The Research Of Small Molecular Recognition About The Imidazole Dicarboxylate-based Lanthanide Metal-organic Frameworks

Eu and Tb metal-organic frameworks(MOFs) usually exhibit excellent photoluminescence properties and are promising materials for luminescent devices and sensing. People found that chemosensors based on the Eu and Tb MOFs have operability, rapid response, high sensitivity and high selectivity advantages. Thus, it is necessary to deeply develop the research in this field.Based on above considerations, we successfully synthesized four novel imidazole dicarboxylate-based MOFs, [Ln(H2DMPh IDC)3(H3DMPh IDC)]n(H3DMPh IDC = 2-(3,4-dimethylphenyl)-1H-imidazole-4,5-dicarboxylic acid; Ln = Tb(1), Eu(2)), and {[Ln(μ3-HPh IDC)(μ2-C2O4)0.5(H2O)]·2H2O}n(H3Ph IDC = 2-phenyl-1H-imidazole-4,5-dicarboxylic acid; Ln = Tb(3), Eu(4)), and further explored their sensing properties to benzaldehydes and nitroaromatics. The sensing mechanism has been proposed as well.This paper is divided into three parts:1. A brief review of investigations on the luminescent rare earth MOFs-based chemosensors.2. Two novel dimethylphenyl imidazole dicarboxylate-based lanthanide(III)-organic frameworks, 1 and 2, have been synthesized. Polymers 1 and 2 exhibit isostructural three-dimensional frameworks. Both complexes indicate characteristic sharp emission bands of Eu3+ or Tb3+ ions, which are selectively sensitive to benzaldehyde-based derivatives(benzaldehyde, m-methylbenzaldehydes, m-carboxylbenzaldehyde and m-hydroxybenzaldehyde). These properties make both complexes potential fluorescence sensors for these chemicals.3. Two highly stable luminescent 3D Eu/Tb-MOFs 3 and 4 based on H3 Ph IDC have been successfully synthesized. Furthermore, they exhibit selective and efficient emission quenching response upon interaction with nitroaromatic compounds via a photoinduce electron transfer quenching mechanism.This study extends the applications of imidazole dicarboxylate-based Ln-MOFs as chemosensors for small molecules.