半胱氨酸基硫醇配体分子侧链结构对其Ag(Ⅰ)配位聚合物的影响

Effects of side-chain structures of cysteine-based thiol ligands on their Ag(Ⅰ)coordination polymers

设计合成了硫醇类配体N-乙酰-L-半胱氨酰基苯胺(L-1)、N-乙酰-L-半胱氨酰基苯酚酯(L-2)和N-乙酰-L-半胱氨酰基乙酯(L-3),并采用紫外-可见光谱、荧光光谱、圆二色(CD)光谱、动态光散射(DLS)和扫描电子显微镜(SEM)等方法研究了乙醇中L-1~L-3与Ag^+配位后的光谱性质和形貌特征.结果表明:L-1和L-3与Ag^+形成了配位聚合物,观察到与Ag(Ⅰ)-Ag(Ⅰ)相互作用相关的吸收和荧光光谱信号,但这两个体系的光谱并不相同;而L-2则与Ag^+形成了配位寡聚物,其对应的吸收和荧光光谱信号均较弱且峰波长较短.Ag(Ⅰ)-L-1和Ag(Ⅰ)-L-3配位聚合物体系中还观察到对应吸收的CD信号,意味着手性氨基酸残基的分子手性已传递至超分子聚合物中与Ag(Ⅰ)-Ag(Ⅰ)相互作用相关的生色团上,这归因于配体侧链间的相互作用;而Ag(Ⅰ)-L-2配位寡聚物体系则无CD信号.据此推测,Ag(Ⅰ)-L-1和Ag(Ⅰ)-L-3配位聚合物中配体侧链间的相互作用可能是氢键作用,且二者的作用模式并不相同.

Three N-acetyl-L-cysteine-based thiol ligands,i.e.its aniline amide(L-1),phenol ester(L-2),and ethanol ester(L-3)were developed and their spectroscopic properties and morphologies in the presence of Ag^+in ethanol were investigated,using a variety of spectral methods such as absorption,fluorescence and circular dichroism(CD)spectroscopy,dynamic light scattering(DLS),and scanning electron microscopy(SEM).It was found that L-1 and L-3 formed coordination polymers with Ag^+,respectively,both of which exhibited absorption and fluorescence signals characteristic of the Ag(Ⅰ)-Ag(Ⅰ)interaction,although the signals differed in the two systems.With L-2,however,only coordination oligomers were formed,with much lower absorption and fluorescence signals at shorter wavelengths.CD signals corresponding to the absorption bands were observed with the Ag(Ⅰ)-L-1 and Ag(Ⅰ)-L-3 coordination polymers,suggesting that the molecular chirality of chiral amino acid residues has been transferred to the chromophores related to the Ag(Ⅰ)-Ag(Ⅰ)interactions within the supramolecular polymers,which could be ascribed to the side-chain interactions taking place within each coordination polymer.No CD signal was observed with the Ag(Ⅰ)-L-2 coordination oligomers.Thus the side-chain interactions within the Ag(Ⅰ)-L-1 and Ag(Ⅰ)-L-3 coordination polymers were proposed to be hydrogen bonding,featuring different interaction models in the two cases.