Co-reporter:Meng Yang, Jing Xie, Zan Sun, Licun Li, and Jean-Pascal Sutter
Inorganic Chemistry November 6, 2017 Volume 56(Issue 21) pp:13482-13482
Publication Date(Web):October 9, 2017
DOI:10.1021/acs.inorgchem.7b02204
Ladder-type and chain 2p–3d–4f complexes based on a bridging nitronyl nitroxide radical, namely, [LnCu(hfac)5(NIT-Ph-p-OCH2trz)]·0.5C6H14 [Ln = Y (1a), Dy (1b)] and [LnCu(hfac)5(NIT-Ph-p-OCH2trz)] [Ln = Y (2a), Dy (2b); NIT-Ph-p-OCH2trz = 2-[4-[(1H-1,2,4-triazol-1-yl)methoxy]phenyl]-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide; hfac = hexafluoroacetylacetonate) have been successfully achieved through a one-pot reaction of the NIT-Ph-p-OCH2trz radical with Cu(hfac)2 and Ln(hfac)3·2H2O. Complexes 1a and 1b feature a ladder-like structure, where the rails are made of Ln(III) and Cu(II) ions alternatively bridged by nitronyl nitroxide and the triazole units while the NIT-Ph-p-OCH2trz moieties act as the rungs of the ladder. Complexes 2a and 2b consist of one-dimensional nitronyl nitroxide bridged Ln coordination polymers with dangly Cu(II) units connected to the triazole moieties. All of compounds exhibit ferromagnetic NIT-Dy and/or NIT-Cu interactions. Both Dy derivatives (1b and 2b) show frequency-dependent out-of-phase magnetic susceptibility signals in a zero field indicating slow magnetic relaxation behavior.
Co-reporter:Cun Li, Juan Sun, Meng Yang, Guifang Sun, Jianni Guo, Yue Ma, and Licun Li
Crystal Growth & Design December 7, 2016 Volume 16(Issue 12) pp:
Publication Date(Web):November 14, 2016
DOI:10.1021/acs.cgd.6b01369
By reacting nitronyl nirtroxide radical NIT-Ph2OEt (NIT-Ph2OEt = 2-(2′-ethoxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide) with Ln(hfac)3(hfac = hexafluoroacetylacetonate), four new Ln–nitronyl nitroxide complexes, namely, mononuclear species [Ln(hfac)3(NIT-Ph2OEt)2](LnIII = Gd 1a, Tb 1b) and one-dimensional chains [Ln(hfac)3(NIT-Ph2OEt)]n (LnIII = Gd 2a, Tb 2b), have been successfully obtained through controlling the reaction temperature and the ratio of radical ligand and Ln(hfac)3. DC magnetic susceptibilities indicate that the ferromagnetic couplings occur between the coordination radicals and the Ln(III) ions for four complexes. No nonzero out-of-phase signals are observed for mononuclear segment 1b, whereas the corresponding 1D chain 2b exhibits frequency-dependent out-of-phase signals indicating single-chain magnet behavior, which implies that the intrachain next-nearest-neighbor (NNN) Ln—Ln magnetic interactions play a crucial role for enhancing slow magnetic relaxation in the chain. Moreover, Tb chain exhibits rare three-step field-induced metamagnetic behavior.
Co-reporter:Zan Sun, Meng Yang, Yue Ma, and Licun Li
Crystal Growth & Design August 2, 2017 Volume 17(Issue 8) pp:4326-4326
Publication Date(Web):July 3, 2017
DOI:10.1021/acs.cgd.7b00638
Four new isostructural two-dimensional lanthanide(III)–metal organic frameworks (MOFs), namely, [Ln(L)(HCOO)(H2O)]n (Ln = Eu 1, Gd 2, Ho 3, and Tb 4, H2L = 5-((2′-cyano-[1,1′-biphenyl]-4-yl)methoxy)isophthalic acid), with a uninodal {44.62}-sql topology have been successfully isolated. Compounds 1 and 4 exhibit excellent applications as luminescent sensors for sensing benzaldehyde in methanol and Cr3+, CrO42–, and Cr2O72– in water with high sensitivity and selectivity based on luminescence quenching effects. Interestingly, 1 and 4 display excellent recyclable behaviors and can be recycled at least five times for sensing benzaldehyde, Cr(III) and Cr(VI) ions. These two compounds are the first multifunctional Ln–MOFs sensors for detecting benzaldehyde, Cr(III) and Cr(VI) ions, simultaneously. Therefore, these two materials may be excellent multifunctional recyclable luminescent sensors.
Co-reporter:Juan Sun;Meng Yang;Zan Sun;Xiufeng Wang;Yue Ma;Licun Li
Dalton Transactions 2017 vol. 46(Issue 31) pp:10189-10192
Publication Date(Web):2017/08/08
DOI:10.1039/C7DT02232H
A novel lanthanide(III)–nitronyl nitroxide chain {[Gd(hfac)3(Nit-Ph-3,5-bIm)(H2O)]·C4H10O}n (1) was prepared and characterized. Strikingly, an unexpected ferromagnetic coupling between the Gd(III) ion and the nitroxide group mediated by hydrogen bonding has been observed for the first time.
Co-reporter:Hongdao Li, Jianni Guo, Guifang Sun, Jing Xie, Licun Li
Inorganic Chemistry Communications 2017 Volume 85(Volume 85) pp:
Publication Date(Web):1 November 2017
DOI:10.1016/j.inoche.2017.06.011
•Metal-biradical complexes have been successfully obtained.•Nitronyl nitroxide biradical acts as a bridging ligand to link two Ln(III) ions to form one-dimensional chain structure.•AC susceptibility confirms the presence of a slow magnetic relaxation process for complex Dy at low temperature.Two novel lanthanide-biradical complexes [Ln(hfac)3(BNPhOEt)]·C6H14 (LnIII = Gd 1, Dy 2; hfac = hexafiuoroacetylacetonate; BNPhOEt = 1,2-[bis-2,2′-(4,4,5,5-tetramethylimidazolyl-1-oxyl-3-oxide)phenoxy]ethane) have been isolated and magnetically characterized. Both complexes consist of neutral one-dimensional chain in which the BNPhOEt biradical bridges two Ln(hfac)3 units through the NO groups. Magnetic investigations show that the Gd(III) ion interacts ferromagnetically with the directly NO group while the antiferromagnetic interaction was observed between two NO groups through the Gd(III) ion. Moreover, complex Dy exhibits the field induced magnetic relaxation behavior.Two novel lanthanide-biradical one-dimensional chains have been achieved. Compound Dy displays field-induced magnetic relaxation behavior.Download high-res image (142KB)Download full-size image
Co-reporter:Zan Sun, Peng Hu, Yue Ma, Licun Li
Dyes and Pigments 2017 Volume 143(Volume 143) pp:
Publication Date(Web):1 August 2017
DOI:10.1016/j.dyepig.2017.04.015
•A series of Ln-MOFs are obtained and exhibit an interesting 3D pcu topology.•Tb compound can sense nitrobenzene and 2-, 3- and 4-nitrophenol simultaneously.•Tb material may be an excellent luminescent sensor for nitroaromatic compounds.A series of lanthanide(III)–organic frameworks, namely {[Ln2(L)3(H2O)4]·10H2O}n (Sm 1, Eu 2, Gd 3, Tb 4, Dy 5 and Ho 6, H2L = 5-(pyridine-4-ylmethoxy)isophthalic acid) have been synthesized under solvothermal conditions. Compounds 1–6 are isostructural and exhibit an interesting 3D pcu topology with binuclear [Ln2(CO2)6] units as 6-connected nodes, and free water molecules are filled in 3D coordination frameworks through hydrogen-bonding interactions. Compound 4 can be used as a fluorescent probe for sensing nitroaromatic compounds with high sensitivity and selectivity based on luminescence quenching effects arising from host−guest interactions in DMF system. In particular, compound 4 can sense nitrobenzene (NB) and nitrophenol isomers (2-, 3- and 4-NP) simultaneously. Thus, this material can be potentially used as a luminescent sensor for nitroaromatic compounds.A series of Ln MOFs based on the binuclear units have been obtained. Tb MOF can sense 4-nitrophenol with high sensitivity and selectivity.Download high-res image (337KB)Download full-size image
Co-reporter:Hongdao Li;Juan Sun;Meng Yang;Zan Sun;Jing Xie;Yue Ma;Licun Li
New Journal of Chemistry (1998-Present) 2017 vol. 41(Issue 18) pp:10181-10188
Publication Date(Web):2017/09/11
DOI:10.1039/C7NJ02006F
The functionalized nitronyl nitroxide biradical bridged one-dimensional lanthanide chains [Ln(tfa)3(NITPhImbis)]·CH2Cl2 (LnIII = Gd 1, Tb 2, Dy 3 and Nd 4; tfa = trifluoroacetylacetonate; NITPhImbis = 1-imidazole-3,5-bis(1′-oxyl-3′-oxido-4′,4′,5′,5′-tetramethyl-4,5-hydro-1H-imidazol-2-yl)benzene) have been prepared and characterized. Single crystal X-ray diffraction analyses reveal that complexes 1–4 possess a one-dimensional chain structure in which each nitronyl nitroxide biradical acts as a bridging ligand to link two different lanthanide ions via one of the NO groups and the imidazole ring of the biradical ligand to form a one-dimensional chain with a ‘head-to-tail’ structural motif. DC magnetic studies show that the magnetic interaction between the Gd atom and the coordinated NO group is ferromagnetic while the intramolecular magnetic coupling between two monoradicals is antiferromagnetic. Moreover, the spin dynamics indicates the presence of slow magnetic relaxation for Tb and Dy analogues, which could be attributed to the Dy/Tb-bis(nitronyl nitroxide) moieties. Thus, complexes Tb and Dy behave like chains of single-molecule magnets (SMMs).
Co-reporter:Xiufeng Wang;Hongdao Li;Juan Sun;Meng Yang;Cun Li;Licun Li
New Journal of Chemistry (1998-Present) 2017 vol. 41(Issue 8) pp:2973-2979
Publication Date(Web):2017/04/10
DOI:10.1039/C6NJ03849B
Four novel nitronyl nitroxide bridged heterometallic one-dimensional chains, [Ln(hfac)3Co(hfac)2(NIT-4py)2] (LnIII = Y 1, Gd 2, Dy 3) and [Dy(hfac)3Co(hfac)2(NIT-3py)2] 4 (hfac = hexafluoroacetylacetonate; NIT-4py = 2-(4-pyridyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide; NIT-3py = 2-(3-pyridyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide), have been prepared and characterized. Complexes 1–4 exhibit a 1D chain structure in which Ln(hfac)3 and Co(hfac)2 units are linked by pyridine substituted nitronyl nitroxides through the NO groups of the radicals and the nitrogen atoms of pyridine rings. Complexes 1–4 represent the first examples of 2p–3d–4f compounds containing Co(II) ions. The magnetic properties of these compounds were investigated. The magnetic behavior of the Y(III)–Co(II) complex has been analyzed by using an appropriate magnetic model, which indicates an antiferromagnetic interaction between the Co(II) ion and the radical. The ac magnetic susceptibility measurements of compound 4 display slow relaxation of its magnetization.
Co-reporter:Zan Sun, Yungai Li, Yue Ma, Licun Li
Dyes and Pigments 2017 Volume 146(Volume 146) pp:
Publication Date(Web):1 November 2017
DOI:10.1016/j.dyepig.2017.07.015
•Four isostructural 2D Ln-MOFs are obtained and exhibit an interesting 2D corrugated layer structure with sql topology.•Eu and Tb compounds are the first reported dual-functional luminescent sensors which can sense 2,4-dinitrophenol and Fe3+.•Eu and Tb materials are excellent recyclable luminescent sensors for the detection of 2,4-dinitrophenol and Fe3+.A series of lanthanide-based metal-organic frameworks (Ln-MOFs), namely [Ln(L2−)(HL–)(H2O)2]n (Ln = Eu 1, Gd 2, Tb 3 and Dy 4, H2L = 5-(imidazol-1-yl)isophthalic acid) have been successfully assembled under solvothermal conditions. Compounds 1–4 exhibit a 2D corrugated layer structure with {44.62}-sql topology based on [Ln2(CO2)6(H2O)4] units containing uncoordinated carboxylate groups, which further forms a 3D supramolecular structure through hydrogen bond interactions. Compounds 1 and 3 display excellent applications as luminescent sensors for sensing 2,4-dinitrophenol (2,4-DNP) in ethanol system and Fe3+ in aqueous solution with high sensitivity and selectivity based on luminescence quenching effects. Interestingly, 1 and 3 display excellent recyclable behaviors and can be recycled at least 5 times for sensing 2,4-DNP and Fe3+. These two compounds are the first reported dual-functional Ln-MOFs sensors for detecting 2,4-DNP and Fe3+. Therefore, these two materials may be an excellent dual-functional recyclable luminescent sensor for 2,4-dinitrophenol and Fe3+.Two novel lanthanide-based metal-organic frameworks (Ln = Eu and Tb) exhibit dual-functional luminescent sensors for the highly sensitive detection of Fe3+ and 2,4-dinitrophenol and display excellent recyclable behaviors.Download high-res image (210KB)Download full-size image
Co-reporter:Mei Zhu, Cun Li, Xiufeng Wang, Licun Li, and Jean-Pascal Sutter
Inorganic Chemistry 2016 Volume 55(Issue 6) pp:2676-2678
Publication Date(Web):February 25, 2016
DOI:10.1021/acs.inorgchem.6b00004
Magnetic bistability spanning over a temperature domain of 40 K can result from a small structural deformation of the gadolinium aminoxyl coordination. This is illustrated for a nitronyl nitroxide 3d–4f chain, [Ln(hfac)3Cu(hfac)2(NIT-Pyrim)2] (LnIII = Gd, Dy), which is the first example of a bistable lanthanide-based complex.
Co-reporter:Junqing Zhang;Cun Li;Juanjuan Wang;Mei Zhu ;Licun Li
European Journal of Inorganic Chemistry 2016 Volume 2016( Issue 9) pp:1383-1388
Publication Date(Web):
DOI:10.1002/ejic.201501388
Abstract
Three novel heterotrinuclear complexes {[Ln(hfac)3]2CuL2} [LnIII = Gd (1), Tb (2), and Dy (3); HL = 4-methoxysalicylaldehyde, hfac = hexafluoroacetylacetone] have been synthesized and characterized by X-ray crystallography as well as by a study of their magnetic properties. In these compounds, CuII and LnIII ions are bridged by two phenolato and aldehyde oxygen atoms from two 4-methoxysalicylaldehyde ligands and one oxygen atom from one hfac ligand, resulting in a linear trinuclear core of Ln–Cu–Ln with one central CuII ion and two terminal LnIII ions. Furthermore, the linear trinuclear units generate a pseudo-one-dimensional chain through π–π interactions. Direct-current magnetic susceptibility studies show that there is a ferromagnetic interaction between CuII and GdIII ions. Tb and Dy complexes exhibit frequency-dependent out-of-phase signals, indicating slow magnetic relaxation behavior.
Co-reporter:Dr. Mei Zhu;Meng Yang;Juanjuan Wang;Hongdao Li ; Licun Li
Chemistry – An Asian Journal 2016 Volume 11( Issue 13) pp:1900-1905
Publication Date(Web):
DOI:10.1002/asia.201600383
Abstract
A new family of 2p-3d-4f hetero-tri-spin complexes [Ln(hfac)3{Cu(hfac)2(NIT-3 PyPh)}2] (Ln=Gd (1), Tb (2), Dy (3), Ho (4); NIT-3 PyPh=2-[4-(3-pyridinylmethoxy)phenyl]-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide; hfac=hexafluoroacetylacetonate) have been synthesized. Four complexes possess a 1D chain structure in which two radical ligands join two Cu(hfac)2 molecules to form a [{Cu(hfac)2-rad)}2] dimer cycle and the dimer rings are linked by Ln(hfac)3 units. Magnetic studies show that ferromagnetic exchange couplings exist between the coordinated NO groups of radical ligands and metal ions. Field-induced slow relaxation of the magnetization was observed in the Tb and Dy compounds.
Co-reporter:Juan-Juan Wang, Juan Sun, Meng Yang, and Li-Cun Li
Inorganic Chemistry 2015 Volume 54(Issue 23) pp:11307-11313
Publication Date(Web):November 11, 2015
DOI:10.1021/acs.inorgchem.5b01915
New 2p–4f and 2p–3d–4f compounds [Tb(hfac)3(NIT-PhNO2)2]·0.5C7H16 (1) and [Ln(hfac)3(NIT-PhNO2)2]2[Cu(hfac)2(NIT-PhNO2)2] (LnIII = Gd 2, Tb 3; hfac = hexafluoroacetylacetonate; NIT-PhNO2 = 2-(p-nitrophenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide) have been obtained. Complex 1 consists of mononuclear trispin [Tb(hfac)3(NIT-PhNO2)2] units in which two radical ligands are ligated to the Tb(III) ion as monodentate ligands through the NO groups, while complexes 2 and 3 contain two kinds of trispin moieties, namely, [Ln(hfac)3(NIT-PhNO2)2] and [Cu(hfac)2(NIT-PhNO2)2]. In the [Cu(hfac)2(NIT-PhNO2)2] moiety, the radicals are bonded to the copper(II) ion in the axial positions via the nitroxides. For three compounds, 1D supramolecular chains are formed via the π–π stacking interactions involving the radical ligands. Magnetic investigations show that both Tb complexes exhibit slow relaxation of magnetization at low temperature; strikingly, complex 3 displays a higher energy barrier than that of 1. It represents the first example to use the paramagnetic complex to tune magnetic relaxation of 4f-based compounds.
Co-reporter:Xiufeng Wang; Peng Hu; Licun Li;Jean-Pascal Sutter
Inorganic Chemistry 2015 Volume 54(Issue 19) pp:9664-9669
Publication Date(Web):September 24, 2015
DOI:10.1021/acs.inorgchem.5b01761
Novel hetero-tri-spin coordination polymers formed of ring-shaped Cu-nitronyl nitroxide spin clusters and LnIII linkers are reported. These mixed 2p-3d-4f compounds of formula {[Ln(hfac)3][Cu(hfac)2(NIT-3Py)]2·C6H14}n [LnIII = Y (1), Gd (2), Tb (3), and Dy (4); NIT-3Py = 2-(3-pyridyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide; hfac = hexa-fluoroacetylacetonate], exhibit a 1D chain structure consisting of [Cu(NIT-3Py)]2 rings linked by Ln(hfac)3 units. Their magnetic behavior is characteristic for ferromagnetic interactions between the metal centers and the coordinated radical units. The Tb derivative was found to exhibit slow relaxation of its magnetization.
Co-reporter:Xiufeng Wang, Yungai Li, Peng Hu, Juanjuan Wang and Licun Li
Dalton Transactions 2015 vol. 44(Issue 10) pp:4560-4567
Publication Date(Web):05 Feb 2015
DOI:10.1039/C4DT01878H
The combination of lanthanide ions and nitronyl nitroxide radicals resulted in four new Ln-radical one-dimensional compounds, namely, [Ln(hfac)3{NIT-Ph(OMe)2}]n(LnIII = Sm (1), Eu (2), Gd (3), Dy (4); hfac = hexafluoroacetylacetonate; NIT-Ph(OMe)2 = 2-(2′,4′-dimethoxyphenyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazolyl-1-oxyl-3-oxide). The four complexes were found to be isomorphous and exhibit nitronyl nitroxide radicals-bridged lanthanides linear chains. DC magnetic susceptibilities show that the directly bonded nitronyl nitroxide interacts ferromagnetically with Gd and Dy ions. The Dy complex exhibits three-step metamagnetism and frequency-dependent ac magnetic susceptibilities, indicating single-chain magnet behavior. This work shows that the magnetic behaviors of one-dimensional Ln-nitronyl nitroxide chains can be fine tuned by the substituents of the radicals.
Co-reporter:Mei Zhu, Juanjuan Wang, Meng Yang, Yue Ma and Licun Li
Dalton Transactions 2015 vol. 44(Issue 21) pp:9815-9822
Publication Date(Web):17 Apr 2015
DOI:10.1039/C4DT03330B
Three isostructural two-dimensional 2p–3d–4f complexes, namely, {Tb(hfac)3[Cu(hfac)2]3(NITPhPyrim)2}·2CH2Cl21 and {Ln(hfac)3[Cu(hfac)2]3(NITPhPyrim)2} (LnIII = Ho 2, Yb 3; hfac = hexafluoroacetylacetonate; NITPhPyrim = 2-[4-(5-pyrimidyl)phenyl]-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide), were characterized in terms of structure and magnetism. These heterospin compounds possess a two-dimensional sheet structure involving CuII and LnIII ions bridged by NITPhPyrim radicals through their NO groups and pyrimidine rings. DC magnetic studies show that these complexes exhibit ferromagnetic exchange coupling between radical ligands and metal atoms. AC measurements of the Tb complex reveal slow relaxation of the magnetization. Interestingly, the Tb complex displays two field-induced relaxation processes.
Co-reporter:Xiufeng Wang, Cun Li, Juan Sun and Licun Li
Dalton Transactions 2015 vol. 44(Issue 42) pp:18411-18417
Publication Date(Web):22 Sep 2015
DOI:10.1039/C5DT02783G
Four new nitronyl nitroxide radical based hetero-tri-spin one-dimensional compounds, namely [{Ln(hfac)3}3{Cu(hfac)2}{NIT–Ph(OMe)2}4]n (Ln = Gd (1), Tb (2), Dy (3), Er (4); hfac = hexafluoroacetylacetonate; NIT–Ph(OMe)2 = 2-(2′,4′-dimethoxyphenyl)-4,4,5,5-tetramethyl-imidazolyl-1-oxyl-3-oxide) have been successfully prepared. Single crystal X-ray crystallographic analysis reveals that complexes 1–4 possess a 1D chain structure with a repeating [Cu–Rad–Ln–Rad–Ln–Rad–Ln–Rad] moiety in which Ln(hfac)3 and Cu(hfac)2 units are bridged by nitronyl nitroxide radicals through the NO groups. DC magnetic studies found that ferromagnetic interactions between metals and the coordinated NO groups are active in all four compounds. The Tb derivative displays frequency dependent ac magnetic susceptibilities, indicating slow magnetic relaxation behavior. The Gd complex shows an important cryogenic magnetocaloric effect with the entropy change (−ΔSm) of 13.5 J kg−1 K−1 at 2 K and a magnetic field of 7 T, representing the first example of Gd–radical molecular species exhibiting the magnetocaloric effect.
Co-reporter:Xiufeng Wang, Mei Zhu, Juanjuan Wang and Licun Li
Dalton Transactions 2015 vol. 44(Issue 31) pp:13890-13896
Publication Date(Web):24 Jun 2015
DOI:10.1039/C5DT01487E
The lanthanide–radical approach has been applied to construct three isomorphous mononuclear lanthanide complexes [Ln(hfac)3(NIT2-PyOCH3)] (LnIII = Gd 1, Tb 2, Er 3) in which the nitronyl nitroxide radical NIT2-PyOCH3 (NIT2-PyOCH3 = 2-(3′-methoxy-2′-pyridyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide) acts as a tridentate chelating ligand via the pyridyl nitrogen atom, the oxygen atom from the NO group and the oxygen atom from the methoxy group. The central lanthanide ions are nine-coordinated and their coordination geometry can be considered as an intermediate between muffin and spherical capped square antiprisms. Interestingly, an unusual antiferromagnetic interaction was observed between the Gd(III) and the coordinated nitronyl nitroxide radical in complex 1. Moreover, ac magnetic susceptibilities display frequency-dependent out-of-phase signals in the case of the anisotropic Tb complex, indicating magnetic relaxation behavior.
Co-reporter:Juanjuan Wang;Mei Zhu;Cun Li;Junqing Zhang ;Licun Li
European Journal of Inorganic Chemistry 2015 Volume 2015( Issue 8) pp:1368-1375
Publication Date(Web):
DOI:10.1002/ejic.201403184
Abstract
The reactions of the nitronyl nitroxide radical 2-(p-nitrophenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (NIT-PhNO2) with Ln(hfac)3 (hfac = hexafluoroacetylacetonate) afford two mononuclear lanthanide nitronyl nitroxide complexes [Ln(hfac)3(NIT-PhNO2)2]·0.5C7H16 [Ln = GdIII (1), DyIII (2)]. X-ray structural analysis shows that both complexes have a similar mononuclear structure, in which two NIT-PhNO2 radicals are bonded to the LnIII center as monodentate ligands through the oxygen atoms of the NO groups. Interestingly, those mononuclear units form a pseudo-one-dimensional chain structure through π–π interactions. Direct current (dc) magnetic measurements show that there is ferromagnetic coupling between the lanthanide ion and the radical ligand for both complexes. Alternating current (ac) magnetic susceptibility studies reveal that the DyIII complex shows slow relaxation of magnetization in zero field, which is observed for the first time in a lanthanide–radical complex with a pseudo one-dimensional structure through π–π interactions.
Co-reporter:Xiu-Feng Wang;Peng Hu;Yun-Gai Li ; Li-Cun Li
Chemistry – An Asian Journal 2015 Volume 10( Issue 2) pp:325-328
Publication Date(Web):
DOI:10.1002/asia.201403165
Abstract
Three unprecedented nitronyl nitroxide radical-bridged 3d–4f clusters, [Ln2Cu2(hfac)10(NIT-3py)2(H2O)2](LnIII=Y, Gd, Dy), have been obtained from the self-assembly of Ln(hfac)3, Cu(hfac)2, and the radical ligand. The Dy complex shows a slow relaxation of magnetization, representing the first nitronyl nitroxide radical-based 3d–4f cluster with single-molecule magnet behavior.
Co-reporter:Mei Zhu, Xuelan Mei, Yue Ma, Licun Li, Daizheng Liao and Jean-Pascal Sutter
Chemical Communications 2014 vol. 50(Issue 15) pp:1906-1908
Publication Date(Web):09 Jan 2014
DOI:10.1039/C3CC48110G
A novel approach for the preparation of hetero-tri-spin magnetic compounds is described. It consists in using preformed metal–nitronyl nitroxide complexes as metallo-ligands in an assembling process involving an additional metal centre. This is illustrated by two unprecedented radical–Cu–Ln chain compounds (Ln = Gd3+, Tb3+).
Co-reporter:Yi-Xia Ren, Xiang-Jun Zheng, Li-Cun Li, Da-Qiang Yuan, Miao An, and Lin-Pei Jin
Inorganic Chemistry 2014 Volume 53(Issue 23) pp:12234-12236
Publication Date(Web):November 13, 2014
DOI:10.1021/ic502042h
Two new heterometallic coordination polymers, [Na4Ln12(stp)8(OH)16(H2O)12]·10H2O [Ln = Dy (1) and Ho (2)], have been prepared from monosodium 2-sulfoterephthalate (NaH2stp), dysprosium acetate, or holmium acetate. They are isostructural, possessing a [Ln12(μ3-OH)16]20+ wheel-cluster core based on four vertex-sharing cubane-like [Ln4(μ3-OH)4]8+ units. The Ln12 cores are linked by stp ligands into a three-dimensional (3D) architecture. Magnetic studies indicate that complex 1 exhibits slow relaxation of magnetization, and it can be regarded as the first 3D coordination assembly of a Dy12 cluster single-molecule magnet.
Co-reporter:Peng Hu, Xiufeng Wang, Yue Ma, Qinglun Wang, Licun Li and Daizheng Liao
Dalton Transactions 2014 vol. 43(Issue 5) pp:2234-2243
Publication Date(Web):19 Nov 2013
DOI:10.1039/C3DT52959B
Five new one-dimensional rare earth–nitronyl nitroxide radical complexes [Ln(hfac)3(NIT-3BrPhOMe)]n (Ln = Nd (1), Sm (2), Gd (3), Tb (4), Dy (5); hfac = hexafluoroacetylacetonate; NIT-3BrPhOMe = 2-(3′-bromo-4′-methoxyl)-4,4,5,5-tetramethyl-imidazolyl-1-oxyl-3-oxide) have been successfully prepared and structurally characterized. Five complexes possess linear chain structure in which the NIT-3BrPhOMe radical ligands link Ln(hfac)3 units through the oxygen atoms of nitronyl nitroxide groups. DC magnetic studies show that Nd, Sm and Gd complexes are paramagnetic above 2.0 K, whereas Tb and Dy complexes show antiferromagnetic ordering with TN = 19.9 K and 6.4 K, respectively. Moreover, Tb and Dy complexes exhibit frequency-dependence of ac magnetic susceptibilities, suggesting the presence of slow magnetic relaxation. This work demonstrated that the substituents of the nitronyl nitroxide radical and the lanthanide ion can play a crucial role in modulating the magnetic behavior for one-dimensional lanthanide–radical systems.
Co-reporter:Yungai Li, Yaowei Guo, Haixia Tian, Peng Hu, Zan Sun, Yue Ma, Licun Li, Daizheng Liao
Inorganic Chemistry Communications 2014 Volume 43() pp:135-137
Publication Date(Web):May 2014
DOI:10.1016/j.inoche.2014.02.029
•One unique radical-bridged Mn(II) cluster.•Four Mn(II) ions form a crown-like ring structure.•The complex exhibits strong antiferromagnetic interaction.One unique radical-bridged Mn(II) cluster [Mn4(hfac)6(NIToBA)2(HIMoBAH)(H2O)3] (1) (hfac = hexafluoroacetylacetonate, NIToBAH = 2-(2-carboxyphenyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazol-1-oxyl-3-oxide, HIMoBAH = 2-(2-carboxyphenyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazol-1-hydroxy) has been synthesized and structurally and magnetically characterized. The core of complex 1 features four Mn(II) ions bridged by three carboxyl groups and two nitroxide groups to form a crown-like ring structure. This complex exhibits strong antiferromagnetic interaction because the NO groups are directly coordinated to the metal ions.One unique radical-bridged Mn(II) cluster has been synthesized by using carboxyl substituted nitronyl nitroxide radical. This complex exhibits strong antiferromagnetic interaction because the NO groups are directly coordinated to the metal ions.
Co-reporter:Mei Zhu;Peng Hu;Yungai Li;Xiufeng Wang; Licun Li; Daizheng Liao;V. M. L. DurgaPrasadGoli; S. Ramasesha;Dr. Jean-Pascal Sutter
Chemistry - A European Journal 2014 Volume 20( Issue 41) pp:13356-13365
Publication Date(Web):
DOI:10.1002/chem.201403581
Abstract
Employing nitronyl nitroxide lanthanide(III) complexes as metallo-ligands allowed the efficient and highly selective preparation of three series of unprecedented hetero-tri-spin (CuLn-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.
Co-reporter:Juanjuan Wang, Xiaoyan Xing, Yungai Li, Zan Sun, Qinglun Wang, Licun Li
Journal of Molecular Structure 2014 1068() pp: 255-260
Publication Date(Web):25 June 2014
DOI:10.1016/j.molstruc.2014.04.038
•New transition metal coordination polymers with flexible bis(N-heterocycle) ligand.•Both complexes show 2D network.•The oxalate ligands mediate important antiferromagnetic coupling in cobalt complex.Two new transition metal coordination polymers with 1,4-bis(1,2,4-triazol-1-ylmethyl)-benzene(btx), [Ni(btx)(ip)(H2O)] (1) and [Co(btx)(ox)]·2H2O (2) (H2ip = isophthalic acid; ox = oxalate) have been synthesized and characterized. Single crystal X-ray diffraction analyses reveal compounds 1 and 2 are two-dimensional structure in which the flexible bis(triazole) ligands act as bridging ligands. The variable-temperature magnetic susceptibility data show that two compounds exhibit weak antiferromagnetic interactions. The magnetic behaviors are explained in connection with the crystal structure.Two transition metal compounds based on 1,4-bis(1,2,4-triazol-1- ylmethyl)benzene ligand have been achieved. Both compounds exhibit 2D network structure. The magnetic studies show that cobalt compound exists important antiferromagnetic coupling transmitted by oxalate ligands.
Co-reporter:Mei Zhu ; Yun-Gai Li ; Yue Ma ; Li-Cun Li ;Dai-Zheng Liao
Inorganic Chemistry 2013 Volume 52(Issue 21) pp:12326-12328
Publication Date(Web):October 23, 2013
DOI:10.1021/ic402241f
Two novel 2p–3d–4f compounds, {Ln(hfac)3[Cu(hfac)2]3(NITPhPyrim)2} [Ln = Gd (1), Dy (2)], have been obtained by reacting phenyl pyrimidyl nitronyl nitroxide with Cu(hfac)2 and Ln(hfac)3. These two compounds are the first examples of two-dimensional 3d–4f complexes bridged by nitronyl nitroxide radicals. Overall ferromagnetic behaviors were observed in both compounds.
Co-reporter:Haixia Tian;Xiufeng Wang;Xuelan Mei;Ruina Liu;Mei Zhu;Congming Zhang;Yue Ma;Licun Li ;Daizheng Liao
European Journal of Inorganic Chemistry 2013 Volume 2013( Issue 8) pp:1320-1325
Publication Date(Web):
DOI:10.1002/ejic.201201223
Abstract
Two new one-dimensional nitronyl nitroxide radical–LnIII chain complexes, [Gd(hfac)3(NIT-I)] (1) and [Tb(hfac)3(NIT-I)] (2) (hfac = hexafluoroacetylacetonate; NIT-I = 2-iodo-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide), have been synthesized. Both complexes have linear chain structures in which the NIT-I radical ligands link the Ln(hfac)3 units through the oxygen atoms of the nitronyl nitroxide groups. Direct-current magnetic studies show that the Gd complex is paramagnetic above 2.0 K, whereas the Tb complex exhibits 3D antiferromagnetic ordering with TN = 4.0 K. Furthermore, complex 2 possesses frequency-dependent ac magnetic susceptibilities, which suggests slow magnetic relaxation.
Co-reporter:Xuelan Mei, Xiufeng Wang, Juanjuan Wang, Yue Ma, Licun Li and Daizheng Liao
New Journal of Chemistry 2013 vol. 37(Issue 11) pp:3620-3626
Publication Date(Web):02 Sep 2013
DOI:10.1039/C3NJ00739A
Three novel binuclear lanthanide–radical complexes [Ln2(acac)4(NITPhO)2] (Ln(III) = Gd 1, Eu 2, Dy 3; acac = acetylacetonato and NITPhOH = 2-(2′-hydroxyphenyl)-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide) have been achieved. These compounds possess dinuclear structure in which two radical ligands link two lanthanide ions through their phenoxo-O atoms. Magnetic studies show that the Gd(III) ion interacts ferromagnetically with the directly bonding NO group while magnetic interaction between two lanthanide ions through two phenoxo groups is antiferromagnetic. No frequency-dependent out-of-phase signals were found for the Dy complex, which shows that the ligand field around the metal center plays a crucial role in modulating the magnetic relaxation of lanthanide compounds.
Co-reporter:Cong-Ming Zhang, Xi-Feng Gao, Mei Zhu, Yun-Gai Li, Qing-Lun Wang, Li-Cun Li
Journal of Molecular Structure 2013 Volume 1033() pp:8-13
Publication Date(Web):6 February 2013
DOI:10.1016/j.molstruc.2012.08.011
Two new one-dimensional manganese(III) complexes [Mn2III(L1)4(piv)2] (1) and [MnIII(L2)(bix)]·2H2O⋅ClO4 (2) (H2L1 = N-(2-hydroxyethyl)-3-methoxysalicylaldimine, H2L2 = N,N′-bis(salicylidene)phenylenediamine, bix = 1,4-bis-(imidazol-1-ylmethyl)benzene, piv = pivalate) have been synthesized and characterized by X-ray crystallography and magnetic measurements. Crystal structure studies reveal that complex 1 consists one-dimensional manganese(III) chains linked by L12- ligand in η1:η1:η1:μ2 mode. In complex 2, the Mn(III) ion is coordinated by the tetradentate L22- ligand in the equatorial plane, whereas bix ligand acts as bridge in the axial direction. Magnetic studies show that both complexes exhibit weak antiferromagnetic exchange coupling between Mn(III) ions.Highlights► Two Mn(III) one-dimensional chains have been obtained and complex 1 represents a kind of new type Mn(III) chain. ► Ligand L1 is coordinated to metal ions in rare η1:η1:η1:μ2 mode. ► The magnetic behavior of both complexes are dominated by the zero-field splitting of Mn(III) ions.
Co-reporter:Peng Hu, Congming Zhang, Yuanyuan Gao, Yungai Li, Yue Ma, Licun Li, Daizheng Liao
Inorganica Chimica Acta 2013 Volume 398() pp:136-140
Publication Date(Web):24 March 2013
DOI:10.1016/j.ica.2012.12.025
Two one-dimensional nitronyl nitroxide–lanthanide complexes [Ln(hfac)3(NITMe)]n (Ln(III) = Y (1), Dy(2), hfac = hexafluoroacetylacetonate; NITMe = 2,4,4,5,5-pentamethylimidazolyl-1-oxyl-3-oxide) have been successfully prepared and characterized. Single crystal X-ray crystallographic analysis reveals that complexes 1 and 2 show similar linear chain structures composed of Ln(hfac)3 units bridged by NITMe radicals through their NO groups. Variable-temperature magnetic susceptibilities of Y complex show that there exists weak antiferromagnetic coupling between the radical ligands through the diamagnetic Y(III) ions. Alternating current (ac) susceptibilities of Dy complex reveal frequency dependent out-of-phase signals, indicating that it behaves as single-chain magnet.Graphical abstractTwo new one-dimensional Ln–nitronyl nitroxide complexes with Ln = Y, Dy have been successfully synthesized and characterized. Single crystal X-ray crystallographic analysis reveals that two complexes show similar linear chain structures composed of Ln(hfac)3 units bridged by NITMe radicals through their NO groups. AC magnetic susceptibility studies of Dy complex show slow clear frequency-dependent out-of-phase signals, suggesting a SCM behavior.Highlights► Two new one-dimensional Ln–radical complexes with Ln = Y, Dy have been prepared. ► The diamagnetic Y ion can mediate weak magnetic coupling between radical ligands. ► The Dy complex exhibits frequency-dependent ac signals indicating SCM behavior.
Co-reporter:Peng Hu, Mei Zhu, Xuelan Mei, Haixia Tian, Yue Ma, Licun Li and Daizheng Liao
Dalton Transactions 2012 vol. 41(Issue 48) pp:14651-14656
Publication Date(Web):11 Oct 2012
DOI:10.1039/C2DT31806G
Three rare earth–nitronyl nitroxide radical complexes [Ln(tfa)3(NIT-BzImH)] (Ln(III) = Gd 1, Tb 2, Dy 3; tfa = trifluoroacetylacetonate; NIT-BzImH = 2-(2′-benzimidazolyl)-4,4,5,5-tetramethylimidazolyl-1-oxyl-3-oxide) have been successfully prepared and structurally characterized. X-Ray crystallographic analysis reveals that all three complexes are isomorphous. Their crystal structures consist of mononuclear molecule units in which lanthanide(III) is 8-coordinated to one NIT-BzImH and three trifluoroacetylacetonate ligands. The NIT-BzImH acts as a bidentate ligand via its nitrogen atom of the imidazole ring and the oxygen atom of the N–O group. The magnetic properties of complexes 1–3 were studied. All the three complexes exhibit ferromagnetic Ln(III)–radical coupling. AC magnetic susceptibility studies of 2 and 3 show slow magnetic relaxation suggesting that they behave as SMMs.
Co-reporter:Ruina Liu, Congming Zhang, Licun Li, Daizheng Liao and Jean-Pascal Sutter
Dalton Transactions 2012 vol. 41(Issue 39) pp:12139-12144
Publication Date(Web):14 Aug 2012
DOI:10.1039/C2DT31310C
Reaction of Dy(hfac)3·2H2O (hfac = hexafluoroacetyl acetonate) with 2-(2-hydroxyphenyl)nitronyl nitroxide (NITPhOH) and 2-(5-bromo-2-hydroxyphenyl)nitronyl nitroxide (NIT5BrPhOH) yielded [Dy2(hfac)4(NITPhO)2] 1 and [Dy2(hfac)4(NIT5BrPhO)2] 2, respectively. These compounds are phenoxo-O bridged binuclear complexes with the radical unit of a ligand coordinated to a single Dy. The Ln centers exhibit a heptacoordinated environment. Despite having very similar structures, these compounds exhibit distinct magnetic behaviors. Compound 1 shows slow relaxation of its magnetization indicating single-molecule magnet behavior, while no frequency-dependent out-of-phase signals were found for complex 2. This difference is likely to result from electronic effects induced by halogen substitution.
Co-reporter:Xue-Lan Mei, Rui-Na Liu, Chao Wang, Pei-Pei Yang, Li-Cun Li and Dai-Zheng Liao
Dalton Transactions 2012 vol. 41(Issue 10) pp:2904-2909
Publication Date(Web):20 Jan 2012
DOI:10.1039/C2DT11671E
Three novel ring-like compounds formulated as [Ln(Phtfac)3(NITpPy)]2 (LnIII = Gd 1, Tb 2, Dy 3; HPhtfac = 4,4,4-trifluoro-1-phenylbutane-1,3-dione; NITpPy = 2-(4-pyridyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazolyl-1-oxyl-3-oxide) were synthesized and structurally and magnetically characterized. Three compounds possess cyclic dimer structure in which each pyridine substituted radical links two different metal ions through the oxygen of nitroxide group and the pyridine nitrogen. DC magnetic studies show the Ln(III) ion interacts ferromagnetically with the directly bonding nitronyl nitroxide. Both Tb(III) and Dy(III) clusters show frequency-dependent ac magnetic susceptibilities, indicating single-molecule magnet behavior. It is demonstrated that the β-diketonate coligand may play an important role in determining the magnetic relaxation for the lanthanide-radical system.
Co-reporter:Yi-Xia Ren, Shan-Shan Xiao, Xiang-Jun Zheng, Li-Cun Li and Lin-Pei Jin
Dalton Transactions 2012 vol. 41(Issue 9) pp:2639-2647
Publication Date(Web):06 Jan 2012
DOI:10.1039/C2DT11532H
Hydro- and solvo-thermal reactions of d-block metal ions (Mn2+, Co2+, Zn2+ and Cd2+) with monosodium 2-sulfoterephthalate (NaH2stp) form six 3D coordination polymers featuring cluster core [M4(μ3-OH)2]6+ in common: [M2(μ3-OH)(stp)(H2O)] (M = Co (1), Mn (2) and Zn (3)), [Zn2(μ3-OH)(stp)(H2O)2] (4), [Zn4(μ3-OH)2(stp)2(bpy)2(H2O)]·3.5H2O (5) and [Cd2(μ3-OH)(stp) (bpp)2]·H2O (6) (stp = 2-sulfoterephthalate, bpy = 4,4′-bipyridine and bpp = 1,3-di(4-pyridyl)propane). All these coordination polymers were characterized by single crystal X-ray diffraction, IR spectroscopy, thermogravimetric and elemental analysis. Complexes 1–3 are isostructural coordination polymers with 3D frameworks based on the chair-like [Zn4(μ3-OH)2]6+ core and the quintuple helixes. In complex 4, there exist double helixes in the 3D framework based on the chair-like cluster cores. Complex 5 possesses a 2-fold interpenetration structure constructed from boat-like cluster core and the bridging ligands stp and bpy. For complex 6, the chair-like cluster cores and stp ligands form a 2D (4,4) network which is further pillared by bpp linkers to a 3D architecture. Magnetic studies indicate that complex 1 exhibits magnetic ordering below 4.9 K with spin canting, and complex 2 shows weak antiferromagnetic coupling between the Mn(II) ions with g = 2.02, Jwb = −2.88 cm−1, Jbb = −0.37 cm−1. The fluorescence studies show that the emissions of complexes 3–6 are attributed to the ligand π–π* transition.
Co-reporter:Xue-Lan Mei, Yue Ma, Li-Cun Li and Dai-Zheng Liao
Dalton Transactions 2012 vol. 41(Issue 2) pp:505-511
Publication Date(Web):31 Oct 2011
DOI:10.1039/C1DT11795E
Three new 2p–4f complexes of [Ln(acac)3(NIT-2Py)]·0.5NIT-2Py [Ln(III) = Gd(1), Dy(2)] and [Dy(tfa)3(NIT-2Py)]·0.5C7H16 (3) (NIT-2Py = 2-(2′-pyridyl)- 4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide; acac = acetylacetonate and tfa = trifluoroacetylacetonate) have been synthesized, and structurally and magnetically characterized. The X-ray structural analysis exhibits that the three complexes show similar mononuclear structures, in which NIT-2Py radical chelates the Ln(III) ion through the oxygen atom of the NO group and the nitrogen atom from the pyridine ring. The static magnetic measurements on the three complexes exhibit ferromagnetic coupling between the lanthanide ion and the radical. Compared to the silence of the out-of-phase ac susceptibility of complex 3, the magnetic relaxation behavior of complex 2 is observed, suggesting single-molecule magnet behavior. The different magnetic relaxation behaviours of 2 and 3 are due to their slightly different crystal structure around the Dy(III) ions. It was demonstrated that the spin dynamic can be modified by the careful adjustment of the ligand field around the metal center.
Co-reporter:Ruina Liu, Congming Zhang, Xuelan Mei, Peng Hu, Haixia Tian, Licun Li, Daizheng Liao and Jean-Pascal Sutter
New Journal of Chemistry 2012 vol. 36(Issue 10) pp:2088-2093
Publication Date(Web):18 Jul 2012
DOI:10.1039/C2NJ40570A
Reaction of the nitronyl nitroxide radical NIT-3Brthien with Ln(hfac)3 affords two one-dimensional lanthanide–nitronyl nitroxide compounds [Ln(hfac)3(NIT-3Brthien)] (Ln = Gd(III) 1, Tb(III) 2; NIT-3Brthien = 2-(3′-bromo-2′-thienyl)-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide). Single crystal X-ray crystallographic analysis reveals that both compounds are composed of linear chains built up by Ln(hfac)3 units bridged by NIT-5Brthien radicals through their NO groups. DC magnetic measurements reveal that the Gd complex is paramagnetic above 2.0 K, while the Tb complex orders antiferromagnetically at 4.0 K. Moreover, complex 2 possesses frequency-dependence of ac magnetic susceptibilities. The magnetic behavior of complex 2 is unique and exhibits the coexistence of slow magnetic relaxation, metamagnetism and antiferromagnetic three-dimensional magnetic ordering.
Co-reporter:RuiNa Liu;Peng Hu;LiCun Li;DaiZheng Liao;Jean-Pascal Sutter
Science China Chemistry 2012 Volume 55( Issue 6) pp:997-1003
Publication Date(Web):2012 June
DOI:10.1007/s11426-012-4580-3
A series of new lanthanide-radical complexes [{Ln(hfac)3}2(NITPhIM)2] (Ln = Nd (1), Eu (2), Tb (3), Er (4); hfac = hexafluoroacetylacetonate; NITPhIM = 2-[4-(1-imidazole)phenyl]-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide) have been prepared and characterized. Single crystal X-ray diffraction analyses reveal that these complexes are isostructural with one-dimensional chain structures. These consist in Ln(hfac)3 units bridged by the paramagnetic ligands by the means of coordination of their nitronyl nitroxide groups and imidazole rings. Interestingly, each Ln ion is either bound to two nitronyl nitroxide groups or to two imidazole units, and the different Ln centers alternate along the chain. Magnetic studies show that complex 3 exhibits a single-chain magnet behavior.
Co-reporter:Pei-Pei Yang ; Xi-Feng Gao ; Hai-Bin Song ; Sai Zhang ; Xue-Lan Mei ; Li-Cun Li ;Dai-Zheng Liao
Inorganic Chemistry 2011 Volume 50(Issue 3) pp:720-722
Publication Date(Web):December 27, 2010
DOI:10.1021/ic1021643
Two novel dysprosium(III) clusters have been prepared and structurally characterized. One has a tetranuclear core with a rare zigzag arrangement, and the other is an unprecedented octanuclear cluster with six triangular Dy3 units sharing vertices. Both dysprosium(III) clusters possess frequency-dependent on alternating-current magnetic susceptibilities, indicating possible single-molecule magnet behavior.
Co-reporter:Pei-Pei Yang, Xiao-Ling Wang, Li-Cun Li and Dai-Zheng Liao
Dalton Transactions 2011 vol. 40(Issue 16) pp:4155-4161
Publication Date(Web):08 Mar 2011
DOI:10.1039/C0DT01746A
The structures and magnetic properties of four isomorphous nonanuclear heterometallic complexes [Na2{Mn3III(μ3-O2−)}2LnIII(hmmp)6(O2CPh)4(N3)2]OH·0.5 CH3CN·1.5H2O are reported, where LnIII = Eu (1), Gd (2), Tb (3) and Dy (4), H2hmmp = 2-[(2-hydroxyethylimino)methyl]-6-methoxyphenol. Complexes 1–4 were prepared by the reactions of hmmpH2 with a manganese salt and the respective lanthanide salt together with NaO2CPh and NaN3. Single-crystal X-ray diffraction analyses reveal that the six MnIII and one LnIII metal topology in the aggregate can be described as a bitetrahedron. The two peripheral [MnIII3(μ3-O2−)]7+ triangles are each bonded to a central LnIII ion with rare distorted octahedral geometry. The magnetic properties of all the complexes were investigated using variable temperature magnetic susceptibility and both antiferromagnetic and ferromagnetic interactions exist in the [MnIII3(μ3-O2−)]7+ triangle. Weak ferromagnetic exchange between the LnIII and MnIII ions has been established for the corresponding Gd derivative. The Gd, Tb and Dy complexes show no evidence of slow relaxation behaviour above 2.0 K.
Co-reporter:Xiao-Yan Xing, Xue-Lan Mei, Li-Cun Li
Journal of Molecular Structure 2011 Volume 992(1–3) pp:89-95
Publication Date(Web):19 April 2011
DOI:10.1016/j.molstruc.2011.02.050
Four new diverse structural iron(II) coordination polymers, namely, [Fe(btx)3(H2O)2](ClO4)2·2H2O·btx (1), [Fe(btx)(N(CN)2)2(H2O)2] (2), [Fe(btx)2(SCN)2]·0.5EtOH·CH3CN (3) and [Fe(btx)2(N(CN)2)(H2O)](ClO4)·EtOH·H2O (4) [btx = 1,4-bis(1,2,4-triazol-1-ylmethyl)benzene], are reported with their crystal structures and magnetic properties. Compounds 1 and 2 possess 1D chain bridged by btx ligands, while compounds 3 and 4 have similar 2D (4,4) sheet-like structure. Variable temperature magnetic susceptibility measurements indicate that all of these iron(II) polymers retain a high-spin ground state and the values of χMT at low temperature are attributed to the zero-field splitting of the iron(II) ions and weak antiferromagnetic coupling.
Co-reporter:Xiao-Ling Wang, Hai-Xia Tian, Yue Ma, Pei-Pei Yang, Li-Cun Li, Dai-Zheng Liao
Inorganic Chemistry Communications 2011 Volume 14(Issue 11) pp:1728-1731
Publication Date(Web):November 2011
DOI:10.1016/j.inoche.2011.07.016
Two lanthanide-radical complexes [Tb(hfac)3(IM-2py)] (1) and [Tb(hfac)3(IM-2thz)] (2) (hfac = hexafluoroacetylacetonate; IM-2py = 2-(2′-pyridyl)-4,4,5,5-tetramethyl- imidazoline-1-oxyl; IM-2thz = 2-(2′-thiazolyl)-4,4,5,5-tetramethylimidazoline-1-oxyl) have been synthesized. Single crystal X-ray diffraction analysis reveals that complexes 1 and 2 are mononuclear complexes in which the IM-2py/IM-2thz radical is coordinated to the Tb(III) ion in a chelating way. The similar magnetic behavior is observed for two compounds through direct current magnetic measurements, implying antiferromagnetic coupling between Tb(III) and imino nitroxide radical. Alternating current magnetic susceptibility studies show that both complexes exhibit frequency-dependent out-of-phase signals indicative of a slow relaxation of magnetization.Two imino nitroxide radical-Tb(III) complexes have been synthesized. In two complexes, the imino nitroxide coordinates to the Tb(III) ion as chelating ligand. Both complexes show slow relaxation of magnetization.Highlights► It is the first time to use chelating imino nitroxide ligands to synthesize the SMM. ► Two complexes exhibit the slow magnetic relaxation resembling SMM behavior. ► To explore the magnetic relaxation, the ferromagnetic interaction is favorable.
Co-reporter:Xiao-Ling Wang, Li-Cun Li and Dai-Zheng Liao
Inorganic Chemistry 2010 Volume 49(Issue 11) pp:4735-4737
Publication Date(Web):May 3, 2010
DOI:10.1021/ic100008g
Two rare-earth radical complexes [Ln(hfac)3NIT-2Py]·0.5C7H16 [Ln = Tb (1), Dy (2)] have been synthesized and characterized structurally as well as magnetically. Both complexes are isomorphous, in which the NIT-2Py radical is coordinated to the LnIII ion in a chelating manner. Magnetic studies reveal that complex 1 shows a frequency-dependent, alternating-current magnetic susceptibility typical of a single-molecule magnet, whereas slow magnetic relaxation is observed in 2 under an applied direct-current field.
Co-reporter:Ruina Liu, Yue Ma, Peipei Yang, Xueyan Song, Gongfeng Xu, Jinkui Tang, Licun Li, Daizheng Liao and Shiping Yan
Dalton Transactions 2010 vol. 39(Issue 13) pp:3321-3325
Publication Date(Web):17 Feb 2010
DOI:10.1039/B924303H
A new nitronyl nitroxide bridged one-dimensional lanthanide complex [Tb3(hfac)9(NIT-2thien)3]n (1) (NIT-2thien = 2-(2′-thienyl)-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide) has been successfully prepared. Single crystal X-ray crystallographic analysis reveals that complex 1 consists of linear chains built up by Tb(hfac)3 units bridged by NIT-2thien radicals through their NO groups; the chains run along the crystallographic a-axis. The magnetic behavior of complex 1 is quite unusual. The complex shows the concomitant existence of slow magnetic relaxation and three-dimensional magnetic ordering.
Co-reporter:Xueyan Song;PeiPei Yang;Xuelan Mei;Licun Li ;Daizheng Liao
European Journal of Inorganic Chemistry 2010 Volume 2010( Issue 11) pp:1689-1695
Publication Date(Web):
DOI:10.1002/ejic.200901244
Abstract
The synthesis, crystal structure, and magnetic properties of two new MnIII single-chain magnets, [Mn3O(L)3(HCOO)(CH3OH)4]·2CH3OH (1) and [Mn3O(L)3N3(C2H5OH)3(H2O)] (2) (H2L = 3-tert-butyl-5-methylsalicylaldoxime) are reported. Complexes 1 and 2 consist of a triangle of MnIII ions with an oxido-center bridge and three 3-tert-butyl-5-methylsalicylaldoxime ligands that form a plane with the metal ions. Both complexes contain the same cores with the general formula [Mn3(μ3-O)(L)3]+, which are further connected by formate (complex 1) or azide (complex 2) ligands into chain structures. Temperature-dependent magnetic susceptibility studies indicate the presence of antiferromagnetic interactions between the MnIII ions in 1, whereas predominantly ferromagnetic interactions are observed in 2. Both complexes show slow relaxation of their magnetizations associated with single-chain magnet behavior.
Co-reporter:Xueyan Song, Ruina Liu, Sai Zhang, Licun Li
Inorganic Chemistry Communications 2010 Volume 13(Issue 7) pp:828-830
Publication Date(Web):July 2010
DOI:10.1016/j.inoche.2010.04.003
The reaction of salicylaldoxime (H2sao) with Mn(ClO4)2·6H2O, sodium 3,5-dinitrobenzoate and NEt4(OH) in MeOH/EtOH affords a MnIII hexanuclear compound [Mn6O2(sao)6(ArCO2)2(MeOH)2(EtOH)2(H2O)2] (ArCO2H = 3,5-dinitrobenzoic acid) (1). 1 contains [MnIII6(µ3-O)2]14+ core, with a known structural type in the family of Mn6 clusters. Temperature-dependent magnetic susceptibility study shows presence of predominant ferromagnetic interactions between MnIII ions. Alternating current (ac) susceptibility measurements reveal a frequency-dependent out-of-phase (χM′′) signal below 4 K, suggesting 1 to be a single-molecule magnet (SMM).A new Mn6 SMM with salicylaldoxime ligand was synthesized and characterized crystallographically and magnetically that shows a rare ferromagnetic interaction due to the large Mn–N–O–Mn torsion angle.
Co-reporter:Xiaoyan Xing, Xueyan Song, Peipei Yang, Ruina Liu, Licun Li, Daizheng Liao
Journal of Molecular Structure 2010 Volume 967(1–3) pp:196-200
Publication Date(Web):1 April 2010
DOI:10.1016/j.molstruc.2009.12.052
Two new metal–organic frameworks (MOFs) [Co(btx)(bdc)(H2O)]n1 and [Co3(btx)3(btc)2(H2O)2]n2, (btx = 1,4-bis(1,2,4-triazol-1-ylmethyl)benzene; H2bdc = 1,4-terephthalate acid; H3btc = 1,3,5-benzenetricarboxylate acid) have been synthesized and characterized by single-crystal X-ray diffraction studies and low temperature magnetic measurements. Compounds 1 and 2 are three-dimensional compounds whose structures can be described as layers of Co2 units (1) and Co3 (2) units with the carboxylate groups acting as mono or bidentate ligand, which are further connected through the flexible bis(triazole) ligand. The study of the magnetic properties of 1 and 2 in the temperature range 2–300 K shows the occurrence of weak ferromagnetic interactions in 1 due to the anti–syn carboxylate bridge and weak antiferromagnetic interactions in 2 between the high-spin Co(II) ions.
Co-reporter:Xiao-Ling Wang, Rui-Na Liu, Pei-Pei Yang, Xue-Yan Song, Li-Cun Li
Inorganica Chimica Acta 2010 Volume 363(Issue 7) pp:1415-1420
Publication Date(Web):20 April 2010
DOI:10.1016/j.ica.2010.01.039
Three new ion-pair complexes (m-MPYNN)2Ni(mnt)2 (1), (p-MPYNN)2Ni(mnt)2 (2) and (p-MPYNN)2Cu(mnt)2 (3) (m- or p-MPYNNI = [3- or4- (4,4,5,5-tetramethyl-1-oxido-3-oxyl-4,5-dihydro-3H-imidazol-2′-yl)-1-methylpyridinium] iodide, mnt = maleonitriledithiolate) have been prepared and characterized by elemental analyses, IR, single crystal X-ray diffraction and magnetic susceptibility. In complex 1, the m-MPYNN cations form a centrosymmetric dimer, and the [Ni(mnt)2]2− anion lies on a center of inversion. Complexes 2 and 3 show layered packing, and the p-MPYNN cations lie between the layers of the anions. Magnetic susceptibility measurements in the temperature range 2–300 K show that the three complexes exhibit weak antiferromagnetic behaviors. The behavior of complex 1 was explained with the singlet-triplet model.Three ion-pair complexes with M(mnt)22- (M = Cu, Ni) cations and m- or p-MPYNN cations have been synthesized and characterized. The m-MPYNN cations in complex 1 show a centrosymmetric dimer. Magnetic investigations reveal that they all have weak antiferromagnetic interactions.
Co-reporter:Haixia Tian;Ruina Liu;Xiaoling Wang;Peipei Yang;Zuoxi Li;Licun Li ;Daizheng Liao
European Journal of Inorganic Chemistry 2009 Volume 2009( Issue 29-30) pp:4498-4502
Publication Date(Web):
DOI:10.1002/ejic.200900584
Abstract
Two nitronyl nitroxide radical-TbIII complexes, [Tb(hfac)3(NIT-3Py)]2 (1) and [Tb(hfac)3(NIT-4Py)]2 (2) {hfac = hexafluoroacetylacetonate; NIT-3Py = 2-(3′-pyridyl)-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide; NIT-4Py = 2-(4′-pyridyl)-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide} have been synthesized. Both complexes possess cyclic dimer structure in which each pyridyl-substituted radical links two different metal ions through the oxygen of nitroxide group and the pyridine nitrogen. DC magnetic studies show the TbIII ion interacts ferromagnetically with the directly bonding nitronyl nitroxide. Complex 1 exhibits magnetic slow relaxation resembling SMM behavior, while there are no clearly the frequency-dependent out-of-phase signals for complex 2.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Co-reporter:Rui-Na Liu, Li-Cun Li, Xiao-Yan Xing, Dai-Zheng Liao
Inorganica Chimica Acta 2009 Volume 362(Issue 7) pp:2253-2258
Publication Date(Web):15 May 2009
DOI:10.1016/j.ica.2008.10.017
Using new nitronyl nitroxide radical ligand 2-[4-(1-imidazole)phenyl]-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (NITPhIm), three new complexes [M(hfac)2(NITPhIm)]2 (M = Cu(II) 1, Mn(II) 2, Co(II) 3; hfac = hexafluoroacetylacetonate) have been prepared. Three complexes possess cyclic dimer structure in which each NITPhIm radical links two different metal ions through the oxygen of nitroxide group and the nitrogen of imidazole. The magnetic studies show the copper(II) ion interacts ferromagnetically with the directly bonding nitronyl nitroxide while manganese(II) and cobalt(II) ions strong antiferromagnetically interact with the directly coordinated nitroxide groups. There is a weak antiferromagnetic coupling between the metal ion and the nitroxide through phenyl and imidazole rings of the radical ligand, which is agreement with spin polarization mechanism. The results show that the minor changes in the structure of radical ligand can change the magnetic behavior of radical–metal complex.Three new metal–radical complexes [Cu(hfac)2(NITPhIm)]2 · 2C6H14 (hfac) = hexafluoroacetylacetonate) (1), [Mn(hfac)2(NITPhIm)]2 (2) and [Co(hfac)2(NITPhIm)]2 (3) are prepared with new nitronyl nitroxide radical ligand 2-[4-(1-imidazole)phenyl]-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (NITPhIm). The complexes are four-spin cyclic dimers. Complex 1 shows ferromagnetic coupling while strong antiferromagnetic interactions are observed for complexes 2 and 3.
Co-reporter:Zong-Wei Li, Pei-Pei Yang, Li-Cun Li, Dai-Zheng Liao
Inorganica Chimica Acta 2009 Volume 362(Issue 9) pp:3381-3384
Publication Date(Web):1 July 2009
DOI:10.1016/j.ica.2009.02.047
A new heterometallic complex [CuMn(5-Brsap)2(MeOH)(Ac)] ⋅ CH3OH (1) (5-Brsap = 5-bromo-2-salicylideneamino-1-propanol) has been synthesized and characterized structurally as well as magnetically. Complex 1 has an alkoxo-bridged Cu(II) and Mn(III) heterobinuclear core, where the Mn(III) and Cu(II) ions have elongated octahedral and square–pyramidal geometries, respectively. In dc magnetic susceptibility measurements reveal that there is strong ferromagnetic interaction between the Mn(III) and Cu(II) ions with an exchange coupling constant J = 67.64 cm−1. The ac magnetic susceptibility measurements, frequency dependence in both the real and imaginary signals is observed, which indicates slow relaxation of magnetization. An Arrhenius plot gave the effective anisotropy barrier Δ/kB = 11.58 K and the pre-exponential factor ι0 = 1.28 × 10−6 s.A new heterobinuclear complex [CuMn(5-Brsap)2(MeOH)(Ac)] ⋅ CH3OH (1) (5-Brsap = 5-bromo-2-salicylideneamino-1-propanol) has been synthesized and characterized structurally as well as magnetically. The complex exhibits strong ferromagnetic interaction between the Cu(II) and Mn(III) ions and slow relaxation of magnetization.
Co-reporter:Xiao-Ling Wang, Pei-Pei Yang, Zong-Wei Li, Li-Cun Li, Dai-Zheng Liao
Inorganica Chimica Acta 2009 Volume 362(Issue 6) pp:1901-1906
Publication Date(Web):20 April 2009
DOI:10.1016/j.ica.2008.09.001
Co-reporter:Yun-He Xu;Xiao-Ling Wang;Zong-Hui Jiang
Journal of Chemical Crystallography 2009 Volume 39( Issue 1) pp:
Publication Date(Web):2009 January
DOI:10.1007/s10870-008-9434-7
Two novel complexes [Zn(NIT3-py)(tp)]n1 and [Zn(im3-py)(tp)]n2 (NIT3-py = 2-(3′-pyridyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, im3-py = 2-(3′-pyridyl)-4,4,5,5-tetramethylimidazoline-1-oxyl, tp = terephthalato) have been synthesized and structurally determined by X-ray diffraction analysis. Complex 1 is, monoclinic, space group P2/c, with a = 12.6459(14), b = 6.9110(8), c = 20.0376(17) Å, β = 112.030(5), V = 1623.3(3) Å3 with Z = 2, for dcalc = 1.428 Mg/m3. The analog 2 is, monoclinic, space group P2/n, with a = 12.2313(15), b = 6.8478(9), c = 19.908(3) Å, β = 107.368(2), V = 1591.4(3) Å3, with Z = 2 for dcalc = 1.390 Mg/m3. X-ray analysis reveals that both Zn(II) ions are four-coordinated by two carboxylate oxygen atoms and two pyridyl-N atoms from nitroxide radicals to form a tetrahedron geometry. Each terephthalate dianion bridges two Zn(II) ions in bis-monodentate mode, resulting in a 1D chain structure.
Co-reporter:Xiaoni Qu;Xueyan Song;Wei Li;Yunhe Xu;Licun Li;Daizheng Liao;Zonghui Jiang
European Journal of Inorganic Chemistry 2008 Volume 2008( Issue 8) pp:1287-1292
Publication Date(Web):
DOI:10.1002/ejic.200701090
Abstract
Two new oxamato-bridged copper(II) complexes of formula Na10[{Cu2(mpba)2}2(μ1,1-N3)2]·18H2O (1) and [{Cu2(mpba)2}Cu2(H2O)8]·6H2O (2) [mpba = 1,3-phenylenebis(oxamato-N,N′)] have been synthesized and characterized. X-ray crystallographic studies of complex 1 reveal a metallamacrocycle structure in which two dinuclear copper(II) metallacyclophane anions are linked by two single symmetric azido ligands in an end-on mode at axial–axial positions. These metallamacrocycle units are self-assembled through sodium cations and water molecules, affording an intricate 3D network. Complex 2 consists of 2D brick-wall-like layers assembled from dinuclear metallacyclophane [Cu2(mpba)2]4– anions and copper(II) cations. Magnetic susceptibility measurements of complex 1 in the temperature range 2–300 K show dominating ferromagnetic coupling mediated by the m-phenylenediamide bridge and weak antiferromagnetic interaction transmitted by the azido ligand.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Co-reporter:Wei Li, Xiao-Ling Wang, Xue-Yan Song, Li-Cun Li, Dai-Zheng Liao, Zong-Hui Jiang
Journal of Molecular Structure 2008 Volume 885(1–3) pp:1-6
Publication Date(Web):14 August 2008
DOI:10.1016/j.molstruc.2007.09.029
Two novel lanthanide picolinate complexes [Ln(pic)3](Ln = Nd(1) and Sm(2); Hpic = picolinic acid) were prepared by hydrothermal method. The results of an X-ray crystallographic analysis reveal that both of complexes are unique tris-carboxylato-bridged one-dimensional chain structures. This 1D chain consists of one zigzag strand and two helical strands formed by oxygen atoms of the carboxylato groups and metal ions. The luminescence properties of complex 2 show the characteristic transition of the Sm(III). The magnetic properties of complexes 1 and 2 also have been studied.
Co-reporter:Wei Li, Zongwei Li, Licun Li, Daizheng Liao, Zonghui Jiang
Journal of Solid State Chemistry 2007 Volume 180(Issue 10) pp:2973-2977
Publication Date(Web):October 2007
DOI:10.1016/j.jssc.2007.09.006
The synthesis, structural characterization, and magnetic behavior of a novel one-dimensional azido-bridged manganese(III) complex of formula [Mn(L)2N3] (1) is reported, where HL is the bidentate Schiff base obtained from the condensation of salicylaldehyde with 4-methoxy aniline. Complex 1 crystallizes in the monoclinic system, space group P21/n, with a=11.743(4) Å, b=24.986(9) Å, c=13.081(5) Å, β=95.387(7)° and Z=2. The complex is of one-dimensional chain structure with single end-to-end azido bridges and the manganese(III) ion has an elongated octahedral geometry. Magnetic studies show that the weak antiferromagnetic interaction is mediated by the single end-to-end azido bridge with the exchange parameter J=−5.84 cm−1.A novel azido-bridged manganese(III) complex with bidentate Schiff base ligands has been prepared and characterized structurally and magnetically. The complex is of one-dimensional chain structure with single end-to-end azido bridges in axial positions. Two bidentate Schiff base ligands coordinate in the equatorial mode. The magnetic measurements show that the complex exhibits weak antiferromagnetic interaction.
Co-reporter:Xue-yan Song, Yun-he Xu, Li-cun Li, Dai-zheng Liao, Zong-hui Jiang
Inorganica Chimica Acta 2007 Volume 360(Issue 6) pp:2039-2044
Publication Date(Web):20 April 2007
DOI:10.1016/j.ica.2006.10.037
A novel tetranuclear cubane-like complex [Ni4(hbzim)4(N3)4(mal)2(CH3OH)(H2O)] (Hhbzim = 2-hydroxymethylbenzimidazole, mal = 4-methoxyaniline) has been synthesized and characterized structurally as well as magnetically. The structure analyses reveal that this complex consists of a Ni4O4 cubane core and the different coordinate environments of the nickel(II) ions result in a cubane structure with differing Ni–Ni distances and Ni–O–Ni angles. The magnetic properties of this complex have been interpreted by employing one-J and two-J model. The results show that ferromagnetic interaction dominates in the complex.A novel tetranuclear cubane-like complex [Ni4(hbzim)4(N3)4(mal)2(CH3OH)(H2O)] (Hhbzim = 2-hydroxymethylbenzimidazole, mal = 4-methoxyaniline) has been synthesized. The magnetic properties of this complex have been interpreted by the employing one-J and two-J model. The results show that the ferromagnetic interaction dominates in the complex.
Co-reporter:Xu-Da Wang;Mao Liang;Zong-Hui Jiang;Dai-Zheng Liao
Structural Chemistry 2007 Volume 18( Issue 1) pp:5-8
Publication Date(Web):2007 February
DOI:10.1007/s11224-006-9010-8
A novel malonate-bridged copper (II) compound of formula {[Cu4(4,4′-bpy)8(mal)2(H2O)4](ClO4)2(H2O)4(CH3OH)2}n (4,4′-bpy = 4,4′-bipyridine; mal = malonate dianion) has been prepared and structurally characterized by X-ray crystallography. This compound exhibits a novel three-dimensional network being composed of Cu-4,4′-bipyridine layers which are pillared by malonate bridge ligands. The copper(II) ions has two different coordination environment.
Co-reporter:Meng Yang, Hongdao Li, Licun Li
Inorganic Chemistry Communications (February 2017) Volume 76() pp:
Publication Date(Web):February 2017
DOI:10.1016/j.inoche.2017.01.014
•Two rare Ln-rad 1D chains were obtained by using functionalized nitronyl nitroxides.•The radicals bridge the Ln ions with a ‘head-to-tail’ motif.•Short distances of interchain NO groups are observed.•Important interchain antiferromagnetic couplings dominate in the system.Two novel Ln-radical chains [Ln(hfac)3NIT-3Py-5Im]n (LnIII = Gd 1, Dy 2; hfac = hexafluoroacetylacetonate; NIT-3Py-5Im = 2-(5-(1-imidazole)-3-pyridyl)-4,4,5,5- tetramethylimidazoline-1-oxyl-3-oxide) have been achieved. In two complexes, the functionalized radical ligand NIT-3Py-5Im acts as bridge ligand to link two Ln(III) ions through the NO group and the imidazole ring, leading to rare 1D lanthanide-radical chains. Magnetic studies show that antiferromagnetic interactions dominate in the system owing to the short contacts of NO groups between the chains.Two novel 1D chain Ln-rad complexes were obtained and antiferromagnetic interactions dominated in these complexes due to the short contacts of inter-chain NO groups.
Co-reporter:Gui-Fang Sun, Cong-Ming Zhang, Jian-Ni Guo, Meng Yang, Li-Cun Li
Journal of Molecular Structure (5 May 2017) Volume 1135() pp:
Publication Date(Web):5 May 2017
DOI:10.1016/j.molstruc.2017.01.053
•New binuclear LnIII complexes were synthesized by using amino alcoholate ligand.•Dy derivative exhibits slow magnetic relaxation behavior.•Dy and Tb derivatives displayed characteristic luminescent properties.Two binuclear lanthanide complexes [Ln2(hfac)6(HL)2] (LnIII = Dy(1), Tb(2); hfac = hexafluoroacetylacetonate, HL = (R)-2-amino-2-phenylethanol) have been successfully obtained by using amino alcoholate ligand. In two complexes, the Ln(III) ions are bridged by two alkoxido groups from HL ligands, resulting in binuclear complexes. The variable-temperature magnetic susceptibility studies indicate that there exists ferromagnetic interaction between two Ln(III) ions. Frequency dependent out-of-phase signals are observed for complex 1, suggesting SMM type behavior. Complexes 1 and 2 display intensely characteristic luminescent properties.Two new binuclear lanthanide complexes [Ln2(hfac)6(HL)2] (LnIII = Dy, Tb) have been obtained by means of amino alcoholate ligand. Complex Dy shows SMM behavior and fluorescence properties, simultaneously.
Co-reporter:Ruina Liu, Yue Ma, Peipei Yang, Xueyan Song, Gongfeng Xu, Jinkui Tang, Licun Li, Daizheng Liao and Shiping Yan
Dalton Transactions 2010 - vol. 39(Issue 13) pp:NaN3325-3325
Publication Date(Web):2010/02/17
DOI:10.1039/B924303H
A new nitronyl nitroxide bridged one-dimensional lanthanide complex [Tb3(hfac)9(NIT-2thien)3]n (1) (NIT-2thien = 2-(2′-thienyl)-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide) has been successfully prepared. Single crystal X-ray crystallographic analysis reveals that complex 1 consists of linear chains built up by Tb(hfac)3 units bridged by NIT-2thien radicals through their NO groups; the chains run along the crystallographic a-axis. The magnetic behavior of complex 1 is quite unusual. The complex shows the concomitant existence of slow magnetic relaxation and three-dimensional magnetic ordering.
Co-reporter:Mei Zhu, Juanjuan Wang, Meng Yang, Yue Ma and Licun Li
Dalton Transactions 2015 - vol. 44(Issue 21) pp:NaN9822-9822
Publication Date(Web):2015/04/17
DOI:10.1039/C4DT03330B
Three isostructural two-dimensional 2p–3d–4f complexes, namely, {Tb(hfac)3[Cu(hfac)2]3(NITPhPyrim)2}·2CH2Cl21 and {Ln(hfac)3[Cu(hfac)2]3(NITPhPyrim)2} (LnIII = Ho 2, Yb 3; hfac = hexafluoroacetylacetonate; NITPhPyrim = 2-[4-(5-pyrimidyl)phenyl]-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide), were characterized in terms of structure and magnetism. These heterospin compounds possess a two-dimensional sheet structure involving CuII and LnIII ions bridged by NITPhPyrim radicals through their NO groups and pyrimidine rings. DC magnetic studies show that these complexes exhibit ferromagnetic exchange coupling between radical ligands and metal atoms. AC measurements of the Tb complex reveal slow relaxation of the magnetization. Interestingly, the Tb complex displays two field-induced relaxation processes.
Co-reporter:Mei Zhu, Licun Li and Jean-Pascal Sutter
Inorganic Chemistry Frontiers 2016 - vol. 3(Issue 8) pp:NaN1003-1003
Publication Date(Web):2016/05/04
DOI:10.1039/C6QI00075D
The promising magnetic behavior of heterospin systems has spurred the research of 2p–3d–4f hetero-tri-spin compounds. Such a magnetic system has crucial advantages: the strongest possible magnetic interactions resulting from the direct binding of the radicals to the metal ions, access to strong magnetic anisotropies arising from 4f ions, and novel magnetic behavior derived from the synergic or competitive magnetic interactions between three different spin carriers. Herein we review recent advances made toward a rational development of 2p–3d–4f complexes. Special attention is given to the 2p–3d–4f compounds exhibiting slow magnetic relaxation.
Introduction to the international collaboration
Licun Li obtained his Ph.D. from Nankai University (2002). Now he is a Professor of Chemistry at Nankai University and his current research interests are in the field of molecular magnetism, especially metal–radical compounds. Dr Jean-Pascal Sutter received his Ph.D. from Strasbourg University in 1992. He joined the French National Center for Scientific Research (CNRS) and currently is a research director at the Coordination Chemistry Lab (LCC) in Toulouse (France). Both have worked together in 1995 in the group of Prof. Olivier Kahn at the Institut de Chimie de la Matière Condensée de Bordeaux (ICMCB). Since 2010 they have actively collaborated on the topic covered by the present review.
Co-reporter:Mei Zhu, Xuelan Mei, Yue Ma, Licun Li, Daizheng Liao and Jean-Pascal Sutter
Chemical Communications 2014 - vol. 50(Issue 15) pp:NaN1908-1908
Publication Date(Web):2014/01/09
DOI:10.1039/C3CC48110G
A novel approach for the preparation of hetero-tri-spin magnetic compounds is described. It consists in using preformed metal–nitronyl nitroxide complexes as metallo-ligands in an assembling process involving an additional metal centre. This is illustrated by two unprecedented radical–Cu–Ln chain compounds (Ln = Gd3+, Tb3+).
Co-reporter:Pei-Pei Yang, Xiao-Ling Wang, Li-Cun Li and Dai-Zheng Liao
Dalton Transactions 2011 - vol. 40(Issue 16) pp:NaN4161-4161
Publication Date(Web):2011/03/08
DOI:10.1039/C0DT01746A
The structures and magnetic properties of four isomorphous nonanuclear heterometallic complexes [Na2{Mn3III(μ3-O2−)}2LnIII(hmmp)6(O2CPh)4(N3)2]OH·0.5 CH3CN·1.5H2O are reported, where LnIII = Eu (1), Gd (2), Tb (3) and Dy (4), H2hmmp = 2-[(2-hydroxyethylimino)methyl]-6-methoxyphenol. Complexes 1–4 were prepared by the reactions of hmmpH2 with a manganese salt and the respective lanthanide salt together with NaO2CPh and NaN3. Single-crystal X-ray diffraction analyses reveal that the six MnIII and one LnIII metal topology in the aggregate can be described as a bitetrahedron. The two peripheral [MnIII3(μ3-O2−)]7+ triangles are each bonded to a central LnIII ion with rare distorted octahedral geometry. The magnetic properties of all the complexes were investigated using variable temperature magnetic susceptibility and both antiferromagnetic and ferromagnetic interactions exist in the [MnIII3(μ3-O2−)]7+ triangle. Weak ferromagnetic exchange between the LnIII and MnIII ions has been established for the corresponding Gd derivative. The Gd, Tb and Dy complexes show no evidence of slow relaxation behaviour above 2.0 K.
Co-reporter:Peng Hu, Mei Zhu, Xuelan Mei, Haixia Tian, Yue Ma, Licun Li and Daizheng Liao
Dalton Transactions 2012 - vol. 41(Issue 48) pp:NaN14656-14656
Publication Date(Web):2012/10/11
DOI:10.1039/C2DT31806G
Three rare earth–nitronyl nitroxide radical complexes [Ln(tfa)3(NIT-BzImH)] (Ln(III) = Gd 1, Tb 2, Dy 3; tfa = trifluoroacetylacetonate; NIT-BzImH = 2-(2′-benzimidazolyl)-4,4,5,5-tetramethylimidazolyl-1-oxyl-3-oxide) have been successfully prepared and structurally characterized. X-Ray crystallographic analysis reveals that all three complexes are isomorphous. Their crystal structures consist of mononuclear molecule units in which lanthanide(III) is 8-coordinated to one NIT-BzImH and three trifluoroacetylacetonate ligands. The NIT-BzImH acts as a bidentate ligand via its nitrogen atom of the imidazole ring and the oxygen atom of the N–O group. The magnetic properties of complexes 1–3 were studied. All the three complexes exhibit ferromagnetic Ln(III)–radical coupling. AC magnetic susceptibility studies of 2 and 3 show slow magnetic relaxation suggesting that they behave as SMMs.
Co-reporter:Ruina Liu, Congming Zhang, Licun Li, Daizheng Liao and Jean-Pascal Sutter
Dalton Transactions 2012 - vol. 41(Issue 39) pp:NaN12144-12144
Publication Date(Web):2012/08/14
DOI:10.1039/C2DT31310C
Reaction of Dy(hfac)3·2H2O (hfac = hexafluoroacetyl acetonate) with 2-(2-hydroxyphenyl)nitronyl nitroxide (NITPhOH) and 2-(5-bromo-2-hydroxyphenyl)nitronyl nitroxide (NIT5BrPhOH) yielded [Dy2(hfac)4(NITPhO)2] 1 and [Dy2(hfac)4(NIT5BrPhO)2] 2, respectively. These compounds are phenoxo-O bridged binuclear complexes with the radical unit of a ligand coordinated to a single Dy. The Ln centers exhibit a heptacoordinated environment. Despite having very similar structures, these compounds exhibit distinct magnetic behaviors. Compound 1 shows slow relaxation of its magnetization indicating single-molecule magnet behavior, while no frequency-dependent out-of-phase signals were found for complex 2. This difference is likely to result from electronic effects induced by halogen substitution.
Co-reporter:Xue-Lan Mei, Yue Ma, Li-Cun Li and Dai-Zheng Liao
Dalton Transactions 2012 - vol. 41(Issue 2) pp:NaN511-511
Publication Date(Web):2011/10/31
DOI:10.1039/C1DT11795E
Three new 2p–4f complexes of [Ln(acac)3(NIT-2Py)]·0.5NIT-2Py [Ln(III) = Gd(1), Dy(2)] and [Dy(tfa)3(NIT-2Py)]·0.5C7H16 (3) (NIT-2Py = 2-(2′-pyridyl)- 4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide; acac = acetylacetonate and tfa = trifluoroacetylacetonate) have been synthesized, and structurally and magnetically characterized. The X-ray structural analysis exhibits that the three complexes show similar mononuclear structures, in which NIT-2Py radical chelates the Ln(III) ion through the oxygen atom of the NO group and the nitrogen atom from the pyridine ring. The static magnetic measurements on the three complexes exhibit ferromagnetic coupling between the lanthanide ion and the radical. Compared to the silence of the out-of-phase ac susceptibility of complex 3, the magnetic relaxation behavior of complex 2 is observed, suggesting single-molecule magnet behavior. The different magnetic relaxation behaviours of 2 and 3 are due to their slightly different crystal structure around the Dy(III) ions. It was demonstrated that the spin dynamic can be modified by the careful adjustment of the ligand field around the metal center.
Co-reporter:Xue-Lan Mei, Rui-Na Liu, Chao Wang, Pei-Pei Yang, Li-Cun Li and Dai-Zheng Liao
Dalton Transactions 2012 - vol. 41(Issue 10) pp:NaN2909-2909
Publication Date(Web):2012/01/20
DOI:10.1039/C2DT11671E
Three novel ring-like compounds formulated as [Ln(Phtfac)3(NITpPy)]2 (LnIII = Gd 1, Tb 2, Dy 3; HPhtfac = 4,4,4-trifluoro-1-phenylbutane-1,3-dione; NITpPy = 2-(4-pyridyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazolyl-1-oxyl-3-oxide) were synthesized and structurally and magnetically characterized. Three compounds possess cyclic dimer structure in which each pyridine substituted radical links two different metal ions through the oxygen of nitroxide group and the pyridine nitrogen. DC magnetic studies show the Ln(III) ion interacts ferromagnetically with the directly bonding nitronyl nitroxide. Both Tb(III) and Dy(III) clusters show frequency-dependent ac magnetic susceptibilities, indicating single-molecule magnet behavior. It is demonstrated that the β-diketonate coligand may play an important role in determining the magnetic relaxation for the lanthanide-radical system.
Co-reporter:Yi-Xia Ren, Shan-Shan Xiao, Xiang-Jun Zheng, Li-Cun Li and Lin-Pei Jin
Dalton Transactions 2012 - vol. 41(Issue 9) pp:NaN2647-2647
Publication Date(Web):2012/01/06
DOI:10.1039/C2DT11532H
Hydro- and solvo-thermal reactions of d-block metal ions (Mn2+, Co2+, Zn2+ and Cd2+) with monosodium 2-sulfoterephthalate (NaH2stp) form six 3D coordination polymers featuring cluster core [M4(μ3-OH)2]6+ in common: [M2(μ3-OH)(stp)(H2O)] (M = Co (1), Mn (2) and Zn (3)), [Zn2(μ3-OH)(stp)(H2O)2] (4), [Zn4(μ3-OH)2(stp)2(bpy)2(H2O)]·3.5H2O (5) and [Cd2(μ3-OH)(stp) (bpp)2]·H2O (6) (stp = 2-sulfoterephthalate, bpy = 4,4′-bipyridine and bpp = 1,3-di(4-pyridyl)propane). All these coordination polymers were characterized by single crystal X-ray diffraction, IR spectroscopy, thermogravimetric and elemental analysis. Complexes 1–3 are isostructural coordination polymers with 3D frameworks based on the chair-like [Zn4(μ3-OH)2]6+ core and the quintuple helixes. In complex 4, there exist double helixes in the 3D framework based on the chair-like cluster cores. Complex 5 possesses a 2-fold interpenetration structure constructed from boat-like cluster core and the bridging ligands stp and bpy. For complex 6, the chair-like cluster cores and stp ligands form a 2D (4,4) network which is further pillared by bpp linkers to a 3D architecture. Magnetic studies indicate that complex 1 exhibits magnetic ordering below 4.9 K with spin canting, and complex 2 shows weak antiferromagnetic coupling between the Mn(II) ions with g = 2.02, Jwb = −2.88 cm−1, Jbb = −0.37 cm−1. The fluorescence studies show that the emissions of complexes 3–6 are attributed to the ligand π–π* transition.
Co-reporter:Peng Hu, Xiufeng Wang, Yue Ma, Qinglun Wang, Licun Li and Daizheng Liao
Dalton Transactions 2014 - vol. 43(Issue 5) pp:NaN2243-2243
Publication Date(Web):2013/11/19
DOI:10.1039/C3DT52959B
Five new one-dimensional rare earth–nitronyl nitroxide radical complexes [Ln(hfac)3(NIT-3BrPhOMe)]n (Ln = Nd (1), Sm (2), Gd (3), Tb (4), Dy (5); hfac = hexafluoroacetylacetonate; NIT-3BrPhOMe = 2-(3′-bromo-4′-methoxyl)-4,4,5,5-tetramethyl-imidazolyl-1-oxyl-3-oxide) have been successfully prepared and structurally characterized. Five complexes possess linear chain structure in which the NIT-3BrPhOMe radical ligands link Ln(hfac)3 units through the oxygen atoms of nitronyl nitroxide groups. DC magnetic studies show that Nd, Sm and Gd complexes are paramagnetic above 2.0 K, whereas Tb and Dy complexes show antiferromagnetic ordering with TN = 19.9 K and 6.4 K, respectively. Moreover, Tb and Dy complexes exhibit frequency-dependence of ac magnetic susceptibilities, suggesting the presence of slow magnetic relaxation. This work demonstrated that the substituents of the nitronyl nitroxide radical and the lanthanide ion can play a crucial role in modulating the magnetic behavior for one-dimensional lanthanide–radical systems.
Co-reporter:Xiufeng Wang, Cun Li, Juan Sun and Licun Li
Dalton Transactions 2015 - vol. 44(Issue 42) pp:NaN18417-18417
Publication Date(Web):2015/09/22
DOI:10.1039/C5DT02783G
Four new nitronyl nitroxide radical based hetero-tri-spin one-dimensional compounds, namely [{Ln(hfac)3}3{Cu(hfac)2}{NIT–Ph(OMe)2}4]n (Ln = Gd (1), Tb (2), Dy (3), Er (4); hfac = hexafluoroacetylacetonate; NIT–Ph(OMe)2 = 2-(2′,4′-dimethoxyphenyl)-4,4,5,5-tetramethyl-imidazolyl-1-oxyl-3-oxide) have been successfully prepared. Single crystal X-ray crystallographic analysis reveals that complexes 1–4 possess a 1D chain structure with a repeating [Cu–Rad–Ln–Rad–Ln–Rad–Ln–Rad] moiety in which Ln(hfac)3 and Cu(hfac)2 units are bridged by nitronyl nitroxide radicals through the NO groups. DC magnetic studies found that ferromagnetic interactions between metals and the coordinated NO groups are active in all four compounds. The Tb derivative displays frequency dependent ac magnetic susceptibilities, indicating slow magnetic relaxation behavior. The Gd complex shows an important cryogenic magnetocaloric effect with the entropy change (−ΔSm) of 13.5 J kg−1 K−1 at 2 K and a magnetic field of 7 T, representing the first example of Gd–radical molecular species exhibiting the magnetocaloric effect.
Co-reporter:Xiufeng Wang, Mei Zhu, Juanjuan Wang and Licun Li
Dalton Transactions 2015 - vol. 44(Issue 31) pp:NaN13896-13896
Publication Date(Web):2015/06/24
DOI:10.1039/C5DT01487E
The lanthanide–radical approach has been applied to construct three isomorphous mononuclear lanthanide complexes [Ln(hfac)3(NIT2-PyOCH3)] (LnIII = Gd 1, Tb 2, Er 3) in which the nitronyl nitroxide radical NIT2-PyOCH3 (NIT2-PyOCH3 = 2-(3′-methoxy-2′-pyridyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide) acts as a tridentate chelating ligand via the pyridyl nitrogen atom, the oxygen atom from the NO group and the oxygen atom from the methoxy group. The central lanthanide ions are nine-coordinated and their coordination geometry can be considered as an intermediate between muffin and spherical capped square antiprisms. Interestingly, an unusual antiferromagnetic interaction was observed between the Gd(III) and the coordinated nitronyl nitroxide radical in complex 1. Moreover, ac magnetic susceptibilities display frequency-dependent out-of-phase signals in the case of the anisotropic Tb complex, indicating magnetic relaxation behavior.
Co-reporter:Xiufeng Wang, Yungai Li, Peng Hu, Juanjuan Wang and Licun Li
Dalton Transactions 2015 - vol. 44(Issue 10) pp:NaN4567-4567
Publication Date(Web):2015/02/05
DOI:10.1039/C4DT01878H
The combination of lanthanide ions and nitronyl nitroxide radicals resulted in four new Ln-radical one-dimensional compounds, namely, [Ln(hfac)3{NIT-Ph(OMe)2}]n(LnIII = Sm (1), Eu (2), Gd (3), Dy (4); hfac = hexafluoroacetylacetonate; NIT-Ph(OMe)2 = 2-(2′,4′-dimethoxyphenyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazolyl-1-oxyl-3-oxide). The four complexes were found to be isomorphous and exhibit nitronyl nitroxide radicals-bridged lanthanides linear chains. DC magnetic susceptibilities show that the directly bonded nitronyl nitroxide interacts ferromagnetically with Gd and Dy ions. The Dy complex exhibits three-step metamagnetism and frequency-dependent ac magnetic susceptibilities, indicating single-chain magnet behavior. This work shows that the magnetic behaviors of one-dimensional Ln-nitronyl nitroxide chains can be fine tuned by the substituents of the radicals.
![1H-Imidazole, 1-[4-(1,3-dihydroxy-4,4,5,5-tetramethyl-2-imidazolidinyl)phenyl]-](/data/chemimg/141300/1228019-75-7.png)
![1H-Imidazole, 1-[4-(1,3-dihydroxy-4,4,5,5-tetramethyl-2-imidazolidinyl)phenyl]-](/data/chemimg/141300/1228019-75-7_b.png)
![1H-1,2,4-Triazole, 1,1'-[1,4-phenylenebis(methylene)]bis-](/data/chemimg/105500/143131-66-2.png)
![1H-1,2,4-Triazole, 1,1'-[1,4-phenylenebis(methylene)]bis-](/data/chemimg/105500/143131-66-2_b.png)
