Tarran William A, Freeman Gemma R, Murphy Lisa, Benham Adam M, Kataky Ritu, Williams J A Gareth
Department of Chemistry, Durham University , Durham DH1 3LE, U.K.
Inorg Chem. 2014 Jun 2;53(11):5738-49. doi: 10.1021/ic500555w. Epub 2014 May 21.
A new family of platinum(II) complexes of the form PtL(n)SR have been prepared, where L(n) represents a cyclometalating, N^C^N-bound tridentate ligand and SR is a monodentate thiolate ligand. The complexes fall into two groups, those of PtL(1)SR where HL(1) = 1,3-bis(2-pyridyl)benzene, and those of PtL(2)SR, where HL(2) = methyl 3,5-bis(2-pyridyl)benzoate. Each group consists of five complexes, where R = CH3, C6H5, p-C6H4-CH3, p-C6H4-OMe, p-C6H4-NO2. These compounds, which are bright red, orange, or yellow solids, are formed readily upon treatment of PtL(n)Cl with the corresponding potassium thiolate KSR in solution at room temperature. The replacement of the chloride by the thiolate ligand is accompanied by profound changes in the photophysical properties. A broad, structureless, low-energy band appears in the absorption spectra, not present in the spectra of PtL(n)Cl. In the photoluminescence spectra, the characteristic, highly structured phosphorescence bands of PtL(n)Cl in the green region are replaced by a broad, structureless emission band in the red region. These new bands are assigned to a πS/dPt → π*N^C^N charge-transfer transition from the thiolate/platinum to the N^C^N ligand. This assignment is supported by electrochemical data and TD-DFT calculations and by the observation that the decreasing energies of the bands correlate with the electron-donating ability of the substituent, as do the increasing nonradiative decay rate constants, in line with the energy-gap law. However, the pair of nitro-substituted complexes do not fit the trends. Their properties, including much longer luminescence lifetimes, indicate that the lowest-energy excited state is localized predominantly on the arenethiolate ligand for these two complexes. Red-emitting thiolate adducts may be relevant to the use of PtL(n)Cl complexes in bioimaging, as revealed by the different distributions of emission intensity within live fibroplast cells doped with the parent complex, according to the region of the spectrum examined.
已制备出一类新型的铂（II）配合物，其形式为PtL(n)SR，其中L(n)代表一种环金属化的、N^C^N配位的三齿配体，SR是一种单齿硫醇盐配体。这些配合物分为两组，一组是PtL(1)SR，其中HL(1) = 1,3 - 双（2 - 吡啶基）苯；另一组是PtL(2)SR，其中HL(2) = 3,5 - 双（2 - 吡啶基）苯甲酸甲酯。每组由五个配合物组成，其中R = CH3、C6H5、p - C6H4 - CH3、p - C6H4 - OMe、p - C6H4 - NO2。这些化合物为亮红色、橙色或黄色固体，在室温下于溶液中用相应的硫醇钾KSR处理PtL(n)Cl时很容易形成。硫醇盐配体取代氯离子伴随着光物理性质的深刻变化。在吸收光谱中出现一个宽的、无结构的低能带，这在PtL(n)Cl的光谱中不存在。在光致发光光谱中，PtL(n)Cl在绿色区域的特征性、高度结构化的磷光带被红色区域的一个宽的、无结构的发射带所取代。这些新带被归因于从硫醇盐/铂到N^C^N配体的πS/dPt → π*N^C^N电荷转移跃迁。这一归属得到电化学数据和TD - DFT计算的支持，以及观察到这些带的能量降低与取代基的给电子能力相关，非辐射衰减速率常数增加也与之相关，这符合能隙定律。然而，一对硝基取代的配合物不符合这些趋势。它们的性质，包括长得多的发光寿命，表明这两个配合物的最低能量激发态主要定域在芳基硫醇盐配体上。如根据所检查光谱区域，在掺杂母体配合物的活成纤维细胞内发射强度的不同分布所揭示的那样，发红光的硫醇盐加合物可能与PtL(n)Cl配合物在生物成像中的应用有关。
