萘咪唑类稀土配合物的晶体结构和荧光性质（英文）

通过2-(2′-羟基-3′-甲氧基)萘咪唑(HL)和Ln(NO)_3·6H_2O反应,合成了4种单核稀土配合物[Ln(HL)_2(NO_3)_3]·CH_2Cl_2(Ln=Sm(1),Eu(2),Tb(3))和[Ln(HL)_2(NO_3)_2(CH_3OH)]NO_3·CH_3OH(Ln=Yb(4))。X射线单晶衍射分析表明配合物1~4均通过配体萘环间的π-π作用呈现蝴蝶状结构。荧光性质表明仅有配合物4显示Yb3+稀土离子的特征发光,固态和在乙腈溶液中的荧光寿命分别为8.27μs和4.40μs。     

含2，2＇-联嘧啶桥Ir^III-Ln^III（Ln=Nd，Yb，Er）双金属配合物的合成和光物理性质

选择具有（N^N）（N^N）位点的四齿配体2,2’-联嘧啶fbpm）作为桥联配体,利用铱配合物Ir（dfppy）2（bpm）Cl作为配体与稀土配合物Ln（TTA）3·2H2O配位,得到了Ir^III-Ln^III（Ln=Nd,Yb,Er）双金属配合物[Ir（dfppy）2（bpm）Ln（TTA）3]Cl．通过荧光滴定的方法,测定了该铱配合物与稀土离子之间的络合稳定常数．通过对铱配合物及Ir^III-Ln^III（Ln=Nd,Yb,Er）双金属配合物在可见区光谱的测定,可以观察到明显的铱配合物发光的猝灭,说明从铱中心到稀土中心发生了能量传递．同时,利用可见光选择性激发铱配合物可以获得在稀土Nd^III,Yb^III,E^III离子红外区的发光．说明了铱配合物Ir（dfppy）2（bpm）Cl作为配体可以较好地敏化稀土离子的红外发光．     

吡啶—2，6—二甲酸类配体稀土配合物的荧光性能

以13种配体分别与10余种稀土离子形成二元配合物, 研究其水溶液荧光强度 , 结果发现, 只有Tb3+和Eu3+有较强荧光, Dy3+和Sm3+只有非常弱的荧光, 而其他稀土离子不发光.荧光强度顺序除配体DPA为Eu3+＞Tb3+ ＞Dy3+＞Sm3+外, 其余配体的荧光强度顺序为Tb3+＞Eu3+＞D y3+＞Sm3+. 以数种4-位取代吡啶-2,6-二甲酸衍生物为配体, 与Tb3 +形成二元配合物体系, 研究了pH、溶剂等因素对体系荧光强度的影响, 测定了pH近中性情况下配合物体系的激发与发射光谱, 发光寿命等; 研究了3或4-位不同取代基对体系发光性能的影响. 结果表明 (1) 当pH值近中性时体系的发光性能最好; (2) 不同取代基对体系的发光性能也有较大的影响, 取代基为供电子基团时, 体系的发光性能要优于取代基为吸电子基团的发光体系; (3) 溶剂效应的影响对体系的发光性能影响较大, 其中低极性溶剂对体系的发光性能要优于高极性溶剂. 其中4-异丙氧基吡啶-2,6-二甲酸、 4 -乙酰氨基吡啶-2,6-二甲酸和3-乙酰氨基吡啶-2,6-二甲酸为Tb3+的理想敏化剂.     

稀土2-[2-(4-苯甲酸甲酯)乙烯基]-8-羟基喹啉配合物的合成、表征及荧光性质

在甲醇体系中,用常规溶液法由自行设计合成的配体2-[2-(4-苯甲酸甲酯)乙烯基]-8-羟基喹啉(C_(19)H_(15)NO_3, HL)和稀土硝酸盐(Ln(NO_3)_3·nH_2O)反应合成了6个相应的配合物[Ln(NO_3)(L)_2](Ln=Nd,1; Sm,2; Eu,3; Gd,4; Tb,5; Dy,6);配体用红外光谱、核磁共振、单晶X射线衍射进行表征和结构测定;配合物用元素分析、红外光谱、摩尔电导、热重分析进行表征。室温下,测定了配体和配合物的荧光光谱及配合物的荧光寿命,结果表明:配体本身在575 nm处有较强的荧光发射,当形成配合物后,仍然表现为配体的发光而没有出现稀土中心离子的特征发光;与此同时,依中心离子的不同出现了不同程度的荧光增强或减弱现象,并伴随一定程度的红移或蓝移现象。     

三个喹啉氧基乙酰胺镧系(Eu、Gd、Er)配合物的合成、结构及Eu配合物的荧光性质（英文）

合成并通过单晶衍射表征了3个稀土配合物Ln(L)(NO3)3(H2O)(L=N-苯基-2-(5-氯-8-喹啉氧基)乙酰胺,Ln=Eu(1),Gd(2),Er(3)),结构与拥有相同有机配体的Pr,Nd和Sm配合物同构。在每个配合物中,十配位的稀土离子采取扭曲的双帽四方反棱柱配位构型,分别与来自1个配体L的2个氧原子和1个氮原子,3个双齿配位硝酸根和1个水分子配位。配合物1能够发射Eu(Ⅲ)离子特征荧光,荧光寿命为437μs。     

镱(Ⅲ)卟啉配合物的合成、结构表征和近红外光谱研究

合成了5个meso-位和β-位具有不同取代基的Yb(Ⅲ)卟啉配合物(2a~2e), 并对其结构进行了表征; 研究了配合物的可见光谱和近红外光谱性质, 测得了相关的量子产率和荧光寿命. 研究结果表明, 此类中性单核Yb(Ⅲ)卟啉配合物由于Yb³⁺的存在, 导致卟啉配体发生π→π*跃迁, 并将吸收的可见光能量传递给Yb³⁺的激发态, 使得配合物在近红外光区有很强的发光, 且meso-位为供电子基团的Yb(Ⅲ)卟啉配合物的发光效率比含吸电子基团的Yb(Ⅲ)卟啉配合物高, 而β-位溴化的Yb(Ⅲ)卟啉配合物的发光效率较差.     

烟酸稀土分子杂化发光材料的制备与性能研究

利用烯-巯加成的方法,合成了一种带有三联吡啶基团的有机硅氧烷,该中间体用核磁共振、红外、质谱等手段进行了表征确认.以该中间体作为第二配体,加入稀土(Eu3+、Tb3+)烟酸配合物,在正硅酸乙酯的存在下用溶胶-凝胶法原位制备了稀土(Eu3+、Tb3+)烟酸配合物与二氧化硅基质以共价键相连的烟酸稀土分子杂化发光材料.通过红外光谱、紫外-可见光漫反射光谱、荧光光谱和寿命测试表征了制备的杂化发光材料.荧光光谱数据表明在杂化材料中,由于三联吡啶配体通过有效的分子内传能过程将其激发态的能量传递给稀土离子的发射能级,从而极大地提高了稀土离子的特征发射.掺铕离子的最强发射为617nm,是纯红光发射;而掺铽离子的最强发射为543nm,是典型的绿光发射.掺铕和铽的分子杂化材的荧光寿命分别为0.66ms,0.68ms,同时荧光衰减均为一级指数衰减,说明稀土离子在杂化材料中分散得很均匀.     

喹啉氧基乙酰胺的Pr(Ⅲ)、Nd(Ⅲ)、Sm(Ⅲ)配合物的结构、表征和荧光性质

合成并通过单晶衍射表征了3个同构稀土配合物Ln(L)(NO3)3(H2O)(L=N-苯基-2-(5-氯-8-喹啉氧基)乙酰胺,Ln=Pr(Ⅲ),1;Nd(Ⅲ),2;Sm(Ⅲ),3)。在每个配合物中,十配位的稀土离子采取扭曲的双帽四方反棱柱配位构型,分别与来自1个配体L的2个氧原子和1个氮原子,2个双齿配位硝酸根和1个水分子配位。配合物3能够发射Sm(Ⅲ)离子特征荧光,荧光寿命为11.7μs。     

喹啉氧基乙酰胺的Pr(Ⅲ)、Nd(Ⅲ)、Sm(Ⅲ)配合物的结构、表征和荧光性质（英文）

合成并通过单晶衍射表征了3个同构稀土配合物Ln(L)(NO3)3(H2O)(L=N-苯基-2-(5-氯-8-喹啉氧基)乙酰胺,Ln=Pr(Ⅲ),1;Nd(Ⅲ),2;Sm(Ⅲ),3)。在每个配合物中,十配位的稀土离子采取扭曲的双帽四方反棱柱配位构型,分别与来自1个配体L的2个氧原子和1个氮原子,2个双齿配位硝酸根和1个水分子配位。配合物3能够发射Sm(Ⅲ)离子特征荧光,荧光寿命为11.7μs。     

三个镧系金属氮氧自由基配合物的合成、结构及磁性（英文）

以氮氧自由基为配体,合成了3例氮氧自由基-稀土三自旋单核配合物[Ln(hfac)3(NIT-Ph-4-Br)2](Ln=Gd(1),Tb(2),Dy(3),hfac=六氟乙酰丙酮,NIT-Ph-4-Br=4,4,5,5-四甲基-2-(4′-溴)-咪唑啉-3-氧化-1-氧基自由基。单晶结构分析表明3个配合物均属单斜晶系P21/c空间群,配合物中的Ln髥离子为八配位模式,并且拥有相似的自由基-稀土-自由基单核结构。对配合物的磁性测试结果表明,配合物1中自由基与Gd髥离子之间存在着铁磁相互作用,自由基与自由基之间存在着反铁磁相互作用;配合物2,3中,稀土离子与自由基之间存在弱的反铁磁相互作用     

Structural and photophysical properties of coordination networks combining [Ru(bipy)(CN)4]2- anions and lanthanide(III) cations: rates of photoinduced Ru-to-lanthanide energy transfer and sensitized near-infrared luminescence

Co-crystallization of K2[Ru(bipy)(CN)4] with lanthanide(III) salts (Ln = Pr, Nd, Gd, Er, Yb) from aqueous solution affords coordination oligomers and networks in which the [Ru(bipy)(CN)4]2- unit is connected to the lanthanide cation via Ru-CN-Ln bridges. The complexes fall into two structural types: [{Ru(bipy)(CN)4}2{Ln(H2O)m}{K(H2O)n}] x xH2O (Ln = Pr, Er, Yb; m = 7, 6, 6, respectively), in which two [Ru(bipy)(CN)4]2- units are connected to a single lanthanide ion by single cyanide bridges to give discrete trinuclear fragments, and [{Ru(bipy)(CN)4}3{Ln(H2O)4}2] x xH2O (Ln = Nd, Gd), which contain two-dimensional sheets of interconnected, cyanide-bridged Ru2Ln2 squares. In the Ru-Gd system, the [Ru(bipy)(CN)4]2- unit shows the characteristic intense (3)metal-to-ligand charge transfer luminescence at 580 nm with tau = 550 ns; with the other lanthanides, the intensity and lifetime of this luminescence are diminished because of a Ru --> Ln photoinduced energy transfer to low-lying emissive states of the lanthanide ions, resulting in sensitized near-infrared luminescence in every case. From the degree of quenching of the Ru-based emission, Ru --> Ln energy-transfer rates can be estimated, which are in the order Yb (k(EnT) approximately 3 x 10(6) sec(-1), the slowest energy transfer) < Er < Pr < Nd (k(EnT) approximately 2 x 10(8) sec(-1), the fastest energy transfer). This order may be rationalized on the basis of the availability of excited f-f levels on the lanthanide ions at energies that overlap with the Ru-based emission spectrum. In every case, the lifetime of the lanthanide-based luminescence is short (tens/hundreds of nanoseconds, instead of the more usual microseconds), even when the water ligands on the lanthanide ions are replaced by D2O to eliminate the quenching effects of OH oscillators; we tentatively ascribe this quenching effect to the cyanide ligands.     

Cyanide-bridged Os(II)/Ln(III) coordination networks containing [Os(phen)(CN)4]2- as an energy donor: structural and photophysical properties

Slow evaporation of aqueous solutions containing mixtures of Na 2[Os(phen)(CN) 4], Ln(III) salts (Ln = Pr, Nd, Gd, Er, Yb), and (in some cases) an additional ligand such as 1,10-phenanthroline (phen) or 2,2'-bipyrimidine (bpym) afforded crystalline coordination networks in which the [Os(phen)(CN) 4] (2-) anions are coordinated to Ln(III) cations via Os-CN-Ln cyanide bridges. The additional diimine ligands, if present, also coordinate to the Ln(III) centers. Several types of structure have been identified by X-ray crystallographic studies. Photophysical studies showed that the characteristic emission of the [Os(phen)(CN) 4] (2-) chromophore, which occurs at approximately 680 nm in this type of coordination environment with a triplet metal-to-ligand charge transfer ( (3)MLCT) energy content of approximately 16 000 cm (-1), is quenched by energy transfer to those Ln(III) centers (Pr, Nd, Er, Yb) that have low-lying f-f states capable of accepting energy from the Os(II)-based (3)MLCT state. Time-resolved studies on the residual (partially quenched) Os(II)-based luminescence allowed the rates of Os(II) --> Ln(III) energy transfer to be evaluated. The measured rates varied substantially, having values of >5 x 10 (8), approximately 1 x 10 (8), and 2.5 x 10 (7) s (-1) for Ln = Nd, Er or Yb, and Pr, respectively. These differing rates of Os(II) --> Ln(III) energy transfer can be rationalized on the basis of the availability of f-f states of the different Ln(III) centers that are capable of acting as energy acceptors. In general, the rates of Os(II) --> Ln(III) energy transfer are an order of magnitude faster than the rates of Ru(II) --> Ln(III) energy transfer in a previously described series of [Ru(bipy)(CN) 4] (2-)/Ln(III) networks. This is ascribed principally to the lower energy of the Os(II)-based (3)MLCT state, which provides better spectroscopic overlap with the low-lying f-f states of the Ln(III) ions.     

Enantiopure, supramolecular helices containing three-dimensional tetranuclear lanthanide(III) arrays: synthesis, structure, properties, and solvent-driven trinuclear/tetranuclear interconversion

The enantiomerically pure pinene-bipyridine-based receptor, (-) or (+) L(-), diastereoselectively self-assembles in dry acetonitrile in the presence of Ln(III) ions (Ln = La, Pr, Nd, Sm, Eu, Gd, and Tb) to give a C3-symmetrical, pyramidal architecture with the general formula [Ln4(L)9(mu3-OH)](ClO4)2) (abbreviated as tetra-Ln4L9). Three metal centers shape the base: an equilateral triangle surrounded by two sets of helically wrapping ligands with opposite configurations. This part of the structure is very similar to the species [Ln3(L)6(mu3-OH)(H2O)3](ClO4)2) (recently reported by us and abbreviated as tris-LnL2) formed by the ligand and the Ln(III) ions when the reactions are performed in methanol. The tetranuclear structure is completed by a capping, helical unit LnL3 whose chirality is also predetermined by the chirality of the ligand. A complete characterization of these isostructural, chiral compounds was performed in solid state (X-ray, IR) and in solution (ES-MS, NMR, CD, UV-vis and emission spectroscopies). The sign and the intensity of the CD bands in the region of the pi pi* transitions of the bipyridine (absolute Delta epsilon values at 327 nm are about 280 M(-1) x cm(-1)) are highly influenced by the helicity of the capping fragment LnL3. The photophysical properties (lifetime, quantum yield) of the visible (Eu and Tb complexes) and NIR (Nd complex) emitters indicate a good energy transfer between the ligands and the metal centers. The two related superstructures tetra-Ln4L9 and tris-LnL2 can be interconverted in acetonitrile, the switching process depending on the amount of water present in the solvent, the size of the Ln(III) ion, and the concentration. The weak chiral recognition capabilities of the self-assembly leading to the formation of tetra-Ln4L9 either by direct synthesis from a racemic mixture of the ligand and Ln(III) ions or by the conversion of a tris-Ln[(+/-)-L]2 racemate were likewise demonstrated.     

Syntheses, structures, and sensitized lanthanide luminescence by Pt --> Ln (Ln = Eu, Nd, Yb) energy transfer for heteronuclear PtLn2 and Pt2Ln4 complexes with a terpyridyl-functionalized alkynyl ligand

Reaction of Pt(dppm-P,P')Cl2 (dppm = 1,2-bis(diphenylphosphino)methane) with HCCPhtpy (HCCPhtpy = 4'-(4-ethynylphenyl)-2,2':6',2"-terpyridine) in the presence of copper(I) iodide and diisopropylamine induced isolation of mononuclear complex cis-Pt(dppm-P,P')(C[triple bond]CPhtpy)2 (1), which can be converted into face-to-face diplatinum(II) species Pt2(mu-dppm)2(C[triple bond]CPhtpy)4 (5) when equivalent dppm is added. Incorporating 1 or 5 to Ln(hfac)3(H2O)2 (Hhfac = hexafluoroacetylacetone) gave PtLn2 (Ln = Nd (2), Eu (3), Yb (4)) or Pt2Ln4 (Ln = Nd (6), Eu (7), Gd (8), Yb (9)) adducts with the lanthanide centers chelated by terdentate terpyridyl in the bridging C[triple bond]CPhtpy. The structures of 1, 6, 7, and 9 were determined by X-ray crystallography. Upon excitation at lambdaex = 360-450 nm (2-4) or 360-500 nm (6-9), where the PtII alkynyl antenna chromophores absorb strongly but the model complexes Ln(hfac)3(HC[triple bond]CPhtpy) lack obvious absorption in this region, these PtLn2 and Pt2Ln4 (Ln = Nd, Eu, Yb) species exhibit band-like lanthanide luminescence that is typical of the corresponding Ln3+ ions, demonstrating unambiguously that efficient Pt --> Ln energy transfer occurs indeed from the PtII alkynyl antenna chromophores to the lanthanide centers across the bridging CCPhtpy with intramolecular Pt...Ln distances being ca. 14.2 A. The Pt --> Ln energy transfer rate (kET) is 6.07 x 10(7) s(-1) for Pt2Nd4 (6) and 2.12 x 10(5) s(-1) for Pt2Yb4 (9) species.     

Syntheses and crystal structures of dinuclear complexes containing d-block and f-block luminophores. Sensitization of NIR luminescence from Yb(III), Nd(III), and Er(III) centers by energy transfer from Re(I)- and Pt(II)-bipyrimidine metal centers

Mononuclear complexes [Re(bpym)(CO)(3)Cl] and [Pt(bpym)(CC-C(6)H(4)CF(3))(2)] (bpym = 2,2'-bipyrimidine), in which one of the bipyrimidine sites is vacant, have been used as "complex ligands" to prepare heterodinuclear d-f complexes in which a lanthanide tris(1,3-diketonate) unit is attached to the secondary bipyrimidine site to evaluate the ability of d-block chromophores to act as antennae for causing sensitized near-infrared (NIR) luminescence from adjacent lanthanide(III) centers. The two sets of complexes so prepared are [Re(CO)(3)Cl(mu-bpym)Ln(fod)(3)] (abbreviated as Re-Ln; where Ln = Yb, Nd, Er) and [(F(3)C-C(6)H(4)-CC)(2)Pt(mu-bpym)Ln(hfac)(3)] (abbreviated as Pt-Ln; where Ln = Nd, Gd). Members of both series have been structurally characterized; the metal-metal separation across the bipyrimidine bridge is approximately 6.3 A in each case. In these complexes, the (3)MLCT (MLCT = metal to ligand charge-transfer) luminescences of the mononuclear [Re(bpym)(CO)(3)Cl] and [Pt(bpym)(CC-C(6)H(4)CF(3))(2)] complexes are quenched by energy transfer to those lanthanides (Ln = Yb, Nd, Er) that have low-lying f-f states capable of NIR luminescence; as a result, sensitized NIR luminescence is seen from the lanthanide center following excitation of the d-block unit. In the solid state, quenching of the luminescence from the d-block chromophore is complete, indicating efficient d --> f energy transfer, as a result of the short metal-metal separation across the bipyrimidine bridge. In a CH(2)Cl(2) solution, partial dissociation of the dinuclear complexes into the mononuclear units occurs, with the result that some (3)MLCT luminescence is observed from mononuclear [Re(bpym)(CO)(3)Cl] or [Pt(bpym)(CC-C(6)H(4)CF(3))(2)] present in the equilibrium mixture. Solution UV-vis and luminescence titrations, carried out by the addition of portions of Ln(fod)(3)(H(2)O)(2) or Ln(hfac)(3)(H(2)O)(2) to the d-block complex ligands, indicate that binding of the lanthanide tris(1,3-diketonate) unit at the secondary bipyrimidine site to give the d-f dinuclear complexes occurs with an association constant of ca. 10(5) M(-)(1).     

Luminescence properties and quenching mechanisms of Ln(Tf2N)3 complexes in the ionic liquid bmpyr Tf2N

The emission properties, including luminescence lifetimes, of the lanthanide complexes Ln(Tf(2)N)(3) (Tf(2)N = bis(trifluoromethanesulfonyl)amide); Ln(3+) = Eu(3+), Tm(3+), Dy(3+), Sm(3+), Pr(3+), Nd(3+), Er(3+)) in the ionic liquid bmpyr Tf(2)N (bmpyr = 1-n-butyl-1-methylpyrrolidinium) are presented. The luminescence quantum efficiencies, η, and radiative lifetimes, τ(R), are determined for Eu(3+)((5)D(0)), Tm(3+)((1)D(2)), Dy(3+)((4)F(9/2)), Sm(3+)((4)G(5/2)), and Pr(3+)((3)P(0)) emission. The luminescence lifetimes in these systems are remarkably long compared to values typically reported for Ln(3+) complexes in solution, reflecting weak vibrational quenching. The 1.5 μm emission corresponding to the Er(3+) ((4)I(13/2)→(4)I(15/2)) transition, for example, exhibits a lifetime of 77 μs. The multiphonon relaxation rate constants are determined for 10 different Ln(3+) emitting states, and the trend in multiphonon relaxation is analyzed in terms of the energy gap law. The energy gap law does describe the general trend in multiphonon relaxation, but deviations from the trend are much larger than those normally observed for crystal systems. The parameters determined from the energy gap law analysis are consistent with those reported for crystalline hosts. Because Ln(3+) emission is known to be particularly sensitive to quenching by water in bmpyr Tf(2)N, the binding properties of water to Eu(3+) in solutions of Eu(Tf(2)N)(3) in bmpyr Tf(2)N have been quantified. It is observed that water introduced into these systems binds quantitatively to Ln(3+). It is demonstrated that Eu(Tf(2)N)(3) can be used as a reasonable internal standard, both for monitoring the dryness of the solutions and for estimating the quantum efficiencies and radiative lifetimes for visible-emitting [Ln(Tf(2)N)(x)](3-x) complexes in bmpyr Tf(2)N.     

Syntheses, structures, and luminescent and magnetic properties of novel three-dimensional lanthanide complexes with 1,3,5-benzenetriacetate

Five novel lanthanide complexes with the formulas [Nd(bta)(H2O)2.4.35H2O]n(1), [Sm(bta)(H2O)2.4.5H2O]n (2), [Eu(bta)(H2O).1.48H2O]n (3), [Tb(bta)(H2O).1.31H2O]n (4), and [Yb(bta)(H2O).H2O]n (5) (H3bta = 1,3,5-benzenetriacetic acid) have been prepared by using the corresponding lanthanide salt and H3bta. The results of an X-ray crystallographic analysis revealed that all the complexes have three-dimensional channel-like structures, in which the bta3- ligands adopt different coordination modes: monodentate and mu2-eta2:eta1-bridging coordination modes in 1, 2, and 5 and mu2-eta1:eta1-bridging and mu2-eta2:eta1-bridging coordination modes in 3 and 4, respectively. Complexes 1 and 2, as well as 3 and 4, are isostructural, respectively, in which all the Ln(III) (Ln = Nd, Sm, Eu, and Tb) atoms are nine-coordinated, while the Yb(III) atoms in complex 5 are eight-coordinated. Both complexes 3 and 4 showed strong luminescence upon excitation, and their luminescence decay curves fit well with single exponential decays of which the lifetime is 0.45 ms for 3 and 1.0 ms for 4. The magnetic properties of the complexes were investigated in the temperature range of 1.8-300 K.     

Fully fluorinated imidodiphosphinate shells for visible- and NIR-emitting lanthanides: hitherto unexpected effects of sensitizer fluorination on lanthanide emission properties

In this paper we demonstrate that the effect of aromatic C--F substitution in ligands does not always abide by conventional wisdom for ligand design to enhance sensitisation for visible lanthanide emission, in contrast with NIR emission for which the same effect coupled with shell formation leads to unprecedented long luminescence lifetimes. We have chosen an imidodiphosphinate ligand, N-{P,P-di(pentafluorophinoyl)}-P,P-dipentafluorophenylphosphinimidic acid (HF20tpip), to form ideal fluorinated shells about all visible- and NIR-emitting lanthanides. The shell, formed by three ligands, comprises twelve fully fluorinated aryl sensitiser groups, yet no-high energy X--H vibrations that quench lanthanide emission. The synthesis, full characterisation including X-ray and NMR analysis as well as the photophysical properties of the emissive complexes [Ln(F20tpip)3], in which Ln=Nd, Sm, Eu, Gd, Tb, Dy, Er, Yb, Y, Gd, are reported. The photophysical results contrast previous studies, in which fluorination of alkyl chains tends to lead to more emissive lanthanide complexes for both visible and NIR emission. Analysis of the fluorescence properties of the HF20tpip and [Gd(F20tpip)3] reveals that there is a low-lying state at around 715 nm that is responsible for partially quenching of the signal of the visible emitting lanthanides and we attribute it to a pi-sigma* state. However, all visible emitting lanthanides have long lifetimes and unexpectedly the [Dy(F20tpip)3] complex shows a lifetime of 0.3 ms, indicating that the elimination of high-energy vibrations from the ligand framework is particularly favourable for Dy. The NIR emitting lanthanides show strong emission signals in powder and solution with unprecedented lifetimes. The luminescence lifetimes of [Nd(F20tpip)3], [Er(F20tpip)3] and [Yb(F20tpip)3] in deuteurated acetonitrile are 44, 741 and 1111 micros. The highest value observed for the [Yb(F20tpip)3] complex is more than half the value of the Yb ion radiative lifetime.     

Photoluminescent microporous lanthanide silicate AV-21 frameworks

The hydrothermal synthesis and structural characterization of the lanthanide silicate system [Na(6)Ln(2)Si(12)O(30).x H(2)O] (Ln=La(3+), Sm(3+), Eu(3+), Gd(3+), and Tb(3+)), named AV-21, has been reported. Structural elucidation of the Sm(3+) analogue (isomorphous with the Eu(3+), Gd(3+), and Tb(3+) frameworks) using single-crystal synchrotron X-ray diffraction and solid-state NMR spectroscopy reveal disorder in the Si(1) second coordination sphere. La-AV-21 presents a distinct framework. These materials combine microporosity and interesting photoluminescence features with structural flexibility that allows the introduction of a second or third type of lanthanide center. Room-temperature lifetime decay dynamics have been used to estimate the Ln(3+)-Ln(3+) distances and the maximum distance over which energy transfer is active. Though the majority of Ln(3+) centers occupy regular framework positions, the Ln(2) defect centers are disordered over the Na(1) sites in the pores and greatly influence the energy-transfer process, providing a unique opportunity for studying the relationship between structural disorder and photoluminescence properties in framework solids.     

Synthesis, crystal structure, and luminescent properties of 2-(2,2,2-trifluoroethyl)-1-indone lanthanide complexes

A new β-diketone, 2-(2,2,2-trifluoroethyl)-1-indone (TFI), which contains a trifluorinated alkyl group and a rigid indone group, has been designed and employed for the synthesis of two series of new TFI lanthanide complexes with a general formula [Ln(TFI)(3)L] [Ln = Eu, L = (H(2)O)(2) (1), bpy (2), and phen (3); Ln = Sm, L = (H(2)O)(2) (4), bpy (5), and phen (6); bpy = 2,2'-bipyridine, phen = 1,10-phenanthroline]. X-ray crystallographic analysis reveals that complexes 1-6 are mononuclear, with the central Ln(3+) ion eight-coordinated by six oxygen atoms furnished by three TFI ligands and two O/N atoms from ancillary ligand(s). The room-temperature photoluminescence (PL) spectra of complexes 1-6 show strong characteristic emissions of the corresponding Eu(3+) and Sm(3+) ions, and the substitution of the solvent molecules by bidentate nitrogen ligands essentially enhances the luminescence quantum yields and lifetimes of the complexes.