X-Ray and EPR study on copper (II) complexes with an enamine ligand

The enamine (HEAID) obtained from aniline and 2-acetyl-1,3-indandione (2AID) behaves as a bidentate ligand in coordination with copper (II) ion. Two types of crystals, apparently different in shape, were isolated and studied by single-crystal X-ray diffraction. The X-ray data for the brown rhombic crystals of compound 1 shows a mononuclear complex of Cu(II) coordinated with two EAID-anions, Cu(EAID)₂. The X-ray data for the green crystals of compound 2 shows a dinuclear Cu(II) complex with two OH⁻ groups acting as bridging ligands, [Cu₂(μ-OH)₂(EAID)₂]. In both cases the ligand coordinates after deprotonation of the amine group.     

A microwave improvement in the synthesis of the quinazoline scaffold

A rapid and efficient microwave-assisted protocol is described that greatly improves a recent synthetic method developed for quinazoline synthesis. The synthetic protocol is based on the use of cycles of microwave irradiation. The optimization process is reported and the experimental results are compared with those of the conventional synthetic route.     

Synthesis and characterisation of estrogenic carriers for cytotoxic Pt(II) fragments: biological activity of the resulting complexes

This paper describes the synthesis and the spectroscopic characterisation of cis-dichloro[N-(4-(17alpha-ethynylestradiolyl)-benzyl)-ethylenediamine]platinum(II) and cis-diamino[2-(4-(17alpha-ethynylestradiolyl)-benzoylamino)-malonato]platinum(II). These complexes were synthesised in good yield according to multi-step procedures based on the classical and non-classical Sonogashira coupling reaction, respectively. These compounds retain an acceptable degree of relative binding affinity (RBA) for the alpha form of estrogen receptor. Combined treatment of breast cancer cell lines, namely hormone-sensitive MCF-7 and hormone-insensitive MDA-MB-231 cell lines, indicates that these compounds maintain agonistic activity so that the potential advantage in vehiculation of the cytotoxic moiety by means of the receptor system is counteracted by the proliferative effect of the estrogenic component of the entire molecule, especially at low concentrations.     

Inorganic-organic hybrids formed by P,P'-diphenylmethylenediphosphinate, pcp2-, with the Cu2+ ion. X-ray crystal structures of [Cu(pcp)(H2O)2] x H2O and [Cu(pcp)(bipy)(H2O)

Weakly coordinated [Cu(pcp)(H2O)n] complexes are formed in aqueous solution, at room temperature, by interaction of P,P'-diphenylmethylene diphosphinic acid (H2pcp) with copper(II) ions. However, heating of the solutions gives rise to the formation of two extended metal-oxygen networks of formulas [Cu(pcp)(H2O)2] x H2O, 1, and [Cu(pcp)(H2O)2], 2. In the presence of 2,2'-bipyridyl (bipy) the diamine derivative [Cu(pcp)(bipy)(H2O)], 4, has been isolated. Complex 1 easily loses water to form a monohydrated derivative [Cu(pcp)H2O], 3, whereas 2 is completely dehydrated after prolonged heating at 150 degrees C, under vacuum. The compounds 1 and 2 have substantially different solid-state structures as shown by X-ray powder diffraction spectra, IR spectra, and thermogravimetric analyses. Consistently, the two complexes cannot be directly interconverted and present different dehydration pathways. Rehydration of these materials in both cases allows quantitative formation of 1. X-ray analysis established that the structure of 1 consists of a corrugated two-dimensional layered polymeric array, where infinite zigzag chains of Cu centers and bridging phenylphosphinate ligands are linked together through strong hydrogen-bonding interactions; the structure of 4 consists of monodimensional polymers, where the hydrogen-bonding interactions play an essential bridging role in the extended architecture. In both structures the metal center displays a five-coordinate environment with approximate square pyramidal geometry, with the pcp ligand acting as bidentate and monodentate in 1 and solely as bidentate in 4. In 1 the coordination sphere is completed through water molecules; in 4, through water and diamine ligands. The thermogravimetric analyses of the complexes are compared with those of the related hybrids [M(pcp)(H2O)3] x H2O, where M = Mn, Co, or Ni, confirming that noncoordinated water molecules also play a basic role in determining the molecular packing.     

An Accurate Approach for Computational pKa Determination of Phenolic Compounds

Computational chemistry is a valuable tool, as it allows for in silico prediction of key parameters of novel compounds, such as pKa. In the framework of computational pKa determination, the literature offers several approaches based on different level of theories, functionals and continuum solvation models. However, correction factors are often used to provide reliable models that adequately predict pKa. In this work, an accurate protocol based on a direct approach is proposed for computing phenols pKa. Importantly, this methodology does not require the use of correction factors or mathematical fitting, making it highly practical, easy to use and fast. Above all, DFT calculations performed in the presence two explicit water molecules using CAM-B3LYP functional with 6-311G+dp basis set and a solvation model based on density (SMD) led to accurate pKa values. In particular, calculations performed on a series of 13 differently substituted phenols provided reliable results, with a mean absolute error of 0.3. Furthermore, the model achieves accurate results with -CN and -NO₂ substituents, which are usually excluded from computational pKa studies, enabling easy and reliable pKa determination in a wide range of phenols.     

Hierarchical differential evolution for minimal cut sets identification: Application to nuclear safety systems

In this paper, we present a Hierarchical Differential Evolution (HDE) algorithm for minimal cut set (mcs) identification of coherent and non-coherent Fault Trees (FTs). In realistic application of large-size systems, problems may be encountered in handling a large number of gates and events. In this work, to avoid any approximation, mcs identification is originally transformed into a hierarchical optimization problem, stated as the search for the minimum combination of cut sets that can guarantee the best coverage of all the minterms that make the system fail: during the first step of the iterative search, a multiple-population, parallel search policy is used to expedite the convergence of the second step of the exploration algorithm. The proposed hierarchical method is applied to the Reactor Protection System (RPS) of a Pressurized Water Reactor (PWR) and to the the Airlock System (AS) of a CANadian Deuterium Uranium (CANDU) reactor. Results are evaluated with respect to the accuracy and computational demand of the solution found.     

Thiol‐ene and thiol‐yne‐based synthesis of glycodendrimers as nanomolar inhibitors of wheat germ agglutinin

Alkene and alkyne functional polyester‐based dendrimers of generation 1 to 4 have been prepared and reacted under free‐radical conditions with 2‐acetamido‐2‐deoxy‐1‐thio‐β‐D ‐glucose (GlcNAc‐SH). As the alkene‐dendrimers underwent the addition of one thiyl radical per ene group whereas each yne group of alkyne‐dendrimers was saturated by two thiyl radicals, a collection of glycodendrimers with glycan density ranging from six to ninety‐six GlcNAc per dendrimer was obtained. The recognition properties of the prepared glycodendrimers toward the wheat germ agglutinin (WGA) were evaluated by enzyme‐linked lectin assay (ELLA). The eight glycodendrimers were excellent ligands showing IC₅₀ values in the nanomolar range and relative potencies per sugar unit up to 2.27 e⁶ when compared to monosaccharidic GlcNAc used as monovalent reference. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2422–2433     

On novel bio-hybrid system based on PLA and POSS

In this work, a novel strategy for the preparation of bio-hybrid systems based on polylactic acid (PLA) and polyhedral oligomeric silsesquioxane (POSS) was developed. Indeed, the new method consists in a preliminary functionalization of the polymer matrix and a subsequent reaction of silsesquioxane molecules, characterized by amino or hydroxyl functionalities, potentially capable of reacting with maleic anhydride groups created onto PLA by a free radical process. The method adopted to create maleic anhydride-grafted polylactic acid (PLA-g-MA) allowed to graft 0.7 wt% of MA onto the polymer backbone, avoiding a dramatic reduction of PLA molecular mass. ¹H-NMR measurements demonstrated a different reactivity of the two used POSS, namely trans-cyclohexanediolisobutyl POSS (POSS-OH) and aminopropyl heptaisobutyl POSS (POSS-NH₂). Indeed, the amino group of POSS-NH₂ was found to react with the maleic anhydride group of PLA-g-MA allowing to obtain a hybrid system, carrying silsesquioxane molecules along the polymer backbone while the reactivity of POSS-OH turned out to be much lower. Thermal properties of the synthesized hybrid systems were assessed by means of DSC measurements. Indeed, the presence of POSS grafted onto the macromolecular chain was found to improve PLA crystallinity, by affecting the crystal nucleation density. Moreover, a decrease of surface water wettability was observed in the films made of PLA-g-MA/POSS-NH₂.