Synthesis Of HOFs Of Phosphonic-carboxylic Acid-amidine And Their Proton Conduction

As an important class of emerging porous crystalline materials,hydrogen-bonded organic frameworks（HOFs）materials have received a lot of attention from researchers in the last decade or so.Currently,HOFs are mainly constructed around one-component ligands and two-component（carboxylic acid-amidine/guanidine,sulfonic acid-guanidine）containing functional groups such as carboxylic acid,amide,diaminotriazine,etc.Some of these materials exhibit good proton conductivity properties due to their continuous hydrogen bonds.Compared with carboxylic acids and sulfonic acids,phosphonic acids with double protons have more diverse hydrogen bonding modes,and the phosphonic acid groups that are not completely deprotonated in the backbone can provide a proton source for proton conductor materials.There is still a gap in the research on the use of phosphonic acid/amidine two-component ligands for the construction of conducting HOFs,mainly because of the difficulties in crystallization of phosphonates,the diversity of linkage modes of phosphonic acids,and the lack of clear correlation between their structures and the properties of proton conductivity.In this thesis,we have selected a series of organocrystalline HOFs materials with different structures by using a mixture of phosphonic acid carboxylic acid ligands including two major groups of monosubstituted phosphonic acids and multisubstituted phosphonic acids on the benzene ring and the selected amidine salts（hydrochloric acid complexes of terephthalimidines）.Their proton conduction properties were investigated for different structural features and the conductivity mechanism was explained.In this thesis,we have chosen mixed phosphonic-carboxylic acid ligands including two major groups of monosubstituted phosphonic acid and polysubstituted phosphonic acid on benzene ring,and the chosen amidine salt is a hydrochloric acid complex of terephthalamidine,and the organocrystalline materials with different structures were synthesized by solvent self-assembly.Different structures were synthesized by changing the solvation environment of the ligands,and the different proton conduction properties exhibited by the different structures were investigated to try to explain the application mechanism.First,two new water-stable two-dimensional lamellar materials and three-dimensional frameworks,HOF-FJU-12 and HOF-FJU-13,were synthesized by varying reaction conditions and the ratio of ligands using two monomers,3,5-dicarboxylic acid phenylphosphonic acid and terephthalamidine,respectively.The proton conductivity of HOF-FJU-13(1.14×10^-4 S·cm^-1)is about 7.4 times higher than that of HOF-FJU-12(1.54×10^-5 S·cm^-1)at 60℃ and 98%relative humidity（RH）,mainly due to the presence of more free oxygen atom sites in the phosphonic acid moiety,and the construction of a continuous hydrogen bonding network with the H₂O molecule.To further prove this idea,we continued to construct HOF-FJU-27,HOF-FJU-28by varying the synthesis conditions using two monomers,3,5-diphosphonic acid benzoic acid and terephthalamidine.the conductivity of the proton conductivity of HOF-FJU-27 reached the highest value of 2.12×10^-4 S·cm^-1 at 60℃,98%RH;the conductivity of the proton conductivity of HOF-FJU-28 reached the highest value of3.0×10^-3 S·cm^-1 at 70℃ In the range of 20 to 60℃ and 98%RH,HOF-FJU-28achieves an order of magnitude higher proton conductivity than HOF-FJU-27 under the same conditions,both in terms of temperature tolerance and maximum values of conductivity,and HOF-FJU-28 achieves an order of magnitude higher proton conductivity than HOF-FJU-27 under the same conditions,both in terms of temperature tolerance and maximum values of conductivity.FJU-28 conductivity demonstrated better proton conductivity than HOF-FJU-27 both in terms of temperature tolerance and conductivity maximum.This is due to the fact that HOF-FJU-28 builds a rectangular pore filled with disordered water molecules,and the guest molecules（H₂O）in the pore are more likely to form a continuous hydrogen bonding grid under high temperature and high humidity conditions,and HOF-FJU-28 itself has a continuous hydrogen bonding network along the b-axis direction.The materials of HOF-FJU-29 and HOF-FJU-30 were synthesized by using the ligands of DPBA and BPAM,H₄P₂BC₂P and PAM via solvent self-assembly.We have been analyzed and discussed the structures of six charge-assisted HOFs,and explored the assembly regulation of functional groups.It was found that the preparation of these materials is predictable and designable,and also enables the modulation of the guest molecules.The construction of these crystalline materials also enriches the crystal network science and provides an experimental basis for the application of phosphonic acid and multi-component acid-amidine salt systems in the field of proton conduction.