Intercalation ofn-alkylamines into α-titanium phosphate from aqueous solutions

The intercalation reactions betweenn-alkylamines and -titanium phosphate in aqueous media have been investigated. The compounds with the maximum intercalation have the formula -Ti(HOPO₃)₂ · 2 C _n H _2n+1 NH₂ · H₂O (n=1–10). Defined crystalline phases with lower amine content are described, the general formula being -Ti(HOPO₃)₂ · _m C _n H _2n+1 NH₂ ·pH₂O (m=1.0 1.3, 1.5, 1.7). Whenm=1.0 then-alkylamines form a monomolecular layer. Whenm>1.0 the layer is bimolecular. The inclination angle and the packing density of then-alkylamines in the interlayer space is determined.     

Equation of state of a seven-dimensional hard-sphere fluid. Percus-Yevick theory and molecular-dynamics simulations

Following the work of Leutheusser [Physica A 127, 667 (1984)], the solution to the Percus-Yevick equation for a seven-dimensional hard-sphere fluid is explicitly found. This allows the derivation of the equation of state for the fluid taking both the virial and the compressibility routes. An analysis of the virial coefficients and the determination of the radius of convergence of the virial series are carried out. Molecular-dynamics simulations of the same system are also performed and a comparison between the simulation results for the compressibility factor and theoretical expressions for the same quantity is presented.     

Modular synthesis of the C9-C27 degradation product of aflastatin A via alkyne-epoxide cross-couplings

A modular approach to the synthesis of complex polyketide natural products is demonstrated for the synthesis of the C9-C27 degradation product from aflastatin A. The product of the cross-coupling of C23-C27 terminal alkyne with C17-C22 epoxide underwent functionalization of the resulting internal alkyne, which was then coupled similarly with C9-C16 epoxide. This synthesis concluded with regio- and stereoselective addition of methyl onto the internal alkyne followed by stereoselective hydroboration-oxidation.     

Virial series for fluids of hard hyperspheres in odd dimensions

A recently derived method [R. D. Rohrmann and A. Santos, Phys. Rev. E 76, 051202 (2007)] to obtain the exact solution of the Percus-Yevick equation for a fluid of hard spheres in (odd) d dimensions is used to investigate the convergence properties of the resulting virial series. This is done both for the virial and compressibility routes, in which the virial coefficients B(j) are expressed in terms of the solution of a set of (d-1)/2 coupled algebraic equations which become nonlinear for d>/=5. Results have been derived up to d=13. A confirmation of the alternating character of the series for d>/=5, due to the existence of a branch point on the negative real axis, is found and the radius of convergence is explicitly determined for each dimension. The resulting scaled density per dimension 2eta(1/d), where eta is the packing fraction, is wholly consistent with the limiting value of 1 for d-->infinity. Finally, the values for B(j) predicted by the virial and compressibility routes in the Percus-Yevick approximation are compared with the known exact values [N. Clisby and B. M. McCoy, J. Stat. Phys. 122, 15 (2006)].     

Eutectic Molten Salt Synthesis of Highly Microporous Macrocyclic Porous Organic Polymers for CO2 Capture

The development of porous materials is of great interest for the capture of CO₂ from various emission sources, which is essential to mitigate its detrimental environmental impact. In this direction, porous organic polymers (POPs) have emerged as prime candidates owing to their structural tunability, physiochemical stability and high surface areas. In an effort to transfer an intrinsic property of a cyclotetrabenzoin-derived macrocycle – its high CO₂ affinity – into porous networks, herein we report the synthesis of three-dimensional (3D) macrocycle-based POPs through the polycondensation of an octaketone macrocycle with phenazine-2,3,7,8-tetraamine hydrochloride. This polycondensation was performed under ionothermal conditions, using a eutectic salt mixture in the temperature range of 200 to 300 °C. The resulting polymers, named 3D-mmPOPs, showed reaction temperature-dependent surface areas and gas uptake properties. 3D-mmPOP-250 synthesized at 250 °C exhibited a surface area of 752 m² g⁻¹ and high microporosity originating from the macrocyclic units, thus resulting in an excellent CO₂ binding enthalpy of 40.6 kJ mol⁻¹ and CO₂ uptake capacity of 3.51 mmol g⁻¹ at 273 K, 1.1 bar.     

Understanding the structure,electronic properties,solubility in water,and protein interactions of three novel nano-devices against ovarian cancer: a computational study

All kinds of different treatments for cancer have been proposed in the last years, being these mostly non-selective to neoplastic cells, but with the development of nanoscience, new approaches have developed, proposing nano-vectors as drug carriers and thus avoiding or diminishing the collateral and secondary effects of anticancer drugs. However, the structure, electronic properties, and protein interactions of these kinds of nanosystems have not been deeply studied. For this reason, we are proposing the design of three novel nano-devices against ovarian cancer, using a finite single-wall carbon nanotube functionalized with three commercial anticancer drugs (altretamine, melphalan, and cyclophosphamide) and glucosamine as solubilizing molecule, with a size range of 29.8 to 34.5 Å, which were characterized by a state-of-the-art methodology within density functional theory, obtaining their optimized structures, which were verified to be minima in the potential energy surfaces. We have calculated the changes in their electronic parameters, as compared with the respective free drugs; we also studied the interaction of these nano-vectors with KLK5, a protein overexpressed in ovarian cancer, which we suggest may contribute to the drug delivery process.

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Design,Synthesis, and Biological Evaluation of 5,6,7,8-Tetrahydrobenzo[4,5]thieno[2,3-d]pyrimidines as Microtubule Targeting Agents

A series of eleven 4-substituted 5,6,7,8-tetrahydrobenzo[4,5]thieno[2,3-d]pyrimidines were designed and synthesized and their biological activities were evaluated. Synthesis involved the Gewald reaction to synthesize ethyl 2-amino-4,5,6,7-tetrahydrobenzo[b]thiophene-3-carboxylate ring, and S_NAr reactions. Compound 4 was 1.6- and ~7-fold more potent than the lead compound 1 in cell proliferation and microtubule depolymerization assays, respectively. Compounds 4, 5 and 7 showed the most potent antiproliferative effects (IC₅₀ values < 40 nM), while compounds 6, 8, 10, 12 and 13 had lower antiproliferative potencies (IC₅₀ values of 53–125 nM). Additionally, compounds 4–8, 10 and 12–13 circumvented Pgp and βIII-tubulin mediated drug resistance, mechanisms that diminish the clinical efficacy of paclitaxel (PTX). In the NCI-60 cell line panel, compound 4 exhibited an average GI₅₀ of ~10 nM in the 40 most sensitive cell lines. Compound 4 demonstrated statistically significant antitumor effects in a murine MDA-MB-435 xenograft model.     

Conformational Effects of [Ni2(μ‐ArS)2] Cores on Their Electrocatalytic Activity

Two nickel complexes supported by tridentate NS₂ ligands, [Ni₂(κ‐N,S,S,S′‐N^Ph{CH₂(MeC₆H₂R′)S}₂)₂] ( 1 ; R′=3,5‐(CF₃)₂C₆H₃) and [Ni₂(κ‐N,S,S,S′‐N^iBu{CH₂C₆H₄S}₂)₂] ( 2 ), were prepared as bioinspired models of the active site of [NiFe] hydrogenases. The solid‐state structure of 1 reveals that the [Ni₂(μ‐ArS)₂] core is bent, with the planes of the nickel centers at a hinge angle of 81.3(5)°, whereas 2 shows a coplanar arrangement between both nickel(II) ions in the dimeric structure. Complex 1 electrocatalyzes proton reduction from CF₃COOH at ?1.93 (overpotential of 1.04 V, with i_cat/i_p≈21.8) and ?1.47 V (overpotential of 580 mV, with i_cat/i_p≈5.9) versus the ferrocene/ferrocenium redox couple. The electrochemical behavior of 1 relative to that of 2 may be related to the bent [Ni₂(μ‐ArS)₂] core, which allows proximity of the two Ni???Ni centers at 2.730(8) Å; thus possibly favoring H⁺ reduction. In contrast, the planar [Ni₂(μ‐ArS)₂] core of 2 results in a Ni???Ni distance of 3.364(4) Å and is unstable in the presence of acid.     

Assessment of Bleached and Unbleached Nanofibers from Pistachio Shells for Nanopaper Making

Cellulose and lignocellulose nanofibrils were extracted from pistachio shells utilizing environmentally friendly pulping and totally chlorine-free bleaching. The extracted nanofibers were used to elaborate nanopaper, a continuous film made by gravimetric entanglement of the nanofibers and hot-pressed to enhance intramolecular bonding. The elaborated nanopapers were analyzed through their mechanical, optical, and surface properties to evaluate the influence of non-cellulosic macromolecules on the final properties of the nanopaper. Results have shown that the presence of lignin augmented the viscoelastic properties of the nanopapers by ≈25% compared with fully bleached nanopaper; moreover, the hydrophobicity of the lignocellulose nanopaper was achieved, as the surface free energy was diminished from 62.65 to 32.45 mNm⁻¹ with an almost non-polar component and a water contact angle of 93.52°. On the other hand, the presence of lignin had an apparent visual effect on the color of the nanopapers, with a ΔE of 51.33 and a ΔL of −44.91, meaning a substantial darkening of the film. However, in terms of ultraviolet transmittance, the presence of lignin resulted in a practically nonexistent transmission in the UV spectra, with low transmittance in the visible wavelengths. In general, the presence of lignin resulted in the enhancement of selected properties which are desirable for packaging materials, which makes pistachio shell nano-lignocellulose an attractive option for this field.