Enhanced Analytic Approach for Describing pH Triggered Fast Drug Release Systems.

Background: pH sensitive dendrimers attached to nanocarriers, as one of the drug release systems, have become quite popular due to their ease of manufacture in experimental conditions and the ability to generate fast drug release in the targeted area. This kind of fast release behavior cannot be represented properly in most of the existing kinetic mathematical models. Besides, these models have either no pH dependence or pH dependence added separately.

Synthesis, Characterization and DFT-Based Investigation of a Novel Trinuclear Singly-Chloro-Bridged Copper(II)-1-Vinylimidazole Complex.

A novel trinuclear copper(II) complex [Cu3(μ-Cl)2Cl4(1-Vim)6] with monodentate 1-vinylimidazole (1-Vim) and chloro ligands has been prepared and experimentally characterized by elemental analysis, thermogravimetry (TGA, DTG, DTA), X-ray single crystal diffractometry, TOF-MS and FT-IR spectroscopies. The electronic and structural properties of the complex were further investigated by DFT/TD-DFT methods. Density functional hybrid method (B3LYP) was applied throughout the calculations.

trans-Bis(nitrato-κO)tetra-kis-(1-vinyl-1H-imidazole-κN(3))copper(II).

In the title compound, [Cu(NO(3))(2)(C(5)H(6)N(2))(4)], the Cu(II) ion is located on an inversion centre. It features a Jahn-Teller-distorted octa-hedral coordination geometry, defined by four N atoms of four 1-vinyl-imidazole ligands in the equatorial plane and two nitrate O atoms in the axial positions. The nitrate anion is disordered over two sets of sites in a 0.

Electronic structure modeling of dinuclear copper(II)-methacrylic acid complex by density functional theory.

A dinuclear centrosymmetric copper(II) complex with the formula [Cu(2)(mu-maa)(4)(maaH)(2)] has been synthesized and experimentally characterized by IR, electronic spectroscopy, and X-ray single-crystal diffractometry. Starting from experimental X-ray geometry and using antiferromagnetic singlet ground state, gas phase geometry optimization was performed by density functional hybrid (B3LYP) method with 6-31G(d) and LANL2DZ basis sets. Gas-phase vibrational frequencies and single point energy (SPE) calculations have been carried out at the geometry-optimized structure.

3-[2-(4,4-Dimethyl-2,6-dioxocyclo-hexyl-idene)hydrazin-yl]benzonitrile.

The title compound, C(15)H(15)N(3)O(2), contains benzonitrile and 4,4-dimethyl-2,6-dioxocyclo-hexyl-idene groups connected via a hydrazinyl group. The structure is in the hydrazone tautomeric form in the solid state. The benzonitrile and hydrazinyl groups (3-hydrazinylbenzonitrile) are essentially coplanar with an r.

(Carbonato-κO,O')bis-(1,10-phenan-throline-κN,N')cobalt(III) nitrate monohydrate.

The crystal structure of the title compound, [Co(CO(3))(C(12)H(8)N(2))(2)]NO(3)·H(2)O, consists of Co(III) complex cations, nitrate anions and uncoordinated water mol-ecules. The Co(III) cation is chelated by a carbonate anion and two phenanthroline ligands in a distorted octa-hedral coordination geometry. A three-dimensional supra-molecular structure is formed by O-H⋯O and C-H⋯O hydrogen bonding, C-H⋯π and aromatic π-π stacking [centroid-centroid distance = 3.

Bis(2-pyridylmethanol)bis(saccharinato)zinc(II) and -cadmium(II) at 120 K: three-dimensional structures containing both N-and O-coordinated ambidentate saccharinate ligands.

The title complexes [M(sac)(2)(mpy)(2)] [sac is saccharinate (C(7)H(4)NO(3)S) and mpy is 2-pyridylmethanol (C(6)H(7)NO)], with M = Zn(II) and Cd(II), are isostructural and consist of neutral molecules. The Zn(II) or Cd(II) cations are octahedrally coordinated by the two neutral mpy and two anionic sac ligands. The mpy ligand acts as a bidentate donor through the amine N and hydroxyl O atoms.

N-(2-hydroxyethyl)ethylenediammonium hydrogenphosphate monohydrate.

The title compound, C(4)H(14)N(2)O(2+) x HPO(4)(2-) x H(2)O, contains alternating interleaved layers of hydrogenphosphate and N-(2-hydroxyethyl)ethylenediammonium moieties. The water molecules are associated with channel-like voids in the structure and a network of hydrogen bonds stabilizes the crystal packing.

Sodium p-nitrobenzoxasulfamate monohydrate.

The title compound, alternatively named sodium 6-nitro-3H-1,2,3-benzoxathiazole 2,2-dioxide monohydrate, Na+*C6H3N2O5S-*H2O, consists of chains of NaO7 units, with the seven donor-O atoms coming from two water molecules and five p-nitrobenzoxasulfamate anions. The seven-coordinate geometry around the Na+ ion is described as monocapped trigonal prismatic, but with a large distortion from ideal geometry. Each triangular face is defined by one O atom each from a water molecule, a nitro group and a sulfonyl group.

Bis(pyridine-2,6-dimethanol-N,O,O')cobalt(II) and -copper(II) disaccharinate dihydrate: three-dimensional structures with extensive hydrogen bonds and aromatic pi-pi-stacking interactions.

Bis(pyridine-2,6-dimethanol-N,O,O')cobalt(II) disaccharinate dihydrate, [Co(C7H9NO2)2](C7H4NO3S)2*2H2O, (I), and bis(pyridine-2,6-dimethanol-N,O,O')copper(II) disaccharinate dihydrate, [Cu(C7H9NO2)2](C7H4NO3S)2*2H2O, (II), collectively [M(dmpy)2](sac)2*2H2O (where M is Co(II) or Cu(II), sac is the saccharinate anion and dmpy is pyridine-2,6-dimethanol), are isostructural. The [M(dmpy)2]2+ cations exhibit distorted octahedral geometry in which the two neutral dmpy species act as tripodal N,O,O'-tridentate ligands. The crystal packing is determined by hydrogen bonding, as well as by weak pyridine-saccharinate pi-pi-stacking interactions.

trans-Bis(diethanolamine-N,O)bis(saccharinato-N)cadmium(II).

The structure of the title complex consists of isolated [Cd(C7H4NO3S)2(C4H11NO2)2] units. The Cd2+ cation lies on an inversion centre and is octahedrally coordinated by two N,O-bidentate diethanolamine (dea) and two N-bonded saccharinate (sac) ligands [saccharin is 1,2-benzisothiazol-3(2H)-one 1,1-dioxide]. The dea ligands constitute the equatorial plane of the octahedron, forming two five-membered chelate rings around the Cd(II) ion, while the sac ligands are localized at the axial positions.