Phen Molecules Research Articles

Synthesis and characterization of a novel coordination polymer {[Mn(L)(Phen)2] · 2H2O} n 1

A novel coordination polymer {[Mn(L)(Phen)2] · 2H2O}n (I) has been synthesized by the reaction of Mn(CH3COO)2, 2,2′-bipyridine-5,5′-dicarboxylic acid (HL) and 1,10-phenanthroline (Phen). The structure of the complex was charactered by single-crystal X-ray diffractometry. The unit cell parameters for complex I: a = 11.796(3), b = 17.837(5), c = 15.081(4) A; β = 101.804(5)°; V = 3106.0(15) A3; Z = 4; space group C2/c. The Mn(II) atom is coordinated by four nitrogen atoms from two Phen molecules and two oxygen atoms from two molecules L with a distorted octahedral geometry. Complex was dibridged by the L ligand forming a 1D infinite chain. Intramolecular weak interactions, such as hydrogen bonds and π...π-stacking, were found in the title complex, and 3D supramolecular framework was constructed by intermolecular weak interactions mentioned above.

Structure and properties of terbium(III) dipivaloylmethanate and its adducts with Bipy and Phen

The complex of terbium(III) with dipivaloylmethane (2,2,6,6-tetramethylheptane-3,5-dione = Htmhd) [Tb(tmhd)3]2 (1) and two its adducts with bipyridyl (Bipy) and phenanthroline (Tb(tmhd)3·Bipy (2) and Tb(tmhd)3·Phen (3)) are synthesized and analyzed by single crystal X-ray diffraction. The crystals of [Tb(tmhd)3]2 (1) belong to the monoclinic crystal system: P21/n space group, a = 12.2238(2) A, b = 27.6369(5) A, c = 21.8740(4) A, β = 105.146(1)°, V = 7133.0(2)A3, Z = 4; the crystals of Tb(tmhd)3·Bipy (2) and Tb(tmhd)3·Phen (3) belong to the triclinic crystal system with unit cell parameters: (2) \(P\bar 1\) space group, a = 11.0554(6) A, b = 12.2761(7) A, c = 17.7096(8) A, α = 77.457(2)°, β = 85.557(2)°, γ = 69.659(2)°, V = 2199.8(2) A3, Z = 2; (3) \(P\bar 1\) space group, a = 10.8814(3) A, b = 12.2852(4) A, c = 18.3590(6) A, α = 80.463(1)°, β = 87.587(1)°, γ = 68.640(1)°, V = 2253.6(1) A3, Z = 2. The structures of the complexes are molecular and involve isolated [Tb2(tmhd)6] (1), Tb(tmhd)3·Bipy (2), and Tb(tmhd)3·Phen (3) molecules. The thermal properties of the obtained terbium complexes are studied by TG-DTA.

Understanding the Enhancement Mechanisms in the Surface-Enhanced Raman Spectra of the 1,10-Phenanthroline Molecule Adsorbed on a Au@Ag Bimetallic Nanocolloid

Adsorption of 1,10-phenanthroline (PHEN) on the Aucore–Agshell (Au@Ag) bimetallic nanocolloid surface has been investigated. Bimetallic nanocolloids have been synthesized using β-cyclodextrin (β-CD) in alkaline solution. Nanocolloids of different Aucore:Agshell ratio were synthesized keeping the same Aucore size. Again, for the preparation, the total metal concentrations were always kept constant. The structure and composition of the bimetallic particles were characterized by UV–vis and high-resolution transmission electron microscopy. Detailed normal Raman (NRS) and surface-enhanced Raman spectra (SERS) of PHEN in aqueous solution have been studied. The relative contributions of the electromagnetic (EM) and charge-transfer (CT) mechanism to the overall enhancement of the SERS bands of the PHEN molecule have been estimated. PHEN molecules are adsorbed on the Agshell surface through both the nitrogen atoms with the molecular plane almost perpendicular to the surface, which has been confirmed from Ag–N stre...

Lanthanide complexes with disulfide ligand generated in situ: Syntheses, crystal structures and fluorescent properties

Five new lanthanide complexes [Ln 2(DTDN) 4(phen) 4]·7H 2O·2H 3O + (Ln = Nd ( 1), Sm ( 2), Eu ( 3), Tb ( 4), Dy ( 5), H 2DTDN = 2,2′-dithiodinicotinic acid, phen = 1,10-phenanthroline) have been solvothermally synthesized and characterized by single-crystal X-ray diffraction, elemental analyses, IR spectra, and TG analyses. By in situ oxidation of 2-mercaptonanicotinic acid (2-H 2MN), the expected ligand H 2DTDN was generated. All crystals are isostructural and crystallize in monoclinic system with space group C2/ c. The metal center is eight-coordinated completely by four carboxylic oxygen atoms from four different DTDN 2− ligands, and four nitrogen atoms from two phen molecules with a distorted square-antiprismatic geometry. The structures can be considered as two-dimensional (2D) structures and further linked by hydrogen bonds into the final trinodal 4-connected network. Photoluminescence studies revealed that complexes 2– 5 exhibit strong fluorescent emission bands in the solid state at room temperature.

New 4,5-dichlorophthalhydrazidate-bridged chained coordination polymers

The hydrothermal self-assemblies of Pb 2+/Cd 2+ salt, 4,5-dichlorophthalic acid (dcpha), N 2H 4·H 2O together with 1,10-phenanthroline·H 2O (phen) or 2,2′-bipyridine (bpy) generated two new monoacylhydrazidate-bridged 1-D chained coordination polymers [Pb 2(DCPTH) 4(phen) 2] 1 and [Cd 3(DCPTH) 2(dcph) 2(bpy) 2] 2 (DCPTH=4,5-dichlorophthalhydrazidate, dcph=4,5-dichlorophthalate). The monoacylhydrazidate ligand DCPTH originated from the hydrothermal in situ acylation reaction between dcpha and N 2H 4·H 2O. In compound 1, two types of coordination modes for DCPTH are found, which link alternately the Pb(II) centers into a 1-D chain structure of compound 1 with ancillary phen molecules. In compound 2, DCPTH and dcph as the mixed bridges extend the Cd(II) centers into a 1-D chain structure of compound 2 with auxiliary bpy molecules. DCPTH in compound 2 shows a different coordination mode from those observed in compound 1.

Molecular structure of a coordination compound tris(phenanthroline)zinc(II) 2,2′-Bipyridyl-5,5′-dicarboxylate dodecahydrate

The [Zn(phen)3](2,2′-Bipy-5,5′-dicarboxylate)·12H2O complex is synthesized and its crystal structure is determined by single crystal X-ray crystallography. The crystals of the coordination compound have a monoclinic unit cell with parameters a = 12.2533(14) A, b = 18.976(2) A, c = 22.426(3) A, β = 105.675(2)°, V = 5020.54(300) A3, Z = 4, P21/n space group. The environment of the Zn atom is a distorted octahedron of six N atoms belonging to three coordinated phen molecules. In the structure, π-π interactions between phen molecules as well as between phen molecules and 2,2′-bipyridyl-5,5′-dicarboxylate anions give rise to the formation of three-dimensional ensembles. The 2,2′-bipyridyl-5,5′-dicarboxylate anion and twelve water molecules are not coordinated, and the molecules of water of crystallization make clusters.

Single Crystal EPR Study of the Dinuclear Cu(II) Complex [Cu(tda)(phen)]2·H2tda (tda = Thiodiacetate, phen = Phenanthroline): Influence of Weak Interdimeric Magnetic Interactions

We report powder and single crystal EPR measurements of [Cu(tda)(phen)](2)·H(2)tda (tda = thiodiacetate, phen = phenanthroline) at 9.7 GHz. This compound consists of centrosymmetric copper(II) ion dimers, weakly ferromagnetically exchange-coupled (J = +3.2 cm(-1)), in which the dimeric units are linked by hydrophobic chemical paths involving the phen molecules. EPR revealed that the triplet spectra are collapsed by interdimeric exchange interactions mediated by that chemical path. Analysis and simulation of the single crystal EPR spectra were performed using Anderson's exchange narrowing model, together with statistical arguments. This approach allowed us to interpret the spectra modulated by the interdimeric interactions in situations of weak, intermediate, and strong exchange. We evaluated an interdimeric exchange constant J' = 0.0070(3) cm(-1), indicating that hydrophobic paths can transmit weak exchange interactions between centers at relatively long distances of the order of ∼10 Å.

Diaqua(2,6-dihydroxybenzoato-κ2O1,O1′)bis(2,6-dihydroxybenzoato-κO1)bis(1,10-phenanthroline-κ2N,N′)lanthanum(III)–1,10-phenanthroline (1/1)

In the title compound, [La(C7H5O4)3(C12H8N2)3(H2O)2]·C12H8N2, the LaIII atom is coordinated by four N atoms from two chelating 1,10-phenanthroline (phen) ligands, four O atoms from three 2,6-dihy­droxy­benzoate (DHB) anions (one monodentate, the other bidentate) and two water O atoms, completing a distorted LaN4O6 bicapped square-anti­prismatic geometry. Within the mononuclear complex mol­ecule, intra­molecular π–π stacking inter­actions are observed, the first between a coordinated phen mol­ecule and a DHB ligand [centroid–centroid distance = 3.7291 (16) Å], and the second between a coordinated phen mol­ecule and an uncoordinated phen ligand [centroid–centroid distance = 3.933 (2) Å]. Inter­molecular π–π stacking is observed between adjacent complexes [inter­planar distance = 3.461 (3) Å]. Intra- and inter­molecular O—H⋯O hydrogen bonds are observed in the DHB ligands and between a water mol­ecule and DHB ligands, respectively. O—H⋯N hydrogen bonds are also observed in the DHB ligands and between uncoordinated phen mol­ecules and aqua ligands.

Crystal structure and luminescence of a terbium complex with p-methyl benzoate and 1,10-phenanthroline

A terbium p-methyl benzoate complex with 1,10-phenanthroline, [Tb(p-MBA)3(Phen)]2 (p-MBA = p-methyl benzoate and Phen = 1,10-phenanthroline), has been prepared and structurally characterized by X-ray diffraction. It crystallizes in triclinic system, space group P\( \bar 1 \) with a = 12.8064(12), b = 13.3589(12), c = 19.8277(19) A, α = 91.668(2)°, β = 97.775(2)°, γ = 106.312(2)°, C72H58N4O12Tb2, Mr = 1489.06, V = 3217.6(5) A3, Z = 2, ρc = 1.537 g/cm3, μ(MoKα) = 2.246 mm−1, F(000) = 1488, the final R = 0.0622 and wR = 0.0962 for 14128 independent reflections with Rint = 0.0843. It consists of two types of crystallographically independent dimeric molecules [Tb(p-MBA)3(Phen)]2 noted as [Tb-1] and [Tb-2]. In the dimeric molecule [Tb-1], each Tb(III) is eight-coordinated with one Phen molecule, two bridging carboxylate groups, and two bidentate chelating carboxylate groups, while in [Tb-2] each Tb(III) is eight-coordinated with one Phen molecule, four bridging carboxylate groups, and one bidentate chelating carboxylate group. The title complex shows intense green luminescence under UV light at room temperature.

Synthesis, Structures and Photoluminescent Properties of Two Novel Zinc(II) Compounds Constructed from 5-Sulfoisophthalic Acid

Hydrothermal reaction of zinc(II) salts with 5-sulfoisophthalic acid monosodium salt (NaO 3 SC 6 H 3 -1,3-(COOH) 2, NaH 2 -SIP) and 1,10-phenanthroline (phen) led to two new compounds, [Zn(phen) 3 ]·2H 2 SIP·4H 2 O (1) and [Zn(phen) 2 (H 2 O) 2 ]· 2H 2 SIP·2H 2 O (2). They were characterized by element analysis, IR spectroscopy, thermalgravimetric analysis (TGA), X-ray powder diffraction (XRD), and single-crystal X-ray diffraction. Both compounds 1-2 represent the first example ofZn/phen/SIP system. The Zn (II) ion in 1 is six-coordinated by six nitrogen atoms from three phen molecules, and the H 2 SIP - ligands engage in the formation of hydrogen bond. The Zn(II) ion in 2 is coordinated by four nitrogen atoms from two phen molecules and two oxygen atoms from two water molecules. Moreover, both 1 and 2 are assembled into 3 D supramolecular architectures by hydrogen bonds (O-H···O) and π-π interactions. Solvent water molecules occupying voids of the compounds serve as receptors or donors of the extensive O-H···O hydrogen bonds.

Theoretical and Experimental Spectroscopic Approach of Fluorinated Ln3+−β-Diketonate Complexes

In this paper we report the synthesis of two new complexes, [Eu(fod)(3)(phen)] and [Tb(fod)(3)(phen)] (fod = 6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octadionate and phen = 1,10-phenanthroline), and their complete characterization, including single-crystal X-ray diffraction, UV-vis spectroscopy, IR spectroscopy, and TGA. The complexes were studied in detail via both theoretical and experimental approaches to the photophysical properties. The [Eu(fod)(3)(phen)] complex crystallizes in the monoclinic space group P2(1)/c. The crystal structure of [Eu(fod)(3)(phen)] exhibits an offset pi-pi stacking interaction between the phenanthroline ligands of adjacent lanthanide complexes. The Eu(3+) cation is coordinated to three fod anionic ligands and to one phen. The symmetry around Eu(3+) is best described as a highly distorted square antiprism. The molar absorption coefficients of [Eu(fod)(3)(phen)] and [Tb(fod)(3)(phen)] revealed an improved ability to absorb light in comparison with the stand-alone phen and fod molecules. [Tb(fod)(3)(phen)] emits weak UV excitation, with this feature being explained by the triplet-(5)D(4) resonance, which contributes significantly to the nonradiative deactivation of Tb(3+), causing a short lifetime and low quantum yield. The intensity parameters (Omega(2), Omega(4), and Omega(6)) of [Eu(fod)(3)(phen)] were calculated for the X-ray and Sparkle/AM1 structures and compared with values obtained for [Eu(fod)(3)(H(2)O)(2)] and [Eu(fod)(3)(phen-N-O)] (phen-N-O = 1,10-phenanthroline N-oxide) samples. Intensity parameters were used to predict the radiative decay rate. The theoretical quantum efficiencies from the X-ray and Sparkle/AM1 structures are in good agreement with the experimental values, clearly attesting to the efficacy of the theoretical models.

Structure and sensitized near-infrared luminescence of Yb(III) complexes with sulfonylamidophosphate type ligand

A series of new lanthanide complexes with dimethyl(phenylsulfonyl)amidophosphate (H SP) was synthesized ({Na[Ln(SP) 4]} n ( Ln1), [Ln(SP) 3phen] ( Ln2) and [Ln(SP) 3bpy]·H 2O ( Ln3) (where Ln = Gd III, Er III, Yb III and Lu III; phen = 1,10-phenantroline; and bpy = 2,2′-bipyridine) and the crystal structures of [Er(SP) 3phen] and [Yb(SP) 3bpy]·H 2O were resolved. Absorption (at 295, 4 K), emission (at 295, 77, 4 K) and IR (at 295 K) spectra as well as luminescence decay time measurements were used to characterize the photophysical properties of single crystals. Effective energy transfer from a [SP] − ligand to the Yb III ion was demonstrated despite a large energy gap Δ E = E trip − E 2 F 5 / 2 . Replacing one molecule of the [SP] − ligand with the phen or bpy molecule caused reduction of the emission decay time from 35 μs for Yb1 to 20 and 15.5 μs for Yb2 and Yb3, respectively at the temperature of 295 K. Using the absorption spectra τ rad (1.1 ms— Yb1, 943 μs— Yb2 and 914 μs— Yb3) and Q Ln Ln (3.14%— Yb1, 2.19%— Yb2, 1.64%— Yb3) were estimated. On the basis of low temperature, high-resolution absorption and luminescence spectra, the ligand-field splittings of the excited and ground states of Yb III complexes were determined.

Low-Dimensional Compounds Containing Cyanido Groups. XX. Synthesis, Crystal Structure and Spectroscopic Properties of Polymeric 1,10-Phenanthroline-N,N′-Copper(II) Tetracyanidoplatinate(II)

Polymeric {[Cu(phen)][Pt(CN)4]} n compound (phen = 1,10-phenanthroline) has been prepared under hydrothermal conditions using CuSO4 · 5H2O, phen and K2[Pt(CN)4] · 3H2O, and characterized by chemical analysis and IR spectroscopy. The X-ray structure analysis [C2/c, a = 6.6057(7), b = 19.747(2), c = 11.5891(13) A, β = 91.723(10)°] has revealed that the coordination geometry of the Cu(II) atom, situated on a two-fold rotation axis, is tetragonally distorted octahedral. Two nitrogen donor atoms originate from one blocking phen ligand, chelate coordinated in the equatorial plane at the distance of 2.026(4) A (2×). The remaining four coordination sites are occupied by the nitrogen atoms [Cu–N = 1.975(5) (2×) and 2.574(5) A (2×)] of two pairs symmetrically related bridging cyanido groups. These link Cu(II) with Pt(II) atoms, which lie on symmetry centers and are coordinated by four C-bonded cyanido ligands in the square planar form. Thus infinite 2D wave-like net is formed in the ac plane stabilized by π–π interactions between the phen molecules. Polymeric {[Cu(phen)][Pt(CN)4]}n (phen = 1,10-phenanthroline) compound creates a wave-like 2D structural network stabilized by π–π interactions between the phen molecules.

Synthesis and fluorescence properties of novel 1,10‐phenanthroline‐functionalized polyaryletherketone and its rare earth complexes

Abstract1,10‐Phenanthroline‐functionalized polyaryletherketone (PPEK) was synthesized by the amidation reaction of 5‐amino‐1,10‐phenanthroline with polyaryletherketone containing pendant acyl chloride groups. Subsequently, a series of novel rare earth coordination polymers (with rare earths Eu3+, Tb3+, Sm3+ and Dy3+) were prepared, using PPEK as macromolecular ligand and the small 1,10‐phenanthroline (Phen) molecule as synergistic ligand. Their structures were characterized using Fourier transform infrared spectroscopy, elemental analysis and X‐ray diffraction, which confirmed that both PPEK and Phen participated in the coordination reaction with the rare earth ions, and that the rare earth ions could disperse homogeneously in the polymer matrix. The rare earth coordination polymers were soluble in polar solvents such as N,N‐dimethylformamide, N,N‐dimethylacetamide and N‐methylpyrrolidone, and could be easily cast into transparent tough thin films. Fluorescence measurements indicated that all the coordination polymers exhibited the intense characteristic fluorescence of the corresponding rare earth ions under ultraviolet excitation, showing their application potential in optical display devices. Copyright © 2010 Society of Chemical Industry

Tetrakis(μ-3,4-dimethoxyphenylacetato)bis[(3,4-dimethoxyphenylacetato)(1,10-phenanthroline)dysprosium(III)

The title centrosymmetric dinuclear dysprosium(III) complex, [Dy2(C10H11O4)6(C12H8N2)2] or [Dy(L)3phen]2, is comprised of six 3,4-dimethoxy­phenylacetate (L) anions, two 1,10-phenanthroline (phen) mol­ecules and two DyIII ions. The DyIII atom is nine-coordinated by seven O atoms from five L ligands and two N atoms from the phen mol­ecules. The L ligands are coordinated to the DyIII ion in three coordination modes: chelating, bridging and bridging-tridentate. C—H⋯O hydrogen bonding interactions consolidate the crystal packing.

Structural regularities and luminescence properties of dimeric europium and terbium carboxylates with 1,10-phenanthroline (C.N. = 9)

A systematic comparison of the spectroscopic and structural data for series of related dimeric lanthanide carboxylates with 1,10-phenanthroline Ln(RCOO) 3·Phen (Ln = Eu, Gd, Tb): 1-naphthylcarboxylates, benzoates, 2-furancarboxylates, phenoxyacetates, caproates, acetates, propionates, 3-nitropropionates was undertaken in search for methods of regulation of quantum yield of the Ln 3+ luminescence and for paths of the control of excitation energy transfer. The crystal structures of europium propionate and europium and terbium 3-nitropropionates were solved by X-ray diffraction methods. Effect of stepwise distortions of Ln coordination polyhedron derived from X-ray data of the succession of compounds, which determine details of the charge distribution in the surroundings of the Ln 3+ ion, on luminescence spectra, on lifetimes of Ln 3+ states, and on efficiency of Ln 3+ luminescence was investigated. Polyhedron distortions are to a great extent caused by the range of the Ln–O bond lengths related to bridging-cyclic carboxylic group that is conditioned by the type and the size of carboxylate anion. Relative contributions of the rates of radiative and various nonradiative processes to the lifetimes of europium 5D 0 and terbium 5D 4 metastable states were estimated. Multiphonon relaxation is the main nonradiative process in europium compounds at temperatures from 77 to 295 K and in terbium compounds at low temperatures, but the radiative processes are appreciably prevailing. Dependence of the lifetimes due to radiative processes determined from the integral intensity of europium 5D 0– 7F J transitions related to the intensity of magnetic-dipole 5D 0– 7F 1 transition on distortions of Eu polyhedron in the sequence of compounds is in agreement with the same dependence obtained from the measured lifetimes, if nonradiative processes are taken into account. A back energy transfer from 5D 4 state of Tb 3+ ions to the lowest triplet state related to Phen molecule in most of compounds studied is another nonradiative process contributing to quenching in terbium compounds at high temperatures. An influence of this process on luminescence intrinsic quantum yield can be predominant. It leads to abrupt lowering the luminescence intensity of some terbium carboxylates, for example, benzoate at increasing the temperature. It was found, that lifetime of 5D 4 state and luminescence efficiency of terbium compounds at high temperatures depend on the bonding strength of Phen ligand with Tb 3+ ion. A range of the lowest triplet state energies of Phen ligand, from 20,850 to 21,750 cm −1, was revealed in lanthanide carboxylates under investigation. Closeness of the natural lifetimes of 5D 0 and 5D 4 states of Eu 3+ and Tb 3+ ions, respectively, in the same charge surroundings was demonstrated.

The concentration controlled 1D and 2D supramolecular isomers of lanthanide with 2,2’-bipyridyl-3,3’-dicarboxylate and phenanthroline

The reactions of 2,2′-bipyridyl-3,3′-dicarboxylic acid (H 2bpdc) and 1,10-phenanthroline (phen) with lanthanide (III) salts in different concentrations under hydrothermal conditions formed two series of supramolecular isomers of 1D zigzag chains of [Ln(bpdc) 1.5(phen)(H 2O)] n ·3 nH 2O ( 1Ln·3H 2O), and 2D frameworks of [Ln(bpdc) 1.5(phen)(H 2O)] n ( 2Ln), (Ln = Ho, Er, Tm, and Yb). At lower concentrations, the supramolecular isomers of 1Ln were formed, in which each isomer has a dinuclear centrosymmetric dimeric unit of [Ln 2(phen) 2(H 2O) 2(μ 2-bpdc) 2] 2+, and the dimeric units are alternately connected by μ 2-bpdc 2− to form a 1D zigzag chain of 1Ln. At higher concentrations, the supramolecular isomers of 2Ln were formed. All the compounds of 2Ln are isomorphous, in which two μ 3-bpdc 2− bridge two [Ln(phen)(H 2O)] 3+ units to yield a 1D double-chains of [Ln 2(phen) 2(H 2O) 2(bpdc) 2] n 2 n +, and [Ln 2(phen) 2(H 2O) 2(bpdc) 2] n 2 n + chains are further connected by μ 4-bpdc 2− to form a 2D network of [Ln(bpdc) 1.5(phen)(H 2O)] n . The 2D sheets are combined through the intersheet π– π interactions between the adjacent phen molecules to form a 3D structure of 2Ln. The compounds of Er(III), and Yb(III) exhibit corresponding characteristic photoluminescence in the near-infrared (NIR) region, in which 1Ln and 2Ln show obviously different emission intensity due to their different structures.

A novel two-dimensional Ni(II) fumarato complex: Solvothermal synthesis, crystal structure and magnetic properties

Dark green single crystals of [Ni( fum)( phen)] ( fum = fumarato, phen = 1,10-phenanthroline) ( 1) have been prepared under solvothermal conditions. Its crystal structure exhibits two dimensional (2D) character. The formed layers are built of dimers of crystallographically non-equivalent Ni(II) atoms linked by bridging fumarato ligands; one is of the μ 4-bridge type with both carboxylato groups coordinated in syn- anti fashion while in the second one both carboxylate groups form a chelate-like coordination. Both Ni(II) atoms are hexa-coordinated in the cis-NiO 4N 2 form; two coordination positions are occupied by a N-bonded chelate phen molecule and four positions by oxygen atoms from the fum ligands. The layers are interconnected by π–π interactions operating between aromatic rings of the phen ligands. The analysis of the experimental thermodynamic data supports the structural assumptions and showed that magnetic subsystem of 1 can be approximated by an array of antiferromagnetic S = 1 dimers with easy-axis uniaxial magnetic anisotropy D comparable to intradimer exchange coupling J, D/ J ≈ 1 and D/ k B = −6 K. The specific heat data clearly indicate the absence of a phase transition to the ordered state at least at temperatures down to 2 K.

Synthesis, crystal structure, and luminescence properties of [TbGd(NAA)6(phen)2] and [Tb2(NNA)6(phen)2] · 2C3H7NO

Lanthanide(III) heteronuclear and binuclear complexes [TbGd(NAA)6(phen)2] (1) and [Tb2(NAA)6(phen)2] · 2C3H7NO (2) (NAA = 1-naphthylacetic acid, phen = 1,10-phenanthroline) were prepared and their crystal structures were determined. In 1 and 2, each lanthanide is nine-coordinate by two bidentate-bridging and two tridentate chelating-bridging carboxylate groups, one bidentate chelating carboxylate and one phen molecule in a distorted monocapped square antiprism. The solid-state luminescence behavior and the antibacterial activities were studied. Complexes 1 and 2 exhibited characteristic emission of Tb(III) ion 5D4 → 7FJ (J = 6–0) under UV radiation at room temperature. A main excitation peak (359 nm) of 2 appears under red emission of 615 nm. By contrast, all emission peak intensities of 1 were enhanced by addition of gadolinium(III), and the 545 nm band is much stronger than the 615 nm band, attributed to, under perturbation of the ligand field, the probability of 5D4 → 7F3 transition of Tb(III) was greatly enhanced in 2. Because of perturbation of the ligand field by addition of gadolinium(III), the probability of 5D4 → 7F5 transition of Tb(III) was greatly enhanced in 1 and green fluorescence was observed. The antibacterial activity showed that the two complexes were active against Escherichia coli, Staphylococcus aureus and Bacillus subtilis.

Hydrothermal syntheses, crystal structures and luminescence properties of two lanthanide dinuclear complexes with hexafluoroglutarate

Two complexes [Ln2(hfga)2(phen)4(H2O)6] · hfga · 2H2O (H2hfga = hexafluoroglutaric acid, phen = 1, 10-phenanthroline, Ln=Tb, 1; Eu, 2) were synthesized under hydrothermal conditions and their structures determined by X-ray crystallography. The complexes consist of dinuclear units with an inversion center. Each Ln(III) is nine-coordinate with two carboxylate oxygens from two hfga ligands, three oxygens from water and four nitrogens from two phen molecules. Two carboxylate groups of one hfga adopt monodentate coordination to Ln(III) as a long bidentate bridge linking two Ln(III) ions to form a dimer. Ln(III) ··· Ln(III) distances of 9.027(3) Å for 1 and 9.043(3) Å for 2 were observed. Both complexes emit strong fluorescence and show characteristic emission of Tb(III) and Eu(III) ions, respectively.