Beaujean Pierre, Sanguinet Lionel, Rodriguez Vincent, Castet Frédéric, Champagne Benoît
Theoretical Chemistry Laboratory, Unit of Theoretical and Structural Physical Chemistry, Namur Institute of Structured Matter, University of Namur, B-5000 Namur, Belgium.
MOLTECH-Anjou (CNRS-UMR 6200), Université d'Angers, F-49045 Angers, France.
Molecules. 2022 Apr 26;27(9):2770. doi: 10.3390/molecules27092770.
This contribution employs quantum chemistry methods to describe the variations of the second nonlinear optical responses of molecular switches based on benzazolo-oxazolidine (BOX) units, connected by -linkers, along their successive opening/closing. Under the fully closed forms, all of them display negligible first hyperpolarizability () values. When one BOX is opened, which is sketched as →, a push-pull -conjugated segment is formed, having the potential to enhance and to set the depolarization ratio (DR) to its one-dimensional-like value (DR = 5). This is observed when only one BOX is open, either for the monoBOX species (→) or for the diBOX (→) and triBOX (→) compounds, i.e., when the remaining BOXs stay closed. The next BOX openings have much different effects. For the diBOXs, the second opening (→) is associated with a decrease of , and this decrease is tuned by controlling the conformation of the -linker, i.e., the centrosymmetry of the whole compound because vanishes in centrosymmetric compounds. For the triBOXs, the second opening gives rise to a -shape compound, with a negligible change of , but a decrease of the DR whereas, along the third opening, remains similar and the DR decreases to the typical value of octupolar systems (DR = 1.5).
本论文采用量子化学方法，描述了基于苯并唑并恶唑烷（BOX）单元、通过-连接体相连的分子开关在连续打开/关闭过程中二阶非线性光学响应的变化。在完全关闭形式下，它们的第一超极化率（）值均可忽略不计。当一个BOX打开时（示意如下：→），会形成一个推-拉-共轭片段，有可能增强并将去极化率（DR）设定为其类似一维的值（DR = 5）。当只有一个BOX打开时，无论是单BOX物种（→）、双BOX（→）还是三BOX（→）化合物，即当其余的BOX保持关闭时，都会观察到这种情况。接下来的BOX打开会产生非常不同的效果。对于双BOX化合物，第二次打开（→）伴随着的减小，并且这种减小可通过控制-连接体的构象来调节，即整个化合物的中心对称性，因为在中心对称化合物中会消失。对于三BOX化合物，第二次打开会产生一个-形化合物，的变化可忽略不计，但DR减小，而在第三次打开时，保持相似，DR减小到八极体系的典型值（DR = 1.5）。
