Self-assembly structures of 1H-indazoles in the solution and solid phases: a vibrational (IR, FIR, Raman, and VCD) spectroscopy and computational study.

1H-indazoles are good candidates for studying the phenomena of molecular association and spontaneous resolution of chiral compounds. Thus, because the 1H-indazoles can crystallize as dimers, trimers, or catemers, depending on their structure and the phase that they are in, the difficulty in the experimental analysis of the structure of the family of 1H-indazoles becomes clear. This difficulty leads us to contemplate several questions: How can we determine the presence of different structures of a given molecular species if they change according to the phase? Could these different structures be present in the same phase simultaneously? How can they be determined? To shed light on these questions, we outline a very complete strategy by using various vibrational spectroscopic techniques that are sensitive (VCD) and insensitive (IR, FIR, and Raman) towards the chirality, together with quantum chemical calculations.

Synthesis and biological evaluation of curcuminoid pyrazoles as new therapeutic agents in inflammatory bowel disease: effect on matrix metalloproteinases.

Seven N-unsubstituted curcuminoid pyrazoles have been synthesized from the corresponding beta-diketones (including curcumin). We evaluated the possibility of curcuminoid pyrazoles regulating the activity of matrix metalloproteinases (MMPs) by human intestinal epithelial cells in vitro. Zymographic analysis revealed that three compounds significantly down-regulated MMP-9 activity on inflammation-induced intestinal epithelial cells, making them original candidates for the treatment of inflammatory bowel disease (IBD).

Current progress on antioxidants incorporating the pyrazole core.

The search of new antioxidants, as drugs candidates, is an active field of medicinal chemistry. The synthesis of compounds with antioxidant potential has increased in recent years and a high number of structurally diverse compounds have been published. This review aims to show the current state-of-the-art on the development of antioxidant compounds incorporating the pyrazole pharmacophore. It is a well-timed review driven by the increasing number of papers, on this issue, that have been published since the beginning of the 21st century (from 2000 to 2017). The aim is to look deeper into the structures already published in the literature containing the pyrazole core as the unique pharmacophore or combined with other pharmacophores and see the relationship between the presence of this five-membered nitrogen heterocycle and the behaviour of the compounds as potential antioxidant agents. An attempt was made to whenever possible establish structure-activity relationships that could help the design of new and more potent antioxidant agents containing this important pharmacophore.

Novel Oxazolidinone-Based Peroxisome Proliferator Activated Receptor Agonists: Molecular Modeling, Synthesis, and Biological Evaluation.

A series of new peroxisome proliferator activated receptors (PPARs) chiral ligands have been designed following the accepted three-module structure comprising a polar head, linker, and hydrophobic tail. The majority of the ligands incorporate the oxazolidinone moiety as a novel polar head, and the nature of the hydrophobic tail has also been varied. Docking studies using the crystal structure of an agonist bound to the ligand binding domain of the PPARα receptor have been performed as a tool for their design. Suitable synthetic procedures have been developed, and compounds with different stereochemistries have been prepared. Evaluation of basal and ligand-induced activity proved that several compounds showed agonist activity at the PPARα receptor, thus validating the oxazolidinone template for PPAR activity. In addition, two compounds, 2 and 4, showed dual PPARα/PPARγ agonism and interesting food intake reduction in rats.

Spontaneous self-ionization in the gas phase: a theoretical prediction.

Proton transfer between dimers is associated with strong bases and very good hydrogen bond donors, namely, between very different chemical species. A spontaneous self-ionization and concomitant proton transfer can occur in dimers involving phosphinic acid derivatives (see picture), even when they present the same functional group. It is also possible, by choosing the appropriate substituents, to modulate the degree of the interaction, from a hydrogen bonded complex to an ion pair, without changing the nature of the functional groups involved.

High-performance liquid chromatographic determination of the pi values of azol-N-yl substituents.

The pi (hydrophobic constant) values for 16 parent azoles (pyrrole, imidazole, pyrazole, four triazoles, two tetrazoles, indole, benzimidazole, 1H- and 2H-indazoles, 1H- and 2H-benzotriazoles, and carbazole) were calculated from the logarithms of the capacity factors (log k') determined by HPLC. The values thus obtained are discussed according to an additive model in which the number and position of pyridinelike nitrogen atoms and the annelation effect are considered.

3(5),4-Dimethyl- and 3,4,5-trimethylpyrazole at 200 K. X-ray crystallography and quantum-chemical analysis.

The crystal and molecular structures of 3(5),4-dimethylpyrazole, C(5)H(8)N(2), (I), and of 3,4,5-trimethylpyrazole, C(6)H(10)N(2), (II), have been determined at 200 K. In (I) the 4,5-dimethylpyrazole tautomer is present in the solid state and the six independent molecules in the asymmetric unit form trimers via NH.N hydrogen bonds related by a pseudo centre of symmetry. The asymmetric unit of (II) contains one and a half molecules: these exhibit NH proton disorder and are hydrogen bonded to each other via their respective NH groups to form chains. Ab initio calculations at HF and B3LYP/6-31G** levels indicate that the 3,4-dimethylpyrazole tautomer is more stable than the 4,5-dimethylpyrazole tautomer by only approximately 0.5 kcal mol(-1) (1 kcal mol(-1) = 4.184 kJ mol(-1)).

Molecular electrostatic potential-anthelmintic activity relationships of 5H-mebendazole and some related heterocyclic carbamates.

5H-Mebendazole and some related heterocyclic methyl carbamates were synthesized and their anthelmintic activity against Caenorhabditis elegans was determined. In order to study the influence of the heteroaromatic region with regard to the carbamate moiety on biological activity, the molecular electrostatic potentials (MEP) of all structures were calculated and a structure-activity relationship (SAR) was established. The electrostatic pattern of activity includes two minima of the carbamate moiety, a third heterocyclic minimum, and a pi-electronic region.

Synthesis and anthelmintic activity of carbamates derived from imidazo[2,1-b][1,3,4]thiadiazole and imidazo[2,1-b]thiazole.

The anthelmintic activity of 25 compounds, most of them carbamates, was determined. The in vitro results are interesting and show that an aromatic azapentalene can replace the benzimidazole ring without loss of its biological properties. The in vivo results, however, show that the compounds are devoid of practical interest.

New derivatives of 5-nitroimidazole: synthesis and antiparasitic activity.

The synthesis and the antiparasitic evaluation of twelve new 5-nitroimidaole derivatives has been carried out. The most effective compounds were the less hydrophilic pyridinium and imidazolium salts (IV), (V) and (X), and above all the tetrahydropyridine derivatives (XII) and (XIII).

Vibrational spectra of 3,5-dimethylpyrazole and deuterated derivatives.

The infrared (IR) and Raman spectra of 3,5-dimethylpyrazole have been recorded in the vapor, liquid (melt and solution) and solid states. Two deuterated derivatives, C5H7N-ND and C5D7N-NH, were also studied in solid state and in solutions. Instrumental resolution was relatively low, 2.0 cm(-1) in the IR and approximately 2.7 cm(-1) in the Raman spectra. The solids are made of cyclic hydrogen-bonded trimers. These trimers, present also in chloroform and acetone solutions, give rise to characteristic high absorption IR spectra in the 3200-2500 cm(-1) region, related to Fermi resonance involving nu(NH) vibrations. Bands from trimers are not present in water solutions but these solutions show spectral features similar in several ways to those of the trimer, attributable to solvent-bonded complexes. Evidence of H-bonding interactions with the other solvents is also visible in the high-frequency region. The two very intense bands in the Raman spectra of the solids appearing at 115 and 82 cm(-1) in the parent compound are also connected with a trimer formation. To interpret the experimental data, ab initio computations of the harmonic vibrational frequencies and IR and Raman intensities were carried out using the Gaussian 94 program package after full optimization at the RHF/6-31G* level for the three monomeric compounds as well as for three models of the trimer, with C3h, C3 and C1 symmetry. The combined use of experiments and computations allow a firm assignment of most of the observed bands for all the systems. In general, the agreement between theory and experiment is very good, with the exception of the IR and Raman intensities of some transitions. Particularly noticeable is the failure of the theoretical calculation in accounting for the high intensity of the Raman bands of the solid about 115 and 82 cm(-1).

Synthesis and antimicrobial evaluation of new derivatives of diphenylsulfone.

New derivatives of diphenylsulfone have been synthesized and their antibacterial and antifungal activities evaluated. Their chemical structures have been established by means of analytical and NMR spectroscopic data.

(1)H and (13)C NMR studies of asymmetrically substituted bis- and tris-Tröger's bases.

The (1)H and (13)C NMR spectra of two stereoisomeric bis-Tröger's bases and four stereoisomeric tris-Tröger's bases asymmetrically substituted on the external aromatic rings were recorded and the corresponding signals assigned. The relative configuration of the stereogenic units has been unequivocally determined on the basis of homoallylic couplings and NOE experiments.

Supramolecular structure of 1H-pyrazoles in the solid state: a crystallographic and ab initio study.

The secondary structure of 1H-unsubstituted pyrazole derivatives bearing only one hydrogen donor group and one or more acceptor groups has been analyzed in terms of some descriptors representing the substituents at C3 and C5. The substituent at C4 appears to affect mainly the tertiary or quaternary structure of these compounds. The proposed semi-quantitative model, which explains most hydrogen-bonded motifs as a combination of the effects of substituents at C3 and C5, has also been examined as a function of the steric and polarizability effects of these substituents represented by molar refractivity. The model also applies to other five-membered rings (1,2,4-triazoles, 1,2,4-diazaphospholes and 1,2, 4-diazaarsoles). Furthermore, ab initio calculations at RHF/6-31G* have been performed to discover the relative stability of three of the four hydrogen-bond patterns displayed by several symmetrical pyrazoles (dimers, trimers, tetramers). The fourth motif, catemers, has only been discussed geometrically.

The structure and absolute configuration of acetomycin.

C10H14O5, Mr = 214.22, orthorhombic, P2(1)2(1)2(1), a = 14.1084 (6), b = 10.6443 (3), c = 7.1970 (1) A, V = 1080.80 (6) A3, Z = 4, D chi = 1.317 Mg m-3, Cu K alpha, lambda = 1.5418 A, mu = 0.8571 mm-1, F(000) = 456, T = 293 K, R = 0.052 for 816 observed [3 sigma (I)] Friedel pairs. The determined absolute configuration may be described as 3S, 4R, 5R, the five-membered ring having an envelope conformation, with the bulky substituents at cis positions. The bond lengths and angles are in agreement with those of the bromoacetoxy derivative.

Group contributions to hydrophobicity and elution behaviour of pyridine derivatives in reversed-phase high-performance liquid chromatography.

The mean hydrophobic contributions, pi*m, of substituents in a sample of 34 monosubstituted pyridines has been determined by using reversed-phase high-performance liquid chromatography. The values are compared with those obtained for benzene.

Effect of heterocyclic analogues of triphenylmethane dyes against Trypanosoma cruzi.

Several heterocyclic analogues of triphenylmethane dyes have been synthesized. Their in vitro activity has been evaluated using the epimastigote forms of Trypanosoma cruzi as an assay system. The malachite green and gentian violet dyes previously reported as trypanocidal agents were also tested for comparison. Among the compounds tested, the 2-benzothienyl-bis-(4,4'-dimethylaminophenyl) derivative proved to be the most interesting, because of its high selectivity in killing parasites. The ID50, defined as the concentration which produced 50% reduction in (3H) thymidine incorporation in DNA after 18 hours or in viable parasites after five days of incubation with the above compounds, was 0.2 ng ml-1 and less than 1 ng ml-1, respectively. The relative toxicity, measured by its effect on cultured human HeLa cells, was over 10,000-fold higher. By contrast, gentian violet only showed a ten-fold higher inhibitory effect for T. cruzi. The other derivatives synthesized were active in various degrees. According to these results, a structure-activity relationship for these compounds is proposed.

Conformation-activity relationship in hexapeptides related to substance P.

Two hexapeptides related to the undecapeptide substance P (SP) Glu-Phe-Phe-Gly-Leu-Met-NH2 and Glu-Phe-Phe-Pro-Leu-Met-NH2, have been synthesized and their selectivity for the SP receptors studied. Conformational analyses of both peptides have been carried out using a molecular modeling program. Activity appears to be related to the adoption of a U-shape conformation since the Pro9 containing peptide in which this folding is favoured is much more active than the hexapeptide containing Gly9. Moreover, such a substitution induces a significant selectivity for the SP-P receptor compared to the SP-E receptor.