Synthesis And Fluorescence Properties Of Adenine-Based Biological Metal-Organic Frameworks

Biologcial metal-organic frameworks（Bio-MOFs）are metal-organic frameworks（MOFs）constructed with biological molecules（nucleobases,amino acids,peptides,proteins,porphyrins/metal porphyrins,etc.）or used in biological research.Bio-MOFs have received widespread attention due to their diverse structures and low toxicity.To obtain environment-friendly materials for specifical detection of pollutants in the environment,adenine and biphenyl-4,4’-dicarboxylic acid as well as its derivatives were selected as organic ligands to synthesize BioMOFs.Four BioMOFs（1-4）were synthesized and their structures and properties were studied.Considering that zinc ion is less toxic than other metal ions,zinc salts were used as metal source.The main work of this paper is as follows:（1）In the experiment,2,2’-diaminobiphenyl-4,4’-dicarboxylic acid（H₂L₂）was synthesized,and four Bio-MOFs（including JXNU-4 reported in the literature）were obtained.Crystal structure analysis was performed on 2,3 and 4,and basic properties of complexes 1,2 were studied.（2）Sensing experiments of inorganic ions with complexes 1 and 2:Three kinds of ions,Fe³⁺,CrO₄^2-and Cr₂O₇^2-,were selected for detection,and showed excellent luminescence sensing performance,respectively,and the quenching mechanism was analyzed.When 1 was used to detect three metal ions,it was found that Al³⁺,Zr²⁺,and Cr³⁺had specific enhancement effects on 1.（3）Experiments on the recognition of organic molecules by complexes 2.2 was tested with nitro explosives（nitrobenzene,2,4-dinitrotoluene,2,6-dinitrotoluene,3-nitrophenol and 4-nitrophenol）,and exhibit excellent luminous sensing performance.In addition,the experimental results show that the formaldehyde solution has a fluorescence enhancement effect on 2,and its enhancement intensity is far more significant than other organic solvents.Compared with the initial fluorescence intensity,the increase is about 23 times.It was found that fatty aldehydes had a significant fluorescence enhancement effect on 2,and the increase was in the order of formaldehyde>glyoxal>acetaldehyde>propanal.Compared with the aromatic aldehyde,2 has a significant fluorescence quenching effect.