Two novel six-membered perimidocarbene (PIC)-based tetradentate Pt(II) complexes were designed and successfully synthesized. Systematical experimental and theoretical studies suggest that the PIC moiety greatly affects the frontier orbitals, as well as the photophysical and excited-state properties of the Pt(II) complexes. PtYK2 has a broad emission spectrum peaking at 576 nm with a shoulder band at 620 nm, along with a full width at half-maximum (FWHM) value of 100.0 nm at 77 K in 2-MeTHF; however, the emission spectrum is slightly red-shifted with a dominant peak at 610 nm and a FWHM value of 125.0 nm at room temperature in a poly(methyl methacrylate) (PMMA) film. Time-dependent-density functional theory and natural transition orbital analyses reveal that PtYK2 has a ³LC (³π_PIC* → π_PIC)-dominated character with an unexpectedly negligible contribution of ³MLCT transition (0.68%) in the T₁ state, which results in a broad emission spectrum and a relatively low quantum efficiency of 7.4% in the PMMA film.

中文翻译：

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具有意外可忽略的 3MLCT 特征的基于哌啶基卡宾的四齿铂 (II) 配合物

设计并成功合成了两种新型六元perimidocarbene (PIC)基四齿Pt(II)配合物。系统的实验和理论研究表明，PIC 部分极大地影响了 Pt(II) 配合物的前线轨道以及光物理和激发态性质。 PtYK2 具有宽发射光谱，峰值为 576 nm，肩带为 620 nm，在 2-MeTHF 中 77 K 时半峰全宽 (FWHM) 值为 100.0 nm；然而，在室温下，聚甲基丙烯酸甲酯（PMMA）薄膜的发射光谱略有红移，主峰位于 610 nm，半高宽值为 125.0 nm。时间相关密度泛函理论和自然跃迁轨道分析表明，PtYK2 具有³ LC ( ³ π _PIC * → π _PIC ) 主导特征，在 T ₁态下³ MLCT 跃迁 (0.68%)的贡献出人意料地可以忽略不计，这导致 PMMA 薄膜具有宽发射光谱和相对较低的 7.4% 量子效率。