Search

Over the last years, several regulations have been used to rule the dynamics of the transport of dangerous substances. As a consequence, a number of regulations concerning the international railway transport of dangerous goods impacted on rail transport, Regulation 1907/2006 and Regulation 1272/2008, increased toxicological information assets and tools that can be addressed in the event of a health emergency. The purpose of this study is to analyze dispersion scenarios to describe the consequences of an intentional release of propane, butane, or chlorine. Every scenario is designed to outline a hypothetical terrorist attack in a railway station where the compounds are released in the form of aerosol, boiling liquid expanding vapor explosion, or explosion. The toxicological exposure dynamics were modeled by means of tools such as the ALOHA software (Environmental Protection Agency). The simulations show different dispersions for all considered chemicals: chlorine covers a larger area, liquid butane is the most persistent and much hazardous for inflammability and toxicity, and propane shows destructive shock wave power and relative acute outdoor toxicity. The exposure rates were eventually estimated using the “Green Book” parameters (Netherlands Organization for Applied Scientific Research).

Curcumin, a chemical compound present in the well-known Indian spice turmeric, has uses in many different fields ranging from medicinal chemistry to the dye industry. Its poor water solubility, though, makes Curcumin difficult to handle, making it less appealing for potential uses. The principal aim of this work is to perform a computational study of the structural and electronic properties of Curcumin {IUPAC name: 1,7-bis(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione} in several solvents, and a comparison with experimental data. Rotameric equilibria, vibrational and thermochemical analysis, and electronic absorption spectra (with ab initio and semi-empirical methodologies) have been studied, both in vacuum and in three selected solvents. Different computational techniques have been applied and the results compared. Combined approaches resulted in very satisfactory results. Interesting results have emerged, which suggest subsequent investigations about the nature of the excited states and potential derivatives of Curcumin that possibly have non-linear optical applications, as a π-core for innovative materials in laser engineering and photonics.

Curcumin, a well-known Indian spice, holds a variety of properties in many different fields from medicinal chemistry to dye industry. The peculiar electronic structure makes curcumin a valuable metal chelator. The principal aim of this work is a computational study of the structural and electronic properties of the ground and the first singlet excited states of the curcuminoidic core. Concerning the ground state, tautomeric equilibrium, vibrational and thermochemical analysis and electronic absorption spectra (with ab initio and semi-empirical methodologies) have been studied. A full geometry optimization of the first singlet excited states was obtained, with different computational methodologies. Solvent effects are also implicitly considered. An accurate comparison of the results is presented. Interesting aspects emerge, which suggest successive investigation about the nature of the excited states. The obtained results may be of large applicative interest. If curcuminoids are considered as potential ligands for complexes formation with metallic ions of pharmaceutical, medical–physical and technological interest, exciting the system with photons of appropriate frequencies, a photomodulated release of the metallic ion in the environment might be guessed, because of an important photoinduced geometrical modification.

The Fe3+ chelating ability of some curcumin glucosyl derivatives (Glc-H; Glc-OH; Glc-OCH3) is tested by means of UV and NMR study. The pK a values of the ligands and the overall stability constants of Fe3+ and Ga3+ complexes are evaluated from UV spectra. The only metal binding site of the ligand is the β-diketo moiety in the keto-enolic form; the glucosyl moiety does not interact with metal ion but it contributes to the stability of metal/ligand 1:2 complexes by means of hydrophilic interactions. These glucosyl derivatives are able to bind Fe3+ in a wide pH rage, forming complex species thermodynamically more stable than those of other ligands commonly used in the treatment of iron deficiency. In addition they demonstrate to have a poor affinity for competitive biological metal ions such as Ca2+. All ligands and their iron complexes have a good lypophilicity (log P > −0.7) suggesting an efficient gastrointestinal absorption in view of their possible use as iron supplements in oral therapy. The ligand molecules are also tested for their antioxidant properties in “ex vivo” biological system.

A simple synthetic pathway to obtain glycosilated β-diketo derivatives is proposed. These compounds show a good iron(III) affinity therefore we may suggest the use of their Fe 3+ -complexes as oral iron supplements in the treatment of anaemia. The glycosilated compounds (6-GlcH, 6-GlcOH and 6-GlcOCH 3 ) are characterized by means of spectroscopic (UV, 1 H and 13 C NMR) and potentiometric techniques; they have a good water solubility, are kinetically stable in physiological condition ( t 1/2 > 100 h) and show a low cytotoxicity also in high concentrations (IC 50 > 400 μM). They are able to bind Fe 3+ ion in acid condition (pH ∼ 2) forming complex species thermodynamically more stable than those of other ligands commonly used in the treatment of iron deficiency. The iron complexes show also a good kinetic stability both in acidic and physiological pH and have a good lypophilicity (log P > −0.7) that suggests an efficient gastrointestinal absorption in view of their possible use in oral therapy. In addition they demonstrate a poor affinity for competitive biological metal ion such as Ca 2+ , and in particular 6-GlcOCH 3 is able to inhibit lipid peroxidation.

The novel β-diketo compound (3-acetyl-4-oxopentanoic acid) OPAA is here synthesized and completely characterized in the solid state by means of X-ray crystallography and in solution by potentiometry and 1H and 13C NMR spectroscopy. In the solid state, OPAA exhibits the di-keto (DK) structure, however, in solution, we can observe a strong solvent dependent tautomeric equilibrium. Theoretical ab initio calculations employing DFT at the B3LYP/6-311G** level, and different methods of theoretical model chemistry (CBS-4M, G3MP2, CBS-QB3) are used to extensively investigate the tautomeric equilibrium and compare it with experimental data. Solvent effects are evaluated using a CPCM continuum solvation method; among all applied methods, CBS-4M is the one that better predicts experimental data and is able to qualitatively describe tautomeric equilibrium in solution, allowing thermodynamic calculations of pKa. Furthermore a supermolecular solvent approach is used to better analyze solvent–solute interactions in order to predict chemical properties.

During the last few decades, the oxygenated chelant complexes of the Gallium(III) ion have been utilised in biological and pharmaceutical fields, because of their remarkable therapeutical properties, especially for the clinical anti-cancer treatments. Main purpose of the present work is to investigate, from a theoretical and computational point of view, the thermodynamic, structural and electronic properties of the complexes and the complexation equilibria of the Ga(III) ion with two oxygenated chelant ligands (acetylacetone and 1,7-diphenyl-5-hydroxy-1,4,6-heptatrien-3-one), in vacuo. Comparisons with Literature experimental data are even discussed. (C) 2011 Elsevier B.V. All rights reserved.

In the present study, we investigate the structures of glucosylated curcumin derivatives with DFT at B3LYP/6-31G* level. A conformational analysis is performed in order to determine the conformational minimum (GS) and rotational transition state (TS) of curcumin derivatives and then their electronic features are evaluated. HOMO and LUMO frontier orbitals and maps of electron density potential (MEPs) are plotted and compared. In order to correlate their predicted spectroscopic properties with IR, UV–vis and NMR experimental data we extended the theoretical study on electronic properties to different solvents (H2O, MeOH, ACN, DMSO). The main finding is that the curcuminic core maintains the same geometrical and electronic structures in all compounds miming the metal coordination capability showed by curcumin. Therefore, we may confirm that the presence of glucose does not affect the electronic properties of the derivatives. Copyright © 2010 John Wiley & Sons, Ltd.

Turmeric extracts, among which curcumin and bis-demethoxycurcumin, are by far known for their therapeutic activities. In this study we propose easy and low cost synthetic pathways in order to obtain glucosyl-curcuminoids, safe and water soluble potential drugs and dyes, which may be implied in different fields ranging from pharmacology to food chemistry. The complete (1)H and (13)C NMR characterization of naturally occurring curcumin, bis-demethoxycurcumin and new synthetic glucosyl-curcuminoids is reported.

The main target of this study is a high-level computational analysis of Curcumin, employing DFT approach with two different sets of basis functions (B3LYP/6-31G ∗ and B3LYP/6-311G ∗∗ ). Accurate quantum mechanical studies, both in vacuum and in methanol medium, are carried out with the aim to analyze the conformational equilibria, to find the most stable equilibrium structure and to define the nature of the molecular orbitals, fundamental to explain Curcumin binding characteristic. Our theoretical calculations, performed at B3LYP/6-31G ∗ and B3LYP/6-311G ∗∗ levels both in vacuum and in methanol medium, confirm that the keto-enolic forms are more stable than the di-keto one, whose extremely low population suggests that this structure should not influence Curcumin properties. Keto-enolic form C results the most stable, independently on calculation level and solvent (methanol) effect. HOMO and LUMO molecular orbitals are calculated for all the structures with the two sets of basis with very similar results. MEPs show that the negative charge is localized on the oxygen atoms, which, in the keto-enolic forms, point in the same direction enabling metal coordination. NMR, UV–vis and FT-IR experimental data are employed in the comparison with electronic and conformational properties of Curcumin resulting from theoretical calculations. The two different calculation levels (B3LYP/6-31G ∗ and B3LYP/6-311G ∗∗ ) give very similar results. Good linear correlations between the experimental 1 H and 13 C NMR chemical shifts ( δ exp ), in methanol- d 4 (MeOD) and DMSO- d 6 (DMSO), and calculated magnetic isotropic shielding tensors ( σ calc ) are found ( δ exp = a · σ calc + b ). A good prediction of UV–vis experimental maximum absorption ( λ max ) on the basis of conformer populations is obtained. A linear relation with a good correlation coefficient is observed plotting the FT-IR experimental wavenumbers vs . the calculated ones, allowing to predict FT-IR spectra.