations are carried out on the basis of previous work.By designing a series of thiol ligands,the application of Ag(I)-SR coordination polymers is extended for molecular/ion sensing,dual-chirality transfer,chiral supramolecular gels and an novel strategy for Forster resonance energy transfer(FRET).This dissertation consists of five chapters.Chapter 1 is the introduction for the metal…metal interaction in general.We review and discuss the categories of argentophilic interactions,and experimental evidence for it,including Ag-Ag distance and spectra criterion.Finally,the application of metallophilic interaction in chemosensors for molecule and/or ion sensing,supramolecular self-assembly and luminescent materials are shown in brief.In the second chapter,an achiral coordination polymer Ag(I)-MPBA(MPBA =p-mercaptophenylboronic acid)is developed to probe the chirality of saccharides.To achieve the target of binding and identifying saccharides,MPBA is chosen as the achiral thiol ligand,bearing a boronic acid group which can reversibly interact with saccharides in cyclic boronate ester mode.Thiol ligand usually has strong tendency to coordinate with Ag(I).Achiral polymer is formed in situ with repeating Ag(I)-MPBA units and silver chain skeleton facilitated by Ag(I)…Ag(I)interaction.CD spectra of varying profiles were observed with the tested saccharides such as glucose and fructose,confirming that the chirality of the saccharide is transferred to the Ag(I)…Ag(I)chromophore in the supramolecular sensory ensembles,which are induced to be chiral subsequently,upon interacting with the boronic acid group to form the cyclic boronate ester.Glucose that interacts with the supramolecular sensor in a 1:2 stoichiometry results in stronger CD signals whereas the monovalent fructose induced practically no or very weak CD signals,that could be acquired to correlate to the saccharide identity.As is shown in Chapter 3,a second chiral pool,phenylalanine,is introduced to Ag(I)-Cys framework to explore dual-chirality transfer and the spectra of resulting ensembles.The only structural difference is the variation in the configuration of the phe residue between homochiral dipeptide LLFC and heterochiral DLFC,but chemical environment of cysteine moiety changes a lot,making it could be observed through NMR spectra.The obvious spectroscopy differences between homo-and hetero-Ag(I)-FC could therefore make sense.Furthermore upon extension of the study to different amino acids,the strategy could be further developed for amino acids sensing.Chapter 4 represents Boc-protected dipeptides(BFC)by replacing acetyl-protected groups of FC presented in chapter three,enhancing its hydrophobic interaction.Upon coordination with Ag(I),ethanol solvent could be immobilized instantly by chain-like Ag(I)-BFC polymers facilitated by Ag(I)…Ag(I)interaction cooperated with other weak interactions,namely hydrogen-bond,hydrophobic interaction,and π-π stacking.The highly thermodynamic-stable gels exhibit different colors between Ag(I)-LLBFC and Ag(I)-DLBFC arising from the difference in Ag-Ag distance.The addition of halide ions makes changes to heterochiral gel color,leaving homochiral gel color invariant.Owing to the well-organized construction of Ag(Ⅰ)-LLBFC assemblies,the self-healing ability of homochiral gel tends to be weaker after being treated with I-and Ag+ in sequence.A brand-new pattern for Forster resonance energy transfer(FRET)is demonstrated in the last chapter.It is widely believed that the well spectral overlap of the emission and absorption spectra of the donor and acceptor,distance short enough between the donor and corresponding acceptor,and appropriate dipole moment orientation are three primary factors essential for fabricating an efficient FRET process.In view of the above conditions,we synthesized several thiol derivatives decorated by fluorophores,acting as energy donor and acceptor respectively,and the separated compounds are gathered through argentophilic interaction displaying FRET process upon the coordination with Ag(Ⅰ).更多还原