Synthesis And Application Of Benzoyl Hydrazone Organic-Inorganic Hybrid Mesoporous Materials

A new organosiloxane precursor((E)-3-hydroxy-4-((2-(2-hydroxy-4-(3-(3-(triethoxysilyl)propyl)ureido)benzoyl)hydrazono)methyl)phenyl(3-(triethoxysilyl)-propyl)carbamate,hereinafter referred to as AHBH-Si)and tetraethylorthosilicate(TEOS)are mixed as the mixed Si source,and bridged periodic mesoporous organic silica(AHBH-PMOs)nanoparticles are obtained through co-condensation reaction.AHBH-PMOs nanoparticles possess abilities of "Aggregation Induced Emission "(AIE),"Excited State Intramolecular Proton Transfer"(ESIPT)and "Intramolecular Charge Transfer"(ICT)originated from the molecular structure of AHBH that the compound have a "C=N" bond,ortho hydroxyl groups,etc(Figure 2-1).Therefore,optical properties of AHBH are excellent in the aspect of solvent effect,enhanced fluorescence and dual fluorescence emission of ESIPT effect.The main research contents are as follows:(1)Using 4-aminosalicylic acid,a new type of benzoyl hydrazone compound(AHBH)was synthesized through three-step reaction.AHBH belongs to the benzoyl hydrazone compound and contains the structure of C=N.This structure allows the entire molecule to rotate freely around the nitrogen-nitrogen single bond,so the fluorescence is weak.AHBH was modified into bridged organosilicon precursor by 3-Isocyanatopropyltriethoxysilane(IPTES).We explored the influence of solvent on AHBH's intramolecular charge transfer(ICT),aggregation induced emission(AIE)and excited state intramolecular proton transfer effect(ESIPT)through a series of experiments.After comparison,pure water solvent was selected to study the sensing properties of metal ions.AHBH has high selectivity to Al3+ and Zn2+ in pure aqueous solution,and the detection limits are 5.05×10-8 and 9.45×10-7 M,respectively.AHBH can detect Al3+ and Zn2+ in a wide pH,and is not affected by the surrounding environment.Among them,AHBH is coordinated with Al3+ in a ratio of 2:1,and coordinated with Zn2+in a ratio of 1:2 to realize the sensing of metal ions.(2)When used as an ion probe,AHBH has poor stability and selectivity,and is extremely susceptible to interference from other ions.Using cetyltrimethylammonium bromide(CTAB)as a template,bridging organosilicon precursor(AHBH-Si)and ethyl orthosilicate(TEOS)as a mixed silicon source to synthesize an organic-inorganic hybrid mesoporous materials(AHBH-PMOs,Figure 3-1).For the hybrid materials,the silica framework provides a rigid environment that restricts the rotation of AHBH,thereby turning on the fluorescence of AHBH due to the regulation by AIE effect.In particular,AHBH-PMOs are no longer restricted by organic solvents with help of dissolution,and can really achieve a response to Cu2+ with high sensitivity and selectivity in aqueous solutions of a wide pH range.In addition,the detection limit is as low as 3.26×10-9 M.Methods such as Fourier transform infrared spectroscopy,proton nuclear magnetic resonance spectroscopy and high-resolution mass spectrometry have shown the interaction between AHBH and Cu2+ through coordination interaction.The reducing changes of the energy gaps among AHBH and AHBH-Si before and after addition of Cu2+ showed that the coordination interaction exist in the system using Gaussian 09 software of density functional theory.These results indicate that AHBH-PMOs hybrid materials have potential applications in the field of environmental monitoring.