Facile Fabrication of a Multi-Functional Metal-Organic Framework based Sensor Exhibiting Exclusive Solvochromic Behaviors towards Ketone Molecules.

To probe the efficient strategy for preparing multi-functional sensing material, the facile synthesis strategies and successful examples are urgently required. Through the utilization of a hexa-dentate ligand derived from cyclotriphosphazene which displays spiral configurations and multiple connection modes, a novel Metal-Organic Framework (MOF) has been constructed via one-step synthesis from low-cost raw materials. The presence of multiple interaction sites decorating the helical channels of the reported MOF gives rise to exclusive solvochromic sensing behavior for small ketone molecules, such as acetone, acetophenone and 2,5-diketohexane. Additionally, the helical structure of manganese-carboxylate chain allows for the pore volume to not only be available for the adsorption of large organic molecules, but enables the enantiopure selective separation of 1-phenylethanol (ee. 35.99 %). Furthermore, structural analysis of the acetophenone-encapsulated sample allowed the solvochromic mechanism to be elucidated, which should be ascribed to the strong hydrogen bonding interaction between the guest molecules and specific sites on host matrix. The experimental results have not only clearly manifested the vital role of the starting materials of MOFs, including the connection modes and spatial configuration, but also have provided very valuable insight for the future assembly of novel multi-functional sensing materials.