Quantitative light absorption data of the neutral free flavosemiquinone are reported. It is shown that the visible range of the spectrum of the radical is drastically dependent on the solvent. The spectra of the neutral blue flavosemiquinone are compared with those of the blue flavoprotein radicals and conclusions are drawn concerning the environment of the protein-bound flavosemiquinone. The s...

Guanine-rich sequences of DNA are able to create tetrastranded structures known as G-quadruplexes; they are formed by the stacking of planar G-quartets composed of four guanines paired by Hoogsteen hydrogen bonding. G-quadruplexes act as ligands for metal ions and aptamers for various molecules. Interestingly, the G-quadruplexes form a complex with anionic porphyrin hemin and exhibit peroxidase...

A three-coordinate Cu-NR(2) system (R = p-tolyl) supported by the anionic bis(phosphino)borate ligand [Ph(2)B(CH(2)P(t)Bu(2))(2)](-) has been isolated and structurally characterized in both its anionic Cu(I) and neutral (formally) Cu(II) oxidation states. A large rate constant for the self-exchange electron-transfer reaction (k(S) >or= 10(7) M(-1) s(-1)) makes this system a functional model for...

In the title complex, [Cu(C(14)H(13)N(3)O)(C(14)H(12)N(3)O)](CCl(3)COO), the central Cu(II) ion exhibits a distorted octa-hedral geometry with the two ligands coordinating in an meridional format. The N(4)O(2) ligand environment is defined by two benzoyl O atoms, two pyridyl N atoms and imino N atoms. As evidenced by the bond lengths, the two benzohydrazone ligands exist in distinctively differ...

Abstract The diffusion kinetics of a molecular probe—rhodamine B—in ternary aqueous solutions containing poly(vinyl alcohol), glycerol, and surfactants was investigated using fluorescence correlation spectroscopy dynamic light scattering. We show that the characteristics rhodamine B in such complex systems is determined by synergistic effect crowding intermolecular interactions between chemical...

Considerable interest is currently focused on the interactions of beta-2 glycoprotein I (beta2GPI) and anti-phospholipid antibodies with anionic phospholipids in an attempt to understand the association between these antibodies and clinical diseases such as thrombosis. The interactions of beta2GPI and anionic phospholipids have only been characterized partially, and the physiological role of th...

In the cation of the title compound, {[Y(NO(3))(2)(C(6)H(18)N(3)OP)(4)][AgMoS(4)]}(n), the Y atom is coordinated by eight O atoms from two chelating nitrate groups and four hexa-methyl-phospho-ramide (hmp) ligands, which gives rise to a distorted square-anti-prismatic environment. Together with the two nitrate ligands, the overall charge for the complex cation is +1, which leads to the anionic ...

First-principles calculations based on the generalized gradient approximation to the density functional theory are performed to explore the global geometries, ground-state spin multiplicities, relative stabilities, and energetics of neutral and anionic V(n)(Bz)(m) (n=1-3, m=1-4, with n<m) complexes. The calculated results show that the V(n)(benzene)(m) complexes clearly prefer sandwich structur...

The complex mol-ecule of the title compound, [Zn(C(13)H(9)N(2)O(3))(2)(H(2)O)(2)]·2H(2)O, has 2 symmetry with the Zn(II) cation located on a twofold rotation axis. The Zn cation is N,N'-chelated by two 5-[(pyridin-2-yl)methyl-idene-amino]-2-hy-droxy-benzoate anions and coordinated by two water mol-ecules in a distorted octa-hedral geometry. Within the anionic ligand, the pyridine ring is orient...

Spectral studies on the interaction of acidic capsular polysaccharide (SPS), isolated from Klebsiella K28, with cationic dye and surfactants have een reported. The polymer induced strong metachromasy (∼100 nm blue shift) in the cyanine dye pinacyanol bromide (PCYB). The SPS consists f d-glucose, d-galactose, d-mannose and d-glucuronic acid (2:1:2:1 molar ratio) in hexasaccharide repeating units...