Nuno Martins

Copper(II) and iron(III) complexes with arylhydrazone of ethyl 2-cyanoacetate or formazan ligands as catalysts for oxidation of alcohols

The aquasoluble [Cu(1κN,O2:2κO-HL1)(S)]2 [S = CH3OH (1), (CH3)2NCHO (2)] and [Cu(κN-HL1)(en)2]·CH3OH·H2O (3) CuII complexes were prepared by the reaction of CuII nitrate hydrate with the new ligand (E/Z)-4-(2-(1-cyano-2-ethoxy-2-oxoethylidene)hydrazinyl)-3-hydroxybenzoic acid (H3L1), in the presence (for 3) or absence (for 1 and 2) of ethylenediamine (en), while the FeIII complex [Fe(κN3-HL2)2] (4) was isolated by treatment of iron(III) chloride hexahydrate with the new ligand (1E,1E)-N′,2-di(1H-1,2,4-triazol-3-yl)diazenecarbohydrazonoyl cyanide (H3L2), and characterized by elemental analysis, IR spectroscopy and single crystal X-ray diffraction. Cooperative E,Z → E isomerization of H3L1, induced by coordination and ionic interactions, occurs upon interaction with CuII in the presence of en. Complexes 1–4 act as catalyst precursors for the solvent-free microwave (MW) assisted selective oxidation of primary or secondary alcohols and diols to the corresponding aldehydes, ketones and diketones, respectively, with yields in the 5–99% range (TONs up to 4.96 × 102) after 60 min of MW irradiation at 120 °C. The influence of temperature, time and organic radicals was studied and also the regioselective oxidation of the catalytic systems involving the primary and secondary alcohols.

Vanadium(V) Complexes with Substituted 1,5-bis(2- hydroxybenzaldehyde)carbohydrazones and Their Use As Catalyst Precursors in Oxidation of Cyclohexane

Six dinuclear vanadium(V) complexes have been synthesized: NH4[(VO2)2((H)LH)] (NH4[1]), NH4[(VO2)2((t-Bu)LH)] (NH4[2]), NH4[(VO2)2((Cl)LH)] (NH4[3]), [(VO2)(VO)((H)LH)(CH3O)] (4), [(VO2)(VO)((t-Bu)LH)(C2H5O)] (5), and [(VO2)(VO)((Cl)LH)(CH3O)(CH3OH/H2O)] (6) (where (H)LH4 = 1,5-bis(2-hydroxybenzaldehyde)carbohydrazone, (t-Bu)LH4 = 1,5-bis(3,5-di-tert-butyl-2-hydroxybenzaldehyde)carbohydrazone, and (Cl)LH4 = 1,5-bis(3,5-dichloro-2-hydroxybenzaldehyde)carbohydrazone). The structures of NH4[1] and 4-6 have been determined by X-ray diffraction (XRD) analysis. In all complexes, the triply deprotonated ligand accommodates two V ions, using two different binding sites ONN and ONO separated by a diazine unit -N-N-. In two pockets of NH4[1], two identical VO2(+) entities are present, whereas, in those of 4-6, two different VO2(+) and VO(3+) are bound. The highest oxidation state of V ions was corroborated by X-ray data, indicating the presence of alkoxido ligand bound to VO(3+) in 4-6, charge density measurements on 4, magnetic susceptibility, NMR spectroscopy, spectroelectrochemistry, and density functional theory (DFT) calculations. All four complexes characterized by XRD form dimeric associates in the solid state, which, however, do not remain intact in solution. Compounds NH4[1], NH4[2], and 4-6 were applied as alternative selective homogeneous catalysts for the industrially significant oxidation of cyclohexane to cyclohexanol and cyclohexanone. The peroxidative (with tert-butyl hydroperoxide, TBHP) oxidation of cyclohexane was performed under solvent-free and additive-free conditions and under low-power microwave (MW) irradiation. Cyclohexanol and cyclohexanone were the only products obtained (high selectivity), after 1.5 h of MW irradiation. Theoretical calculations suggest a key mechanistic role played by the carbohydrazone ligand, which can undergo reduction, instead of the metal itself, to form an active reduced form of the catalyst.

Activation of effector immune cells promotes tumor stochastic extinction

In this article we provide homotopy solutions of a cancer nonlinear model describing the dynamics of tumor cells in interaction with healthy and effector immune cells. We apply a semi-analytic technique for solving strongly nonlinear systems - the Step Homotopy Analysis Method (SHAM). This algorithm, based on a modification of the standard homotopy analysis method (HAM), allows to obtain a one-parameter family of explicit series solutions. By using the homotopy solutions, we first investigate the dynamical effect of the activation of the effector immune cells in the deterministic dynamics, showing that an increased activation makes the system to enter into chaotic dynamics via a period-doubling bifurcation scenario. Then, by adding demographic stochasticity into the homotopy solutions, we show, as a difference from the deterministic dynamics, that an increased activation of the immune cells facilitates cancer clearance involving tumor cells extinction and healthy cells persistence. Our results highlight the importance of therapies activating the effector immune cells at early stages of cancer progression.

DNA and BSA binding and cytotoxic properties of copper(II) and iron(III) complexes with arylhydrazone of ethyl 2-cyanoacetate or formazan ligands

Several known water soluble [Cu(1κN,O2:2κO-HL1)(S)]2 [S = CH3OH (1), (CH3)2NCHO (2)] and [Cu(κN-HL1)(en)2]·CH3OH·H2O (3) CuII complexes were prepared by reaction of CuII nitrate hydrate with the new (E/Z)-4-(2-(1-cyano-2-ethoxy-2-oxoethylidene)hydrazinyl)-3-hydroxybenzoic acid (H3L1), in the presence (for 3) or absence (for 1 and 2) of ethylenediamine (en), while the FeIII complex [Fe(κN3-HL2)2] (4) was synthesized by treatment of iron(III) chloride hexahydrate with the new (1E,1E)-N′,2-di(1H-1,2,4-triazol-3-yl)diazenecarbohydrazonoyl cyanide (H3L2). The interaction of calf thymus DNA (CT DNA) and bovine serum albumin (BSA protein) with complexes 1–4 has been investigated by absorption and fluorescence titration methods. The observed DNA binding constants, number of DNA binding sites (s ≤ 1) for the complexes and viscosity data suggest the intercalative mode of binding to CT DNA. All the complexes show good binding propensity to the BSA protein, giving KBSA values of 0.97(±0.10) × 106 (1), 1.19(±0.09) × 106 (2), 0.50(±0.01) × 106 (3) and 1.06(±0.08) × 106 M−1 (4). An in vitro anti-proliferative study establishes the anticancer potency of complexes 1–4 and cisplatin against the human cervical (HeLa) and breast (MCF7) cancer cell lines; noncancer breast epithelial (MCF10) cells were also investigated. The observed IC50 values of complexes 1 (8.3, 11.9 and 44.8 μM), 2 (7.0, 7.1 and 35.6 μM), 3 (18.1, 20.4 and 58.8 μM), 4 (13.2, 15.1 and 79.4 μM) and cisplatin (4.02, 3.42 and 89.5 μM) against the HeLa, MCF7 and MCF-10a cells, respectively, suggest that 2 can be explored further as a potential anticancer drug.

K-theory for Cuntz-Krieger algebras arising from real quadratic maps

We compute the K-groups for the Cuntz-Krieger algebras 𝒪A𝒦(fμ), where A𝒦(fμ) is the Markov transition matrix arising from the kneading sequencern 𝒦(fμ) of the one-parameter familyrnof real quadratic maps fμ.

Bowen–Franks Groups Associated with Linear Mod One Transformations

We consider those linear mod one transformations fβ,α on the unit interval, for which the respective kneading sequences are periodic. Then, we construct the corresponding Markov transition matrices Aβ,α. Using symbolic dynamics techniques, we prove that the Bowen–Franks groups BF(Aβ,α) can be directly computed from the number of symbols of the respective periodic words of the kneading sequences of fβ,α.

Including auditory tube function on models is relevant to assess water exposure after tympanostomy tubes–Multiphase computerized fluid dynamics model

INTRODUCTIONnMyringotomy with tympanostomy tube is the most common otologic surgery and some patients are still advised to avoid water. However, there is no evidence supporting this, with published papers questioning the need for this advice.nnnMETHODSnA Multiphase Computational Fluid Dynamics (CFD) model was created using computerized tomography images of a childs healthy ear. It was then used to study the flow of fluids through the external ear, tympanic cavity, and auditory tube, with and without submersion.nnnRESULTSnThe model accurately described the behavior of the air retained in the patients nasopharynx and tympanic cavity. A simulated elevation of pressure in the external auditory canal without submersion, without increase of pressure in the nasopharynx, demonstrated that fluids promptly crossed the tympanostomy tube into the middle ear. However, simulated elevation of pressure in the external auditory canal with concurrent elevation of air pressure in the nasopharynx during submersion did not lead to passive tube opening nor to any detectable flow through the tympanostomy tube.nnnCONCLUSIONSnIn the model, submersion increases pressure in the nasopharynx which offsets the pressure in the external auditory canal. So, in the absence of a pressure gradient, no passive tubal opening took place, and no air or fluid flow was detected through the transtympanic tube. This model now includes the exhaust function of the auditory tube in the model and shows its relevance.

CCDC 1412837: Experimental Crystal Structure Determination

Related Article: Nuno M. R. Martins, Kamran T. Mahmudov, M. Fatima C. Guedes da Silva, Luisa M. D. R. S. Martins, Armando J. L. Pombeiro|2016|New J.Chem.|40|10071|doi:10.1039/C6NJ02161A