Cu^(I)(2,9-Bis(trifluoromethyl)-1,10-phenanthroline)₂⁺ Complexes: Correlation between Solid-State Structure and Photoluminescent Properties

The 90K solid-state structures, room temperature absorption, and room temperature and 17 K emission spectra of seven different salts of [Cu(I)(bfp)2]+ (bfp = 2,9-bis(trifluoromethyl)-1,10-phenanthroline) have been determined. To quantify the distortion of the Cu coordination environment, a distortion parameter ζ is defined that is a combined measure of the flattening, rocking, and wagging distortions of the complex cations. In general, the distortion in the (bfp) cations is less than found previously for Cu(I)(dmp)2 (dmp = 2,9-dimethyl-1,10-phenanthroline) salts, in particular the flattening is reduced because of the bulkier 2,9-substituents. The 17 K lifetimes range up to 1.8 μs in the series of solids examined and, with the marked exception of the BF4- salt, correlate linearly with the distortion parameter ζ. The emission wavelength red-shifts with decreasing lifetime, which implies that an increased ground-state distortion is associated with a smaller energy gap.本研究测定了7种不同的[Cu(I)(bfp)₂]⁺（bfp=2,9-双(三氟甲基)-1,10-菲咯啉，2,9-bis(trifluoromethyl)-1,10-phenanthroline）盐的90K固态结构、室温吸收光谱以及室温与17K发射光谱。为量化铜配位环境的畸变程度，本研究定义了畸变参数ζ，该参数可综合表征配合物阳离子的扁平化、摇摆及扭摆畸变。总体而言，该配合物阳离子的畸变程度低于此前报道的Cu(I)(dmp)₂（dmp=2,9-二甲基-1,10-菲咯啉，2,9-dimethyl-1,10-phenanthroline）盐，尤其是由于2,9位取代基空间位阻更大，扁平化畸变得到了抑制。在所测试的一系列固态样品中，17K下的发射寿命最高可达1.8 μs；除BF₄⁻盐这一显著例外外，寿命均与畸变参数ζ呈线性相关。发射波长随寿命缩短发生红移，这表明基态畸变程度的提升与更小的能隙存在关联。