Magneto-structural versatility of copper(II)-3-phenylpropionate coordination polymers with N-donor coligands.

A novel series of copper(II) coordination polymers [Cu2(O2CC8H9)4(pyz)]n (1), [Cu2(O2CC8H9)4(dps)]n (2), {[Cu(O2CC8H9)2(dps)(H2O)]·H2O}n (3), {[NaCu(O2CC8H9)2(bpm)(NO3)]·H2O}n (4), and [Cu4(O2CC8H9)6(OH)2(bpp)2]n (5) [O2CC8H9− = 3-phenylpropionate anion, pyz = pyrazine, dps = di(4-pyridyl)sulfide, bpm = 2,2'-bipyrimidine, and bpp = 1,3-bis(4-pyridyl)propane] have been synthesized and magneto-structurally investigated. Compounds 1 and 2 belong to a large group of copper(II) carboxylates where bis-monodentate pyz (1) and dps (2) ligands connect the paddle-wheel [CuII2(µ-O2CC8H9)4] units leading to alternating copper(II) chains. The structure of 3 consists of uniform chains of trans-[CuII(O2CC8H9)2] units linked by the bis-monodentate dps ligand. Compound 4 consists of heterobimetallic chains where [NaI2CuII2(µ-O2CC8H9)4(NO3)2] units are doubly bridged by bis-bidentate bpm ligands. Compound 5 is also a chain compound whose structure is made up by tetranuclear [CuII4(µ3-OH)2(µ-O2CC8H9)4(O2CC8H9)2] units which are doubly bridged by bis-monodentate bpp ligands. The magnetic properties were investigated in the temperature range 1.8­300 K. Strong antiferromagnetic interactions across the quadruple syn­syn carboxylate are observed in 1 and 2 [J = −378 (1) and −348 cm−1 (2)] whereas a weak ferromagnetic coupling through the double out-of-plane oxo(carboxylate) bridge occurs in 4 [J = +2.66 cm−1], the spin Hamiltonian being defined as H = −JS1·S2 with S1 = S2 = SCu = 1/2. A quasi Curie law is observed for 3 (θ = −0.36 cm−1), the bis-monodentate dps ligand being a very poor mediator of magnetic interactions. The analysis of the magnetic properties of 5 is quite complex because of the presence of two crystallographically independent tetracopper(II) units with single-µ-hydroxo, di-µ-hydroxo, µ3-hydroxo and single-µ-hydroxo plus double syn,syn carboxylate bridges in each one. The nature and values of the magnetic couplings for 5 obtained by fitting (intermediate, strong and weak antiferromagnetic interactions for the three former exchange pathways respectively, and intermediate ferromagnetic interactions for the latter one) were substantiated by DFT type calculations.

The zwitterionic structure of 2-hydroxy-4-[(2-hydroxybenzylidene)amino]benzoic acid.

The title compound, C14H11NO4, exists in the solid phase in the zwitterionic form, 2-{[(4-carboxy-3-hydroxyphenyl)iminiumyl]methyl}phenolate, with the H atom from the phenol group on the 2-hydroxybenzylidene ring transferred to the imine N atom, resulting in a strong intramolecular N-H∙∙∙O hydrogen bond between the iminium H atom and the phenolate O atom, forming a six-membered hydrogen-bonded ring. In addition, there is an intramolecular O-H∙∙∙O hydrogen bond between the carboxylic acid group and the adjacent hydroxy group of the other ring, and an intermolecular C-H∙∙∙O contact involving the phenol group and the C-H group adjacent to the imine bond, connecting the molecules into a two-dimensional network in the (103) plane. π-π stacking interactions result in a three-dimensional network. This study is important because it provides crystallographic evidence, supported by IR data, for the iminium zwitterionic form of Schiff bases.

A two-dimensional oxamate- and oxalate-bridged Cu(II)Mn(II) motif: crystal structure and magnetic properties of (Bu4N)2[Mn2{Cu(opba)}2ox].

A new compound of formula (Bu4N)2[Mn2{Cu(opba)}2ox] (1) [Bu4N(+) = tetra-n-butylammonium cation, H4opba = 1,2-phenylenebis(oxamic acid), and H2ox = oxalic acid] has been synthesized and magneto-structurally investigated. The reaction of manganese(II) acetate, [Cu(opba)](2-), and ox(2-) in dimethyl sulfoxide yielded single crystals of 1. The structure of 1 consists of heterobimetallic oxamato-bridged Cu(II)Mn(II) chains which are connected through bis-bidentate oxalate coordinated to the manganese(II) ions to afford anionic heterobimetallic layers of 6(3)-hcb net topology. The layers are interleaved by n-Bu4N(+) counterions. Each copper(II) ion in 1 is four-coordinate in a square planar environment defined by two amidate-nitrogen and two carboxylate-oxygen atoms from the two oxamate groups of the obpa ligand. The manganese(II) ion is six-coordinate in a somewhat distorted octahedral surrounding that is built by two oxalate-oxygen and four carbonyl-oxygen atoms from two [Cu(opba)](2-) units. The magnetic properties of 1 in the temperature range 1.9-300 K correspond to those expected for the coexistence of intralayer antiferromagnetic interactions of the type copper(II)-manganese(II) across oxamato and manganese(II)-manganese(II) through oxalato bridges plus a weak spin canting in the very low temperature domain. Simulation of the magnetic data through quantum Monte Carlo methodology reveals the magnitude of the intralayer magnetic interactions [J(CuMn) = -32.5(3) cm(-1), and J(MnMn) = -2.7(3) cm(-1)], their values being within the range of those previously observed in lower nuclearity systems.

Insights into the multi-equilibrium, superstructure system based on ß-cyclodextrin and a highly water soluble guest.

Pentamidine isethionate (PNT) is an antiprotozoal active in many cases of leishmaniasis, despite the present limitations including high toxicity and parenteral administration. In the present work, a PNT encapsulation strategy into ß-cyclodextrin cavity at 1:1 and 2:1 (ßCD:PNT) molar ratios was used in order to improve the drug's physical and chemical properties. Combining thermodynamic and structural approaches such as isothermal titration calorimetry (ITC), electrospray ionization mass spectrometry (ESI-MS) and nuclear magnetic resonance ((1)H NMR, and ROESY) the inclusion process and the thermodynamics parameters were identified. ITC and ESI-MS experimental data suggest the simultaneous formation of different supramolecular complexes in solution. Moreover, NMR data are in accordance with these results, suggesting a deep inclusion of PNT into the ßCD cavity, through correlations observed in 2D ROESY contour maps. The systems were also characterized by FTIR, TG/DTA and SEM. These techniques indicate the formation of inclusion complex in the solid state. In vivo PNT activity was evaluated orally in mice. The inclusion complex showed a significant reduction of parasite load compared to free PNT.

Dipotassium tetra-aqua-bis-[3,5-bis-(dicyano-methyl-ene)cyclo-pentane-1,2,4-trionato(1-)-κN]cobaltate(II).

The title structure, K(2)[Co(C(11)N(4)O(3))(2)(H(2)O)(4)], is isotypic with K(2)[Fe(C(11)N(4)O(3))(2)(H(2)O)(4)]. The Co(II) atom is in a distorted octa-hedral CoN(2)O(4) geometry, forming a dianionic mononuclear entity. Each dianionic unit is associated with two potassium cations and inter-acts with adjacent units through O-H⋯N and O-H⋯O hydrogen bonds.

Synthesis, crystal structure, and spectroscopic characterization of trans-bis[(mu-1,3-bis(4-pyridyl)propane)(mu-(3-thiopheneacetate-O))(3-thiopheneacetate-O)]dicopper(II), [[Cu2(O2CCH2C4H3S)4mu-(BPP)2]]n: from a dinuclear paddle-wheel copper(II) unit to a 2-D coordination polymer involving monatomic carboxylate bridges.

From the reaction between a dinuclear paddle-wheel carboxylate, namely [Cu2mu-(O2CCH2C4H3S)4] (1), and the flexible ligand 1,3-bis(4-pyridyl)propane (BPP) a neutral 2-D coordination polymer [[Cu2(O2CCH2C4H3S)4mu-(BPP)2]]n (2) was obtained. Compounds 1 and 2 were characterized by means of elemental analysis, thermal analysis (TG/DSC), vibrational spectroscopy, and electron paramagnetic resonance (EPR). The crystal structure of 2 reveals that each Cu(II) is coordinated by two nitrogen atoms from different BPP ligands and two 3-thiopheneacetate groups within a distorted square planar geometry in a trans-[N, N, O, O] arrangement. The BPP ligand adopts a TG conformation bridging two copper centers giving rise to a 1-D sinusoidal polymeric chain along the crystallographic c axis. Adjacent 1-D chains are extended into a 2-D coordination network through pairs of monatomic carboxylate bridges in direction of the b axis. This bridging mode affords centrosymmetric dimeric units Cu2O2, and therefore, the copper ions are involved in a CuN2O2O' chromophore displaying a (4 + 1) square pyramidal coordination in the resultant 2-D polymeric network. The polycrystalline X-band EPR spectrum of 2 at room temperature is characteristic of a triplet state with nonnegligible zero-field splitting in agreement with the crystal structure. Crystal data for 2: monoclinic, space group P2(1)/c, a = 9.4253(10) A, b = 10.9373(10) A, c = 23.6378(10) A, beta = 98.733(4) degrees, Z = 2.

Efeitos hemostático e estrutural da esponja de celulose liofilizada / Hemostatic and structural effects of the lyophilized cellulose sponge

Os efeitos hemostáticos da celulose oxidada (Surgicel) sao bem conhecidos. Baseados na similaridade estrutural e em um possível efeito hemostático, estudamos a esponja de celulose liofilizada utilizando dois modelos experimentais. Fase I - Realizada em 12 caes, consistiu na provocaçao de lesao cortical com sangramento, introduçao de fragmento de esponja de celulose liofilizada no interior da lesao e medida do tempo necessário para obter-se hemostasia. Os animais foram sacrificados em 7, 30 e 90 dias. A hemostasia foi obtida, em média, após 1 minuto e nenhum efeito colateral clínico foi detectado. A microscopia mostrou reaçao histiocitária leve aos 7 e 30 dias, com presença de pequena quantidade de células gigantes tipo corpo estranho. A reaçao histioplasmocitária regrediu e, aos 90 dias, a celulose estava circundada por pobre reaçao inflamatória. A membrana liofilizada revelou ter aspecto peculiar, representado por filamentos eosinofílicos, circundados por reaçao inflamatória, que diminuiu com o tempo. Somente esparsos e irregulares filamenos eosinofílicos foram percebidos aos 90 dias. Fase II - Foram introduzidos fragmentos de dimensoes conhecidas de esponja de celulose, no interior do fígado de 12 ratos, que foram sacrificados em 7, 30 e 90 dias. Na autopsia, a inspeçao a olho desarmado constatou, aos 30 e 90 dias, a formaçao de bridas peritoneais na altura do implante. Em todos os animais, especialmente aos 7 dias, a microscopia revelou intensa reaçao histiolinfoplasmocitária ao redor do implante. Em dois animais, aos 90 dias, detectaram-se grânulos refringentes à luz polarizada, no interior de células gigantes, demonstrando fagocitose ativa de celulose. Em conclusao, observou-se haver necessidade de modelo experimental comparativo para provar a existência de propriedades hemostáticas na esponja. Conseguiu-se, no entanto, provar a existência de reabsorçao da celulose em mamíferos através de fagocitose, fato este ainda nao relatado na literatura.