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1.
Philipp R. Matthes Jörn Nitsch Ana Kuzmanoski Prof. Claus Feldmann Dr. Andreas Steffen Prof. Todd B. Marder Prof. Klaus Müller‐Buschbaum 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(51):17369-17378
A series of 12 dinuclear complexes [Ln2Cl6(μ‐4,4′‐bipy)(py)6], Ln=Y, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, ( 1 – 12 , respectively) was synthesized by an anhydrous solvothermal reaction in pyridine. The complexes contain a 4,4′‐bipyridine bridge and exhibit a coordination sphere closely related to luminescent lanthanide MOFs based on LnCl3 and 4,4‐bipyridine. The dinuclear complexes therefore function as a molecular model system to provide a better understanding of the luminescence mechanisms in the Ln‐N‐MOFs ${\hbox{}{{\hfill 2\atop \hfill \infty }}}$ [Ln2Cl6(4,4′‐bipy)3] ? 2(4,4′‐bipy). Accordingly, the luminescence properties of the complexes with Ln=Y, Sm, Eu, Gd, Tb, Dy, ( 1 , 4 – 8 ) were determined, showing an antenna effect through a ligand–metal energy transfer. The highest efficiency of luminescence is observed for the terbium‐based compound 7 displaying a high quantum yield (QY of 86 %). Excitation with UV light reveals typical emission colors of lanthanide‐dependent intra 4f–4f‐transition emissions in the visible range (TbIII: green, EuIII: red, SmIII: salmon red, DyIII: yellow). For the GdIII‐ and YIII‐containing compounds 6 and 1 , blue emission based on triplet phosphorescence is observed. Furthermore, ligand‐to‐metal charge‐transfer (LMCT) states, based on the interaction of Cl? with EuIII, were observed for the EuIII compound 5 including energy‐transfer processes to the EuIII ion. Altogether, the model complexes give further insights into the luminescence of the related MOFs, for example, rationalization of Ln‐independent quantum yields in the related MOFs. 相似文献
2.
Unprecedented Sensitization of Visible and Near‐Infrared Lanthanide Luminescence by Using a Tetrathiafulvalene‐Based Chromophore
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Min Feng Dr. Fabrice Pointillart Dr. Boris Le Guennic Bertrand Lefeuvre Dr. Stéphane Golhen Dr. Olivier Cador Dr. Olivier Maury Dr. Lahcène Ouahab 《化学:亚洲杂志》2014,9(10):2814-2825
Ligand L was synthesized and then coordinated to [Ln(hfac)3] ? 2 H2O (LnIII=Tb, Dy, Er; hfac?=1,1,1,5,5,5‐hexafluoroacetylacetonate anion) and [Ln(tta)3]?2 H2O (LnIII=Eu, Gd, Tb, Dy, Er, Yb; tta?=2‐thenoyltrifluoroacetonate) to give two families of dinuclear complexes [Ln2(hfac)6( L )] ? C6H14 and [Ln2(tta)6( L )] ? 2 CH2Cl2. Irradiation of the ligand at 37 040 cm?1 and 29 410 cm?1 leads to tetrathiafulvalene‐centered and 2,6‐di(pyrazol‐1‐yl)‐4‐pyridine‐centered fluorescence, respectively. The ligand acts as an organic chromophore for the sensitization of the infrared ErIII (6535 cm?1) and YbIII (10 200 cm?1) luminescence. The energies of the singlet and triplet states of L are high enough to guarantee an efficient sensitization of the visible EuIII luminescence (17 300–14 100 cm?1). The EuIII luminescence decay can be nicely fitted by a monoexponential function that allows a lifetime estimation of (0.49±0.01) ms. Finally, the magnetic and luminescence properties of [Yb2(hfac)6( L )] ? C6H14 were correlated, which allowed the determination of the crystal field splitting of the 2F7/2 multiplet state with MJ=±1/2 as ground states. 相似文献
3.
Ju‐Wen Zhang Yi Man Yu‐Ning Ren Wen‐Hua Liu Bin‐Qiu Liu Yan‐Ping Dong 《无机化学与普通化学杂志》2019,645(6-7):580-587
The syntheses and crystal structures of eight lanthanide complexes with formula [Ln(2,5‐DCB)x(phen)y] are reported, which are characterized via single‐crystal, powder X‐ray diffraction, elemental analysis, IR spectroscopy, thermogravimetric analysis, photoluminescence measurement, and DC/AC magnetic measurement. These eight complexes are isostructural, and possess a discrete dinuclear structure. The adjacent dinuclear molecules are linked by the hydrogen bonding interactions into a one‐dimensional (1D) supramolecular chain. The neighboring 1D chains are further extended into a two‐dimensional (2D) supramolecular layer by the π–π stacking interactions. The photoluminescent properties of complexes 1 (NdIII), 2 (SmIII), 3 (EuIII), 5 (TbIII), 6 (DyIII), and 8 (YbIII) were investigated. Magnetic investigations also reveal the presence of ferromagnetic interactions in complexes 4 (GdIII), 6 (DyIII), and 7 (ErIII). Additionally, complex 6 (DyIII) demonstrates field‐induced slow magnetic relaxation behavior. 相似文献
4.
Hagen Kaemmerer Dr. Valeriu Mereacre Dr. Ayuk M. Ako Dr. Samir Mameri Dr. Christopher E. Anson Dr. Rodolphe Clérac Prof. Annie K. Powell 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(61):15096-15102
In an assisted self-assembly approach starting from the [Mn6O2(piv)10(4-Me-py)2(pivH)2] cluster a family of Mn−Ln compounds (Ln=Pr−Yb) was synthesised. The reaction of [Mn6O2(piv)10(4-Me-py)2(pivH)2] ( 1 ) with N-methyldiethanolamine (mdeaH2) and Ln(NO3)3 ⋅ 6H2O in MeCN generally yields two main structure types: for Ln=Tb−Yb a previously reported Mn5Ln4 motif is obtained, whereas for Ln=Pr−Eu a series of Mn7Ln3 clusters is obtained. Within this series the GdIII analogue represents a special case because it shows both structural types as well as a third Mn2Ln2 inverse butterfly motif. Variation in reaction conditions allows access to different structure types across the whole series. This prompts further studies into the reaction mechanism of this cluster assisted self-assembly approach. For the Mn7Ln3 analogues reported here variable-temperature magnetic susceptibility measurements suggest that antiferromagnetic interactions between the spin carriers are dominant. Compounds incorporating Ln=NdIII( 2 ), SmIII( 3 ) and GdIII ( 5 ) display SMM behaviour. The slow relaxation of the magnetisation for these compounds was confirmed by ac measurements above 1.8 K. 相似文献
5.
Three new homodinuclear lanthanide(III) complexes [Ln2(L)6(2,2′‐bipy)2] [Ln = TbIII ( 1 ), SmIII ( 2 ), EuIII ( 3 ); HL = 3‐hydroxycinnamic acid (3‐HCA); 2,2′‐bipy = 2,2′‐bipyridine] were synthesized and characterized by IR spectroscopy, elemental analyses, and X‐ray diffraction techniques. Complexes 1 – 3 crystallize in triclinic system, space group P$\bar{1}$ . In all complexes the lanthanide ions are nine‐coordinate by two nitrogen atoms from the 2,2′‐bipy ligand and seven oxygen atoms from one chelating L ligands and four bridging L ligands, forming distorted tricapped trigonal prismatic arrangements. The lanthanide(III) ions are intramolecularly bridged by eight carboxylate oxygen atoms forming dimeric complexes with Ln ··· Ln distances of 3.92747(15), 3.9664(6), and 3.9415(4) Å for complexes 1 – 3 , respectively. The luminescent properties in the solid state of HL ligand and EuIII complex are also discussed. 相似文献
6.
《Journal of Coordination Chemistry》2012,65(20):3519-3529
A mesogenic Schiff-base, N,N′-di-(4-decyloxysalicylidene)-1′,3′-diaminobenzene, H2ddsdbz (abbreviated as H2L), that exhibits a nematic mesophase was synthesized and its structure was studied by elemental analysis, mass spectrometry, NMR, and IR spectral techniques. The Schiff-base, H2L, upon condensation with hydrated lanthanide(III) nitrates yields LnIII complexes, [Ln2(LH2)3(NO3)4](NO3)2, where Ln?=?La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, and Ho. Analyses of the IR and NMR spectral data imply bidentate Schiff-base through two phenolate oxygen atoms in its zwitterionic form to LnIII, rendering the overall geometry of the complexes as a seven-coordinate polyhedron – possibly distorted mono-capped octahedron. Polarizing optical microscope and differential scanning calorimetry studies reveal that despite H2L being mesogenic, none of the LnIII complexes synthesized under this study exhibits mesomorphism. 相似文献
7.
Molecular Design Guidelines for Large Magnetic Circular Dichroism Intensities in Lanthanide Complexes
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Dr. Yuichi Kitagawa Satoshi Wada Kei Yanagisawa Dr. Takayuki Nakanishi Dr. Koji Fushimi Dr. Yasuchika Hasegawa 《Chemphyschem》2016,17(6):845-849
Magneto optical devices based on the Faraday effects of lanthanide ion have attracted much attention. Recently, large Faraday effects were found in nano‐sized multinuclear lanthanide complexes. In this study, the Faraday rotation intensities were estimated for lanthanide nitrates [LnIII(NO3)3?n H2O: Ln=Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm) and EuIII complexes with β‐diketone ligands, using magnetic circular dichroism. Eu ions exhibit the largest Faraday rotation intensity for 7F0→5D1 transitions, and high‐symmetry fields around the Eu ions induce larger Faraday effects. The molecular design for the enhancement of Faraday effects in lanthanide complexes is discussed. 相似文献
8.
Katherine R. Johnson Sebastian B. Vittardi Dr. Manuel A. Gracia-Nava Dr. Jeffrey J. Rack Dr. Ana de Bettencourt-Dias 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(32):7274-7280
Lanthanide ion (LnIII) complexes, [Ln(3Tcbx)2]3+ (LnIII=YbIII, NdIII, ErIII) are isolated with a new pyridine-bis(carboxamide)-based ligand with a 2,2′:5′,2′′-terthiophene pendant (3TCbx), and their resulting photophysical properties are explored. Upon excitation of the complexes at 490 nm, only LnIII emission is observed with efficiencies of 0.29 % at 976 nm for LnIII=YbIII and 0.16 % at 1053 nm for LnIII=NdIII. ErIII emission is observed but weak. Upon excitation at 400 nm, concurrent 1O2 formation is seen, with efficiencies of 11 % for the YbIII and NdIII complexes and 13 % for the ErIII complex. Owing to the concurrent generation of 1O2, as expected, the efficiency of metal-centered emission decreases to 0.02 % for YbIII and 0.05 % for NdIII. The ability to control 1O2 generation through the excitation wavelength indicates that the incorporation of 2,2′:5′,2′′-terthiophene results in access to multiple sensitization pathways. These energy pathways are unraveled through transient absorption spectroscopy. 相似文献
9.
Jakub J. Zakrzewski Dr. Szymon Chorazy Dr. Koji Nakabayashi Prof. Dr. Shin-ichi Ohkoshi Prof. Dr. Barbara Sieklucka 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(51):11820-11825
Three-dimensional bimetallic cyanido-bridged frameworks, [LnIII(2,2′-bipyridine N,N′-dioxide)2(H2O)][CuI2(CN)5]⋅5 H2O (Ln=Dy, 1 ; Yb, 2 ), are reported. They exhibit the effect of slow relaxation of magnetization, leading to a magnetic hysteresis loop, and sensitized visible-to-near-infrared photoluminescence. Both physical properties are related to the eight-coordinated lanthanide(III) complexes embedded in the unprecedented coordination skeleton composed of symmetry-breaking polycyanidocuprate linkers. The three-dimensional d–f cyanido-bridged network was shown to serve as an efficient coordination scaffold to achieve emissive lanthanide single-molecule magnets. 相似文献
10.
Bipyrimidines have been chosen as (N∧N)(N∧N) bridging ligands for connecting metal centers. IrIII-LnIII (Ln = Nd, Yb, Er) bimetallic complexes [Ir(dfppy)2(μ-bpm)Ln(TTA)3]Cl were synthesized by using Ir(dfppy)2(bpm)Cl as the ligand coordinating to lanthanide complexes Ln(TTA)3·2H2O. The stability constants between Ir(dfppy)2(bpm)Cl and lanthanide ions were measured by fluorescence titration. The obvious quenching of visible emission from IrIII complex in the IrIII-LnIII (Ln = Nd, Yb, Er) bimetallic complexes indicates that energy transfer occurred from IrIII center to lanthanides. NIR emissions from NdIII, YbIII, and ErIII were obtained under the excitation of visible light by selective excitation of the IrIII-based chromophore. It was proven that Ir(dfppy)2(bpm)Cl as the ligand could effectively sensitize NIR emission from NdIII, YbIII, and ErIII. 相似文献
11.
Dr. Lu Xi Chaoyi Jin Hongwei Song Xiaotong Wang Junfang Xie Prof. Yue Ma Prof. Jinkui Tang Prof. Licun Li 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(65):e202202239
In spite of achievement of a lot of Ln-radical SMMs, how to improve magnetic behavior of Ln-radical system remains challenging. Here, two series of Ln-radical complexes have successfully been built using an imino nitroxide biradical, namely, [Ln2(hfac)6(ImPhPyobis)2] (LnIII=Gd 1 , Tb 2 , Dy 3 ) and [Ln2Cu2(hfac)10(ImPhPyobis)2] (LnIII=Gd 4 , Dy 5 ; hfac=hexafluoroacetylacetonate and ImPhPyobis=5-(4-oxypyridinium-1-yl)-1,3-bis(1’-oxyl-4’,4’,5’,5’-tetramethyl-4,5-hydro-1H-imidazol-2-yl)benzene). For these biradical-metal complexes, two imino nitroxide biradicals bind two Ln(III) ions via their oxygen atoms coming from 4-oxypyridinium units to produce a binuclear {Ln2O2} unit. Those imino nitroxide groups are free for complexes 1 – 3 , however one of imino nitroxide groups of the biradical is ligated to the copper(II) ion for complexes 4 and 5 . The distinct magnetic relaxation behaviors are observed for two Dy derivatives, as revealed by ac magnetic studies: complex 3 presents one magnetic process with the effective energy barrier(Ueff) of 74.0 K while complex 5 exhibits dual relaxation processes with Ueff values for the fast- and slow-relaxation being 20.2 K and 30.9 K, respectively, which implies that the second coordination sphere of Dy ion plays a critical role for magnetic relaxation. 相似文献
12.
Heterotrimetallic Coordination Polymers: {CuIILnIIIFeIII} Chains and {NiIILnIIIFeIII} Layers: Synthesis,Crystal Structures,and Magnetic Properties
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Dr. Maria‐Gabriela Alexandru Dr. Diana Visinescu Prof. Marius Andruh Dr. Nadia Marino Dr. Donatella Armentano Dr. Joan Cano Prof. Francesc Lloret Prof. Miguel Julve 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(14):5429-5446
The use of the [FeIII(AA)(CN)4]? complex anion as metalloligand towards the preformed [CuII(valpn)LnIII]3+ or [NiII(valpn)LnIII]3+ heterometallic complex cations (AA=2,2′‐bipyridine (bipy) and 1,10‐phenathroline (phen); H2valpn=1,3‐propanediyl‐bis(2‐iminomethylene‐6‐methoxyphenol)) allowed the preparation of two families of heterotrimetallic complexes: three isostructural 1D coordination polymers of general formula {[CuII(valpn)LnIII(H2O)3(μ‐NC)2FeIII(phen)(CN)2 {(μ‐NC)FeIII(phen)(CN)3}]NO3 ? 7 H2O}n (Ln=Gd ( 1 ), Tb ( 2 ), and Dy ( 3 )) and the trinuclear complex [CuII(valpn)LaIII(OH2)3(O2NO)(μ‐NC)FeIII(phen)(CN)3] ? NO3 ? H2O ? CH3CN ( 4 ) were obtained with the [CuII(valpn)LnIII]3+ assembling unit, whereas three isostructural heterotrimetallic 2D networks, {[NiII(valpn)LnIII(ONO2)2(H2O)(μ‐NC)3FeIII(bipy)(CN)] ? 2 H2O ? 2 CH3CN}n (Ln=Gd ( 5 ), Tb ( 6 ), and Dy ( 7 )) resulted with the related [NiII(valpn)LnIII]3+ precursor. The crystal structure of compound 4 consists of discrete heterotrimetallic complex cations, [CuII(valpn)LaIII(OH2)3(O2NO)(μ‐NC)FeIII(phen)(CN)3]+, nitrate counterions, and non‐coordinate water and acetonitrile molecules. The heteroleptic {FeIII(bipy)(CN)4} moiety in 5 – 7 acts as a tris‐monodentate ligand towards three {NiII(valpn)LnIII} binuclear nodes leading to heterotrimetallic 2D networks. The ferromagnetic interaction through the diphenoxo bridge in the CuII?LnIII ( 1 – 3 ) and NiII?LnIII ( 5 – 7 ) units, as well as through the single cyanide bridge between the FeIII and either NiII ( 5 – 7 ) or CuII ( 4 ) account for the overall ferromagnetic behavior observed in 1 – 7 . DFT‐type calculations were performed to substantiate the magnetic interactions in 1 , 4 , and 5 . Interestingly, compound 6 exhibits slow relaxation of the magnetization with maxima of the out‐of‐phase ac signals below 4.0 K in the lack of a dc field, the values of the pre‐exponential factor (τo) and energy barrier (Ea) through the Arrhenius equation being 2.0×10?12 s and 29.1 cm?1, respectively. In the case of 7 , the ferromagnetic interactions through the double phenoxo (NiII–DyIII) and single cyanide (FeIII–NiII) pathways are masked by the depopulation of the Stark levels of the DyIII ion, this feature most likely accounting for the continuous decrease of χM T upon cooling observed for this last compound. 相似文献
13.
Rui Jia Ting Gao Yu Yang Wenbin Sun Ruoxi Chen Pengfei Yan Guangfeng Hou 《无机化学与普通化学杂志》2015,641(11):1974
The luminescence properties of the tetranuclear bimetallic lanthanide complexes Sm2Eu2 ( 1 ) and Eu2Tb2 ( 2 ), were compared with those of the analogous homometallic complexes [Sm4(μ3‐OH)2(salen)2(acac)6(CH3OH)2] · CH3OH ( 3 ) and [Eu4(μ3‐OH)2(salen)2(acac)6(CH3OH)2] ( 4 ) [H2salen = N, N′‐ethylenebis(salicylideneimine), Hacac = acetylacetonate]. X‐ray crystallographic analysis reveals that complexes 3 and 4 have planar tetranuclear structures. For the Eu2Tb2 configurational isomer, the TbIII ion in complex 2 mainly serves as a sensitizer. The quantum yields and lifetime measurements for 2 support the premise that Ln/Ln energy transfer occurs in such lanthanide bimetallic complexes, along with the usual ligand‐to‐metal triplet energy pathways. Complexes 3 and 4 exhibit the characteristic metal‐centered emission. 相似文献
14.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(34):10237-10241
Assembly of the triangular, organic radical‐bridged complexes Cp*6Ln3(μ3‐HAN) (Cp*=pentamethylcyclopentadienyl; Ln=Gd, Tb, Dy; HAN=hexaazatrinaphthylene) proceeds through the reaction of Cp*2Ln(BPh4) with HAN under strongly reducing conditions. Significantly, magnetic susceptibility measurements of these complexes support effective magnetic coupling of all three LnIII centers through the HAN3−. radical ligand. Thorough investigation of the DyIII congener through both ac susceptibility and dc magnetic relaxation measurements reveals slow relaxation of the magnetization, with an effective thermal relaxation barrier of Ueff=51 cm−1. Magnetic coupling in the DyIII complex enables a large remnant magnetization at temperatures up to 3.0 K in the magnetic hysteresis measurements and hysteresis loops that are open at zero‐field up to 3.5 K. 相似文献
15.
Xiaoling Wang Panpan Xu Xia Bao Fengwu Wang Yonghong Chen Yijun Wei 《无机化学与普通化学杂志》2013,639(1):176-180
Abstract. Two radical–LnIII–radical complexes, [Ln(hfac)3(NITPh‐Ph)2] [Ln = Gd ( 1 ) and Ho ( 2 ), hfac = hexafluoroacetylacetonate; and NITPh‐Ph = 4′‐biphenyl‐4, 4, 5, 5‐tetramethylimidazoline‐1‐oxyl‐3‐oxide] were synthesized and characterized by X‐ray diffraction, elemental analysis, magnetic measurements, as well as IR and UV/Vis spectroscopy. X‐ray crystal structure analysis revealed that the structures of both complexes are isomorphous, the central LnIII ions are coordinated by six oxygen atoms from three hfac ligand molecules and two oxygen atoms from nitronyl radicals. The temperature dependencies of the magnetic susceptibilities were studied. They showed that in the GdIII complex, ferromagnetic interactions between GdIII and the radicals and antiferromagnetic interactions between the radicals coexist in this system (with JRad–Gd = 0.1 cm–1, JRad–Rad = –0.309 cm–1). 相似文献
16.
Daniel N. Huh Sierra R. Ciccone Samuel Bekoe Saswata Roy Joseph W. Ziller Prof. Filipp Furche Prof. William J. Evans 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(37):16275-16280
Lanthanide triflates have been used to incorporate NdIII and SmIII ions into the 2.2.2-cryptand ligand (crypt) to explore their reductive chemistry. The Ln(OTf)3 complexes (Ln=Nd, Sm; OTf=SO3CF3) react with crypt in THF to form the THF-soluble complexes [LnIII(crypt)(OTf)2][OTf] with two triflates bound to the metal encapsulated in the crypt. Reduction of these LnIII-in-crypt complexes using KC8 in THF forms the neutral LnII-in-crypt triflate complexes [LnII(crypt)(OTf)2]. DFT calculations on [NdII(crypt)]2+], the first NdII cryptand complex, assign a 4f4 electron configuration to this ion. 相似文献
17.
The Building Block [FeIII(pzphen)(CN)4]– and its Lanthanide Complexes: Synthesis,Crystal Structure,and Magnetic Properties
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Jian‐Qing Tao Wen‐Wen Ju Zhou Zhou Li‐Yong Jia Ning‐Ning Chen Yun‐Shan Xue Jun Wang Xing‐Cai Huang 《无机化学与普通化学杂志》2016,642(24):1466-1471
The cyanide building block [FeIII(pzphen)(CN)4]– and its four lanthanide complexes [{FeIII(pzphen)(CN)4}2LnIII(H2O)5(DMF)3] · (NO3) · 2(H2O) · (CH3CN) [Ln = Nd ( 1 ), Sm ( 2 ), DMF = dimethyl formamide] and [{FeIII(pzphen)(CN)4}2LnIII(NO3)(H2O)2(DMF)2](CH3CN) [Ln = Gd ( 3 ), Dy ( 4 )] were synthesized and structurally characterized by single‐crystal X‐ray diffraction. Compounds 1 and 2 are ionic salts with two [FeIII(pzphen)(CN)4]– cations and one LnIII ion, but compounds 3 and 4 are cyano‐bridged FeIII‐LnIII heterometallic 3d‐4f complexes exhibiting a trinuclear structure in the same conditions. Magnetic studies show that compound 3 is antiferromagnetic between the central FeIII and GdIII atoms. Furthermore, the trinuclear cyano‐bridged FeIII2DyIII compound 4 displays no single‐molecular magnets (SMMs) behavior by the alternating current magnetic susceptibility measurements. 相似文献
18.
Claude Piguet Alan F. Williams Grald Bernardinelli Emmanuel Moret Jean-Claude G. Bünzli 《Helvetica chimica acta》1992,75(5):1697-1717
The ligand 2,6-bis(1-methylbenzimidazol-2-yl)pyridine (mbzimpy, 1 ) reacts with EuIII to give [Eu(mbzimpy)(NO3)3(CH3OH)] [ 4 ] whose crystal structure (EuC22H21N8O10, a = 7.658(3) Å, b = 19.136(2) Å, c = 8.882 Å, β = 104.07(1)°, monoclinic, P21, Z = 2) shows a mononuclear structure where EuIII is ten-coordinate by a meridional tridentate mbzimpy ligand, three bidentate nitrates, and one CH3OH molecule, leading to a low-symmetry coordination sphere around the metalion. Essentially the same coordination is found in the crystal structure of [Eu(obzimpy)(NO3)3] ( 8 ) (EuC35H45N8O9, a = 9.095(2) Å, b = 16.624(2) Å, c = 26.198(6) Å, β = 95.85(1)°, monoclinic, P21/c, Z = 4) obtained by reaction of 2,6-bis(1-octylbenzimidazol-2-yl)pyridine (obzimpy, 2 ) with EuIII. Detailed photophysical studies of crystalline [Ln(mbzimpy)(NO3)3(CH3OH)] and [Ln(obzimpy)(NO3)3] complexes (Ln = Eu, Gd, Tb, Lu) show that 1 and 2 display 1ππ* and 3ππ* excited states very similar to those observed in 2,2′:6′,2″-terpyridine, leading to efficient ligand to LnIII intramolecular energy transfer. Spectroscopic results show that an extremely efficient mbzimpy-to-EuIII transfer occurs in [Ln(mbzimpy)(NO3)3(CH3OH)] and in the case of TbIII, a TbIII-to-mbzimpy back transfer is also implied in the deactivation process. The origin of these peculiar effects and the influence of ligand design by going from mbzimpy to obzimpy are discussed. 1H-NMR and luminescence data indicate that the structure found in the crystal is essentially maintained in solution. 相似文献
19.
Dr. Fabrice Pointillart Dr. Thomas Cauchy Dr. Olivier Maury Yann Le Gal Dr. Stéphane Golhen Dr. Olivier Cador Dr. Lahcène Ouahab 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(39):11926-11941
The tetrathiafulvalene‐amido‐2‐pyridine‐N‐oxide ( L ) ligand has been employed to coordinate 4f elements. The architecture of the complexes mainly depends on the ionic radii of the lanthanides. Thus, the reaction of L in the same experimental protocol leads to three different molecular structure series. Binuclear [Ln2(hfac)5(O2CPhCl)( L )3] ? 2 H2O (hfac?=1,1,1,5,5,5‐hexafluoroacetylacetonate anion, O2CPhCl?=3‐chlorobenzoate anion) and mononuclear [Ln(hfac)3( L )2] complexes were obtained by using rare‐earth ions with either large (LnIII=Pr, Gd) or small (LnIII=Y, Yb) ionic radius, respectively, whereas the use of TbIII that possesses an intermediate ionic radius led to the formation of a binuclear complex of formula [Tb2(hfac)4(O2CPhCl)2( L )2]. Antiferromagnetic interactions have been observed in the three dinuclear compounds by using an extended empirical method. Photophysical properties of the coordination complexes have been studied by solid‐state absorption spectroscopy, whereas time‐dependent density functional theory (TD‐DFT) calculations have been carried out on the diamagnetic YIII derivative to build a molecular orbital diagram and to reproduce the absorption spectrum. For the [Yb(hfac)3( L )2] complex, the excitation at 19 600 cm?1 of the HOMO→LUMO+1/LUMO+2 charge‐transfer transition induces both line‐shape emissions in the near‐IR spectral range assigned to the 2F5/2→2F7/2 (9860 cm?1) ytterbium‐centered transition and a residual charge‐transfer emission around 13 150 cm?1. An efficient antenna effect that proceeds through energy transfer from the singlet excited state of the tetrathiafulvalene‐amido‐2‐pyridine‐N‐oxide chromophore is evidence of the YbIII sensitization. 相似文献
20.
Hetero‐tri‐spin [2p‐3d‐4f] Chain Compounds Based on Nitronyl Nitroxide Lanthanide Metallo‐Ligands: Synthesis,Structure, and Magnetic Properties
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Mei Zhu Peng Hu Yungai Li Xiufeng Wang Prof. Licun Li Prof. Daizheng Liao V. M. L. Durga Prasad Goli Prof. S. Ramasesha Dr. Jean‐Pascal Sutter 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(41):13356-13365
Employing nitronyl nitroxide lanthanide(III) complexes as metallo‐ligands allowed the efficient and highly selective preparation of three series of unprecedented hetero‐tri‐spin (Cu?Ln‐radical) one‐dimensional compounds. These 2p–3d–4f spin systems, namely [Ln3Cu(hfac)11(NitPhOAll)4] (LnIII=Gd 1Gd , Tb 1Tb , Dy 1Dy ; NitPhOAll=2‐(4′‐allyloxyphenyl)‐4,4,5,5‐tetramethylimidazoline‐1‐oxyl‐3‐oxide), [Ln3Cu(hfac)11(NitPhOPr)4] (LnIII=Gd 2Gd , Tb 2Tb , Dy 2Dy , Ho 2Ho , Yb 2Yb ; NitPhOPr=2‐(4′‐propoxyphenyl)‐4,4,5,5‐tetramethyl‐imidazoline‐1‐oxyl‐3‐oxide) and [Ln3Cu(hfac)11(NitPhOBz)4] (LnIII=Gd 3Gd , Tb 3Tb , Dy 3Dy ; NitPhOBz=2‐(4′‐benzyloxyphenyl)‐4,4,5,5‐tetramethyl‐imidazoline‐1‐oxyl‐3‐oxide) involve O‐bound nitronyl nitroxide radicals as bridging ligands in chain structures with a [Cu‐Nit‐Ln‐Nit‐Ln‐Nit‐Ln‐Nit] repeating unit. The dc magnetic studies show that ferromagnetic metal–radical interactions take place in these hetero‐tri‐spin chain complexes, these and the next‐neighbor interactions have been quantified for the Gd derivatives. Complexes 1Tb and 2Tb exhibit frequency dependence of ac magnetic susceptibilities, indicating single‐chain magnet behavior. 相似文献