The present study highlights the effects of anionic ligands, i.e., halide or trifluoroacetate, on the emission properties of cycloplatinated(II) complexes with a double rollover structure. In fact, it has been proven that the halide ligands can tune the brightness of organometallic compounds as “organic light emitting diodes (OLEDs) emitters”. Thus, a series of closely related platinum (II) complexes with general formula of [Pt₂(μ-bpy-2H)(X)₂(PPh₃)₂] has been prepared by incorporating a double rollover cyclometalated ligand (μ-bpy-2H), two triphenylphosphine ligands and either two trifluoroacetate ligands (X = CF₃COO, 3) or two halide ligands (X = Cl, 4a, Br, 4b, or I, 4c). The complexes were characterized by multi-nuclear ¹H and ³¹P NMR spectroscopy and the structure of the complex [Pt₂(μ-bpy-2H)(CF₃COO)₂(PPh₃)₂] (3) was typically determined by single crystal X-ray crystallography. The luminescence properties of the newly synthesized complexes were investigated at 298 K and 77 K over the wide range of 295–505 nm for excitation wavelengths. Although the emission bands appeared at almost the same wavelengths for the luminescent complexes, differences in both quantum yield and brightness were observed depending on the nature of X. In fact, the intrinsic ligand field of the X ligands has a substantial impact on the platinum-ligand bond lengths. Complex 4c (having iodo ligands with the lowest ligand field) exhibits the highest thermal population for the higher lying metal-centered electronic state (d–d* character) and consequently the highest non-radiative deactivation rate, which remarkably quenches the emission.

中文翻译：

---

卤化物配体可 简单调节双侧翻环环铂（ii）结构的发光性能†

本研究强调了阴离子配体即卤化物或三氟乙酸盐对具有双侧翻结构的环铂（II）配合物的发射性质的影响。实际上，已经证明卤化物配体可以调节有机金属化合物的亮度，使其成为“有机发光二极管（OLED）发射器”。因此，通过引入双侧翻环金属化配体（μ-bpy ），制备了一系列通式[Pt ₂（μ-bpy-2H）（X）₂（PPh ₃）₂ ]的密切相关的铂（II）配合物。-2H），两个三苯基膦配体和两个三个三氟乙酸酯配体（X = CF ₃ COO，3）或两个卤化物配体（X = Cl，4a，Br，4b或I，4c）。配合物的特征在于多核¹ H和³¹ P NMR光谱学和配合物的结构[Pt ₂（μ-bpy-2H）（CF ₃ COO）₂（PPh ₃）₂ ]（3通常由单晶X射线晶体学测定。在295-505 nm的宽激发波长范围内，在298 K和77 K上研究了新合成的配合物的发光特性。尽管发光带的发光带几乎在相同的波长处出现，但根据X的性质，观察到了量子产率和亮度的差异。实际上，X配体的内在配体场对铂-配体键长。配合物4c（具有配体场最低的碘配体）在较高的以金属为中心的电子态（d–d *特性）下表现出最高的热种群，因此具有最高的非辐射失活速率，从而显着抑制了发射。