On the microstructures of the bulk of P3HT amorphous films obtained from two protocols: Insights from molecular dynamics simulations.

An influential factor for the microstructure of semiconductor polymer films is the solvent chosen for their processing and subsequent performance as an active layer in electronic and optical devices. In this paper, we address the solvent-polymer interplays by reporting a comparison between the microstructure of the bulk of poly(3-hexylthiophene) (P3HT) films formed from two different simulation methodologies: using the o-dichlorobenzene (ODCB) as an aggregation chain parameter and a solvent-free protocol. In comparison to the length of an ideal planar chain, the solvent caused an average reduction of 12% of oligomer chains.

Solvent influence on molecular interactions in the bulk of fluorene copolymer films.

The effect of intermolecular interactions between the chains of the amorphous PFO-MEH-PPV films built from toluene and tetrahydrofuran (THF) were studied by atomistic molecular dynamics simulations, applying a successive solvent removal procedure. In the good solvent toluene, the incidence of topological entanglements is more significant. While in the poor solvent, coplanar interactions between neighbouring segments of the chains were also found, which is characteristics of cohesional entanglements.

Aminated cellulose as a versatile adsorbent for batch removal of As(V) and Cu(II) from mono- and multicomponent aqueous solutions.

A bioadsorbent (CEDA) capable of adsorbing As(V) and Cu(II) simultaneously was prepared by tosylation of microcrystalline cellulose (MC) and nucleophilic substitution of the tosyl group by ethylenediamine. MC, tosyl cellulose, and CEDA were characterized by elemental C, H, N, and S analysis, infrared spectroscopy, and C solid-state nuclear magnetic resonance spectroscopy. The adsorption of As(V) and Cu(II) on CEDA was evaluated as a function of solution pH, contact time, and initial solute concentration.

Interactions of cantharidin-like inhibitors with human protein phosphatase-5 in a Mg system: molecular dynamics and quantum calculations.

The serine/threonine protein phosphatase type 5 (PP5) is a promising target for designing new antitumor drugs. This enzyme is a member of the PPP phosphatases gene family, which catalyzes a dephosphorylation reaction: a regulatory process in the signal transduction pathway that controls various biological processes. The aim of this work is to study and compare the inhibition of PP5 by ten cantharidin-like inhibitors in order to bring about contributions relevant to the better comprehension of their inhibitory activity.

Polymorphic and Quantum Chemistry Characterization of Candesartan Cilexetil: Importance for the Correct Drug Classification According to Biopharmaceutics Classification System.

The recommended method for the biopharmaceutical evaluation of drug solubility is the shake flask; however, there are discrepancies reported about the solubility of certain compounds measured with this method, one of them is candesartan cilexetil. The present work aimed to elucidate the solubility of candesartan cilexetil by associating others assays such as stability determination, polymorphic characterization and in silico calculations of intrinsic solubility, ionized species, and electronic structures using quantum chemistry descriptors (frontier molecular orbitals and Fukui functions). For the complete biopharmaceutical classification, we also reviewed the permeability data available.

Evaluation of the losartan solubility in the biowaiver context by shake-flask method and intrinsic dissolution.

This study aimed at evaluating the shake-flask use as a universal method to evaluate drug solubility in a biowaiver context as proposed by FDA, EMA and ANVISA. The solubility of losartan was determined in three buffers using the shake-flask method, intrinsic dissolution (ID) and Quantum Chemistry. Moreover, the evaluation of a losartan dissolution profile from coated tablets was conducted.

Synthesis and application of a new carboxylated cellulose derivative. Part III: Removal of auramine-O and safranin-T from mono- and bi-component spiked aqueous solutions.

In the third part of this series of studies, the adsorption of the basic textile dyes auramine-O (AO) and safranin-T (ST) on a carboxylated cellulose derivative (CTA) were evaluated in mono- and bi-component spiked aqueous solutions. Adsorption studies were developed as a function of solution pH, contact time, and initial dye concentration. Adsorption kinetic data were modeled by monocomponent kinetic models of pseudo-first- (PFO), pseudo-second-order (PSO), intraparticle diffusion, and Boyd, while the competitive kinetic model of Corsel was used to model bicomponent kinetic data.

Structural dependence of MEH-PPV chromism in solution.

The chromism observed in the MEH-PPV polymer in tetrahydrofuran (THF) solution is discussed as a function of the structural morphology of the backbone chains. To evaluate this phenomenon, we carried out simulations employing a hybrid methodology using molecular dynamics and quantum mechanical approaches. Our results support the hypothesis that the morphological order-disorder transition is related to the change from red to blue phase observed experimentally.

Towards understanding the mechanism of action of antibacterial N-alkyl-3-hydroxypyridinium salts: Biological activities, molecular modeling and QSAR studies.

In this study, we have carried out a combined experimental and computational investigation to elucidate several bred-in-the-bone ideas standing out in rational design of novel cationic surfactants as antibacterial agents. Five 3-hydroxypyridinium salts differing in the length of N-alkyl side chain have been synthesized, analyzed by high performance liquid chromatography, tested for in vitro activity against a panel of pathogenic bacterial and fungal strains, computationally modeled in water by a SCRF B3LYP/6-311++G(d,p) method, and evaluated by a systematic QSAR analysis. Given the results of this work, the hypothesis suggesting that higher positive charge of the quaternary nitrogen should increase antimicrobial efficacy can be rejected since 3-hydroxyl group does increase the positive charge on the nitrogen but, simultaneously, it significantly derogates the antimicrobial activity by lowering the lipophilicity and by escalating the desolvation energy of the compounds in comparison with non-hydroxylated analogues.

Effect of Blue Light on the Electronic and Structural Properties of Bilirubin Isomers: Insights into the Photoisomerization and Photooxidation Processes.

The central process of neonatal phototherapy by employing blue light has been attributed to the configurational conversion of (4Z,15Z)-bilirubin to (4Z,15E). Indeed, photoisomerization is the early photochemical event during this procedure. However, in this paper, we show that the bilirubin solutions under continuous blue light exposure undergo a photooxidation process.

Quantum chemical study of electronic and structural properties of retinal and some aromatic analogs.

The electronic and structural properties of retinal and four analogs were studied using semiempirical, ab initio Hartree-Fock, and density functional theory methods with the aim to evaluate the effects caused by some structural modifications in the ring bound to the polyenic chain and compared with the all-E-trans-retinal molecule. Therefore, some properties such as bond lengths, bond angles, atomic charges derived from electrostatic potential charges from electrostatic potential using grid based method as well as frontier orbitals of the polyenic chain were analyzed. Furthermore, the transition energies of the molecules were also calculated using the Zerner's intermediate neglect of differential overlap-spectroscopic, time-dependent Hartree-Fock, and time-dependent density functional theory methods.