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Updated: Sep 3, 2025
Hyperspectral Imaging as a Tool to Study Optical Anisotropy in Lanthanide-Based Molecular Single Crystals
Published on: April 14, 2020
An Optically Anisotropic Crystal with Large Birefringence Arising from Cooperative π Orbitals
Yanqiang Li1,2, Xu Zhang3, Yang Zhou1,2
1State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, 350002, China.
Abstract:
Birefringent materials are highly demanded for high-performance polarized optics. As compared with artificial anisotropic metamaterials, anisotropic crystals have advantages of low optical losses and easy processing, but their birefringence is still limited. Herein, based on first-principles studies, we identified a new type of functional anion units, (Hx C6 N9 )(3-x)- (x=0, 1, 2), and then successfully synthesized a new anisotropic crystal, namely, CsH2 C6 N9 ⋅H2 O (I), whose crystal structure consists of (H2 C6 N9 )- anions. Remarkably, I is ultraviolet transparent and exhibits very large birefringence of about 0.55@550 nm, which is much larger than those of commercial birefringent crystals. These results make I a candidate for highly efficient manipulation of optics and light in optical modulation devices. Theoretical calculations reveal that large birefringence mainly arises from the cooperative π orbitals in (H2 C6 N9 )- anions. This work provides a new insight on the underlying structure-property relationships of anisotropic crystals.
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