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Shifu Weng

Publications and source records attributed to Shifu Weng.

10 recordsLinked to original sources
PubMed2005

Crystal structures and spectroscopic characterization of galactitol complexes of trivalent lanthanide and divalent alkaline earth chlorides.

Crystal structures and FT-IR spectra of metal ion-galactitol (C6H14O6, the ligand here abbreviated as L) complexes: 2LaCl3*C6H14O6*10H2O and SrCl2*C6H14O6 complexes are reported. Crystal data of lanthanide chlorides (La3+, Nd3+, Sm3+, Eu3+, Tb3+)-galactitol complexes and alkaline earth chlorides (Ca2+, Sr2+)-galactitol complexes published earlier are summarized. Unlike other lanthanide ion-galactitol complexes (2MCl3*C6H14O6*14H2O), lanthanum ions give rise to two different structures: LaCl3*C6H14O6*6H2O (LaL1) and 2LaCl3*C6H14O6*10H2O (LaL2). Sr2+-galactitol complexes also crystallized with two structures: SrCl2*C6H14O6*4H2O (SrL1) and SrCl2*C6H14O6 (SrL2). These metal ions thus give different coordination structures with galactitol. The crystal structures and FT-IR spectra of lanthanide ion and alkaline earth ion-galactitol complexes were integrated to interpret the coordination modes of different metal ions. Similar IR spectra demonstrate the same coordination modes of the complexes.

Crystallization↗
PubMed2005

Interactions between metal ions and carbohydrates. The coordination behavior of neutral erythritol to lanthanum and erbium ions.

Lanthanide ions and erythritol form metal-alditol complexes with various structures. Lanthanum nitrate and erbium chloride coordinate to erythritol to give new coordination structures. The lanthanum nitrate-erythritol complex (LaEN), 2La(NO3)3.C4H10O(4).8H2O, La3+ exhibits the coordination number of 11 (namely 11 polar atoms bound to one lanthanum) and is 11-coordinated to two hydroxyl groups from one erythritol molecule, six oxygen atoms from three nitrate ions and three water molecules. One erythritol molecule is coordinated to two La3+ ions and links the two metal ions together. The ratio of M:L is 2:1. The erbium chloride-erythritol complex (ErE), ErCl2.C4H9O(4).2C2H5OH was obtained from ErCl3 and erythritol in aqueous ethanol solution and the structure shows that deprotonation reaction occurs in the reaction process. The Er3+ cation is 8-coordinated with three hydroxyl groups of one erythritol molecule, two hydroxyl groups from another erythritol molecule, two ethanol molecules, and one chloride ion. Erythritol provides its three hydroxyl groups to one erbium cation and two hydroxyl groups to another erbium cation, that is, one hydroxyl group is coordinated to two metal ions and therefore loses its hydrogen atom and becomes a oxygen bridge. Another chloride ion is hydrogen bonded in the structure. The results indicate the complexity of metal-sugar coordination.

Crystallization↗
PubMed2005

New, rapid fluorescence stain method for histologic sections using lanthanide complexes.

A new stain method for histologic sections different from traditional hematoxylin and eosin (H&E) methodology used two newly developed stain reagents from the lanthanide series, the antibiotic ofloxacin chelate of europium(III) and the ciprofloxacin hydrochloride chelate of terbium(III), exhibiting excellent fluorescence. These complexes are unique due to their nontoxicity, attractive fluorescent properties, rapid staining, and high water solubility. In this article, we focus on the interactions between biomolecules and synthesized lanthanide complexes and on the staining effect applied for tissue staining.

Ciprofloxacin↗
PubMed2005

Interactions between metal ions and carbohydrates. The coordination behavior of neutral erythritol to neodymium ion.

A single crystal of a coordinated complex of neutral erythritol (C4H10O4,E) with a neodymium ion, NdE(II), was synthesized and studied using FT-IR and X-ray diffraction analysis. In NdE(II) (NdCl3.2.5C4H10O4.C2H5OH) the Nd3+ coordinates with one chloride ion and eight OH groups from three erythritol molecules. There are two neodymium centers linked by one erythritol molecule with same coordination structure in the molecule. Two erythritol molecules provide 1,3,4-hydroxyl groups to coordinate with a neodymium ion; another erythritol molecule coordinates to two Nd ions via its 1,2-hydroxyl groups and 3,4-hydroxyl groups, respectively. The OH groups of erythritol act as ligand to coordinate to neodymium ions, and OH groups of erythritol form hydrogen bond networks that link chain and layer together to build three-dimensional structures. The ratio of metal to ligand is 1:2.5. The structure of NdE(II) is more complicated than the previously reported NdE(I), which is NdCl3.C4H10O4.6H2O; in NdE(I), Nd3+ is coordinated to four hydroxyl groups from two erythritol molecules, four water molecules and one chloride ion. The results indicate the complexity of metal-sugar interaction.

Journal Article↗
PubMed2004

Interactions between metal ions and carbohydrates: the coordination behavior of neutral erythritol to transition metal ions.

The single crystals of coordinated complexes of neutral erythritol (C4H10O4) with various transition metal ions were synthesized and studied using FT-IR and single crystal X-ray diffraction analysis. Two CuCl2-erythritol complexes (denoted as CuE(I) and CuE(II)) were obtained. In CuE(I), Cu2+ coordinates with two chloride ions and four OH groups from two erythritol molecules. Two copper centers are linked by one erythritol molecule to form a zigzag chain. For CuE(II), each Cu2+ coordinates with two OH groups from an erythritol molecule and two chloride ions. The crystal of CuE(II) contains complexed and free erythritol, the dimers of [Cu2Cl4(C4H10O4)] further form a [Cu2Cl4(C4H10O4)]infinity chain via secondary Cu...Cl bonds, both the dimer unit of [Cu2Cl4.(C4H10O4)] and non-coordinated C4H10O4 unit exist side by side in the crystal. MnCl2-erythritol complex whose structure is similar to CuE(I) is also acquired. The OH groups of erythritol act as ligand to coordinate to metal ions on one hand, one the other hand, OH groups form hydrogen bonds network that link chain and layer together to build three-dimensional structures.

Carbohydrates↗
PubMed2004

The interaction between amino acids and metal ions (I). The FT-IR spectroscopic study of the binding between D,L-homocysteic acid and alkali metal ions.

D,L-Homocysteic acid (DLH), an amino acid in the mammalian central nervous system, can excite the cerebral activities and has been proposed as an agonist of endogenous glutamate receptor. It contains -NH(3)(+), -COOH and -SO(3)(-) groups, therefore, the interactions between DLH and metal ions may be expected. In the present investigation, the complexes of DLH with NH4(+), Li+, Na+ and K+ at different pH conditions were synthesized and characterized by Fourier transform infrared (FT-IR) spectroscopy. It was concluded that the structures of the complexes prepared at pH 2.6 and 4.0 are similar to each other and the C=O groups are mono-dentate coordination for these complexes. However, the structures of the complexes synthesized at pH 13.0 change considerably from the complexes at pH 2.6 and 4.0, which show that dissociation has occurred in aqueous solution. The four cations coordinate to DLH, which result in the rearrangement of the hydrogen bond network and the skeletal structure change of the ligand.

Homocysteine↗
PubMed2003

Interactions between metal ions and carbohydrates. Coordination behavior of neutral erythritol to Ca(II) and lanthanide ions.

The study of the sugar-metal ion interactions remains one of the main objectives of carbohydrate coordination chemistry because the interactions between metal ions and carbohydrates are involved in many biochemical processes. This paper presents a comparison of coordination structures of erythritol with alkaline-earth-metal and lanthanide chloride and nitrate in the solid state using FT-IR and X-ray diffraction. Neutral, nondeprotonated erythritol (E) reacts with CaCl(2) to give three CaCl(2)(-)erythritol (CaE(I), CaE(II), CaE(III)) complexes, showing that three of the five general features of calcium-carbohydrate complexes deduced in the reference encounter contrary examples. Different coordination structures have been observed for calcium and lanthanide chloride and nitrates. The coordination of carbohydrates to metal ions is complicated, and erythritol, chloride ions, nitrates, water molecules, and ethanol (crystallization medium and reaction solvents) have the chance to coordinate to metal ions. IR spectral results show that different lanthanide ions, from LaCl(3) to TbCl(3), have similar coordination structures with erythritol. The results show that erythritol can act as two bidentate neutral ligands (CaE(I), CaE(II), CaE(III), CaEN, PrE, NdE) or as a three-hydroxyl donor (NdEN). The IR results are consistent with the crystal structures.

Calcium↗
PubMed2003

Sugar interaction with metal ion: crystal structure and spectroscopic study of SrCl2.galactitol.4H2O.

The crystal structure of SrCl(2).galactitol.4H(2)O has been determined. It belongs to monoclinic system, C2/c space group with unit cell dimensions: a=13.9849(3), b=14.1601(5), c=8.3026(3) A, beta=104.621(2) degrees, V=1590.9(9) A(3) and Z=4. Each Sr(2+) ion in the unit cell binds to two molecules of galactitol through O2 and O3 in one alditol and O2' and O3' in the other, as well as to four water molecules. Sr-O distances in SrCl(2).galactitol.4H(2)O complex range from 2.5420 to 2.6359 A. FT-IR, Raman and far-IR spectra of SrCl(2).galactitol.4H(2)O all show that SrCl(2) coordinates with galactitol through OH groups of the sugar molecule to form the new complex.

Carbohydrates↗
PubMed2002

A new mechanism of Raman enhancement and its application.

Strong electronic Raman bands corresponding to the transition between 4I9/2 and 4I11/2 manifolds of Nd3+, caused by a Raman-enhancement effect, are observed in the FT-Raman spectrum of Nd2O3. Neither resonance enhancement (RR) nor surface enhancement (SERS) accounts for the Raman enhancement observed here. We propose a new mechanism of Raman enhancement called the "feed-back" mechanism. A YAG laser excites the final state of the Raman transition (4I11/2 of Nd3+) to the 4F3/2 state and causes a significant decrease in the population of Nd3+ at the 4I11/2 state. This causes the population ratio of Nd3+ at 4I9/2 and 4I11/2 to deviate from the value required by Boltzmann's law. To restore equilibrium, Raman scattering is enhanced so that more Nd3+ ions are brought from the 4I9/2 state to the 4I11/2 state. This hypothesis gets support from the temperature-variable FT-Raman spectroscopic results. Additionally, obvious differences between the Stokes and anti-Stokes Raman spectrum of Nd3+ provide further evidence to support the feed-back mechanism. The Raman-enhancement effect confers on the electronic Raman bands a special ability to reflect the variation of coordinated structure around metal ions. The structural variations in polymer-metal ion composites and biomineralization systems have been investigated by using the electronic Raman bands.

Journal Article↗