SiO2-CaO-P2O5 bioactive glasses: A promising curcuminoids delivery system

In this paper, we report the study of the loading and the release of curcuminoids by bioactive glasses (BG) and mesoporous bioactive glasses (MBG). Through a detailed spectroscopic study, it was possible to determine the amount and the type of molecules released in water and in simulated body fluid (SBF). In particular, curcumin and K2T21 show a good ability to be released in di-keto and keto-enolic form, depending from the pH. However, after 24 h, the amount of pristine curcumin release is very low with a consequent increment of degradation products derived by curcuminoids. The presence of -OH groups on curcuminoids is a fundamental pre-requisite in order to obtain a high loading and release in polar solution such as water and SBF. The substrate on which we loaded the drugs does not seem to affect significantly the loading and the release of the drugs. The environment, instead, affects the release: for all the drugs, the release in SBF, buffered at pH of 7.4, is slightly worse than the release in water (basic pH values)

Excited state dynamics of bis-dehydroxycurcumin tert-butyl ester, a diketo-shifted derivative of the photosensitizer curcumin

Bis-dehydroxycurcumin tert-butyl ester (K2T23) is a derivative of the natural spice curcumin. Curcumin is widely studied for its multiple therapeutic properties, including photosensitized cytotoxicity. However, the full exploitation of curcumin phototoxic potential is hindered by the extreme instability of its excited state, caused by very efficient non radiative decay by means of transfer of the enolic proton to the nearby keto oxygen. K2T23 is designed to exhibit a tautomeric equilibrium shifted toward the diketo conformers with respect to natural curcumin. This property should endow K2T23 with superior excited-state stability when excited in the UVB band, i.e., in correspondence of the diketo conformers absorption peaks, making this compound an interesting candidate for topical photodynamic therapy of, e.g., skin tumors or oral infections. In this work, the tautomeric equilibrium of K2T23 between the keto-enolic and diketo conformers is assessed in the ground state in several organic solvents by UV-visible absorption and by nuclear magnetic resonance. The same tautomeric equilibrium is also probed in the excited-state in the same environments by means of steady-state fluorescence and time-correlated single-photon counting measurements. These techniques are also exploited to elucidate the excited state dynamics and excited-state deactivation pathways of K2T23, which are compared to those determined for several other curcuminoids characterized in previous works of ours. The ability of K2T23 in photosensitizing the production of singlet oxygen is compared with that of curcumin

TRANS-TETRAAQUABIS(P-NITROHIPPURATO)-COBALT(II) DIHYDRATE

Crystals of [Co(4-NO2-hip)2(H2O)4].2H2O (4-NO2-hip = p-NO2.C6H4CO.NHCH2CO2-) contain molecules of the centrosymmetric octahedral cobalt(II) complex and lattice water molecules which are interlinked by hydrogen bonds. The Co atom lies on a crystallographic symmetry centre and has a slightly elongated octahedral environment arising from coordination by the carboxylic O atoms of two monodentate 4-nitrophippurate anions and the O atoms of four water molecules

CRYSTAL AND MOLECULAR-STRUCTURE, AND INFRARED STUDY OF BIS(2,2'-BIPYRIDINE) [N-(TOLUENE-P-SULFONYL)GLYCINATO-NO] CADMIUM(II) COMPLEX AND RELATED-COMPOUNDS

A series of complexes of formula [M(II)(bpy)2(ArSO2-N-aminoacidato-NO)1.3H2O [bpy = 2,2'-bipyridine, M(II) = Zn(II), ArSO2 N-aminoacidato NO = N(toluene-p-sulfonyl)- and N(benzenesulfonyl)-glycinate NO dianion,hereafter abbreviated as tsgly-NO and bsgly-NO, respectively, M(II) = Cd(II), ArSO2-N-aminoacidato-NO = tsgly-NO] was separated and investigated by spectroscopic and X-ray methods. The crystal structure of [Cd(bpy)2(tsgly-NO)].3H2O was determined. The compound crystallizes in the monoclinic space group P2(1)/n, Z = 4, a = 15.427(4), b = 13.580(2), c = 15.546(4) angstrom, beta = 110.97(3), R = 0.041, R(w) = 0.043. The structure consists of monomeric, approximately octahedral [Cd(bpy)2(tsgly-NO)] units with a N5O donor atom set, which gives rise to three almost orthogonal five-membered chelate rings. The IR spectra suggest similar environments for all the complexes

Solution and solid state investigation ofthe Cu(II)-N-acetyl-L-glutamine system and its N-methylimidazole adduct.

The interactions of N-acetyl-L-glutamine (AcglnH) with copper(II) ion in aqueous and water-methanol (50% v/v) solutions and in solid state have been investigated. It was found that the N-acetyl-L- glutaminate anion (Acgln) is unable to form stable complexes in solution on varying the pH values, before copper(II) hydroxyde precipitation occurs. In the solid state two compounds of the formulas Cu(Acgln)2·2H2O and Cu(Acgln)2(MeIm)2·2H2O (MeIm = N-methylimidazole) are separated; for the latter complex the crystal and molecular structure was determined by means of the single crystal X-ray diffraction method. The compound crystallizes in the monoclinic space group C2, with cell dimensions: a = 15.606(7), b = 7.353(2), c = 13.951(2) Å, β = 110.69(3)° and Z = 2. The structure was solved by conventional Patterson and Fouder methods and refined by full-matrix least-squares to an R value of 0.026. The structure consists of [Cu(Acgln)2(Me- Im)2] units and uncoordinated watet molecules. The Cu(II) atom lying on the twofold axis exhibits a square-planar N2O2 environment from ligation by two symmetry-related carboxytate oxygens and N-methylimidazole nitrogens. The second non- bonding carboxylate oxygens are 2.813(3) Å from the Cu(II) atom and both are placed under the coordination plane. Spectroscopic and thermal results agree with the crystal stmcture, while for binary Cu(Acgln)2·2H2O a CuO4 chromophore is suggested

Structure of catena-poly{[-(N-acetyl-DL-valinato)O :O ]copper(II)}.

Crystal structure of [Cu(C7H12NO3)2]n is reporte

Catena-Poly[zinc(II)-bis{μ -(N-carbamoylglycinato)}-O:O'';O'':O], [Zn(C3H5N2O3)2].

The structure of [Zn(hyda)2] (hydaH = N-carbamoylglycine or hydantoic acid) consists of polymeric linear chains in which pairs of Zn(II) ions are connected by pairs of hydantoate anions coordinated through their carboxylic and amidic O atoms. The coordination around the metal atom is tetrahedral

N-(ARYLSULFONYL)GLYCINES AS CYCLOMETALATING LIGANDS - CRYSTAL AND MOLECULAR-STRUCTURES OF DISODIUM BIS(MU-CHLORO)BIS[MU-N-(PHENYLSULFONYL)GLYCINATO-O,N,C]-BIS[MU-N-(PHENYLSULFONYL)GLYCINATO-O,O']TETRAPALLADATE(II) HEXAHYDRATE AND DISODIUM BIS(MU-CHLORO)BI

The interaction of N-(phenylsulfonyl)- and N-(4-tolylsulfonyl)- (N-tosyl hereafter) glycine (Bsgly and Tsgly, respectively) with Pd(II) ion at pH congruent-to 3.5 gives rise to cyclometalation reactions leading to complexes of the formulas Na2[Pd4Cl2(Bsgly-O,N,C)2(Bsgly-O,O')2].6H2O (I) and Na2[Pd4Cl2(Tsgly-O,N,C)(Tsgly-O,O')]2.4.5H2O.2TsglyH (II) (Bsgly-O,N,C and Tsgly-O,N,C = O,N,C-bonded ligand; Bsgly-O,O' and Tsgly-O,O' = carboxylate bridging ligand; TsglyH = neutral N-tosylglycine). The complexes crystallize in the triclinic P1BAR space group with a = 13.469 (4) angstrom, b = 13.636 (4) angstrom, c = 15.005 (5) angstrom, alpha = 70.94 (2)-degrees, beta = 66.32 (2)-degrees, gamma = 88.59 (2)-degrees, and Z = 2 for I and a = 17.058 (1) angstrom, 18.897 (2) angstrom, c = 13.194 (1) angstrom, alpha = 94.61 (1)-degrees, beta = 107.98 (1)-degrees, gamma = 74.32 (1)-degrees, and Z = 2 for II. Both structures consist of two tetrameric units, symmetry generated from two independent [Pd2Cl(L-O,N,C)(L-O,O')] (L = Bsgly or Tsgly) monoanions. In each tetramer one Pd(II) atom is coordinated with the deprotonated sulfonamide nitrogen and the carbon atom of the aromatic ring in the ortho position to the sulfonyl group of a ligand molecule, the bridging chlorine atom, and one oxygen atom of a bridging carboxyl from a second ligand molecule. The other crystallographically independent Pd(II) atom is coordinated with the other oxygen of the bridging carboxyl, the chlorine atom, the deprotonated sulfonamide nitrogen, and the oxygen atom of a monodentate carboxylate group forming a N,O-chelate glycine-like ring. Both of the Pd(II) atoms show a slightly distorted square-planar coordination geometry. Infrared and NMR results are also reported

COORDINATION BEHAVIOR OF SULFA-DRUGS - SYNTHESIS, STRUCTURAL, AND SPECTROSCOPIC INVESTIGATION ON M(II) (N(1)-PYRIMIDIN-2YL-SULFANILAMIDO)2. X H2O

Co(II), Ni(II), Zn(II), and Cd(II) complexes of sulfadiazine (HSD) were prepared and characterized by spectroscopic data. For [Cd(SD)2].2H2O the crystal and molecular structure is reported. The compound crystallizes in the monoclinic C2/c space group with Z = 4, in a cell of dimensions a = 1.9.879(3), b = 8.730(3), c = 16.538(3) angstrom, beta = 122.15(2)degrees. Least-squares refinement of 2019 reflections [I greater-than-or-equal-to 2sigma(I)] gave a final R = 0.034. The structure consists of a monodimensional polymeric chain running along the b axis in which the cadmium atom is coordinated to two sulfonamido and two amino nitrogens from four symmetry-related SD anions. The coordination geometry around the metal is distorted tetrahedral. Hydrogen bonds involving the water molecule contribute to crystal stability