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S P Yan

Publications and source records attributed to S P Yan.

8 recordsLinked to original sources
PubMed2001

Crystal structures and magnetic properties of new cyano-bridged two-dimensional grid-like bimetallic assemblies [Ni(tn)2]2[Cr(CN)5((NO)]OH*H2O and [NI(tn)2]2[Co(CN)6]NO3*2H2O (tn=1,3-propanediamine).

Two bimetallic assemblies, [Ni(tn)(2)](2)[Cr(CN)(5)(NO)]OH.H(2)O (1) and [Ni(tn)(2)](2)[Co(CN)(6)]NO(3).2H(2)O (2) (tn = 1,3-diaminopropane), have been prepared and structurally and magnetically characterized. Crystal data for 1 (2): space group P1 (P1), a = 8.698(3) (8.937(2)) A, b = 10.001(2) (9.863(1)) A, c = 10.158(2) (10.064(1)) A, alpha = 87.40(2) (86.064(10)) degrees, beta = 65.10(2) (65.489(10)) degrees, gamma = 81.63(2) (81.572(12)) degrees and Z = 1 (1). Both structures consist of two-dimensional grid-like polycations containing Ni-N triple bond C-M linkages (M = Cr or Co) and counteranions (OH, NO(3)). Magnetic studies of 1 showed that the complex displays a metamagnetic behavior originating from intralayer ferromagnetic and interlayer antiferromagnetic interactions. Long-range antiferromagnetic ordering was observed at T(N) = 3.3 K. Complex 2 exhibits intramolecular ferromagnetic interactions through the diamagnetic N triple bond C-Co-N triple bond C bridges, owing to superexchange involving the empty d(sigma) orbital of the diamagnetic Co(III) ion.

Journal Article↗
PubMed2001

A novel hydrogen-bonded microporous framework constructed from two different metal complexes.

A hydrogen-bonded coordination supramolecule, (meso-5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane-kappa4N)nickel(II) [N,N-o-phenylenebis(oxamato)-kappa4O,N,N',O']nickelate(II) dihydrate, [Ni(C16H36N4)][Ni(C10H4N2O6)]*2H2O or [Ni(meso-cth)][Ni(opba)]*2H2O, has been prepared and characterized by X-ray crystallographic analysis. The two complex ions, i.e. [Ni(meso-cth)]2+ and [Ni(opba)]2-, are hydrogen bonded to each other, resulting in two-dimensional neutral supramolecular sheets. The sheets stack along the a direction to produce a three-dimensional architecture with one-dimensional channels in which hydrogen-bonded chains of water molecules are included.

Journal Article↗
PubMed2001

Oxamato-bridged trinuclear Ni(II)Cu(II)Ni(II) complexes with irregular spin state structures and a binuclear Ni(II)Cu(II) complex with an unusual supramolecular structure: crystal structure and magnetic properties.

Four oxamato-bridged heterotrinuclear Ni(II)Cu(II)Ni(II) complexes of formula ([Ni(bispictn)](2)Cu(pba))(ClO(4))(2).2.5H(2)O (1), ([Ni(bispictn)](2)Cu(pbaOH))(ClO(4))(2).H(2)O (2), ([Ni(cth)](2)Cu(pba))(ClO(4))(2) (3), and ([Ni(cth)](2)Cu(opba))(ClO(4))(2).H(2)O (4) and a binuclear Ni(II)Cu(II) complex of formula [Cu(opba)Ni(cth)].CH(3)OH (5) have been synthesized and characterized by means of elemental analysis, IR, ESR, and electronic spectra, where pba = 1,3-propylenebis(oxamato), pbaOH = 2-hydroxyl-1,3-propylenebis(oxamato), opba = o-phenylenebis(oxamato), bispictn = N,N'-bis(2-pyridylmethyl)-1,3-propanediamine, and cth = rac-5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane. The crystal structures of 1, 3, and 5 have been determined. The structures of complexes 1 and 3 consist of trinuclear cations and perchlorate anions, and that of 5 consists of neutral binuclear molecules which are connected by hydrogen bonds and pi-pi interactions to produce a unique supramolecular "double" sheet. In the three complexes, the copper atom in a square-planar or axially elongated octahedral environment and the nickel atom in a distorted octahedral environment are bridged by the oxamato groups, with Cu.Ni separations between 5.29 and 5.33 A. The magnetic properties of all five complexes have been investigated. The chi(M)T versus T plots for 1-4 exhibit the minimum characteristic of antiferromagnetically coupled NiCuNi species with an irregular spin state structure and a spin-quartet ground state. The chi(M)T versus T plot for 5 is typical of an antiferromagnetically coupled NiCu pair with a spin-doublet ground state. The Ni(II)-Cu(II) isotropic interaction parameters for the five complexes were evaluated and are between 102 and 108 cm(-)(1) (H = -JS(Cu).S(Ni)).

Journal Article↗
PubMed2001

Two-dimensional coordination polymers of copper(II) with oxalate: lattice water control of structure.

Three oxalate copper(II) complexes, [Cu(bipy)(C(2)O(4))(H(2)O)].2H(2)O (1), [Cu(nphen)(C(2)O(4))(H(2)O)].2H(2)O (2), and [Cu(phen)(C(2)O(4))(H(2)O)].H(2)O (3) (bipy = 2,2'-bipyridine, nphen = 5-nitro-1,10-phenanthroline and phen = 1,10-phenanthroline), have been synthesized and their crystal structures have been determined. Compound 1 crystallizes in the triclinic space group P1 with a = 7.2554(10) A, b = 10.5712(14) A, c = 10.8178(15) A, alpha = 62.086(2) degrees, beta = 77.478(3) degrees, gamma = 81.773(3) degrees, and Z = 2. Compound 2 crystallizes in the triclinic space group P1 with a = 9.582(2) A, b = 10.086(2) A, c = 10.592(2) A, alpha = 64.18(3) degrees, beta = 79.47(3) degrees, gamma = 60.06(3) degrees, and Z = 2. Compound 3 crystallizes in the monoclinic space group P2(1)/n with a = 8.4655(7) A, b = 9.7057(8) A, c = 17.4572(14) A; beta = 103.865(2) degrees, and Z = 4. The crystal structures of all complexes consist of neutral [Cu(L)(C(2)O(4))(H(2)O)] (L = bipy, nphen, and phen) units and one or two lattice water molecules in the unit cell. Each copper atom in 1, 2, and 3 involves a five-coordinate CuN(2)O(2)O' environment, with a distorted square-pyramidal structure. In 1 and 2, two lattice water molecules are around each unit of [CuL(C(2)O(4))(H(2)O)] (L = bipy and nphen) and form two-dimensional networks. Only one lattice water molecule is found in the unit cell of 3 and the two-dimensional structure is different from 1 and 2. The extended three-dimensional structure is formed through pi-pi interactions between layers. The influences of hydrogen bonds and the sizes and Lewis basicity of ligands to the structures were discussed.

Journal Article↗
PubMed2000

New alternating ferro- and antiferromagnetic one-dimensional complexes. Synthesis, characterization, crystal structure, and magnetic properties of.

The preparation, X-ray crystal structure, and magnetic properties of alternating 1,1- and 1,3-azido-bridged copper(II) complex [Cu(4,4'-dmbpy)(N3)2]n (1, 4,4'-dmbpy = 4,4'-dimethylbipyridine) have been reported. It crystallizes in triclinic system, space group P1, a = 7.9903(1) A, b = 9.3545(9) A, c = 10.754(2) A, alpha = 113.485(1) degrees, beta = 101.399(1) degrees, gamma = 101.897(1) degrees, Z = 2. The magnetic properties of 1 have been investigated in the temperature range 1.5-300 K. Alternating antiferromagnetic (-J = 191.0 cm(-1)) interaction through a 1,3-N3- bridge and ferromagnetic (J = 297.1 cm(-1)) interaction through a 1,1-N3- bridge are obtained for 1 by analyzing the magnetic susceptibility data with the Hamiltonian H = -Jsigma(S2iS2i-1--alphaS2iS2i+1). It's derivatives ([Mn(4,4'-dmbpy)(N3)2]n (2), [Ni(4,4'-dmbpy)(N3)2]n (3), and [Fe(4,4'-dmbpy)(N3)2]n (4) and the heterometallic derivatives [NiMn(4,4'-dmbpy)2(N3)4]n (5) and [CuMn(4,4'-dmbpy)2(N3)4]n (6) have also been synthesized and characterized by electronic and IR spectra. The X-ray powder diffraction and the magnetic properties of 6 have also been discussed.

Journal Article↗
PubMed1985

Liquid covering for superficial skin wounds and its effect on wound closure in guinea pigs.

An irrigatable bandage has been developed to hold fluid over a wound. Starting with superficial skin wounds on the back of guinea pigs, the bandage has been used to hold saline or phosphate-buffered saline containing antibiotics over the wound for up to 48 hours. Animals tolerated the bandage well for this period and bacterial contamination and wound maceration were not complications. The extent of reepithelialization with time was measured histologically under three separate conditions: wound exposed to air, wound covered and kept moist, and wound covered with liquid. By 24 hours 2 +/- 1%, 16 +/- 4% and 60 +/- 8% of the wound surface interfollicular areas showed some reepithelialization, respectively. On the average, at the same time these areas showed 15 +/- 2%, 19 +/- 2% and 37 +/- 1% coverage by epithelium. By these measurements, the liquid cover enhanced the rate of wound closure significantly.

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