Ewa Huskowska

Application of luminescence and absorption spectroscopy and x-ray methods to studies of Ln+3 ions interaction with aminoacids

Abstract The Nd +3 , Ho +3 and Eu +3 compounds with glycine, alanine and glutamic acid were synthesized and obtained as monocrystals. Absorption spectra in the range 8000–35 500 cm −1 were measured along the crystallographic axes at room temperature on a Cary 14 spectrophotometer Luminescence spectra were recorded at the same temperature in the range 9000–16 600 cm −1 . Intensities of the ff transitions were analyzed on the basis of the Judd theory, taking the dependence of intensity on the crystallographic axis position into account. Considerable differences in hypersensitive transitions in crystals with alanine, glycine and glutamic acid, whose symmetry changed from triclinic to monoclinic, were explained in terms of differences in the MeO distances.

Ligand chirality effect on the structure and its spectroscopic consequences in [Ln2(Ala)4(H2O)8] (C104)6 crystals

Abstract Single crystals of [Ln 2 (Ala) 4 (H 2 O) 8 ](Cl0 4 ) 6 (where Ln = Eu, Nd and Ala = l -, dl -alanine) were grown from aqueous solutions and the neodymium complex has been studied by single-crystal X-ray diffraction. The space groups are triclinic P 1 and monoclinic C2/c for l - and dl -alanine, respectively, and Z = 1 and 4. The crystal structures consist of non-centrosymmetric and centrosymmetric dimer units in the complexes with l and dl ligand forms. In other words, in the latter two the lanthanide ions in the dimer are equivalent but in the former they are not. Thus the chirality of the ligand is responsible for the subtle differences in the structure. Each neodymium ion is coordinated by four carboxylate oxygens of the amino acids and four water molecules. The coordination polyhedra around the neodymium ions are distorted square antiprisms. Well-resolved absorption luminescence measurements down to 5 K are reported. The probabilities of electronic transitions were investigated. An attempt has been made to elucidate the dimer (centrosymmetric and noncentrosymmetric) structure reflection in the splitting pattern of the optical lines. The temperature effect on the spectra was studied and analysed in terms of the cooperative interaction of coupled ions. It is the first, to our knowledge, X-ray evidence of the ligand chirality effect on the dimer structure of lanthanide compounds.

Spectroscopy and crystal structure of neodymium coordination compound with glycine: Nd2(Gly)6·(ClO4)6·9H2O

Abstract Neodymium complex compound with glycine: Nd2(Gly)6·(ClO46·9H2O was synthesized and obtained in the form of monocrystals. Absorption spectra recorded in the region of 8000–35 000 cm-1 were measured along the crystallographic axes. Intensities of the f-f transitions were analysed on the basis of the Judd theory. The X-ray crystal structure determination of the complex is reported. Crystals are triclinic, space group P I , with a = 11.554(4) A, b = 14.108(1) A, c = 15.660(3) A, α = 97.14(1)°, β = 102.82(2)°, γ = 105.28(1)°, V = 2355.25 A3 Z = 2, M.W. = 1495.4, Dc = 2.129)(3) g cm-3, Dm = 2.103(1) g cm-3. The structure was solved by Pattersons method and successive Fourier syntheses giving the locations of all nonhydrogen atoms. The final R factor was 0.062 and Rw = 0.073 for 12869 reflections with |Fo| > 5σ|(Fo)|. The asymmetric unit consists of a dimeric formula unit. The coordination polyhedron of Nd atoms comprises seven oxygen atoms from glycine and two from water molecules. The neodymium-glycine bonding mode is compared with that of the calcium-glycine complex.

Preparation and X-ray crystal structure determination of an octahedral polymeric lutetium compound with ciliatine; {Lu(PO3HCH2CH2NH3)3(ClO4)3·3D2O}n

Abstract The new octahedral compound of lutetium with ciliatine of the formula Lu(PO3HCH2CH2NH3)3(ClO4)3·3D2O was prepared in the form of single crystals from D2O solutions and subjected to X-ray structure determination. Each lutetium ion is coordinated by six oxygen atoms from the phosphoric groups. The coordination polyhedron is an almost ideal octahedron with a mean Lu—O distance of 2.201(6) A. The lutetium ions are bridged by two oxygen atoms from each of three phosphonic groups. In this manner the linear polymer is formed along the x axis.

Spectroscopy and crystal structure of holmium and dysprosium complex compounds with glycine: Ln(Gly)3(H2O)3(ClO4)3

Abstract Lanthanide(III) complexes with the formula Ln(C2H5NO2)3(H2O)3(ClO4)3 (where Ln ≡ Ho, Dy) were obtained in the form of monocrystals which were isomorphic and crystallized in monoclinic space group Cc with the following cell constants: Ho(C2H5NO2)3(H2O)3(C1O4)3: a = 20.506(3) b = 9.245(1) c = 23.989(4) A β = 100.28(1)° V = 4474.7(2) A 3 Z = 8dc = 2.20 g cm−3dm = 2.19(2)MR = 742.53 F(0.00) = 2912 Dy(C2H5NO2)3(H2O)3(ClO4)3: a = 20.56(7) b = 9.42(8) c = 24.16(5) A β = 98.7(5)°Z = 8 dm = 2.19 Results from the X-ray crystal structure determination are given for the Ho3+ complex compound. The coordination polyhedron of a Ho(III) ion comprises seven oxygen atoms from glycine and two from water molecules. Two oxygen bridges fasten the linear polymer running along the b axis. Absorption spectra recorded in the region 5500–40000 cm−1 were measured along the a axis for the Dy3+ complex and the probabilities of f-f transitions were analysed on the basis of the Judd-Ofelt theory. Solid state fluorescence spectra of the Dy3+ ion were recorded at 77 and 300 K. The results are discussed and the Stark levels have been determined. Spectroscopic properties of all the known Dy3+ carboxylates were compared.

Crystal structure and optical properties of Ln(III) octahedral complexes with hexamethylphosphortriamide; [Ln(HMPA)6](ClO4)3

Abstract The neodymium and europium complexes with HMPA (hexamethylophosphortriamide O=P[N(CH 3 ) 2 ] 3 ) of formula Ln(HMPA) 6 (ClO 4 ) 3 were synthesized and obtained as monocrystals from non-aqueous solutions. The structure of the neodymium complex [C 36 H 108 N 18 O 18 P 6 Cl 3 Nd] has been determined by X-ray diffraction. It crystallizes in the cubic space group Fm3m , with the unit cell parameter a = 19.222(1) A. The structure was solved by direct method and refined using the anisotropic full-matrix least-squares method. The final R ( wR ) factors were 0.042 (0.049) for 468 observed reflections (3098 measured). Each metal ion is coordinated to six HMPA molecules through oxygen atoms of a PO group with Nd-O bond lengths of 2.340(8) A. Metal ions occupy symmetry centre in ideal octahedral ( O h ) symmetry. The three −N(CH 3 ) 2 groups statistically occupy four equivalent positions with an occupancy factor 3/4, which is reflected in the spectral properties of the complex. The compounds were characterized by IR, Raman, luminescence and absorption spectroscopy at 5, 77 and 293 K. Probabilities of electronic transitions for the Nd ion were analysed and compared with those for centrosymmetric single crystals with antipyrine with the formula: Nd(AP) 6 (ClO 4 ) 3 . The intensity of the hypersensitive transition of the title compound is lower, moreover a drastic decrease of intensities in the IR region is observed. Attention is focused on a vibronic transition occurring between crystal-field (electronic) levels with simultaneous excitation of phonon or vibrational modes (in the 7 F 0 → 5 D 2 excitation spectrum of Eu 3+ and 4 I 9/2 → 4 G 5/2 , 4 G 7/2 in the absorption spectrum of Nd 3+ ). Using the IR and Raman data of Ln(HMPA) 6 (ClO 4 ) 3 crystals, a preliminary assignment of vibronic lines was made.

Spectroscopy and crystal structure of octaaquatetra-L-α-alaninediholmium(III) hexachloride [Ho2(L-α-AlaH)4(H2O)8]Cl6

Abstract Crystals of holmium with L-a-alanine, [Ho2(L-α-AlaH)4(H2O)8]Cl6 are triclinic with space group P1 and lattice parameters a = 10.284(3) A, b = 10.970(3) A, c = 9.646(2) A, α = 100.54(3)°, β = 102.11(3)°, γ = 119.89(3)°, V = 867.8(4) A3, Z = 1, Mr = 1043.2, Dx = 2.00 g cm−3, Dm = 2.03 g cm−3, μ(Mo Kα) = 52.2 cm−1. The crystal structure consists of pseudosymmetric dimeric units. Each holmium ion is coordinated by four carboxylate oxygens and four oxygens from the water molecules. The coordination polyhedra around the holmium ions are distorted bicapped trigonal prisms. Absorption spectra at room temperature and 119 K were measured over the range 20 300 – 2690 A. Stark sublevels were determined for electronic transitions from 5I8 ground state to the excited states observed in the low temperature spectrum. The intensities of f-f transitions were analysed on the basis of Judd theory.

Crystal structures and spectroscopy studies of lanthanide complexes with l-proline [Ln(l-proH)2(H2O)5]Cl3 (Ln = Ho, Dy)

Abstract The isomorphic crystals of dysprosium(III) and holmium(III) complexes with proline of formula [Ln(C5H9NO2)2(H2O)5]Cl 3 (compound I holmium; compound II, dysprosium) were synthesized and characterized by crystal structures and spectroscopic properties. The space group is P21 with lattice parameters: I a = 11.968(2), b = 11.030(2), c = 8.309(2) A, β = 106.97(3)°; II a = 11.968(4), b = 11.038(4), c = 8.302(2) A, β = 107.00(3)°. The structures of the title compounds differ significantly from that of [Nd(proH)3(H2O)2](ClO4)3, with different bonding modes for the proline ligands. The holmium and dysprosium structure contains one-dimensional polymers with the chains lying along the y-axis. Absorption spectra of the holmium monocrystal were measured along the a-axis at room temperature. Intensities of f-f transitions were analysed on the basis of Judd theory. The influence of the bonding mode of the carboxyl group on the intensity of the 5I8 → 5G6 hypersensitive transition of the Ho3+ ion was considered and confronted for all spectroscopy data available for holmium carboxylate monocrystals.

Spectroscopy of lanthanide single crystals with glycylglycine, Ln(Gly-Gly)2(ClO4)3·4H2O (Ln = Nd, Eu)

Abstract The lanthanide(III) compound with a simple dipeptide (glycylglycine) of the formula Ln(Gly-Gly)2(ClO4)3·4H2O was obtained in the form of mono-crystals. These are the first known single crystals of lanthanides with a dipeptide. Well-resolved absorption and luminescence spectra at room and helium temperatures are reported and analysed. The bonding mode of the Ln3+ ions with a simple peptide is compared with the available X-ray data for the calcium compounds with diglycine and triglycine. Absorption spectra were measured along the a-axis in the region 9000–40,000 cm−1. The probabilities of f-f transitions were analysed and the temperature effect on the intensities considered. Single-ion relaxation processes and cooperative effects are discussed. Stark components were determined and point symmetry was assigned. Energy level diagrams for 4I 9 2 and 4I 11 12 states are proposed. Spectroscopy results are compared with the X-ray data.

Absorption, luminescence and crystal structure studies of dysprosium compound with l-α-Alanine: [Dy(l-α-AlaH)(H2O)6]Cl3

Abstract The dysprosium compound with l -α-Alamine of the formula [Dy( l -α-AlaH)-(H2O)6]Cl3 was obtained from a water solution in the form of single monoclinic crystals with space group P21. Distribution of atoms in the structure of [Dy( l -α-AlaH)(H2O)6]Cl3 is rather close to that of the pseudo P2 1 c group. The other parameters were as follows: a = 8.459(3) A , b = 15.719(4) A , c= 11.518(3) A , β= 102.11(3)°, V = 1497.4 A 3 , Z = 4, dm = 2.08 g cm−3, dc = 2.07 g cm−3, μ(MoKα) = 5.22 mm−1, λ = 0.71069 A, F(000) = 900 and T = 299 K. The structure consists of a polymeric chain with oxygen bridges fastening the linear polymer running along the c-axis. The final R factor was 0.026 for 2586 reflections. Each dysprosium ion is coordinated by two carboxylate oxygens and six oxygens from water molecules. The absorption spectrum in the region 5500–40000 cm−1 was recorded along the a-axis and the probabilities of f-f transitions were analysed on the basis of the Judd-Ofelt theory. Solid state fluorescence spectra were recorded at 77 and 300 K and compared with all known dysprosium carboxylates data.