Department of Chemistry and Biochemistry, North Dakota State University, Fargo, North Dakota 58108-6050, United States.
J Phys Chem A. 2010 Dec 9;114(48):12639-45. doi: 10.1021/jp107348h. Epub 2010 Nov 15.
The photophysical properties of a series of 4,6-diphenyl-2,2'-bipyridyl platinum(II) complexes bearing different σ-alkynyl ancillary ligands (1a-1k) were systematically investigated. All complexes exhibit strong (1)π,π* absorption bands in the UV region; and broad, structureless charge-transfer band(s) in the visible region, which systematically red-shift(s) when the electron-donating ability of the para substituent on the phenylacetylide ligand increases. All complexes are emissive in solution at room temperature. When excited at the charge-transfer absorption band, the complexes exhibit long-lived orange emission (λ(max): 555-601 nm), which is attributed to a triplet metal-to-ligand charge transfer/intraligand charge transfer emission ((3)MLCT/(3)ILCT). Most of these complexes exhibit broad triplet transient difference absorption in the visible to the near-IR region, with a lifetime comparable to those measured from the decay of the (3)MLCT/(3)ILCT emission. The reverse saturable absorption (RSA) of these complexes were demonstrated at 532 nm using nanosecond laser pulses. The degree of RSA follows this trend: 1k ≈ 1a > 1c > 1f ≈ 1i > 1h ≈ 1b > 1e > 1d > 1g, which is mainly determined by the ratio of the triplet excited-state absorption cross section to that of the ground-state and the triplet excited-state quantum yield.
研究了一系列带有不同 σ-炔基辅助配体的 4,6-二苯基-2,2'-联吡啶铂(II)配合物（1a-1k）的光物理性质。所有配合物在紫外区均表现出强的（1）π,π*吸收带；在可见区呈现宽带、无定形的电荷转移带，当苯乙炔配体上的取代基的给电子能力增加时，这些电荷转移带会系统地红移。所有配合物在室温下均在溶液中发射。当在电荷转移吸收带激发时，配合物表现出长寿命的橙色发射（λ(max)：555-601nm），这归因于三重态金属-配体电荷转移/配体内电荷转移发射（(3)MLCT/(3)ILCT）。大多数这些配合物在可见到近红外区域表现出宽的三重态瞬态差分吸收，其寿命与从（3）MLCT/(3)ILCT 发射衰减测量到的寿命相当。使用纳秒激光脉冲在 532nm 处证明了这些配合物的反向饱和吸收（RSA）。RSA 的程度遵循以下趋势：1k≈1a>1c>1f≈1i>1h≈1b>1e>1d>1g，这主要由三重态激发态吸收截面与基态和三重态激发态量子产率的比值决定。
