Jutglar-Lozano Kílian, Deumal Mercè, Ribas-Arino Jordi, Bromley Stefan T
Departament de Ciència de Materials i Química Física & Institut de Química Teòrica i Computacional (IQTCUB), Universitat de Barcelona, c/Martí i Franquès 1-11, Barcelona 08028, Spain.
Institució Catalana de Recerca i Estudis Avançats (ICREA), Passeig Lluís Companys 23, Barcelona 08010, Spain.
J Am Chem Soc. 2025 Jul 2;147(26):22550-22561. doi: 10.1021/jacs.5c02910. Epub 2025 Jun 17.
Development of technologically promising magnetoelectric materials, where magnetic properties can be controlled by electric fields (E-fields), has focused on inorganic systems. Here, we propose a strategy for modulating magnetic exchange coupling () in purely organic systems through experimentally realizable E-fields. Our approach leverages two established concepts: (i) E-field-induced twisting of dipolar organic linkers and (ii) control of via conformational changes in organic diradicals. Using density functional theory calculations, we investigated the effects of applied E-fields on diradicals with two coplanar spin-carrying trioxotriangulene (TOT) radicals connected by dipolar aryl linkers. We find that E-fields induce significant conformational changes in the linkers (twisting) that alters π-conjugation and, in turn, the magnetic coupling between TOT radicals. In-plane E-fields twist the linkers toward the plane of the radicals, enhancing π-conjugation and increasing AFM coupling. Out-of-plane E-fields induce more orthogonal linker conformations and decrease the coupling strength. The magnetoelectric response depends on a combination of steric hindrance, π-conjugation, and polarization. Significant and measurable cumulative changes in of up to 3.9 meV could be achieved by using in-plane and out-of-plane E-fields of up to 0.5 V/Å. In some cases, applied E-fields can also induce switching between paramagnetism and antiferromagnetism. Calculations on a 2D covalent organic framework (COF) based on a network of TOT radicals and dipolar linkers confirm that this approach is also viable for extended systems. Such COFS could also display E-field induced ferroelectric responses. Overall, our proof-of-principle study highlights the interplay between molecular structure, E-fields, and magnetism and establishes an innovative and chemically rational framework for developing all-organic magnetoelectric materials.
具有技术前景的磁电材料的开发，即磁性可由电场（E场）控制，主要集中在无机体系。在此，我们提出一种通过实验可实现的E场来调节纯有机体系中磁交换耦合（）的策略。我们的方法利用了两个既定概念：（i）E场诱导偶极有机连接体的扭曲，以及（ii）通过有机双自由基的构象变化来控制。利用密度泛函理论计算，我们研究了施加的E场对具有两个通过偶极芳基连接体相连的共面自旋携带三氧代三蝶烯（TOT）自由基的双自由基的影响。我们发现E场会在连接体中引起显著的构象变化（扭曲），这会改变π共轭，进而改变TOT自由基之间的磁耦合。面内E场使连接体向自由基平面扭曲，增强π共轭并增加反铁磁耦合。面外E场诱导更正交的连接体构象并降低耦合强度。磁电响应取决于空间位阻、π共轭和极化的综合作用。通过使用高达0.5 V/Å的面内和面外E场，可实现高达3.9 meV的显著且可测量的累积变化。在某些情况下，施加的E场还可诱导顺磁性和反铁磁性之间的转变。基于TOT自由基和偶极连接体网络的二维共价有机框架（COF）的计算证实，该方法对扩展体系也可行。此类COF也可能表现出E场诱导的铁电响应。总体而言，我们的原理验证研究突出了分子结构、E场和磁性之间的相互作用，并为开发全有机磁电材料建立了一个创新且化学合理的框架。
