Subtle structural engineering of a coordination polymer host for the fluorescence modulation of host–guest donor–acceptor systems

Host–guest engineering of donor–acceptor (D–A) coordination polymer (CP) materials has been proved to be a promising emission modulation strategy for the fabrication of highly tunable luminophores. Herein, it is shown that the fluorescence modulation of host–guest D–A CPs could be achieved through subtle structural engineering. Two isoreticular CPs, {M₃(μ₃-F)(BDC)₃(TPT)(solvents)}_n (M = Cd²⁺ for 1 and Zn²⁺ for 2, TPT = 2,4,6-tri(4-pyridyl)-1,3,5-triazine, H₂BDC = 1,4-benzenedicarboxylic acid), were selected as porous host CPs for investigation. By introducing different polyaromatic hydrocarbon (PAH) guests (anthracene; phenanthrene; pyrene; triphenylene; perylene; and coronene) into the host framework, two series of host–guest D–A CPs (PAHs@1 and PAHs@2) were obtained. Detailed investigation indicates that the subtle structural differences originated from the metal center affected D–A interactions between the PAH and TPT ligand, which result in distinct emission properties of PAHs@1 and PAHs@2. These results suggest the potential of structural modulation in the property tuning of the D–A CPs.