Synthesis And Luminescent Properties Of Tetraphenylethene-based Luminescent Metal-organic Frameworks

Tetraphenylethylene（TPE）is a star luminogen with prominent aggregation-induced emission（AIE）character,which is much superior to conventional chromophores that often encounter concentration or aggregation-caused emission quenching.By decorating TPE with carboxylate or pyridine groups as multidentate organic ligands to coordinate with metal ions,TPE-based luminescent metal-organic frameworks（LMOFs）with strong luminescent properties can be constructed.It can be used as a promising fluorescent sensor to detect various explosives and environmental pollutants because of its simple operation,high efficiency,economic feasibility.In this paper,a number of LMOFs have been synthesized using TPE-based derivatives with AIE effect as ligands,and their fluorescence and sensing properties were further studied.There are four main parts:1)Based on BPy TPE organic ligand,a novel 3D pillared-layered and a2D-layered TPE-based LMOF[Zn（HIPA）（BPy TPE）]（1）and[Zn（AIPA）（BPy TPE）]（2）were synthesized by solvothermal method.Studies have shown that the fluorescence quantum yields（Ф_Fs）of complex 1 and complex 2 were 90.1%and 28.9%,respectively,and theФ_Fs of activated 1 and 2 were 38.6%and 33.6%,respectively.The selective fluorescence sensing experiments of activated 1 for the cis/trans isomers in methanol solution and activated 2 for the cis/trans isomers vapor were studies.Under the same conditions,activated 1 and 2 exhibited significant fluorescence quenching effect on the trans isomers,and the selective recognition effect of the activated 1 towards cis/trans isomers could be clearly observed with the naked eye.The limits of detection of activated 1 for trans-DMBEDA and trans-BEDO are 27.3 ppm and 109.7 ppm,respectively,which proves that it can be used as an excellent fluorescence sensor to differentiate cis/trans isomers quickly and sensitively.2)Based on 4-[（3-carboxyphenyl）phenyl]ethene（H₄T³CPPE）organic ligand,a2D-layered TPE-based LMOF[Zn₂（T³CPPE）（H₂O）₂]（3）was synthesized by solvothermal method.TheФ_F of LMOLs 3 was 99.0%,being much higher than that of complex 3（62.9%）.The fluorescence sensing experiments of complex 3 and LMOLs 3 for the antibiotics in water were studies.At 50.5μM titration concentration,the fluorescence of LMOLs 3 can be much more efficiently quenched with efficiency of 84.9%for NFZ and 87.7%for NFT.Compared to complex 3,LMOLs 3 shows higher fluorescence quenching efficiency and more sensitive response.The limits of detection of LMOLs 3 for NFZ and NFT are 0.06 ppm and 0.07 ppm,respectively,showing its great potential as an excellent fluorescence sensor to detect nitrofuran antibiotics in the water phase.3)Based on 4-[（3-carboxyphenyl）phenyl]ethene（H₄T³CPPE）organic ligand,two 3D TPE-based LMOFs[Ca₂（T³CPPE）_1.5（H₂O）₂]（4）and[In（T³CPPE）]（5）were synthesized by solvothermal method.TheФ_Fs of complex 4 and complex 5 were47.2%and 40.0%respectively,and theФ_F of activated 4 was 63.2%.The fluorescence sensing experiments of activated 4 for the monosaccharides in water were studies.At 20 m M titration concentration,the fluorescence of activated 4 can be much more efficiently quenched with efficiency of 95.8%for D-Nxy and 95.6%for D-Nga.While,the quenching efficiency of the remaining seven monosaccharides all were lower than 35%.This shows its great potential as an excellent fluorescence sensor to nitro-containing monosaccharides in the water phase.4)Based on TPy PE organic ligand,a 3D TPE-based LMOF[Cd（TPy PE）（NCS）₂]（6）was synthesized by the diffusion method.Changing the solvent in complex 6 to different proportions of chiral 1,2-propanediol,LMOFs with single chiral configuration were induced respectively by chiral solvent induction.In the test of circularly polarized fluorescence performance,it was found that the CPL spectra of the induced enantiomeric complexes were mirror images of each other.