Modulating Polymer Ultrathin Film Crystalline Fraction and Orientation with Nanoscale Curvature.

We investigated the effect of nanoscale curvature on the structure of thermally equilibrated poly-3-hexylthiophene (P3HT) ultrathin films. The curvature-induced effects were investigated with synchrotron grazing incidence X-ray diffraction (GIXRD) and atomic force microscopy (AFM). Our results demonstrate that nanoscale curvature reduces the polymer crystalline fraction and the crystal length.

1,2-Dibenzoylhydrazine as a Multi-Inhibitor Compound: A Morphological and Docking Study.

In the framework of the multitarget inhibitor study, we report an in silico analysis of 1,2-dibenzoylhydrazine (DBH) with respect to three essential receptors such as the ecdysone receptor (EcR), urease, and HIV-integrase. Starting from a crystallographic structural study of accidentally harvested crystals of this compound, we performed docking studies to evaluate the inhibitory capacity of DBH toward three selected targets. A crystal morphology prediction was then performed.

A Pseudouridine Isoxazolidinyl Nucleoside Analogue Structural Analysis: A Morphological Approach.

An in silico study has been conducted upon (3',5')-5-[2'-benzyl-5'-hydroxymethyl-1',2'-isoxazolidin-3'-yl]uracil through a molecular dynamics/docking approach that highlights its potential inhibitory activity upon the wild-type pseudouridine 5'-monophosphate glycosidase. The crystal structure of this compound has been solved by means of X-ray single crystal diffraction and the data inferred were used to predict its crystal morphology. These data were compared with optical microscopy images and confirmed the validity of the computed models.

(+)-Methyl (1R,2S)-2-{[4-(4-Chlorophenyl)-4-hydroxypiperidin-1-yl]methyl}-1-phenylcyclopropanecarboxylate [(+)-MR200] Derivatives as Potent and Selective Sigma Receptor Ligands: Stereochemistry and Pharmacological Properties.

Methoxycarbonyl-1-phenyl-2-cyclopropylmethyl based derivatives cis-(+)-1a [cis-(+)-MR200], cis-(-)-1a [cis-(-)-MR201], and trans-(±)-1a [trans-(±)-MR204], have been identified as new potent sigma (σ) receptor ligands. In the present paper, novel enantiomerically pure analogues were synthesized and optimized for their σ receptor affinity and selectivity. Docking studies rationalized the results obtained in the radioligand binding assay.

Molecular modeling studies of pseudouridine isoxazolidinyl nucleoside analogues as potential inhibitors of the pseudouridine 5'-monophosphate glycosidase.

In this paper, we investigated the hypothesis that pseudouridine isoxazolidinyl nucleoside analogues could act as potential inhibitors of the pseudouridine 5'-monophosphate glycosidase. This purpose was pursued using molecular modeling and in silico ADME-Tox profiling. From these studies emerged that the isoxazolidinyl derivative 1 5'-monophosphate can be effectively accommodated within the active site of the enzyme with a ligand efficiency higher than that of the natural substrate.

X-Ray crystallographic and computational study on uranyl-salophen complexes bearing nitro groups.

In the solid state, salophen-UO complexes bearing one, two, or three NO groups lack the pronounced ligand curvature that represents a structural hallmark for this class of compounds. A detailed structural study based on single-crystal X-ray crystallography and computational methods, comprising molecular dynamics, gas-phase Hartree Fock, and DFT calculations, was carried out to investigate the coordination properties of the uranyl cation.

Probing nonlinear optical coefficients in self-assembled peptide nanotubes.

Self-assembled l,l-diphenylalanine (FF) peptide micro/nanotubes represent a class of biomimetic materials with a non-centrosymmetric crystal structure and strong piezoelectricity. The peptide nanotubes synthesized by a liquid phase method yield tube lengths in the hundreds of micron range, inner diameters in the few hundred nanometer range, and outer diameters in the 5-15 μm range. Second harmonic generation (SHG) polarimetry from individual self-assembled FF nanotubes is used to obtain the nonlinear (NLO) optical coefficients as a function of the tube diameter and thermal treatment.

Structure and aggregation properties of a Schiff-base zinc(II) complex derived from cis-1,2-diaminocyclohexane.

This contribution explores the effect of the bridging diamine upon the aggregation properties of a Zn(II) Schiff-base complex, , both in the solid state and in solution. The X-ray structure of , resulting from the harvest of good quality crystals using chloroform and diethyl ether as solvents, shows the presence of a densely packed dimer in the solid state which pentacoordinates two Zn atoms involved in a μ-phenoxo bridge. Detailed studies in solution, through (1)H NMR, DOSY NMR, and optical spectroscopic investigations, indicate the typical aggregation/deaggregation behaviour on switching from non-coordinating to coordinating solvents, in relation to the Lewis acidic character of such Zn(II) complexes.

A top-down approach to crystal engineering of a racemic Δ2-isoxazoline.

The crystal structure of racemic dimethyl (4RS,5RS)-3-(4-nitrophenyl)-4,5-dihydroisoxazole-4,5-dicarboxylate, C13H12N2O7, has been determined by single-crystal X-ray diffraction. By analysing the degree of growth of the morphologically important crystal faces, a ranking of the most relevant non-covalent interactions determining the crystal structure can be inferred. The morphological information is considered with an approach opposite to the conventional one: instead of searching inside the structure for the potential key interactions and using them to calculate the crystal habit, the observed crystal morphology is used to define the preferential lines of growth of the crystal, and then this information is interpreted by means of density functional theory (DFT) calculations.

Potassium caffeate/caffeic acid co-crystal: the rat race between the catecholic and carboxylic moieties in an atypical co-crystal.

The vast literature concerning caffeic acid and its derivatives lacks any reference to the solid state structures of its inorganic salts as these crystals are quite difficult grow. Most of the already published works deal with computational studies of these compounds as well as investigations of their behaviour in solution. Having obtained good quality potassium caffeate/caffeic acid co-crystals, we solved their structure and used a robust approach, already applied to caffeic acid alone, to compare the X-ray structure with the one inferred by Molecular Dynamics (MD), focusing our attention on the structure-property relationships.

Crystal morphologies and polymorphs in tolbutamide microcrystalline powder.

The growing interest of pharmaceutical companies toward the crystal morphology prediction of active pharmaceutical ingredients is a consequence of the dramatic effect of the crystal habit on the tableting behavior of drugs. In order to help the optimization of the industrial process, molecular mechanics calculations together with X-ray diffraction analysis and optical microscopy (OM) were used to shed light over the structural properties of N-(butylcarbamoyl)-4-methylbenzenesulfonamide-commercially known as tolbutamide-a drug used in the management of type II diabetes, especially in elderly diabetics because of its rapid metabolism. As there are several known polymorphs of this molecule, we first defined, by means of a quantitative phase analysis, performed by X-ray powder diffraction, which and how much each of the five crystallographic structures present in the Cambridge Crystallographic Database represent the commercial crystalline powder.

Interfacial free energy driven nanophase separation in poly(3-hexylthiophene)/[6,6]-phenyl-C61-butyric acid methyl ester thin films.

The nanostructure of thermally annealed thin films of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) blends on hydrophobic and hydrophilic substrates was studied to unravel the relationship between the substrate properties and the phase structure of polymer blends in confined geometry. Indeed, the nature of the employed substrates was found to affect the extent of phase separation, the PCBM aggregation state and the texture of the whole system. In particular, annealing below the melting temperature of the polymer yielded the formation of PCBM nanometric crystallites on the hydrophobic substrates, while mostly amorphous microscopic aggregates were formed on the hydrophilic ones.

An integrated X-ray and molecular dynamics study of uranyl-salen structures and properties.

Uranium complexes of bis(p-tert-butyl-salicylidene)-1,2-diphenylethylenediamine (1) and bis(salicylidene)-1,2-diphenylethylenediamine (2) have been synthesized and investigated by X-ray single crystal diffraction and MD calculations in Periodic Boundary Conditions. Both compounds form crystals which are densely packed and do not provide voids accessible to solvent molecules. The configurations adopted by 1 and 2 are determined by well defined T-shaped and π-stacking non covalent interactions between phenyl groups of adjacent molecules as well as by a network of hydrogen bonds.

Part I: A comparative study of bismuth-modified screen-printed electrodes for lead detection.

Lead determination was carried out in the frame of the European Union project Biocop (www.biocop.org) using a bismuth-modified screen-printed electrode (Bi-SPE) and the stripping analysis technique.

How molecular interactions affect crystal morphology: the case of haloperidol.

The tableting behaviour of drugs can be dramatically affected by changes in the crystal habit of the drug molecule. Pharmaceutical companies are therefore interested in the morphology prediction as a possible tool to optimise the industrial process. Molecular mechanics calculations embedded in dedicated software together with X-ray diffraction analysis were used to enlighten the structural properties of 4-[4-(4-chlorophenyl)-4-hydroxypiperidin-1-yl]-1-(4-fluorophenyl)butan-1-one-whose commercial name is haloperidol--an antipsychotic drug that contributed to the progress and revolution of psychiatric care.

α-d-Tagatopyran-ose.

The title compound, C(6)H(12)O(6), also known as d-Tagatose, occurs in its furanose and pyranose forms in solution, but only the α-pyran-ose form crystallizes out. In the crystal, the molecules form hydrogen bonded chains propagating in [100] linked by O-H⋯O interactions. Further O-H⋯O bonds cross-link the chains.

Molecular dynamics (MD) simulations and large-angle X-ray scattering (LAXS) studies of the solid-state structure and assembly of isotactic (R)-poly(2,2'-dioxy-1,1'-binaphthyl-)phosphazene in the bulk state and in the cast film.

The intrachain conformation, molecular structure and interchain assembly of isotactic (R)-poly(2,2'-dioxy-1,1'-binaphthyl)phosphazene (P-DBNP) both in the bulk state (I) and in the cast film (II) were studied by molecular dynamics (MD) simulations of models, as implemented by a bias potential for the analysis of the radial distribution function (RDF) obtained from large-angle X-ray scattering (LAXS) data. The microscopic structure and order extension of the polymer changed from I to II, as qualitatively shown in the shapes of their experimentally measured RDF curves. With the use of a bias potential, the MD simulations provided a much more accurate analysis of the models, as seen in the reproduction of the RDFs.

Bile salt aggregates in the gas phase: an electrospray ionization mass spectrometric study.

Helical and ordered structures have previously been identified by X-ray diffraction analysis in crystals and fibers of bile salts, and proposed as models of the micellar aggregates formed by trimeric or dimeric units of dihydroxy and trihydroxy salts, respectively. These models were supported by the results of studies of micellar bile salt solutions performed with different experimental techniques. The study has now been extended to the gas phase by utilizing electrospray ionization mass spectrometry (ESIMS) to investigate the formation and the composition of aggregates stabilized by noncovalent interactions, including polar (ion-ion, ion-dipole, dipole-dipole, hydrogen bonding etc.

Eustachian Valve Endocarditis in an Elderly Woman.

We describe the transesophageal echocardiographic findings in Eustachian valve endocarditis for a 73-year-old woman with a previous history of mitral valve disease. After a 4-week treatment with antibiotics, follow-up echocardiographic examination showed a smaller vegetation.