Ibrahim Muhammad, Khan Farah Tayyaba, Xu Hong-Liang, Ali Muhammad Arif
Institute of Chemistry, The Islamia University of Bahawalpur, Baghdad-ul-Jadeed Campus, Bahawalpur-63100, Pakistan.
Institute of Functional Material Chemistry, Northeast Normal University, Changchun 130024, Jilin, People's Republic of China.
Phys Chem Chem Phys. 2025 Jun 18;27(24):12871-12885. doi: 10.1039/d5cp01227a.
In this study, five tautomer's IB1-IB5 are designed and studied, containing donor (-NH)-π(THDP)-acceptor (-NO) frameworks, formed through the migration of hydrogen atoms from/to the pyrazine rings. The designed and theoretically explored compounds IB2 and IB5 originate from double-hydrogen migration, while IB3 and IB4 are derived by single-hydrogen migration from adjacent pyrazine rings of IB1. Extensive DFT studies were conducted to explore the aromatic behavior, stability, reactivity, natural bond orbitals (NBOs), polarizabilities, and absorption behavior to investigate the effect of electron localization. Remarkably, the migration of hydrogen on the π(THDP) bridge modulates aromaticity single and double hydrogen shifting, enhancing spectroscopic behavior and polarizability amplitudes. The migration of a hydrogen atom successfully lowers the H-L energy gap from 1.87 eV to 0.96 eV in the two identical conformers IB3 and IB4. IB5 exhibits higher aromaticity, reactivity, and the lowest transition energy, providing the highest first hyperpolarizability () value of 70 671 a.u. at the M06-2X level of theory. The vibrational spectrum of IB5 shows a sharp N-H stretching peak at 3589 cm and a weaker NO stretching at 1377 cm, indicating optimal donor-acceptor interactions. TD-DFT analysis reveals that the absorption wavelength exhibits a far-UV red shift upon H-migration in IB5. Similarly, π-π stacking interactions in IB5 facilitate efficient charge transfer pathways, significantly enhancing its hyperpolarizability and establishing it as the most promising compound for optoelectronic applications. Furthermore, charge carrier capacity was analyzed through light-harvesting efficiency (LHE) and radiative lifetime studies. This work provides insights into the development of efficient materials with enhanced aromaticity and charge transport efficiency, which could be beneficial for optical, photovoltaic, and data storage applications.
在本研究中，设计并研究了五种互变异构体IB1 - IB5，它们包含供体（-NH）-π（THDP）-受体（-NO）框架，通过氢原子在吡嗪环之间的迁移形成。设计并经理论探索的化合物IB2和IB5源于双氢迁移，而IB3和IB4是由IB1相邻吡嗪环的单氢迁移衍生而来。进行了广泛的密度泛函理论（DFT）研究，以探索芳香行为、稳定性、反应活性、自然键轨道（NBO）、极化率和吸收行为，从而研究电子定位的影响。值得注意的是，氢在π（THDP）桥上的迁移通过单氢和双氢转移调节芳香性，增强光谱行为和极化率幅度。在两个相同构象体IB3和IB4中，氢原子的迁移成功地将H - L能隙从1.87 eV降低到0.96 eV。IB5表现出更高的芳香性、反应活性和最低的跃迁能量，在M06 - 2X理论水平下提供了高达70671 a.u.的最高第一超极化率（）值。IB5的振动光谱在3589 cm处显示出尖锐的N - H伸缩峰，在1377 cm处显示出较弱的NO伸缩峰，表明供体 - 受体相互作用最佳。含时密度泛函理论（TD - DFT）分析表明，在IB5中氢迁移时吸收波长呈现远紫外红移。同样，IB5中的π - π堆积相互作用促进了有效的电荷转移途径，显著增强了其超极化率，并使其成为最有前途的光电子应用化合物。此外，通过光捕获效率（LHE）和辐射寿命研究分析了电荷载流子容量。这项工作为开发具有增强芳香性和电荷传输效率的高效材料提供了见解，这可能有利于光学、光伏和数据存储应用。
