Preparation,Structure,Thermal Chemical Properties Of Lanthanide Complexes With Tri-substituted Benzoic Acid And 1,10-phenanthroline

In this paper,the ternary complexes are synthesized at room temperature by a solution-precipitation method,in which tri-substituted benzoic acid and 1,10-phenanthroline are used as the ligands,trivalent rare-earth ions are used as the central ions.They are[La(2-cl-4,5-dfba)3phen]n-nH2O,[Nd(2-cl-4,5-dfba)3phenH2O]2,[Ln(2-cl-4,5-dfba)3phen]2(Ln= Eu,Tb,Dy,Ho,Yb),[Ln(2,3,4-TMOBA)3Phen]2(Ln= La,Pr,Nd,Sm,Eu,Tb,Dy,Yb),[Ln(3,4,5-TMOBA)3Phen]2(Ln= La,Pr,Nd,Sm,Eu,Tb,Dy,Ho,Yb).At the same time,the single crystal complexes[Pr(2-cl-4,5-dfba)3phen]n·nH2O is also synthesized by hydrothermal method.All the complexes are characterized and studied by conventional characterization(element analyzer,X-ray single crystal diffraction,infrared,ultraviolent spectroscopy)and nature determination(fluorescence spectroscopy,molar conductance,thermal analysis).The structures of eleven complexes have been determined by X-ray single crystal diffraction,including[La(2-cl-4,5-dfba)3phen]n·nH2O,[Nd(2-cl-4,5-dfba)3phenH2O]2,[Ln(2-cl-4,5-dfba)3phen]2(Ln=Eu,Ho),[Pr(2-cl-4,5-dfba)3phen]n·nH2O,[Ln(2,3,4-TMOBA)3Phen]2(Ln= Eu,Tb,Dy),[Ln(3,4,5-TMOBA)3Phen]2(Ln= Pr,Nd,Ho).They have four different structures.The[La(2-cl-4,5-dfba)3phen]n·nH2O and[Pr(2-cl-4,5-dfba)3phen]n·nH2 are a infinite 1Dchain polymeric structure,which is rare and new structure of the ternary complexes.The other complexes are all dual-core structure.The coordination geometry include a distorted monocapped square antiprismatic comformation and a square antiprismatic comformation.The coordination mode of the rare-earth metal ions and oxygen atoms present four kinds:unidentate,chelating bidentate,bridging bidentate and chelating-bridging tridentate.Using the TG-DTG and TG/DSC-FTIR techniques,the thermal processes of the complexes are inferred.And compared with the different instrument and different atmosphere of the same instrument,the influences of the thermal processes are illustrated.The TG-FTIR spectra of gaseous products are analyzed and further authenticated the thermal decomposition processes.The results showed that:1,10-phenanthroline tends to break firstly,escape in the form of gaseous aromatic macromolecules.The trisubstituted benzoic acid tends to decompose into CO2,H2O and other gaseous aliphatic small molecules.The kinetics of the first thermal decomposition processes of[Ln(3,4,5-TMOBA)3Phen]2(Ln=Pr,Nd,Ho)are studied by the integral isoconversional non-linear(NL-INT)method and Malek method.The NL-INT method is used to calculate the activation energy E.The relationships between E and a indicate that the first thermal decomposition processes of those complexes are all single step reactions.The kinetic model of the first thermal decomposition processes can be determined to be SB(m,n).What is more,the kinetic exponents and the pre-exponential factor A are also calculated by Malek method.The values of the thermodynamic parameters at the DTG peak temperature obtain on the basis of thermodynamic equations.The average molar heat capacities and the thermodynamic parameters relative to the standard reference temperature(298.15 K)of the complexes[Nd(2-cl-4,5-dfba)3phenH2O]2,[Ln(2-cl-4,5-dfba)3phen]2(Ln= Eu,Ho),[Ln(2,3,4-TMOBA)3Phen]2(Ln= Eu,Tb,Dy)are measured and calculated by DSC technology using specific heat comparsion method.