Photoreactive Zn(II) Coordination Compounds: Exploring Biomimetic Mechanical Motion and Photosalient Behavior
Year: 2024
Type: article
Abstract: Locomotion plays a pivotal role in the survival of most organisms, enabling essential activities such as foraging, predator evasion, and reproduction. In the realm of biomimetics, seedpod explosion and bark peeling, well-established biological mechanisms employed by various plant species for defense and reproduction, offer a fascinating avenue for exploration. In this study, we present six novel photoreactive Zn(II)-based coordination compounds capable of significant mechanical motion, including explosion and a peeling effect under UV light irradiation. These compounds were synthesized using aryl derivatives of 4-vinylpyridines, namely, 4spy (4-styrylpyridine), 3tpy (4-(3-(thiophene-3-yl)vinyl)pyridine), and 2tpy (4-(2-(thiophene-2-yl)vinyl)pyridine), in conjunction with chloride or bromide colinkers. The resulting complexes, [ZnCl 2 (4spy) 2 ] ( 1 ), [ZnCl 2 (3tpy) 2 ] ( 2 ), [ZnCl 2 (2tpy) 2 ] ( 3 ), [ZnBr 2 (4spy) 2 ] ( 4 ), [ZnBr 2 (3tpy) 2 ] ( 5 ), and [ZnBr 2 (2tpy) 2 ] ( 6 ), were characterized as isostructural, with slight variations observed in compound 6 ’s structural packing. X-ray diffraction analysis confirmed the tetrahedral geometry of Zn(II) in all six complexes. Notably, compounds 1 – 5 exhibited coordination involving both planar and nonplanar linkers, leading to an expected 50% photoreaction. Interestingly, despite not meeting Schmidt’s criteria, the nonplanar linkers also exhibited photoreaction at slower rates. Furthermore, alongside the UV-induced photoreaction, these compounds displayed intriguing and vigorous mechanical motion reminiscent of a photosalient effect, characterized by rolling, cracking, jumping, and fragmentation. In contrast, compound 6 demonstrated complete photoreaction due to both coordinated linkers adopting planar configurations. Additionally, these crystals exhibited a peeling effect under UV irradiation, akin to the natural peeling of tree bark due to aging. These findings highlight the potential of Zn(II)-based coordination compounds as promising candidates for developing metal-based photoactuators and optical switches, with biomimetic applications.
Source: Crystal Growth & Design
Language: English
Subfield: Organic Chemistry
Field: Chemistry
Domain: Physical Sciences
Open Access status: green
Awards: G1900401978, G5978655055
OpenAlex ID: W4401981611