Well-Designed Syntheses and Luminescent Properties of Rare Earth Crystal Networks Based on Arenesulfonic Acids

Author:Xiao Ying Hui

Supervisor:gao shan


Degree Year:2019





Because of the small absorption coefficient of RE(III)cations and the Laporte forbidden of f-f electrons,the photosensitizers(“antenna”molecules),with broad and strong adsorption in untraviolet region,are introduced into rare earth crystalline network compounds to improve the emission intensity and luminescent efficiency of RE(III)cations.Up to date,single-functional ligands(e.g.β-diketons and N-heterocycle)or bifunctional ligands(e.g.niacin,carboxyl-benzenesulfonic acid,etc.)have been widely used as sensitizers for RE(III)cations.Multifunctional ligands,involving three or more different coordination groups,can not only enhance the stability of rare earth crystalline network structure,but also effectively induce the emission of RE(III)cations.Compared with organic carboxylic acid,β-diketons and N-heterocycle,the studies on the structure and luminescent properties of rare earth crystalline network compounds of aromatic sulfonic acid have received less attention,which may be related to the weak coordination ability of–SO3H group and difficult synthesis of ligands.In order to improve the coordination ability of–SO3H and enrich the network types,three organic“antenna”molecules with similar trifunctional groups have been designed and synthesized in this thesis:2,4-dihydroxyl-5-carboxylbenzenesulfonic acid(H4L1),2-hydroxyl-5-carboxyl-benzenesulfonic acid(H3L2)and 2-hydroxyl-4-carboxylbenzene sulfonic acid(H3L3),in which the–OH group locate are the ortho-position of sulfonate group.In addition,conjugated 2,2’-bipyridine and 1,10-phenanthroline molecules are also utilized to sensitize and enhance the luminescence of RE(III)cations.Therefore,this thesis aims to construct a series of rare earth crystalline network compounds with novel topological structures and excellent luminescent properties.Subsequently,novel multifunctional aromatic sulfonic acids containing carboxyl and hydroxyl groups have been designed and synthesized,which are further utilized to construct 67 new RE(III)-aromatic sulfonate network compounds through room temperature assembly and hydrothermal reaction.These compounds have been characterized by the single crystal X-ray diffraction,IR,TG,PL,and the relationship between structures and luminescent properties are also investigated.The results of this thesis may provide valuable basis for the future design and synthesis of such types of compounds.The main results include the following three aspects:1.Thirteen compounds with four structure types have been synthesized by the reaction of H3L1,RE(III)metal nitrates and 2,2’-bipyridine/1,10-phenanthroline,namely,[RE(NO3)(H2O)8]·2(H3L1)·2H2O(1-RE)(RE=La,Nd,Sm and Tm),([Pr Li(H2L1)2(H2O)4]·3H2O)(2-Pr),([La(HL1’)(2,2’-bipy)(H2O)2]n·2H2O)(3-RE)(RE=La and Lu,2,2’-bipy=2,2’-bipyridine,H4L1’=2,4-dihydroxyl-1,5-benzenedisulfonic acid)and([RE(HL1’)(1,10-phen)(H2O)2]n·2H2O)(4-RE)(RE=Pr,Nd,Eu,Tb,Dy,Er,1,10-phen=1,10-phenanthroline).Compound 1-RE presents mono-nuclear structure,while compound 2-Pr exhibits heteronuclear layer motif formed by the interconnection of Pr(Ⅲ)and Li(I)throughμ3-H2L12-.Compounds 3-RE and 4-RE exhibit the same chain structure,in which the in-situ generated HL1’3-showsμ4 coordination mode.Luminescent investigations indicate that compounds 1-RE(RE=La,Nd,Sm and Tm),3-RE(RE=La,Lu)and 4-RE(RE=Pr,Nd,Er)present blue and green emissions between 412 and 520 nm.Complexes 4-Eu,4-Tb and 4-Dy exhibit characteristic red,green and voilet emissions of RE(III)cations.2.Sixteen complexes with seven structure types have been synthesized by the reaction of H3L2,RE(III)metal nitrates and 1,10-phenanthroline system,namely,[RE(NO3)(H2O)8]·2(H2L2)·2H2O(5-RE)(RE=Nd,Sm,Gd,Tb,Dy),[RE(NO3)2(H2O)6][RE(H2O)9]·4(H2L2)·4H2O(6-RE)(RE=Ho and Y),[La(L2)(H2O)3]n·3nH2O(7-La),[Eu2(L2)2(1,10-phen)2(H2O)2]n·nH2O(8-Eu),[Tb2(L2)2(1,10-phen)3(H2O)2]n·nH2O(9-Tb),[RE(L2)(1,10-phen)2]n·nH2O(10-RE)(RE=Dy,Ho and Y),and[RE(L2)(1,10-phen)(H2O)2]n(11-RE)(RE=Er,Yb and Lu).Compounds 5-RE and6-RE present mono-nuclear structures.The La(III)cations in compound 7-La are interconnected by theμ3-L23-trianions to form(4,4)layer.The Eu(III)cations in compound 8-Eu are joined by two L23-trianions in differentμ3 coordination modes into(4,4)layer.Compound 9-Tb exhibits tubular structure extended by two unique L23-trianions in differentμ2 andμ3 coordination modes.Compounds 10-RE and 11-RE exhibit chain structures through the interconnection of RE(III)cations by differentμ2-andμ3-L23-trianions.Such structure evolutions are highly dependent on the diverse coordination modes of L23-trianion and the participation of 1,10-phen.Luminescence test results show that compounds 5-RE(RE=Nd,Sm,Gd),6-Y,7-La and 11-Lu exhibit violet,blue and green emissions from 362 to 502 nm.Meanwhile,compounds9-Dy and 10-Dy,5-Tb and 9-Tb,as well as 8-Eu exhibit characteristic green and red emissions of RE(III)cations.These results indicate that the present multifunctional H3L2 is a good antenna molecule for sensitizing RE(III)cations luminescence.3.Thirty-eight compounds with seven structure types have been synthesized through the reaction of H3L3,RE(III)metal nitrates and 2,2’-bipyridine/1,10-phenanthroline,namely,[La(H2L3)2(ox)0.5(H2O)4]n·2nH2O(12-La)(ox=oxalate),[RE2(H2L3)2(ox)(H2O)12]·2(H2L3)·8H2O(13-RE)(RE=Nd,Sm,Eu,Gd,Tb,Dy),[RE(SO4)(H2O)7]·(H2L3)·3H2O(14-RE)(RE=Ho,Er,Tm,Yb,Lu and Y),[RE(L3)(H2O)3]n·nH2O(15-RE)(RE=Er,Tm,Yb and Lu),[RE(L3)(2,2’-bipy)(H2O)]n(16-RE)(RE=La,Pr,Nd,Sm,Eu,Gd,Tb,Dy,Ho and Y),[RE(L3)(1,10-phen)(H2O)]n(17-RE)(RE=La,Pr,Nd,Sm and Eu),and[RE(L3’)(1,10-phen)2(H2O)]n(18-RE)(RE=Gd,Tb,Ho,Er,Yb and Lu,H3L3’=2-hydroxy-3-nitro-4-carboxybenzenesulfonic acid).Compounds 13-RE and 14-RE present di-and mono-nuclear structures.Compound 12-La presents zigzag chain extende byμ2-bridging H2L3-anions.Compounds 15-RE and 16-RE exhibit layer structures incorporating helical chains,in which the L33-trianion presentsμ3 andμ4 coordination modes.Compounds 17-RE containing light RE metal cations shows layer structure incorporating helical chains,while compound 18-RE containing heavy RE metal cations has helical chain structures supported by the bridging of in situ generated L3’3-.Fluorescence test results show that compounds 14-RE(RE=Tm,Yb,Lu,Y)and 15-Lu exhibit ultraviolet emissions from354 to 370 nm.Compounds 12-La and 17-La present blue emissions at 442 and 463 nm.Compounds 13-Eu,13-Tb,16-Tb and 18-Tb exhibit characteristic red and green emissions.Compound 16-Y presents rare green emission at 501 nm.Meanwhile,compounds 13-Nd,14-Yb,15-Yb,16-Nd,17-Nd,and 18-Yb show near-infrared(NIR)emissions.Moreover,compounds 13-Eu,13-Tb,16-Tb,18-Tb and 16-Y show longer luminescence lifetimes from 390.47 to 1211.57μs.