RESUMO
Two novel transition metal compounds, [Ni(4,4'-bipyH)2(H2O)4]·2(H4bmt)·9H2O (1) and [Co(4,4'-bipy)(H2O)4][Co(4,4'-bipyH)2(H2O)4]·2(H3bmt)·6H2O (2), have been synthesized. They possess continuous H-bond networks and high-density [PO3] groups, which give conductivity values in the order of 10-3 S cm-1 in a wide temperature range and 98% relative humidity.
RESUMO
Four chair-like hexanuclear Fe-Ln complexes containing mixed organic ligands, namely, [Fe4Ln2{(py)2CO2}4(pdm)2(NO3)2(H2O)2Cl4]·xCH3CN·yH2O (Ln = GdIII (1, x = 1, y = 0), DyIII (2, x = 1, y = 1), HoIII (3, x = 0, y = 2), and ErIII (4, x = 1, y = 3); (py)2CO2H2 = the gem-diol form of di-2-pyridyl ketone and pdmH2 = 2,6-pyridinedimethanol) have been obtained by employing di-2-pyridyl ketone and 2,6-pyridinedimethanol reacting with FeCl3 and Ln(NO3)3 in MeCN. The structures of 1-4 are similar to each other except for the number of lattice solvent molecules. Four FeIII and two LnIII in these complexes comprise a chair-like core with the "body" constructed by four FeIII ions and the "end" constructed by two LnIII ions. Among the four compounds, 2 shows field-induced single molecule magnet behavior as revealed by ac magnetic susceptibility studies, with the effective energy barrier and the pre-exponential factor of 22.07 K and 8.44 × 10-7 s, respectively. Ab initio calculations indicated that, among 2_Dy, 3_Ho and 4_Er fragments, the energy gap between the lowest two spin-orbit states for 2_Dy is the largest, while the tunneling gap for 2 is the smallest. These might be the reasons for complex 2 exhibiting SMM behavior. Additionally, the orientations of the magnetic anisotropy of DyIII in 2 were obtained by electrostatic calculations and ab initio calculations, both indicating that the directions of the main magnetic axis of Dy1 ions are almost aligned along Dy1-O5 (O5 from the pdm2- ligand).
RESUMO
Four tetranuclear 3d-4f complexes, namely [Fe2Ln2(L)2(teaH)2(Cl)2](NO3)2·4CH3CN (H2L = N1,N3-bis(3-methoxysalicylidene)diethylenetriamine, teaH3 = triethanolamine, Ln = Dy for 1 and Ln = Gd for 1') and [Co2Ln2(L)2(pdm)2(CH3COO)2(CH3OH)2](NO3)2·xCH3OH·yH2O (pdmH2 = 2,6-pyridinedimethanol, Ln = Dy, x = 5 and y = 2.5 for 2 and Ln = Gd, x = 6 and y = 1.5 for 2'), have been reported. Two FeIII and two DyIII in 1 formed a zigzag Fe1-Dy1-Dy1a-Fe1a arrangement with a Fe1-Dy1-Dy1a angle of 105.328(3)°. However, in contrast to 1, two CoIII and two DyIII ions in 2 formed a more linear Co1-Dy1-Dy1a-Co1a arrangement with a Co1-Dy1-Dy1a angle of 141.86(2)°. Additionally, two DyIII ions in 1 are eight-coordinated with a triangular dodecahedron geometry, while two DyIII ions in 2 adopt nine-coordination with a muffin geometry. Magnetic studies revealed slow magnetic relaxation behavior for 1, with an energy barrier Ea of 6.9 K. For 2, single molecule magnet behavior was presented under a zero dc field with an effective energy barrier Ueff of 64.0(9) K. Ab initio calculations for 1 and 2 indicate that compared to 2, complex 1 has a larger transversal magnetic moment of its ground Kramers doublets (KD) and a larger value of the tunnelling parameter (Δt) for the exchanged coupled ground state, which may result in poor single molecule magnet behavior for 1.
RESUMO
An unprecedented Tb(iii) polycarboxylate, {[Tb4(TTHA)2(H2O)4]·7H2O}n (1), has been synthesized. It possesses an efficient proton transfer pathway formed by water molecules and carboxyl groups, which exhibits proton conductivity over 10-2 S cm-1 at 295-358 K and 98% relative humidity.
RESUMO
In this work, we report the syntheses, crystal structures and magnetic properties of three novel Zn-Ln mixed metal complexes, namely [Zn4Dy2(L1)2(L2)2(N3)2]Cl2·2H2O (1), [Zn4Tb2(L1)2(L2)2(Cl)2][ZnN3Cl3]·2H2O (2), and [Zn4Gd2(L1)2(L2)2(Cl)2][ZnN3Cl3]·2H2O (3), in which L12- and L23- were formed from the ligand L [L = N1,N3-bis(3-methoxysalicylidene)diethylenetriamine] through in situ reactions. Interestingly, carbon dioxide in air was absorbed in the process of forming carbamate ligand L23-; this can be ascribed to the insertion of CO2 into M-N amide bonds. Moreover, 1 and 2 represent the first series of 3d-4f SMMs containing carbamate ligands by fixation of CO2 in air. Single-crystal X-ray diffraction analyses reveal that the crystal structures of 1 and 2 are anion-dependent, i.e., the apical positions of the two ZnII ions in 1 and 2 are occupied by an N atom of N3- and by Cl-, respectively. However, the topologies of 2 and 3 are similar. Two ZnII ions and one LnIII (Ln = Dy (1), Tb (2) and Gd (3)) form nearly linear trinuclear [Zn2Ln] units which are double-bridged by two L23- ligands. Magnetic studies reveal that two complexes show single molecule magnet behavior under a direct current (dc) field, with effective energy barriers (Ueff) of 30.66(5) K for 1 and 8.87(3) K for 2. Ab initio calculations reveal that the DyIII ions in 1 and the TbIII ions in 2 are axial in nature; however, a difference in the tunnel splitting of 1 and 2 leads to variation in the magnetization blockades of the two complexes. Theoretical calculations also indicate that the directions of the main magnetic axes severely deviate from the coordination atoms of the first spheres of DyIII and TbIII in 1 and 2; thus further results in poor SMM behavior of the two complexes.
RESUMO
We report the syntheses, crystal structures, and magnetic properties of two 3d-4f heterometallic compounds; namely, [Mn8Ln2O2(OH)2{(py)2CO2}4(teaH)4(CH3COO)6]·6CH3CN·2H2O (LnIII = Dy (1), Tb (2); (py)2CO2H2 = the gem-diol form of di-2-pyridyl ketone, teaH3 = triethanolamine). Both compounds were prepared by the reaction of Mn(OAc)2·4H2O, Ln(NO3)3·5H2O (Ln = Dy and Tb) with the ligands di-2-pyridyl ketone and triethanolamine in MeCN, and they crystallize in the monoclinic space group C2/c. [Mn8Ln2] complexes have not been reported before, and the metallic cores of both complexes were unprecedented. In these cores, two Dy or Tb and two Mn ions comprised a well-known butterfly topology, with three of the remaining six Mn atoms each being situated on either side of the butterfly, linked through two µ3-O2- ions. Six MnIII and two MnII were in six-coordinated distorted octahedrons and two LnIII ions were in nine-coordinated distorted muffins. Interestingly, the coordination sites of LnIII ions are occupied by six O and two N atoms from two teaH2- ligands and one µ3-O2- atom, without the presence of coordinated solvent molecules such as H2O and small anions such as NO3- ions, which is rare in 3d-4f complexes. Remarkably, alternating current (ac) magnetic susceptibility measurements revealed that both complexes displayed dynamic anisotropic magnetic behaviour. The effective energy barrier (Ueff) of complex 2 was estimated to be 18.97 K through high frequency (111-9111 Hz) ac susceptibility measurements. The low symmetry of the coordination configuration of Ln3+ in 1 and 2 may be responsible for the small energy barriers of these two compounds.
RESUMO
In the solvated title complex, [Ni(C(46)H(47)N(6)O(2))]ClO(4)·2CH(4)O, the coordination sphere around the Ni(II) ion can be described as distorted cis-NiO(2)N(4) octa-hedral defined by two phenolate O atoms and four N atoms from the hexa-dentate ligand. An intra-molecular bifurcated N-Hâ¯(N,O) hydrogen bond helps to establish the conformation of the complex mol-ecule. In the crystal, the components are connected by O-Hâ¯O and C-Hâ¯O hydrogen bonds.
RESUMO
In the title solvated mol-ecular salt, [CuCl(C(28)H(30)N(4))]ClO(4)·CH(3)OH, the Cu(2+) ion is coordinated by the N,N',N'',N'''-tetra-dentate ligand and a chloride ion, generating a very distorted square-based pyramidal CuN(4)Cl coordination geometry with the Cl(-) ion in the basal position. In the crystal, the solvent mol-ecules and anions are linked by weak O-Hâ¯O hydrogen bonding.
RESUMO
In the title complex, [Cu(ClO(4))(2)(C(7)H(12)N(2)O)(2)], the Cu(II) ion lies on a crystallographic inversion centre. The coordination sphere around Cu(II) ion can be described as tetragonally distorted octa-hedral with two perchlorate O atoms occupying the apical positions and four N atoms from two N(1)-(2-furyl-methyl)ethane-1,2-diamine ligands in the basal plane.
RESUMO
In the title dinuclear nickel(II) complex, [Ni(2)(C(8)H(4)FO(3))(2)(H(2)O)(4)]Cl(2), synthesized by the reaction between 4-fluoro-2,6-diformyl-phenol and nickel(II) chloride in methanol, the coordination cation is located on an inversion center and the Ni(II) atom adopts a slightly distorted octa-hedral coordination geometry. The two Ni atoms are bridged by two phenolate O atoms and the intra-molecular Niâ¯Ni distance is 3.0751â (9)â Å. The crystal structure is stabilized by O-Hâ¯Cl hydrogen bonds.
RESUMO
The title compound, [Cu(2)(C(31)H(30)Cl(2)N(4)O(4))Cl(2)]·CH(3)CN, was synthesized by cyclo-condensation between N,N'-bis-(2-fur-yl)-N,N'-bis-(3-formyl-5-chloro-salicylaldehyde)ethyl-enediamine and 1,3-diamino-propane in the presence of Cu(II) ions. It is an unsymmetrical dinuclear Cu(II) complex. The coordination geometry for each Cu(II) atom can be discribed as distorted square-pyramidal. The two Cu atoms are bridged by two phenolate O atoms with a Cuâ¯Cu distance of 3.0274â (9)â Å.
RESUMO
The title complex, [Cu(2)(C(22)H(20)Br(2)N(4)O(2))(ClO(4))(2)], was prepared by the condensation of 2,6-diformyl-4-bromo-phenol with 1,3-diamino-propane in the presence of copper(II) ions. The macrocyclic ligand shows an approximately planar structure except for the two propene groups in the macrocycle. The coordination polyhedron of each Cu atom can be described as distorted square pyramidal. The two Cu atoms are bridged by two phenolate O atoms of the macrocycle, with a Cuâ¯Cu distance of 3.109â (2)â Å.
RESUMO
In the title compound, [Ni(C(13)H(11)ClN(3)O(2))(2)], the Ni(II) atom is located on a twofold rotation axis and is six-coordinated by four N atoms and two phenolate O atoms from the two equal Schiff base ligands in a distorted octa-hedral coordination geometry. The complex mol-ecules are connected by C-Hâ¯Cl, C-Hâ¯O and N-Hâ¯O hydrogen bonds.
RESUMO
In the centrosymmetric and dinuclear title complex, [Mn(2)(C(22)H(22)N(4)O(2))(ClO(4))(2)], the two Mn atoms are bridged by two phenolate O atoms of the N(4)O(2) macrocycle with an Mnâ¯Mn distance of 2.9228â (11)â Å. The distorted square-pyramidal N(2)O(3) coordination geometry is completed by an O atom derived from a perchlorate anion.
RESUMO
Two new chiral polymers of different molecular weights were synthesized by the copolymerization of (1R,2R)-(+)-1,2-diphenylethylenediamine, phenyl diisocyanate and terephthaloyl chloride. The polymers were immobilized on aminated silica gel to afford two chiral stationary phases. The polymers and the corresponding chiral stationary phases were characterized by Fourier transform-IR, elemental analysis, 1H and 13C NMR. The surface coverages of chiral structural units on the chiral stationary phases were estimated as 0.27 and 0.39 mmol/g, respectively. The enantioseparation ability of these chiral stationary phases was evaluated with a variety of chiral compounds by high-performance liquid chromatography. The effects of the organic additives, the composition of mobile phases, and the injection amount of sample on enantioseparation were investigated. A comparison of enantioseparation ability between these two chiral stationary phases was made. It was believed that the chain length of polymeric chiral selector significantly affected the enantioseparation ability of corresponding chiral stationary phase.
Assuntos
Etilenodiaminas/química , Isocianatos/química , Ácidos Ftálicos/química , Polímeros/síntese química , Cromatografia Líquida de Alta Pressão , Polímeros/análise , EstereoisomerismoRESUMO
The title complex, [Ni(2)(C(42)H(46)Cl(2)N(6)O(2))(C(2)H(3)O(2))]ClO(4)·2CH(3)CN, was synthesized by condensation of 2,6-diformyl-4-chloro-phenol with N,N-bis-(amino-prop-yl)benzyl-amine in the presence of Ni(II) ions. The ligand is a 28-membered macrocycle with two identical pendant arms. The coordination geometries of the Ni atoms are both octa-hedral. The two Ni atoms are bridged by two phenolate O atoms of the macrocyclic ligand and one acetate ligand, with an Niâ¯Ni distance of 3.147â (4)â Å.
