Crystal and molecular structure of bis(imazapyr)diaqua copper(II)

The imidazolinone herbicide imazapyr, 2-(4-isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl)nicotinic acid (H₂imz) interacts with Cu(II) leading to [Cu(Himz)₂(H₂O)₂] which crystallizes in the space group Pbca, with a = 12.5370(3) Å, b = 19.8500(5) Å, c = 22.7720(9) Å, and Z = 8. The Cu(II) atom is octahedrally surrounded by four nitrogen atoms of two Himz^– anions and two water molecules. Each Himz^– acts as a chelating ligand by means of N pyridine and N lactam atoms leading to five-membered chelate rings. The Cu N distances vary from 1.948(4) to 2.299(5) Å while the Cu O are 2.114(5) and 2.256(6) Å. The imidazol N-H are involved in short intramolecular hydrogen bonds with the carboxylate groups. The structure is stabilized by an intermolecular hydrogen-bonded network involving the water molecules and the carboxylate groups.     

Organized growth of GaAs/AlAs lateral structures on atomic step arrays: What is possible to do?

Laterally modulated nanostructures, exhibiting large optical and electrical anisotropy, can be grown an vicinal surfaces. However the lateral organization of Ga and Al atoms is far from ideal. We discuss our way of understanding the growth of these structures.     

Synthesis and radical polymerization of pyrocarbonate‐functionalized monomers: application to positive‐tone photoresists

The synthesis of two new tert‐butyl carbonic anhydride monomers, 4‐vinylbenzoic and methacrylic tert‐butylcarbonic anhydride was achieved successfully. Radical polymerization at 45°C yielded tert‐butyl pyrocarbonate protected materials. Thermographic analysis showed that both polymers decompose cleanly at 135°C. The lithographic performance of both materials was evaluated in the presence of 2,4,6‐tris‐(trichloromethyl)‐s‐triazine as photoacid generating species. It was demonstrated that the large polarity change results in a positively working chemically amplified photoresist system.     

Cationic Homoleptic Vanadium(II), (IV), and (V) Complexes Arising from Protonolysis of [V(NEt2)4]

At least three different cationic species arise in the classic protonolysis of [V^IV(NEt₂)₄] with a borate ammonium salt. The unexpected formation of the vanadium(V ) species [V(NEt₂)₄][B(C₆H₅)₄] (shown in the picture without its counterion) underlines the problem of deducing the true oxidation state of vanadium species in Ziegler–Natta reactions.     

Development of Amino Acids Functionalized SBA-15 for the Improvement of Protein Adsorption

Ordered mesoporous materials and their modification with multiple functional groups are of wide scientific interest for many applications involving interaction with biological systems and biomolecules (e.g., catalysis, separation, sensor design, nano-science or drug delivery). In particular, the immobilization of enzymes onto solid supports is highly attractive for industry and synthetic chemistry, as it allows the development of stable and cheap biocatalysts. In this context, we developed novel silylated amino acid derivatives (Si-AA-NH₂) that have been immobilized onto SBA-15 materials in biocompatible conditions avoiding the use of toxic catalyst, solvents or reagents. The resulting amino acid-functionalized materials (SBA-15@AA) were characterized by XRD, TGA, EA, Zeta potential, nitrogen sorption and FT-IR. Differences of the physical properties (e.g., charges) were observed while the structural ones remained unchanged. The adsorption of the enzyme lysozyme (Lyz) onto the resulting functionalized SBA-15@AA materials was evaluated at different pHs. The presence of different functional groups compared with bare SBA-15 showed better adsorption results, for example, 79.6 nmol of Lyz adsorbed per m² of SBA-15@Tyr compared with the 44.9 nmol/m² of the bare SBA-15.     

Indium tellurium trioxide chloride,InTeO3Cl

The new oxy­chloride InTeO₃Cl was synthesized from a mixture of In₂O₃, InCl₃ and TeO₂. Its structure has been determined from single‐crystal X‐ray diffraction data. The structure is composed of layers separated by a van der Waals gap. The layers consist of edge‐sharing chains of [InO₄Cl₂] octahedra linked through [TeO₃] trigonal pyramids. No free Cl atoms are located between the layers.     

Reconstructing f(T) modified gravity from ECHDE and ECNADE models

We investigate alternative candidates to dark energy (DE) that can explain the current state of the Universe in the framework of the generalized teleparallel theory of gravity f(T), where T denotes the torsion scalar. To achieve this, we carry out a series of reconstructions taking into account the ordinary and entropy-corrected versions of the holographic and new agegraphic DE models. These models are used as alternatives to DE in the literature in order to describe the current state of our Universe. It is remarked that the proposed models indicate behavior akin to phantom or quintessence models. Furthermore, we also generate the parameters of the equation of state associated with entropy-corrected models and we observe a phase transition between the quintessence state and phantom state as it is shown by the recent observational data. We also investigate the stability of these models and we create the $\{r-s\}$ trajectories and compare with the ΛCDM limit. The behavior of certain physical parameters such as the speed of sound and the Statefinder diagnostic pair $\{r-s\}$ is compatible with the current observational data.     

A novel and versatile potassium‐based catalyst for the ring opening polymerization of cyclic esters

Poly(lactide) (PLA), poly(ε‐caprolactone) (PCL) and poly(trimethylene carbonate) (PTMC) homopolymers of high molecular weight were prepared using potassium‐based catalyst. Polymerizations were carried out in toluene at room temperature. The chemical structure of the polymers was investigated by ¹H and ¹³C NMR. The physical properties investigated by GPC and DSC for the polymers obtained are similar to those prepared using tin octanoate based catalyst. Using a sequential polymerization procedure, PLA‐b‐PCL, PLA‐b‐PTMC, and PCL‐b‐PTMC diblock copolymers were synthesized and characterized in terms of their composition and physical properties. The formation of diblock copolymers was confirmed by NMR and DSC measurements. In vitro cytotoxicity tests have been carried out using MTS assay and the results show the biocompatibility of these polymers in the presence of the fibroblast cells. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5348–5362, 2008