Unlike the previous several investigations on planar donor-π-acceptor chromophores, the present investigation highlights the importance of twisted molecular configurations to effectively tune the optical and nonlinear optical (NLO) response properties. A variety of substitutions are made to design several twisted molecular compounds (1–7). These compounds are designed using pyrenyl and naphthalimide moieties, which are twisted with each other in their molecular configurations. The calculated versus experimental highest intensity absorption energy peaks (3.482 V. 3.444 eV) and experimental ionization potentials (6.07 V. 5.93 eV) of parent compound 1 reproduced reasonably well at M06/6-311G∗∗ methodology. The twisted chromophores show significantly larger amplitudes of third-order NLO polarizabilities (<γ>), which are found to be as large as 778.31 × 10⁻³⁶ esu for compound 7 at the M06/6-311G∗∗ methodology. The <γ> amplitudes were also compared with planar donor-π-acceptor prototype para-nitroaniline (p-NA) molecule to provide the semi-quantitative assessment. For instance, the <γ> amplitudes of all compounds are about ∼7–∼39 times bigger from the amplitude of p-NA at the same computational level. The origin of larger amplitudes has been traced though three-level model using the TD-DFT results. The larger oscillator strengths, lower transitions energies and larger change between the electronic dipole moment between the ground and the excited states. We believe the present study will not only put these compounds under the spotlight of material science but also provide structure-property relationships in designed compounds.

与先前对平面供体-π-受体发色团的研究不同，本研究强调了扭曲分子构型对有效调节光学和非线性光学（NLO）反应特性的重要性。设计了几种替代的扭曲分子化合物（1 – 7）。这些化合物是使用pyr烯基和萘二甲酰亚胺基团设计的，它们的分子构型相互缠绕。母体化合物1的计算值与实验值的最高强度吸收能峰（3.482 V. 3.444 eV）和实验电离势（6.07 V. 5.93 eV）在M06 / 6-311G ***方法中可以很好地再现。扭曲的生色团显示出明显更大的三阶NLO极化率（<γ>）， 在M06 / 6-311G ***方法中 ，发现化合物7的振幅高达778.31×10 ^-36 esu 。还将<γ>振幅与平面供体-π-受体原型对硝基苯胺（p -NA）分子进行比较，以提供半定量评估。例如，所有化合物的<γ>振幅大约是p振幅的约7至39倍。-NA在相同的计算级别。使用TD-DFT结果通过三级模型追踪了较大幅度的起因。更大的振荡器强度，更低的跃迁能量以及在基态和激发态之间的电子偶极矩之间的较大变化。我们相信，本研究将不仅将这些化合物置于材料科学的关注之下，而且还将在设计的化合物中提供结构-性质关系。