Syntheses,Structures And Photoelectric Properties Of Lanthanide-Titanium Oxo Clusters Based On 3,5-di-tert-butylsalicylic Acid

Lanthanide-titanium oxo clusters(LnTOCs)have a lower bandgap width and can effectively improve the utilization of solar energy.Hence,LnTOCs are attracting widespread current interest.However,due to the special electron configuration of lanthanide and titanium,complex chemical reactions between metals,ligands and solvents will occur,so it is difficult to achieve precise synthesis of clusters.The chelating ligand such as salicylic acid,oxime and hydroxypyridine can control the hydrolysis of metal ions and form stable topological structures.Based on this,3,5-di-tert-butylsalicylic acid was selected as ligand to synthesize a series of lanthanide-titanium oxo clusters,and their syntheses and photoelectric properties were studied.Specific research contents are as follows:?:Based on triangular single cone structural unit[LnTi2(?3-O)]9+,nine lanthanide-titanium oxo clusters Gd2Ti4(1),Gd2Ti3(2),LnTi6(Ln=Eu,3;Tb,4),LnTi7(Ln=Eu,5;Tb,6),LnTi7(Ln=Eu,7;Tb,8),La2Ti14(9)were synthesized through solvothermal methods using 3,5-di-tert-butylsalicylic acid as ligand.It was found that the structural units[LnTi2(?3-O)]9+could be converted to dimer[Gd2Ti4(?3-O)2]18+(1)and[Gd2Ti3(?3-O)]18+(2),and the trimer structure[EuTi6(?3-O)3]21+(3).By expanding the reaction concentration,3 could be dimerized to obtain the cluster[LaTi7(?3-O)3(?2-OH)2(OC2H5)]244+(9).Changing the solvent,[EuTi7(?3-O)3(?2-OH)2]23+(7)was obtained.Based on 7,changing the rare earth salt into LnCl3,cluster 5 with the same metal oxo core could be obtained.The photoelectric properties showed that the cluster 5 had the best performance.?:Four lanthanide-titanium oxo clusters 10-13 were synthesized through solvothermal methods using 3,5-di-tert-butylsalicylic acid as ligand.It was found that when Ti and Ln reacts according to 1:1,Eu4Ti4(13)was obtained.Keeping the ratio unchanged and reducing the concentration of metal ions,Eu4Ti2(12)was obtained.When Ti:Ln=2:1,Eu2Ti4(11)was obtained.And when Ti:Ln=3:2,Gd2Ti3(11)was obtained.The photoelectric properties showed that the cluster 13 had the best performance.?:Two lanthanide-titanium oxo clusters 14 and 15 were synthesized through solvothermal methods.Discussion found that when adding 3,5-di-tert-butylbenzoic acid to the reaction solution,we obtained cluster[Ti12(?3-O)14(OiPr)18][Eu(NO3)5](15)formed by the combination of the cage cationic cluster and mononuclear lanthanide ion.Removing the organic ligand,a "hand basket" cluster[EuTi11(?3-O)14(OiPr)17(NO3)2](14)was generated.Due to the synergistic effect between Eu3+ and Ti4+,the fluorescence of cluster 14 has a higher fluorescence quantum yield.