Halogen-Regulated Noncovalent Interactions in Coordination Polymers Enable Photothermal Conversion

Abstract

Regulating intermolecular noncovalent interactions at the atomic level poses a significant challenge for the design and optimization of photothermal conversion materials in coordination polymers. Herein, we develop a series of one-dimensional zinc-based coordination polymers, [ZnX₂(μ-dptz)]_n (X = Cl, Br, I; 4,4′-dptz = 3,6-di(pyridin-4-yl)-1,2,4,5-tetrazine), where systematic variation of the terminal halogen modulates interchain C–H···X hydrogen bonds and anion···π interactions, whose strengths decrease in the order ZnCl₂-dptz > ZnBr₂-dptz > ZnI₂-dptz. Halogen substitution effectively modulates the crystal packing and electronic distribution, endowing all CPs with broad visible-light absorption and excellent thermal stability. Under 525 nm laser irradiation, the CPs exhibit stable and reversible photothermal performance, and the photothermal conversion efficiency (η) follows ZnCl₂-dptz (52.3%) > ZnBr₂-dptz (44.0%) > ZnI₂-dptz (41.9%). Photoluminescence results confirm that the strengthened noncovalent networks in ZnCl₂-dptz significantly restrain radiative decay and maximize thermal energy dissipation. This work elucidates the halogen-modulated supramolecular interaction–photothermal performance relationship, offering a rational strategy for designing high-efficiency photothermal CPs.