| 摘要: | Guest-free and porous [In(OH)(bdc)](n) (bdc =1,4-benzenedicarboxylate) microcrystals were produced by heating indium(III) nitrate hydrate (In(NO(3))(3)center dot xH(2)O) and terephthalic acid (H(2)bdc) in N,N-dimethylformamide (DMF) with the addition of ethyl acetate as a crystal habit modifier at 100 degrees C for 10 h and then vacuum drying them in an oven at 250 degrees C for 48 h to remove lattice DMF. These microcrystals were monodispersed and hexagonal rod-like in shape with a length of 30 mu m, an aspect ratio of 7.5, a BET surface area of 1148.74 m(2)/g, and the total pore volume of 0.57 cm(3)/g. The oriented films of those hexagonal rods were fabricated first through the self-assembly of as-synthesized [In(OH)(bdc)center dot 2DMF](n) microcrystals at the water/n-heptane interface and then followed by the removal of DMF upon vacuum drying in an oven at 250 C for 48 h. The stereochemical sensing capability of both guest-free and porous [In(OH)(bdc)] microcrystals and oriented films toward odorants emanated from the analytes such as cumin, cinnamon, vanillin, p-xylene, m-xylene, o-xylene, water, and ethanol, was successfully transduced to the first set of photoluminescence (PL) emission responses. The original emission of the guest-free, porous [In(OH)(bdc)](n) framework might be attributed to the ligand-to-metal charge transfer (LMCT). The inclusions of guest odorant molecules in the guess-free, porous [In(OH)(bdc)] microcrystals could have quenched the excitons through: (1) delocalization over the conjugated polymer backbone, (2) interchain energy migration in the solid state, and (3) a highly organized molecular stacking structure, attributed to the pore confinement of the analyte inside the molecular-sized cavities of [In (OH)(bdc)l, framework which facilitated strong interactions between the analyte (or the odorant) and the host framework. Therefore, specific guest host stereochemical interactions would dictate the characteristic quenching response of a given analyte. Red shifts were observed for cumin-, cinnamon-, vanillin-, p-xylene-, m-xylene-, o-xylene-, water-, and ethanol-adsorbed samples of [In(OH)(bdc)] microcrystals, with emission lambda(max) at 390, 425, 343, 428, 422, 400, 390, and 389 nm respectively, upon excitation at 270 nm in solid state. A second set of PL emission responses of the same analytes produced from the analyte-adsorbed Zn(4)O(bdc)(3) (MOP-5) microcrystals for a demonstration purpose was also determined and coplotted with the first set of PL emission values to construct a 2D map of PL emission responses for our MOF-based "biomimetic nose". The biomimetic nose could distinguish the odors of the analytes based on a pattern recognition method (i.e., principal component analysis) because on the 2D map of PL emission responses, ethanol, m-xylene, o-xylene, vanillin, cumin, p-xylene, cinnamon, and water, were represented by a line, a point, a point, a point, a line, a point, a rectangle and a point respectively. |
