Study On The Copper/Silver Compounds Constructed By Xanthene-9-Carboxylic Acid And Their Photothermal Properties

At present,the design and development of photothermal conversion materials with excellent performance is still a challenging work.Functional coordination compounds are complicated molecules that coordination organic functional ligands with specific performance metal centres.They are ideal molecules for the development of photothermal conversion materials due to their wide varieties and atomic precisely structures.Organic ligands containing aromatic groups are used to participate in the preparation of metal compounds,in order to improve the spectral absorption range and light capture ability of compounds through the antenna effect of aromatic compounds,so as to realize the construction of efficient photothermal conversion functional compounds.Xanthene-9-carboxylic acid,as a typical derivative of polycyclic aromatic hydrocarbons,is easy to coordinate with coin metal ions to form functional compounds with various structures and rich properties.It is an ideal ligand group for introducing the xanthene group into the copper/silver functional compounds.In this paper,the photothermal conversion properties of copper/silver compounds are studied.Xanthene-9-carboxylic acid was combined with copper/silver salt by coordination self-assembly.Five photothermal conversion materials with atomic precisely structures and superior performances were designed and prepared.The main research contents are as follows:1)Xanthene-9-carboxylic acid was used as the main ligand in the presence of the second auxiliary ligand diphenylphosphonane(dppm)and 2,2 '-bipyridine(bpy).Five compounds were successfully constructed by solvothermal method.The X-ray single crystal diffraction analysis(SXRD)showed that the molecular formulas were[Ag2(dppm)2(X9A)2](1),[Ag4(X9A)4(dppm)2]·6CH3OH(2),[Cu2(X9A)4(CH3CN)2](3),[Cu2(X9A)(dppm)2(CH3CN)2BF4](4),[Cu4(X9A)6(bpy)4(BF4)2·H2O](5).Their structures were further characterized by X-ray powder diffraction(PXRD),infrared spectroscopy,and ultraviolet spectrum.Related research has successfully realized the systematic construction of copper/silver complexes with xanthene-9-carboxylic acid as the ligand,laying a foundation for further research on its properties and structure-activity relationships.2)The thermal stability and light absorption properties of the series of compounds were studied by thermal analysis(TGA)and Solid-state UV.Thermal analysis shows that the thermal stability of the complound 1,2,3,5 are all over 150?,and the initial thermal decomposition temperature of compound 5 is as high as 211?,which is related to the large number of intramolecular ?…? stacking interactions in the molecular structure.Solid-state UV shows that the energy gap values of the series of compound molecules are 3.18 eV,3.25 eV,2.39 eV,3.12 eV,and 2.62 eV,among which compound 3 and 5 are in the ultraviolet region(<400 nm)and near-infrared region(?600 nm)shows a certain light absorption capacity.Those results show that introducing the molecular group of xanthene carboxylic acid into the center of the divalent copper ion can expand the spectral absorption range of the compounds.Compound 5 is an potential molecule for developing photothermal conversion materials due to its excellent thermal stability and light absorption properties.3)The photothermal conversion performance of the series of compounds was comparatively studied through photothermal conversion experiments.The results show compound 5 has the fastest heating rate(close to 2?/min at the beginning),the largest temperature increment(19.1?)and the highest photothermal equilibrium temperature(31.6?).These results give new direction for the molecular design to improve the performance of photothermal conversion materials and provide the experimental basis for the application of functional coordination compounds in the field of photothermal conversion.