Li Xiao-Yu, Su Hai-Feng, Zhou Rui-Qi, Feng Sheng, Tan Yuan-Zhi, Wang Xing-Po, Jia Jiong, Kurmoo Mohamedally, Sun Di, Zheng Lan-Sun
Key Lab for Colloid and Interface Chemistry of Education Ministry, School of Chemistry and Chemical Engineering, Shandong University, Jinan, 250100, P.R. China.
Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, P.R. China.
Chemistry. 2016 Feb 24;22(9):3019-28. doi: 10.1002/chem.201504799. Epub 2016 Jan 25.
A general class of C3 -symmetric Ag9 clusters, [Ag9 S(tBuC6 H4 S)6 (dpph)3 (CF3 SO3 )] (1), [Ag9 (tBuC6 H4 S)6 (dpph)3 (CF3 SO3 )2 ]⋅CF3 SO3 (2), [Ag9 (tBuC6 H4 S)6 (dpph)3 (NO3 )2 ] ⋅NO3 (3), and [Ag9 (tBuC6 H4 S)7 (dpph)3 (Mo2 O7 )0.5 ]2 ⋅2 CF3 COO (4) (dpph=1,6-bis(diphenylphosphino)hexane), with a twisted trigonal-prism geometry was isolated by the reaction of polymeric {(HNEt3 )2 [Ag10 (tBuC6 H4 S)12 ]}n , 1,6-bis(diphenylphosphino)hexane, and various silver salts under solvothermal conditions. The structures consist of discrete clusters constructed from a girdling Ag9 twisted trigonal prism with the top and bottom trigonal faces capped by diverse anions (i.e., S(2-) and CF3 SO3 (-) for compound 1, 2×CF3 SO3 (-) for compound 2, 2×NO3 (-) for compound 3, and tBuC6 H4 S(-) and Mo2 O7 (2-) for compound 4). This trigonal prism is bisected by another shrunken Ag3 trigon at its waist position. Interestingly, two inversion-related Ag9 trigonal-prismatic clusters are dimerized by the Mo2 O7 (2-) ion in compound 4. The twist is amplified by the bulkier thiolate, which also introduces high steric-hindrance for the capping ligand, that is, the longer dpph ligand. Four more silver-sulfur clusters (namely, compounds 5-8) with their nuclearity ranging from 6-10 were solely characterized by single-crystal X-ray diffraction to verify the above-described synergetic effect of mixed ligands in the construction of Ag9 twisted trigonal prisms. Surprisingly, only cluster 1 emits yellow luminescence at λ=584 nm at room temperature, which may be attributed to a charge transfer from the S 3p orbital to the Ag 5s orbital, or mixed with metal-centered (MC) d(10) →d(9) s(1) transitions. Upon cooling from 300 to 80 K, the emission intensity was enhanced along with a hypsochromic shift. The good linear relationship between the maximum emission intensity and the temperature for compound 1 in the range of 180-300 K indicates that this is a promising molecular luminescent thermometer. Furthermore, cyclic voltammetric studies indicated that the diffusion- and surface-controlled redox processes were determined for compounds 1 and 3 as well as compound 4, respectively.
通过在溶剂热条件下，使聚合的{(HNEt3)2[Ag10(tBuC6H4S)12]}n、1,6 - 双（二苯基膦基）己烷（dpph）与各种银盐反应，分离出了一类具有扭曲三角棱柱几何结构的C3对称Ag9簇合物，即[Ag9S(tBuC6H4S)6(dpph)3(CF3SO3)] (1)、[Ag9(tBuC6H4S)6(dpph)3(CF3SO3)2]⋅CF3SO3 (2)、[Ag9(tBuC6H4S)6(dpph)3(NO3)2] ⋅NO3 (3)和[Ag9(tBuC6H4S)7(dpph)3(Mo2O7)0.5]2 ⋅2 CF3COO (4)（dpph = 1,6 - 双（二苯基膦基）己烷）。这些结构由离散的簇组成，这些簇由一个环绕的Ag9扭曲三角棱柱构成，其顶部和底部三角面由不同的阴离子封端（即化合物1中的S(2 - )和CF3SO3(-)，化合物2中的2×CF3SO3(-)，化合物3中的2×NO3(-)，化合物4中的tBuC6H4S(-)和Mo2O7(2 - )）。这个三角棱柱在其腰部位置被另一个缩小的Ag3三角平分。有趣的是，化合物4中两个与反演相关的Ag9三角棱柱簇通过Mo2O7(2 - )离子二聚。较大的硫醇盐使扭曲加剧，这也给封端配体带来了高空间位阻，即较长的dpph配体。另外四个银 - 硫簇合物（即化合物5 - 8），其核数范围为6 - 10，仅通过单晶X射线衍射进行了表征，以验证上述混合配体在构建Ag9扭曲三角棱柱中的协同效应。令人惊讶的是，只有簇合物1在室温下于λ = 584 nm处发射黄色发光，这可能归因于从S 3p轨道到Ag 5s轨道的电荷转移，或与金属中心（MC）的d(10)→d(9)s(1)跃迁混合。从300 K冷却到80 K时，发射强度增强，同时伴有蓝移。化合物1在180 - 300 K范围内最大发射强度与温度之间的良好线性关系表明这是一种有前景的分子发光温度计。此外，循环伏安研究表明，分别确定了化合物1和3以及化合物4的扩散控制和表面控制的氧化还原过程。
