Spotlight on Zinc: Exploring the Visible Light Responsiveness of Zinc Complexes

Group 12 element zinc(II)-based d¹⁰ complexes have long been known for their inherent colorlessness, which has limited their applications in visible light-driven photophysical and photochemical applications, despite the attractiveness of inexpensive and low-toxicity zinc metal. Based on precedents with nickel(0) and copper(I) complexes, which also adopt the d¹⁰ electronic configuration, achieving a visible light response from zinc(II) complexes seems feasible; however, investigations and proactive design strategies specifically tailored to zinc remain lacking. In this context, the present invited concept paper highlights zinc's potential for visible light responsiveness and evaluates how molecular designs can achieve this capability. After delineating the differences between zinc and other d¹⁰ metal centers, we review recent developments in zinc complexes that exhibit visible light absorption and compare these complexes with previously reported colorless complexes to identify key distinctions. This study provides critical insights into the molecular design guidelines that are pivotal for harnessing the emerging potential of zinc for visible light responses.