Multifunctional Properties of a Zn(II) Coordination Complex

• Published in: Crystal growth & design 2021-06, Vol.21 (6), p.3401-3408
• Main Authors: Bolla, Geetha, Chen, Qiuhang, Gallo, Gianpiero, Park, In-Hyeok, Kwon, Ki Chang, Wu, Xiao, Xu, Qing-Hua, Loh, Kian Ping, Chen, Shuang, Dinnebier, Robert E, Ji, Wei, Vittal, Jagadese J
• Format: Article
• Language: English
• ISSN: 1528-7483; 1528-7505
• DOI: 10.1021/acs.cgd.1c00179

Metal complexes exhibiting multifunctional properties are very rare. Here, we report a Zn­(II) complex, [Zn­(benzoate)­(25F-spy)2], where 25F-spy = 2′,5′-difluoro-4-styrylpyridine, displays unpredicted photosalient behavior while it undergoes a [2 + 2] cycloaddition reaction and exhibits unusual thermal expansion with occasional jumping, second-harmonic generation (SHG), and two-photon photoluminescence (2PPL). In the solid state, the 25F-spy ligands are packed in a head-to-tail manner. The distance between the pairs of olefin bonds, 4.279(2) Å, is not suitable for undergoing a [2 + 2] photocycloaddition reaction. However, these crystals not only undergo photodimerization quantitatively but also exhibit a photosalient effect under UV light. An interesting anisotropic thermal expansion facilitates the crystals to jump occasionally when they are heated to 140 °C, similarly to the thermosalient effect. Thermal expansion values along X1, X2, and X3 are −54.46, 106.42, and 151.69 × 10–6 K–1, respectively, with V = 204.26 × 10–6 K–1 (30–140 °C). Furthermore, these crystals exhibit light-frequency upconversion via both SHG and 2PPL. Altogether, a single crystal shows all of these diverse solid-state properties.