A superior polypyridine ligand for platinum(II) lumaphors. Methyl substituents with a large stereoelectronic influence.
A superior polypyridine ligand for platinum(II) lumaphors. Methyl substituents with a large stereoelectronic influence.
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DOI：
10.1021/ic025922c
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发表时间：
2002-10
影响因子：
4.6
通讯作者：
Jeffrey J. Moore;John J Nash;P. Fanwick;D. McMillin
中科院分区：
文献类型：
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作者：
Jeffrey J. Moore;John J Nash;P. Fanwick;D. McMillin
这项研究涉及一系列新的铂（II）聚吡啶络合物的合成和表征，该络合物包含相对刚性和疏水的配体。母体配合物 Pt(php)Cl(+)（其中 php 表示 2-(2'-吡啶基)-1,10-菲咯啉）类似于 Pt(trpy)Cl(+)（其中 trpy 表示 2,2':6',2''-三联吡啶），但在溶液中具有光致发光作用。因此，php 衍生物应该被证明是生物系统的优质标签和/或光谱探针。理论分析揭示了 php 作为平台相对于 trpy 的一些优势。由于配体 pi 系统具有相对较小的 HOMO-LUMO 间隙，Pt(php)Cl(+) 的发射表现出显着的振动结构和混合的 (3)pi-pi*/(3)d-pi* 轨道来源。在脱氧二氯甲烷溶液中，php配合物在室温下表现出3.1 x 10(-3)的发射量子产率和0.23微米的激发态寿命。然而，甲基具有异常强烈的立体电子影响，特别是在菲咯啉部分的 5,6 位。铂(II)与2-(2'-吡啶基)-3,5,6,8-四甲基-1,10-菲咯啉的配合物是最好的发射体，在二氯甲烷中的发射产率为0.055，寿命为9.3微米。二甲基甲酰胺等强供体溶剂是有效的发射猝灭剂。使用的表征方法包括吸收和发射光谱、电化学，以及在[Pt[2-(2'-吡啶基)-4,7-二甲基-1,10-菲咯啉]Cl]O(3)SCF(3)的情况下，X射线晶体学。另一个有趣的发现是甲基取代基相对于菲咯啉配体具有优选的方向。
This research deals with the synthesis and characterization of a new series of platinum(II) polypyridine complexes that incorporate a relatively rigid and hydrophobic ligand. The parent complex Pt(php)Cl(+), where php denotes 2-(2'-pyridyl)-1,10-phenanthroline, resembles Pt(trpy)Cl(+), where trpy denotes 2,2':6',2''-terpyridine, but is photoluminescent in solution. Hence php derivatives should prove to be superior tags and/or spectroscopic probes for biological systems. A theoretical analysis reveals some of the advantages of php over trpy as a platform. Due to a ligand pi system with a relatively small HOMO-LUMO gap, the emission from Pt(php)Cl(+) exhibits significant vibrational structure and a mixed (3)pi-pi*/(3)d-pi* orbital parentage. In deoxygenated dichloromethane solution the php complex exhibits an emission quantum yield of 3.1 x 10(-3) and an excited-state lifetime of 0.23 micros at room temperature. However, methyl groups have an unusually strong stereoelectronic influence, particularly at the 5,6-positions of the phenanthroline moiety. The platinum(II) complex with 2-(2'-pyridyl)-3,5,6,8-tetramethyl-1,10-phenanthroline is the best emitter with an emission yield of 0.055 and a lifetime of 9.3 micros in dichloromethane. Strongly donating solvents like dimethylformamide are potent quenchers of the emission. The methods of characterization used include absorption and emission spectroscopies, electrochemistry, and, in the case of [Pt[2-(2'-pyridyl)-4,7-dimethyl-1,10-phenanthroline]Cl]O(3)SCF(3), X-ray crystallography. Another intriguing finding is that methyl substituents have preferred orientations with respect to the phenanthroline ligand.