Biomedical subjects

L Iordanidis

Publications and source records attributed to L Iordanidis.

6 recordsLinked to original sources

PubMed2001

New members of the homologous series A(m)[M(6)Se(8)](m)[M(5+n)Se(9+n)]: The quaternary phases A(1-x)M'(3-x)Bi(11+x)Se(20) and A(1+x)M'(3-2x)Bi(7+x)Se(14) (A = K, Rb, Cs; M' = Sn, Pb).

The compounds A(1+x)M'(3-2x)Bi(7+x)Se(14) and A(1-x)M'(3-x)Bi(11+x)Se(20) (A = K, Rb, Cs; M' = Sn, Pb) were discovered from reactions involving A(2)Se, Bi(2)Se(3), M', and Se at 760 degrees C. The single-crystal structures reveal that A(1+x)M'(3-2x)Bi(7+x)Se(14) are isostructural to K(2.5)Bi(8.5)Se(14) whereas A(1-x)M'(3-x)Bi(11+x)Se(20) adopt a new structure type. Both compound types belong to the homologous series A(m)[M(6)Se(8)](m)[M(5+n)Se(9+n)] (M = di- and trivalent metal), whose characteristics are three-dimensional anionic frameworks with tunnels filled with alkali ions. The building units are derived from different sections of the NaCl lattice, perpendicular to the [111] (NaCl(111)-type) and [100] (NaCl(100)-type) directions, respectively, with dimensions and shapes defined by m and n. The structures of A(1+x)M'(3-2x)Bi(7+x)Se(14) (m = 2, n = 3) and A(1-x)M'(3-x)Bi(11+x)Se(20) (m = 1, n = 3) exhibit the same type of step-shaped NaCl(111)-type layer but differ in the size of the NaCl(100)-type unit. In both structures, the Bi and Sn (Pb) atoms are extensively disordered over the metal sites of the chalcogenide network. The physicochemical and charge transport properties of A(1+x)M'(3-2x)Bi(7+x)Se(14) and A(1-x)M'(3-x)Bi(11+x)Se(20) (A = K, Rb, Cs; M' = Sn, Pb) are reported.

Journal Article↗

PubMed2001

Cs1-xSn1-xBi9+Se15 and Cs1.5-3xBi9.5+xSe15: members of the homologous superseries Am[M1+lSe2+l]2m[M1 + 2l+nSe3 + 3l+n] (A = alkali metal, M = Sn and Bi) allowing structural evolution in three different dimensions.

Cs1-xSn1-xBi9+xSe15 and Cs1.5-3xBi9.5+xSe15 crystallize in a new structure type which does not belong to but is closely related to the members of the homologous series Am[M6-Se8]m[M5+nSe9+n]; the new phases reveal a third dimension of structural evolution for this series according to the formula Am[M1+lSe2+l]2m[M1 + 2l + nSe3 + 3l+n].

Journal Article↗

PubMed2001

Synthesis, pH-dependent structural characterization, and solution behavior of aqueous aluminum and gallium citrate complexes.

Reactions of Al(III) and Ga(III) with citric acid in aqueous solutions, yielded the complexes (NH(4))(5)[M(C(6)H(4)O(7))(2)].2H(2)O (M(III) = Al (1), Ga (2)) at alkaline pH, and the complexes (Cat)(4)[M(C(6)H(5)O(7))(C(6)H(4)O(7))].nH(2)O (M(III) = Al (3), Ga (4), Cat. = NH(4)(+), n = 3; M(III) = Al (5), Ga (6), Cat. = K(+), n = 4) at acidic pH. All compounds were characterized by spectroscopic (FT-IR, (1)H, (13)C, and (27)Al NMR, (13)C-MAS NMR) and X-ray techniques. Complex 1 crystallizes in space group P1, with a = 9.638(5) A, b = 9.715(5) A, c = 7.237(4) A, alpha = 90.96(1) degrees, beta = 105.72(1) degrees, gamma = 119.74(1) degrees, V = 557.1(3) A(3), and Z = 1. Complex 2 crystallizes in space group P1, with a = 9.659(6) A, b = 9.762(7) A, c = 7.258(5) A, alpha = 90.95(2) degrees, beta = 105.86(2) degrees, gamma = 119.28(1) degrees, V = 564.9(7) A(3), and Z = 1. Complex 3 crystallizes in space group I2/a, with a = 19.347(3) A, b = 9.857(1) A, c = 23.412(4) A, beta = 100.549(5) degrees, V = 4389(1) A(3), and Z = 8. Complex 4 crystallizes in space group I2/a, with a = 19.275(1) A, b = 9.9697(6) A, c = 23.476(1) A, beta = 100.694(2) degrees, V = 4432.8(5) A(3), and Z = 8. Complex 5 crystallizes in space group P1, with a = 7.316(1) A, b = 9.454(2) A, c = 9.569(2) A, alpha = 64.218(4) degrees, beta = 69.872(3) degrees, gamma = 69.985(4) degrees, V = 544.9(2) A(3), and Z = 1. Complex 6 crystallizes in space group P1, with a = 7.3242(2) A, b = 9.4363(5) A, c = 9.6435(5) A, alpha = 63.751(2) degrees, beta = 70.091(2) degrees, gamma = 69.941(2) degrees, V = 547.22(4) A(3), and Z = 1. The crystal structures of 1-6 reveal mononuclear octahedral complexes of Al(III) (or Ga(III)) bound to two citrates. Solution NMR, on both 4- and 5- species, reveals rapid intramolecular exchange of the bound and unbound terminal carboxylates. Upon dissolution in water, the complexes, through a complicated reaction cascade, transform to oligonuclear 1:1 species that, in agreement with previous studies, represent the thermodynamically stable state in solution. The data provide, for the first time, structural details of low MW, mononuclear complexes of Al(III) (or Ga(III)) with citrate that are dictated, among other factors, by pH. The properties of 1-6 may provide clues relevant to their biological association with humans.

Aluminum↗

PubMed2001

Novel quaternary lanthanum bismuth sulfides Pb(2)La(x)Bi(8-x)(S(14)), Sr(2)La(x)Bi(8-x)S(14), and Cs(2)La(x)Bi(10-x)S(16) with complex structures.

The compounds Pb(2)La(x)Bi(8-x)S(14) (I), Sr(2)La(x)Bi(8-x)S(14) (II), and Cs(2)La(x)Bi(10-x)S(16) (III) were synthesized from the corresponding elements or binary sulfides at temperatures above 850 degrees C. Compounds I and II are isostructural, forming a new structure type, while the structure of III is related to the structure of the mineral kobellite. All compounds crystallize in the orthorhombic space group Pnma (No. 62) with a = 21.2592(4) A, b = 4.0418(1) A, c = 28.1718(3) A, Z = 4 for I, a = 21.190(1) A, b = 4.0417(2) A, c = 28.285(2) A, Z = 4 for II and a = 34.893(4) A, b = 4.0697(4) A, c = 21.508(2) A, Z = 4 for III. All compounds exhibit mixed site occupancy between Bi and La. Furthermore, I and II exhibit disorder between the divalent atom (Sr or Pb) and/or La and/or Bi. The structures of I and II consist of thin walls made of two metal-atom-thick NaCl-type blocks running in two opposite directions in the ac plane, forming rhombus-shaped tunnels. These tunnels are filled with Bi(2)Te(3)-type fragments. In the points where the walls intersect they form Gd(2)S(3)-type fragments. The structure of III consists of a complex three-dimensional framework with Cs-filled tunnels. All compounds are semiconductors with band gaps around 1.0 eV, and they melt around 740-860 degrees C.

Journal Article↗

PubMed2000

Structurally diverse copper(II)-carboxylato complexes: neutral and ionic mononuclear structures and a novel binuclear structure.

The copper complexes with the commercial auxin herbicides MCPA, 2,4-D, and 2,4,5-T in the presence of a nitrogen donor heterocyclic ligand, phen or bipyam, were prepared and characterized. The available evidence supports a dimeric structure for the 2,4-D complex in the presence of bipyam while phen leads to monomeric forms. The EPR spectrum of Cu2(2,4-D)4(bipyam)2 at 4 K in the solid state exhibits an axial signal which corresponds to almost isolated S = 1/2 magnetic ions. Magnetic data for the dimer show a weak antiferromagnetic interaction between the two metal ions with J = -08 cm-1. The crystal structures of tetrakis[(2,4-dichlorophenoxy)acetato]bis(2,2'-bipyridylamine)dicopper(II), 1, bis(1,10-phenanthroline)[(2,4,5-trichlorophenoxy)acetato]copper(II) chloride, 2, and aqua(1,10-phenanthroline)bis[((2-methyl-4-chlorophenoxyacetato]copper(II), 3, were determined and refined by least-squares methods using three-dimensional MoK alpha data. 1 crystallizes in space group P1, in a cell of dimensions a = 10813(1) A, b = 12138(1) A, c = 11909(1) A, alpha = 86448(3) degrees, beta = 80127(3) degrees, and gamma = 63982(3) degrees, and V = 13837(2) A3, with Z = 1 2 crystallizes in space group I2/a, in a cell of dimensions a = 29958(9) A, b = 11342(3) A, c = 21196(7) A, beta = 10794(1) degrees, and V = 68522(4) A3, with Z = 8 3 crystallizes in space group P1, in a cell of dimensions a = 87419(8) A, b = 12512(1) A, c = 14598(1) A, alpha = 110737(1) degrees, beta = 95742(2) degrees, gamma = 103286(2) degrees, V = 14241(2) A3, with Z = 2.

Journal Article↗

PubMed2000

Redox-Induced "Zipper" Action in Rb(2)Bi(4)Se(7) and Cs(2)Bi(4)Se(7): Coupling of Slabs to a Three-Dimensional Framework through Single-Crystal to Single-Crystal Conversion Financial support from the Office of Naval Research (contract No. N00014-98-1-0443) is gratefully acknowledged. The work made use of the SEM facilities of the Center for Electron Optics at Michigan State University (MSU). The Siemens SMART CCD diffractometer at MSU was purchased with funds from the National Science Foundation (CHE-9634638). We thank Victor G. Young and the X-ray Crystallographic Laboratory of the University of Minnesota for collecting the data set of RbBi(4)Se(7).

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Journal Article↗