Chain‐Length‐Selective Intermolecular Charge‐Transfer Regulation via Competitive and Cooperative Pathways in Solid‐State Macrocyclic Host–Guest Systems
Susu Ren, Yu‐Xiang Sun, Yuan‐Zheng Liu, Xiang‐Shuai Li, Haitao Wang, Jia‐Rui Wu
Abstract
Dynamic regulation of intermolecular charge-transfer (CT) interactions in the solid state remains a key challenge in developing responsive functional materials. Herein, a dual-mode supramolecular strategy-is reported based on competitive and cooperative host-guest interactions-for constructing dynamic macrocycle-based CT complexes with tunable optical and photothermal properties in response to aliphatic aldehyde vapors. Two pillararene-derived macrocyclic hosts, EtLP6 and EtFLP6, form disordered CT assemblies with F4TCNQ via solvent-free grinding. These CT complexes exhibit chain-length-dependent vapochromic behavior governed by distinct mechanisms: guest-triggered disassembly or reassembly of D-A structures in EtLP6-F4TCNQα (competitive regulation), and aldehyde-assisted ternary CT assembly in EtFLP6-F4TCNQα (cooperative regulation). Single-crystal structures incorporating X-ray powder diffraction and spectral analyses reveal vapor-induced structural transformations that correlate directly with near-infrared (NIR) absorption changes. Notably, such CT-state modulation enables the first vapor-regulated organic photothermal cocrystal system, with conversion efficiency tunable from non-detectable levels to over 11% under 808 nm irradiation. This work establishes a versatile framework for designing solid-state supramolecular materials with multi-responsive optical and thermal functions via macrocyclic host-guest chemistry.