Oxazines: A New Class of Second-Order Nonlinear Optical Switches
Oxazines: A New Class of Second-Order Nonlinear Optical Switches
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DOI：
10.1021/jacs.5b13243
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发表时间：
2016-04-20
影响因子：
15
通讯作者：
Champagne, Benoit
中科院分区：
文献类型：
--
作者：
Beaujean, Pierre;Bondu, Flavie;Champagne, Benoit
结合实验的理论研究表明，恶嗪基化合物是多寻址的，多态的，多功能的分子开关表现出对比的线性和二阶非线性光学性质。当取代基是供体基团时，开关特性特别大。在这项研究中，在吲哚和恶嗪环（封闭的a型）的交界处的C-O键的断裂是酸触发的，导致开放的形式（B（+）），其特征在于较大的第一超极化率（β（HRS））和较小的激发能比在封闭的形式。这些结果证实和解释利用从头计算，已进行了广泛的一组化合物，以解开取代基的作用。相对于受体基团，带有供体基团的恶嗪的特征不仅在于较大的β（HRS）和β（HRS）对比度，而且在于较小的激发能、较大的开环诱导电荷转移和键长交替的减少，以及较小的开环反应吉布斯能。与质子化的开放形式（B（+））相比，对两性离子开放形式（B）的计算已经指出在低波长UV/维斯吸收光谱中的相似性，而它们的膜β（HRS）值可能作为取代基的函数而强烈不同。实际上，开放形式存在两个NLO基团，吲哚鎓-取代基实体和硝基苯酚（以质子化开放形式存在，B（+））或硝基苯酚盐（以两性离子开放形式存在，B）部分。然后，硝基酚盐显示出比硝基酚更大的第一超极化率，并且两个实体的β张量可能相互增强或抵消。
A combined experimental theoretical investigation has revealed that oxazine-based compounds are multiaddressable; multistate, and multifunctional molecular switches exhibiting contrasts of both linear and second-order nonlinear optical properties. The switching properties are particularly large when the substituent is a donor group. In this study, the cleavage of the C-O bond at the junction of the indole and oxazine cycles (of the closed a forms) is acido-triggered, leading to an Open form (b(+)) characterized by larger first hyper-polarizablliries (beta(HRS)) and smaller excitation energies than in the closed form. These results are confirmed and interpreted utilizing ab initio calculations that have been carried out on a broad set of compounds to unravel the role of the substituent. With respect to acceptor groups,, oxazines bearing donor groups are characterized not only by larger beta(HRS) and beta(HRS) contrast ratios but also by smaller excitation energies, larger opening-induced charge transfer, and reduction of the bond length alternation, as well as smaller Gibbs energies of the opening reaction. Compared to protonated' open forms (b(+)), calculations on the zwitterionic open forms (b) have pointed out Similarities in the low-wavelength UV/vis absorption spectra, whereas their films beta(HRS) values might differ strongly as a function of the substituent. Indeed, the open forms present two NLOphores, the indoleninium-substituent entity and the nitrophenol (present in the protonated open form, b(+)) or nitrophenolate (present in the zwitterionic open form, b) moiety. Then, nitrophenolate displays a larger first hyperpolarizability than nitrophenol and the beta tensor of the two entities might reinforce or cancel each other.