Electronic stark effect studies of a porphyrin-based push-pull chromophore displaying a large first hyperpolarizability:: State-specific contributions to β
Electronic stark effect studies of a porphyrin-based push-pull chromophore displaying a large first hyperpolarizability:: State-specific contributions to β
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DOI：
10.1021/ja973593v
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发表时间：
1998-03-25
影响因子：
15
通讯作者：
Therien, MJ
中科院分区：
文献类型：
--
作者：
Karki, L;Vance, FW;Therien, MJ
电吸收或斯塔克效应光谱已应用于一对卟啉基发色团，目的是详细了解其中一个发色团：[5-[[4'-（二甲氨基）苯基]乙基]-15-[（4 '-硝基苯基）-乙基]-10,20-二苯基卟啉]锌（II）显著的第一超极化性的起源。测量结果表明，氨基苯基（给体）/硝基苯基（受体）功能化的发色团在x极化跃迁的激发下，分子偶极矩δ mu发生了显著的变化，而缺乏给体和受体基团的相关发色团则没有变化。对于线性发色团，偶极矩的变化是有效的分子第一超极化和入射光倍频行为的先决条件。在传统两级模型的背景下，对可用的\Delta mu\数据进行更详细的考虑，得出以下结论：(a)关于七个电子和振动激发开始在定义β时所起作用的具体信息，(b)对先前在830和1064 nm进行的超瑞利散射实验中发现的β的表观频率无关性的半定量解释，以及(c)对类似含Cu（II）的发色团的非线性光学响应的对比频率依赖性的解释。最后，实验结果与已发表的ZINDO计算结果基本一致，该计算结果指出，在高极化卟啉核心组装的偶联供体和受体部分中，炔键具有特殊的有效性。
Electroabsorption or stark effect spectroscopy has been applied to a pair of porphyrin-based chromophores with the aim of deriving a detailed understanding of the Origin of the remarkable first hyperpolarizability, beta, of one of the chromophores: [5-[[4'-(dimethylamino)phenyl]ethynyl]-15-[(4 "-nitrophenyl)-ethynyl]-10,20-diphenylporphinato]zinc(II). The measurements show that significant changes in molecular dipole moment, Delta mu, accompany excitations of x-polarized transitions of the aminophenyl (donor)/nitrophenyl (acceptor) functionalized chromophore, but an absent for a related chromophore lacking the donor and acceptor groups. For linear chromophores, changes in dipole moment are a prerequisite to effective molecular first hyperpolarization and incident light frequency doubling behavior. A more detailed consideration of the available \Delta mu\ data, within the context of a conventional two-level model, has yielded the following: (a) specific information about the roles of each of seven electronic and vibronic excited starts in defining beta, (b) a semiquantitative explanation for the apparent frequency independence of beta found in previous hyper-Rayleigh scattering experiments performed at 830 and 1064 nm, and (c) an explanation for the contrasting frequency dependence of the nonlinear optical response for the analogous Cu(II)-containing chromophore. Finally, the experimental findings are in generally good agreement with published ZINDO calculations which had pointed toward the exceptional effectiveness of yne linkages in coupling donor and acceptor moieties to the highly polarizable porphyrin core assembly.