Preparation Of Novel Covalent/Metal Organic Framework Materials And Study On Fluorescence Sensing Performance

Covalent organic framework materials（COFs）and Metal organic framework materials（MOFs）are two emerging organic framework materials.COFs are composed of lightweight elements that are joined by covalent bonds to form a two-or three-dimensional porous crystal structure.The porous structures of COFs allow analytes to diffuse through the porous channels,thus COFs have been widely used as chemical sensors to identify and detect different analytes.MOFs are composed of metal ions or ion clusters that coordinate with organic ligands to form a one-,two-or three-dimensional frame structure.MOFs can selectively interact with different ions or molecules through the spatial confinement effect of pore structure and various interactions,so MOFs show excellent sensing ability.In this thesis,we have prepared three kinds of sensors for ion sensing based on the above two materials.The main contents are as follows:In the first part,a novel metal organic framework（HNA@UiO-66-NH₂）was synthesized by grafting of 6-hydroxy-2-naphthalene formaldehyde on MOF-UiO-66,which can be used as a fluorescence sensor to selectively detect Fe³⁺and Cl O₄^-in different solvents,“turn-off”response to Fe³⁺in methanol and“turn-on”response to Cl O₄^-in ethanol,accompanied by obvious changes of fluorescence color.Its fluorescence intensity presented linear changes with the concentrations of Fe³⁺and Cl O₄^-,and the detection limits of Fe³⁺and Cl O₄^-are 0.911μM and 1.44μM,respectively.In addition,HNA@UiO-66-NH₂ was prepared into a test paper,which can be easily and intuitively identified Fe³⁺and Cl O₄^-under UV lamp.The sensor has high accuracy in detecting Fe³⁺in serum,and the recovery rate of Fe³⁺and Cl O₄^-in actual water samples is good.This work provides an idea for the preparation of fluorescence sensor with modified MOFs materials.In the second part,a novel covalent organic framework（TFTH-COF）linked by hydrazone bond was synthesized from benzene-1,3,5-tris（4-formyl-3-hydroxyphenyl）and benzene-1,3,5-trimethylhydrazide raw materials and solvothermal method,which was used as a ratio fluorescence sensor to selectively detect Cl O^-.In ethanol solution,TFTH-COF showed obvious fluorescence blue-shift response to Cl O^-.After adding of Cl O^-,the color of the solution showed obvious changes under the sunlight and the ultraviolet irradiation,which could be used for selective detection of Cl O^-.The fluorescence intensity of TFTH-COF exhibits a good linear relationship with the concentration of Cl O^-,and the detection limit is 0.417μM.The sensor has a good recovery rate of Cl O^-in water samples and 84 disinfectants,and TFTH-COF can be made into fluorescent test strips for simple and intuitive identification of ClO^- under UV lamp.This work provides an idea for COFs materials to be used as ratio fluorescence sensors to detect anions.In the third part,a covalent organic framework（TPDQ-COF）was prepared by solvothermal reaction using 1,3,5-trimethylphloroglucinol and 2,6-diaminoanthraquinone,which was used as a colorimetric sensor to selectively detect Fe²⁺and Fe³⁺.In DMF solution,TPDQ-COF has selective UV absorption enhancement response to Fe²⁺and Fe³⁺,accompanied by obvious color changes.The UV absorption intensity of TPDQ-COF suspension at 283 nm has a good linear relationship with the concentration of Fe²⁺and Fe³⁺,and the detection limits of Fe²⁺and Fe³⁺are 0.691μM and 0.714μM respectively.TPDQ-COF has a good recovery rate of Fe²⁺and Fe³⁺in actual water samples.This test confirms its sensing ability for iron ions in actual water samples.This work provides an idea for covalent organic framework as colorimetric sensor to identify and detect specific metal ions in actual water samples.