Studies On The Synthesis,Crystal Structures,Fluorescence Sensing And Catalytic Properties Of Complexes Based On Bis-Triazole Derivatives

At present,porous metal-organic complexes have been widely used in various fields such as ion channel,catalysis,chemical sensing and drug delivery due to their adjustable pore size,large specific surface area and diverse structure.Therefore,it is of great significance to synthesize porous metal-organic complexes with high performance and versatility.In this paper,17complexesweresynthesizedfromorganicligands bis（3-（2-pyridyl）-（5-1H-1,2,4-triazolyl））methane（H₂L₁）,bis（5-acetylamino-4H-1,2,4-triazole）（H₄L₂）and bis（4-acetamido）-（5-1H-1,2,4-triazolyl）)methane（H₄L₃）with Zn/Cd/Ln-metal salts.Among them,there are 1 case of Zn₁₅ complexe with five-membered ring metal-organic tubes（Tubes）structure that was synthesized by our research group in the early stage but not yet deeply developed,and 13 cases of metal cluster complexes and 3 cases of metal coordination polymers.The structures of the complexes were characterized and the fluorescence sensing and catalytic properties of some complexes have been investigated in detail.The main work of the full text is as follows:1.Based on the previous Zn₁₅ complex（1）with a five-membered ring metal-organic pipe,the 15 Zn（II）skeletons were bridged by ligands to form a five-membered pipe structure with an inner diameter of about 8.0?.We optimized the conditions and improved the yield of the complex,and we conducted a work activation study on it based on its structural novelty.First,we performed complex（1）for thermogravimetry and X-ray powder diffraction,which it shows that complex（1）has high thermal stability.Secondly,we found that complex（1）has good selectivity to Fe³⁺,Cr O₄^2-,Cr₂O₇^2-,Mn O₄^-and 2,4,6-trinitrophenol in solution through the study of the properties of fluorescence sensing and catalysis.We found that the absorption spectra of Fe³⁺,Cr O₄^2-,Cr₂O₇^2-,Mn O₄^-and 2,4,6-trinitrophenol and the emission spectrum of complex（1）has a relatively large overlap.We speculate that it is possible to perform efficient energy resonance transfer between complex（1）and the five analytes in order to make complex（1）have better selectivity and sensitivity detection.By studying the Knoevenagel condensation reaction of complex（1）with nitro-benzaldehyde,we found that the conversion rate of 4-Nitrobenzaldehyde was significantly greater than that of 2-Nitrobenzaldehyde and 3-Nitrobenzaldehyde under the same conditions.We suspect that the molecular size of 4-nitrobenzaldehyde can be highly matched to complex（1）with irregular pentagonal nanochannels,which makes 4-Nitrobenzaldehyde easy to enter and exit the tunnel.However,the molecular size of 3-Nitrobenzaldehyde and 2-Nitrobenzaldehyde may be mismatched to the five-membered nano-pore and the five-membered nano-pore has a large steric hindrance to 3-Nitro-benzaldehyde and 2-Nitrobenzaldehyde,which leads to obvious differences in the conversion rates of the three nitro-benzaldehyde.And it is further illustrated that the reaction is in the cavity of the pentagon nano-channel of complex（1）. Through the expansion of the catalytic substrate,we found that complex（1）also has a good catalytic activity for the Knoevenagel condensation reaction of salicylaldehyde molecules.2.Usingbis（3-（2-pyridyl）-（5-1H-1,2,4-triazolyl））methane（H₂L₁）,bis（5-acetylamino-4H-1,2,4-Triazole）（H₄L₂）and bis（4-acetamido）-（5-1H-1,2,4-triazolyl）)methane（H₄L₃）are reacted with Zn/Cd metal salt to obtain six novel complexes（2）-（7）.Among them,complex（2）is composed of sixteen-core cadmium[Cd₁₆（L₁）₄₈]as a secondary structural unit to form a 3D MOFs with a pore diameter of about 18.34?,complexes（3）-（6）are a series of Zn clusters and complex（7）is a one-dimensional polymer of Cd.First,we performed complex（2）for thermogravimetry and X-ray powder diffraction,which it shows that complex（2）has high thermal stability. Secondly,through the study of the properties of fluorescence sensing and catalysis,we found that complex（2）has good selectivity to Fe³⁺,Cr O₄^2-,Cr₂O₇^2-,Mn O₄^-and 4-nitrophenol,2,4,6-trinitrophenol in solution.We found that the absorption spectra of Fe³⁺,Cr O₄^2-,Cr₂O₇^2-,Mn O₄^-and 4-nitrophenol,2,4,6-trinitrophenol and the emission spectrum of complex（2）has a relatively large overlap.We speculate that it is possible to perform efficient energy resonance transfer between complex（2）and the five analytes in order to make complex（2） have better selectivity and sensitivity detection.At the same time,we also tested the solid-state fluorescence of complexes（3）-（7）and found that complexes（3）-（7）have the maximum emission peak of the ligand.3.Using bis（3-（2-pyridyl）-（5-1H-1,2,4-triazolyl））methane（H₂L₁）are reacted with Ln（Sm/Eu/Tb）metal salt to obtain a series of heterogeneous isomorphous and different core complexes（8）-（17）.Among them,complexes（9）-（11）,（12）-（14）and（15）-（17）are clusters of binuclear,tetranuclear and hexanuclear structures with heterogeneity and homomorphism respectively.Meanwhile,the ligand in（9）-（14）reacted in situ reaction under the action of solvent molecules to form new ligands.For complex（8）,it is composed of twelve-core ruthenium[Tb₁₂（L₅）₂₄（μ₂-4.OH）₁₂]as a secondary structural unit t to form a cage-shaped 3D MOFs with a pore diameter of about 8.40?.According to the fluorescence detection data of the nitroaromatic hydrocarbon of complex（8）,we found that complex（8）has good selectivity to 2,4,6-trinitrophenol in solution.We found that the absorption spectra of 2,4,6-trinitrophenol and the emission spectrum of complex（8）has a relatively large overlap.We speculate that it is possible to perform efficient energy resonance transfer between complex（8）and 2,4,6-trinitrophenol in order to make complex（8）have better selectivity and sensitivity detection.At the same time,we also tested the solid-state fluorescence of complexes（9）-（17） and found that complexes（9）-（17）can emit strong emission peaks of lanthanide ions and maximum emission of ligands.