Metallacyclophanes of 1,6-Bis(diphenylphosphino)pyrene: Excimeric Emission and Effect of Oxygen on Stability of the Rings

1,6-Bis(diphenylphosphino)pyrene (L) was reacted with Ag(I) and Cu(I) ions to form metallacyclophanes [Ag2L2(OTf)2] (1), [Cu2L2(MeCN)4]2+ (2), and [Cu2L2I2] (3) which consisted of two cofacial pyrenyl rings. 1 and 2 exhibited intramolecular excimeric emissions which along with the UV–vis absorption were invoked in understanding the solution dynamics of the metallocyclophanes. The metallacyclophanes were stable toward ring-opening dissociation at concentration as low as 10–7 M. However, air oxidation of the dangling PPh2 groups arising from metal–ligand bond dissociation drove the equilibrium toward dissociation and produced the oxidized phosphine 1,6-bis(diphenylphosphine oxide)pyrene.1,6-双(二苯基膦基)芘（L）与银(I)、铜(I)离子反应生成金属环蕃配合物[Ag₂L₂(OTf)₂]（1）、[Cu₂L₂(MeCN)₄]²⁺（2）以及[Cu₂L₂I₂]（3），这三种配合物均包含两个面对面排布的芘环。配合物1和2表现出分子内激基缔合物发射特性，结合紫外-可见吸收光谱可用于阐明该金属环蕃的溶液动力学行为。该系列金属环蕃在低至10⁻⁷ M的浓度下仍可稳定存在，不易发生开环解离。然而，由金属-配体键解离产生的未配位二苯基膦（PPh₂）基团会被空气氧化，促使配位平衡向解离方向移动，最终生成氧化产物1,6-双(二苯基氧膦基)芘。