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首页> 外文期刊>Chemistry: A European journal >Triarylpyridinium-Functionalized Terpyridyl Ligand for Photosensitized Supramolecular Architectures: Intercomponent Coupling and Photoinduced Processes
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Triarylpyridinium-Functionalized Terpyridyl Ligand for Photosensitized Supramolecular Architectures: Intercomponent Coupling and Photoinduced Processes

机译：三芳基吡啶鎓官能化的三联吡啶基配体用于光敏超分子体系结构：组件间的耦合和光诱导的过程。

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摘要

The electronic (absorption spectra) and electrochemical properties of a novel series of triphenylpyridnium (H_3TP~+ = A) electron-acceptor-based polyad species have been correlated with their steady-state (emission spectra) and time-resolved (ns and ps laser flash photolysis) photophysical behavior (at both 293 and 77 K). These d~6 transition metal complexes (M = Ru~(II), Os~(II) of 2,2':6',2"-terpyridines (tpy) are denoted as P0, P1, depending on whether they incorporate H_3TP~+-tpy or H_3TP~+-ptpy ligands (ptpy = 4'-phenyl-substituted tpy), respectively. For the P0/Ru-based compounds, the luminescence quantum yield and excited-state lifetime of the "{Ru(tpy)_2}~(2")" chromophore have been found to be considerably enhanced at 293 K (e.g., tau = 0.56 ns for isolated P0/Ru in within P0A/Ru and POA_2/Ru (A = electron acceptor), respectively). In spite of the lack of conjugation between P0 and A, this behavior has been ascribed to a through-bond mediated electronic substituent effect originating from the directly connected H_3TP~+ electron-withdrawing group. For the P1-based compounds, the possibility of photoinduced electron-transfer (PET) processes with the formation of charge-separated (CS) states is discussed, and the main results may be summarized as follows: 1) when involved, the electron-donor D (D = Me_2N of Me_2N-ptpy) is strongly electronically coupled to P1 but cannot facilitate a reductive quenching of ~*P1 to give the ~*[D~+-P1~-]- type of CS state for thermodynamic reasons, irrespective of whether M is Ru~(II) or Os~(II); 2) the P1 and A components have been shown to be very weakly electronically coupled; 3) at 293K, P1/Ru- and P1/Os-based polyad systems display distinct photo-physical behavior with respect to A, with only the latter exhibiting a noticeable quenching of luminescence (up to 50% for P1A/Os with respect to P1/Os); 4) for assemblies made up of P1/Os and A components only, comparison between their room-temperature (RT) and low-temperature 9LT; 77K, frozen matrix) photophysical properties, together with information glenaed from combined transient absorption experiments and spectroelectrochemical studies of P1/Os and P1A/Os, further supported by thermodynamic considerations, allowed us to conclude that a PET process does take place within the P1A/Os dyad leading to the ~*[P1~+-A~-] CS state. For the DP1 A/Os triad, the formation of such a CS state followed by an enhanced electron-releasing inductive effect from D is postulated.
机译：一系列新的基于三苯基吡啶鎓（H_3TP〜+ = A）的电子受体的聚合物分子的电子（吸收光谱）和电化学性质已与它们的稳态（发射光谱）和时间分辨（ns和ps激光）相关联闪光光解）的光物理行为（在293和77 K下）。这些d〜6过渡金属络合物（M = Ru〜（II），Os〜（II）的2,2'：6'，2“-吡啶（tpy）表示为P0，P1，取决于它们是否结合了H_3TP 〜+ -tpy或H_3TP〜+ -ptpy配体（ptpy = 4'-苯基取代的tpy）。对于基于P0 / Ru的化合物，“ {Ru（tpy ）_2}〜（2“）”发色团已发现在293 K时显着增强（例如，在P0A / Ru和POA_2 / Ru（分别为A =电子受体）中，分离的P0 / Ru的tau = 0.56 ns）尽管P0和A之间没有共轭，但这种现象仍归因于通过直接连接的H_3TP〜+吸电子基团通过键键介导的电子取代基效应。讨论了形成电荷分离（CS）态的光致电子转移（PET）过程，其主要结果可归纳如下：1）涉及电子给体D（D = Me_2N-ptpy的Me_2N）与P1强烈电子耦合，但由于热力学原因，无法促进〜* P1的还原淬灭以产生CS *状态的〜* [D〜+ -P1〜-]-型，无论M是否是Ru〜（II）或Os〜（II）; 2）已证明P1和A组件之间的电子耦合非常弱; 3）在293K时，基于P1 / Ru和P1 / Os的多元醇体系相对于A表现出不同的光物理行为，只有后者表现出明显的发光猝灭（相对于相对于P1A / O而言，高达50％ P1 / Os）; 4）对于仅由P1 / O和A组件组成的组件，其室温（RT）和低温9LT之间进行比较; 77K，冻结基质）的光物理性质，以及结合P1 / Os和P1A / Os的瞬态吸收实验和光谱电化学研究得到的信息，再加上热力学考虑，可以使我们得出结论，PET工艺确实在P1A / Os dyad导致〜* [P1〜+ -A〜-] CS状态。对于DP1 A / Os三元组，假定形成这样的CS状态，然后由D增强电子释放感应效应。

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