光異方性を高める新しい設計戦略を開発（Researchers Develop New Design Strategy to Enhance Optical Anisotropy in Low-dimensional Structures）

2025-03-18 中国科学院（CAS）

＜関連情報＞

• https://english.cas.cn/newsroom/research_news/chem/202503/t20250319_907260.shtml
• https://pubs.rsc.org/en/content/articlelanding/2025/mh/d4mh01790k

層内水素結合変調とアニオン置換による低次元構造の光学異方性の最適化 Optimizing optical anisotropy in low-dimensional structures via intralayer hydrogen bonding modulation and anionic substitution

Muhammad Arif,Xu Liu,Hangwei Jia,Zhihua Yang,Xueling Hou and Shilie Pan
Materials Horizons  Published:26 Feb 2025
DOI:https://doi.org/10.1039/D4MH01790K

Abstract

Anisotropy is a fundamental prerequisite for achieving significant birefringence (Δn) in optical materials, yet optimizing it to surpass the ideal range (Δn > 0.3) remains a substantial hurdle. In the unabated quest for novel birefringent genes, we have figured out that π-conjugated aminopyrazine, [APZ], is capable of producing low-dimensional linear structures for achieving enhanced birefringence due to their structural diversity and inherent anisotropy. Herein, the systematic substitutions of non-π-conjugated [(H₂PO₄)⁻ and (BF₄)⁻] with heteroatom-substituted tetrahedral anions [(CF₃SO₃)⁻, (NH₂SO₃)⁻, (CH₃SO₃)⁻] and subsequently with the aliphatic [C₄H₆O₄] anion, while keeping the cationic end constant, yield a series of seven compounds with a significant boost in Δn_calc = (0.145–0.658@546 nm) which is optimal in their respective families. The substantial increase in birefringence is ascribed to dimensional transition and the propensity of [APZ] to form low-dimensional frameworks, modulated by hydrogen bonds. The intralayer [N–H⋯O], [O–H⋯N], and [N–H⋯F] interactions regulate the perfect coplanar arrangement (ϑ = 0°) of birefringent active units resulting in more pronounced in-plane anisotropy. Moreover, theoretical calculations corroborate that the sequential anion exchange brings variations in optical polarizability, leading to superior linear optical performance of birefringent materials. This work presents a novel birefringent gene, offering promising prospects for synthesizing compounds with exceptional birefringence within low-dimensional systems.