【作者】 杜洋；

【导师】 林玉妹； 王泉明；

【作者基本信息】 厦门大学 ， 物理化学， 2018， 硕士

【摘要】 纳米团簇因其尺寸的特殊性,在几何结构、电子结构和理化性质方面具有与众不同的特点,因此在催化、发光、生物、传感等众多领域具有良好的应用前景。深入认识币金属纳米团簇的表面配体的配位形式和金属核心结构,对纳米团簇的潜在性质和应用的研究具有重要意义。本论文首先系统研究了低核的金银簇合物的合成和结构特征,进一步拓展至不同配体保护的高核银纳米团簇和金掺杂的银纳米团簇的合成,研究了团簇的表面配体的分布形式和核心结构特征,以及电子结构和光学性质。具体内容如下:(1)合成了 一系列简单的 Ag8R2(dppf)4C14(R =-C≡CPh-p-But,-SPri 或-SC6H11)簇合物,发现了双膦配体dppf在银簇合物表面刚性桥的存在形式,对簇合物结构的稳定性具有重要作用;合成了同构的AuXAg15-XR12(R=-COCFc或-COCBut,X = 0或7)簇合物,发现Au原子的掺杂不影响簇合物结构,而炔配体的改变也不会影响簇合物结构。(2)利用炔配体,双膦配体和卤素配体共同对Au掺杂的Ag纳米团簇进行保护,得到了 Au4Ag23(C≡CBut)0Cl7(dppf)4X2 和 Au5Ag24(C≡CPh-p-But)16Cl4(dppf)4X3(X=PF6或S03CF3)两种类型的结构。研究发现:改变银盐前驱体的阴离子不会影响产物的金属核心结构;改变炔银前驱体中炔配体的结构,发现使用叔丁基乙炔配体得到Au4Ag23团簇,而在乙炔配体中引入刚性的苯基则会得到另一种团簇Au5Ag24。结果表明配体的空间位阻、刚性特征等因素对纳米团簇的结构具有决定性影响。由于几何结构和电子结构的不同,Au4Ag23的固体和溶液状态都具有近红外发射,Au5Ag24则只有固体具有近红外发射。(3)合成了由单一的炔配体保护的Ag49(C≡CBut)32团簇以及炔和三氟甲磺酸配体共同保护的Ag43(COCBut)24(SO3CF3)8。二者的金属核心都可看作由两层结构组合而得到。研究Ag43和Ag49纳米团簇表面炔配体的结构形式,发现炔配体在Ag纳米团簇表面不以构成staple的形式存在,而是以简单配位模式进行配位。更多还原

【Abstract】 Due to the special nanoscale size,nanoclusters exhibit distinctive characteristics in geometric structure,electronic structure and physicochemical properties,which have great applications in many fields,such as catalysis,luminescence,biology,sensing and so on.The determination of structural ordering at the atomic level of metal nanocluster is of extreme significance for fundamental studies of nanomaterials.In this essay,low-nuclearity gold-silver clusters were systematically studied,then high-nuclearity silver nanoclusters and gold-doped silver nanoclusters protected by different ligands were synthesized and charaterized.The research work focused on core and surface structures,electronic structures and optical properties.The details are as follows:(1)A serial of silver clusters Ag8R2(dppf)4Cl4(R =-C=CPh-p-But,-SPri or-SC6H11)were synthesized.In these stuctures,the bisphosphine dppf ligand coordinates with the silver atoms in bridged form,which is helpful for stabilizing the structure.In addition,the AuxAg15-xRi2(R =-C≡CFc or-C≡CBut,X = 0 or 7)clusters with different alkynyl ligands or the doping Au atoms were synthesized.The resulsts indicates that the doping atoms Au and the alkynyl do not have effect on the core structures.(2)The alloy nanoclusters Au4Ag23(C≡CBut)10Cl7(dppf)4X2 and Au5Ag24(C=CPh-p-But)16Cl4(dppf)4X3(X = PF6-or SO3CF3-)were successfully synthesized.The results demonstrate that the anion deriving from silver salt do not affect the metal core structure.The formations of the nanoclusters are induced by the subtle change of group on alkynyl ligand.The steric hindrance and rigidity of ligands can significantly influence the structure of nanoclusters.The two nanoclusters show distinctly different geometric structures and thus exhibit different properties.For exmpale,cluster Au4Ag23 is emissive in the NIR region both in solution and solid state whereas Au5Ag24 is only emissive in solid state.(3)Two silver clusters Ag49(C=CBut)32 and Ag43(C=CBut)24(SO3CF3)8 were successfully synthesized.Both metal cores can be regarded as the combination of two layers.Besides,the stuctures also reveal that alkynyl ligands of silver nanoclusters coordinate with silver atoms via simple modes rather than staple modes on the suface of gold nanoclusters.更多还原