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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >The characterization of the high-frequency vibronic contributions to the 77 K emission spectra of ruthenium-am(m)ine-bipyridyl complexes, their attenuation with decreasing energy gaps, and the implications of strong electronic coupling for inverted-r
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The characterization of the high-frequency vibronic contributions to the 77 K emission spectra of ruthenium-am(m)ine-bipyridyl complexes, their attenuation with decreasing energy gaps, and the implications of strong electronic coupling for inverted-r

机译：钌-am（m）ine-联吡啶配合物的77 K发射光谱的高频振子特性表征，其随着能隙减小的衰减以及强电子耦合对反向r的影响

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摘要

The 77 K emission spectra of a series of [Ru(AM)(6-2n)(bpy)(n)](2+) complexes (n = 1-3) have been determined in order to evaluate the effects of appreciable excited state (e)/ground state (g) configurational mixing on the properties of simple electron-transfer systems. The principal focus is on the vibronic contributions, and the correlated distortions of the bipyridine ligand in the emitting MLCT excited state. To address the issues that are involved, the emission band shape at 77 K is interpreted as the sum of a fundamental component, corresponding to the {e,0'} -> {g,0} transition, and progressions in the ground-state vibrational modes that correlate with the excited-state distortion. Literature values of the vibrational parameters determined from the resonance-Raman (rR) for [Ru(NH3)(4)bpy](2+) and [Ru(bpY)(3)](2+) are used to model the emission spectra and to evaluate the spectral analysis. The Gaussian fundamental component with an energy E-f and bandwidth Delta v(1/2) is deconvoluted from the observed emission spectrum. The first-, second-, and third-order terms in the progressions of the vibrational modes that contribute to the band shape are evaluated as the sums of Gaussian-shaped contributions of width Delta v(1/2). The fundamental and the rR parameters give an excellent fit of the observed emission spectrum of [Ru(NH3)(4)bpy](2+), but not as good for the [Ru(bpy)(3)](2+) emission spectrum probably because the Franck-Condon excited state probed by the rR is different in symmetry from the emitting MLCT excited state. Variations in vibronic contributions for the series of complexes are evaluated in terms of reorganizational energy profiles (emreps, Lambda(x)) derived from the observed spectra, and modeled using the rR parameters. This modeling demonstrates that most of the intensity of the vibronic envelopes obtained from the frozen solution emission spectra arises from the overlapping of first-order vibronic contributions of significant bandwidth with additional convoluted contributions of higher order vibronic terms. The emrep amplitudes of these complexes have their maxima at about 1500 cm(-1) in frozen solution, and Lambda(x(max)) decreases systematically by approximately 2-fold as E-f decreases from 17220 for [Ru(bPY)(3)](2+) to 12040 cm(-1) for [Ru(NH3)(4)bpy](2+) through the series of complexes. Corrections for higher order contributions and bandwidth differences based on the modeling with rR parameters indicate that the variations in Lambda(x(max)) imply somewhat larger decreases in first-order bpy vibrational reorganizational energies. The large attenuation of vibrational reorganizational energies of the [Ru(AM)(6-2n)(bpy)(n)](2+) complexes contrasts with the apparent similarity of reorganizational energy amplitudes for the absorption and emission of [Ru(NH3)(4)bpy](2+).These observations are consistent with increasing and very substantial excited- state/ground-state configurational mixing and decreasing excited-state distortion as Ef decreases, but more severe attenuation for singlet/singlet than triplet/ singlet mixing (alpha(ge) > alpha(eg) for the configurational mixing coefficients at the ground-state and excited-state potential energy minima, respectively); it is infered that 0.18 >= alpha(ge)(2) >= 0.09 for [Ru(bpY)(3)](2+) and 0.37 >= alpha(ge)(2) >= 0.18 for [Ru(NH3)(4)bpy](2+) in DMSO/water glasses, where the ranges are based on models that there is or is not a spin restriction on configurational mixing (alpha(ge) > alpha(eg) and alpha(ge) = alpha(eg)), respectively, for these complexes.
机译：确定了一系列[Ru（AM）（6-2n）（bpy）（n）]（2+）配合物（n = 1-3）的77 K发射光谱，以评估明显激发的效应。态（e）/基态（g）对简单电子传输系统性质的配置混合。主要重点是在发射MLCT激发态时，双吡啶配体的相关振动和相关畸变。为了解决所涉及的问题，将77 K处的发射带形状解释为基本成分之和，对应于{e，0'}-> {g，0}跃迁以及基态的进展与激发态失真相关的振动模式。从[Ru（NH3）（4）bpy]（2+）和[Ru（bpY）（3）]（2+）的共振拉曼（rR）确定的振动参数的文献值用于建模排放光谱并评估光谱分析。从观察到的发射光谱中对具有能量E-f和带宽Delta v（1/2）的高斯基本分量进行反卷积。将对带形有贡献的振动模式的进展中的一阶，二阶和三阶项评估为宽度δv（1/2）的高斯形贡献之和。基本参数和rR参数非常适合[Ru（NH3）（4）bpy]（2+）的发射光谱，但对于[Ru（bpy）（3）]（2+）却不如发射光谱可能是因为rR探测到的Franck-Condon激发态与发射MLCT激发态的对称性不同。根据从观察到的光谱得出的重组能谱（emreps，Lambda（x））评估了一系列配合物的电子振动贡献的变化，并使用rR参数进行了建模。该模型表明，从冻结溶液发射光谱获得的振动包络的大部分强度来自带宽显着的一阶振动贡献与高阶振动项的其他卷积贡献的重叠。这些复合物的emrep振幅在冷冻溶液中的最大值约为1500 cm（-1），随着[Ru（bPY）（3）的Ef从17220的Ef降低，Lambda（x（max））会系统地降低约2倍。通过一系列络合物获得[Ru（NH3）（4）bpy]（2+）的]（2+）至12040 cm（-1）。基于具有rR参数的建模对高阶贡献和带宽差异的校正表明，Lambda（x（max））的变化意味着一阶bpy振动重组能量的减小幅度更大。 [Ru（AM）（6-2n）（bpy）（n）]（2+）络合物的振动重组能的大衰减与[Ru（NH3）的吸收和发射的重组能振幅的表观相似性形成对比）（4）bpy]（2+）。这些观察结果与激发态/基态组态混合的增加和非常明显的一致以及随着Ef的降低而减小的激发态畸变相一致，但是单重态/单重态的衰减比三重态/单重态混合（alpha（ge）> alpha（例如，分别针对基态和激发态势能最小值的组态混合系数）;可以推断出[Ru（bpY）（3）]（2+）的0.18> = alpha（ge）（2）> = 0.09，而[Ru（NH3）的0.37> = alpha（ge）（2）> = 0.18 ）（4）bpy]（2 +）（在DMSO /水玻璃中），其中范围基于对配置混合是否存在自旋限制的模型（alpha（ge）> alpha（例如）和alpha（ge）分别针对这些复合物= = alpha（例如）。

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