On the dimorphism and the pressure-temperature state diagram of gestodene, a steroidal progestogen contraceptive.

The pressure-temperature phase diagram of the dimorphism of the contraceptive drug gestodene is constructed using the temperature and enthalpy of fusion of form I (469.5K, 107Jg-1), and those of the endothermic transition from form II to form I (311K, 8.52Jg-1). At ordinary pressure, the sign of the enthalpy of this transition indicates that these polymorphs are enantiotropically related and that form II, whose melting temperature is calculated to be about 452K, is the stable form at room temperature. Considering the inequality in the specific volumes of the two polymorphs, it is shown that the two forms remain enantiotropically related on increasing pressure, because the I-II equilibrium and the melting equilibria I-L and II-L diverge as a consequence of the negative slope dP/dT of the solid-solid equilibrium. In addition, it is demonstrated that the heats of dissolution, inferred from solubility measurements, lead to virtually the same value of the heat of transition from II to I as for the differential scanning calorimetry measurements.

Experimental and topological determination of the pressure-temperature phase diagram of racemic etifoxine, a pharmaceutical ingredient with anxiolytic properties.

Information about the solid-state properties of etifoxine has been lacking, even if the active pharmaceutical ingredient has been used for its anxiolytic properties for decennia. The crystal structure of the racemic compound possesses a monoclinic space group P21/n with cell parameters a = 8.489(2) Å, b = 17.674(2) Å, c = 20.883(3) Å, ß = 98.860(10)° and a unit-cell volume of 3095.8(9) Å3 at 293 K. The unit cell contains 8 molecules, while 2 independent molecules with different conformations are present in the asymmetric unit. The density of the crystal is 1.291 g/cm3 and its melting point was found at 362.6 ±â€¯0.3 K with a melting enthalpy of 85.6 ±â€¯3.0 J g-1. Its thermal expansion in the liquid and the solid state and the change in volume on melting and between the vitreous state and the crystalline solid have been studied. The results confirm the tendency of small organic molecules to increase about 11% in volume on melting, while the volume difference between the glass and the crystal at the glass transition temperature is about half this value at 6%. These values can be used in the construction of phase diagrams in the case that the experimental data for a given system is incomplete.

A network of weak hydrogen bonds in the crystal structure of Tetrazepam.

The crystal structure of tetrazepam, a benzodiazepine derivative formerly used for its muscle relaxant properties, has been solved and found to be monoclinic, space group P21/c, with lattice parameters a=12.7386(7)Å, b=11.3774(7)Å, c=10.3084(7)Å, ß=103.175(5) and Vunit-cell=1454.69(16) Å3 at room temperature (293K) with Z=4 molecules in the unit-cell. A network of weak hydrogen bonds involving aliphatic hydrogen atoms plays an important role in the formation of this structure.

Regiocontrolled functionalization of 2,3-dihalogenoimidazo[1,2-a]pyridines by Suzuki-Miyaura and Sonogashira cross-coupling reactions.

An efficient method for regiocontrolled functionalization of 2,3-dihalogenoimidazo[1,2-a]pyridine was developed. This sequence allowed the selective introduction of aryl, heteroaryl, alkyl and alkynyl substituents at both 2- and 3-positions, by using Suzuki-Miyaura and Sonogashira cross-coupling reactions. A library of compounds diversely substituted on 2- and 3-positions can be easily prepared from a common, stable and easily accessible starting material.

Characterization of molecular associations involving L-ornithine and α-ketoglutaric acid: crystal structure of L-ornithinium α-ketoglutarate.

The crystal structure of L-ornithinium α-ketoglutarate (C5H13N2O2, C5H5O5) has been solved by direct methods using single crystal X-ray diffraction data. It crystallizes in the monoclinic system, space group P21, unit cell parameters a=15.4326(3), b=5.2015(1), c=16.2067(3) Å and ß=91.986(1)°, containing two independent pairs of molecular ions in the asymmetric unit. An extensive hydrogen-bond network and electrostatic charges due to proton transfer provide an important part of the cohesive energy of the crystal. The conformational versatility of L-ornithine and α-ketoglutaric acid is illustrated by the present results and crystal structures available from the Cambridge Structural Database.

Synthesis of 3-nitrosoimidazo[1,2-a]pyridine derivatives as potential antiretroviral agents.

Ten 2-aryl or heteroaryl-3-nitrosoimidazo[1,2-a]pyridine derivatives were synthesised as potential antiretroviral agents. The new compounds were characterized by elemental analysis, 1H NMR, and by crystallography for (14). The compounds were devoid of any activity against HIV-1 or HIV-2.

3-Benzamido, ureido and thioureidoimidazo[1,2-a]pyridine derivatives as potential antiviral agents.

This work reports the synthesis and the antiviral activities of 3-benzamido, 3-phenylureido and 3-phenylthioureido derivatives in the imidazo[1,2-a]pyridine series. The structure was proven by NMR spectroscopy. The synthesized compounds were evaluated against a large number of viruses. The 3-phenylthioureido derivative 7 showed moderate activity against human cytomegalovirus (HCMV) in vitro. The crystallographic data for 8 are also reported and explain the absence of activity against human immunodeficiency virus (HIV).

Crystal and electronic structure of a fluorescent columnar liquid crystalline electron transport material.

A very favorable LUMO energy for cathodic electron injection is found in the crystalline state of the mesogenic red fluorescent perylene derivative 1. It is one of the rare cases where the columnar crystal structure of such a compound could be established directly by X-ray investigation.

Synthesis of diaryl-substituted imidazo[l,2-a]pyridines designed as potential aromatase inhibitors.

From a pharmacophore model of bicyclic heterocycles as aromatase inhibitors we have designed three series of imidazo[1,2-a]pyridine derivatives. The synthesis and the spectroscopy determination of various compounds are reported. The crystal data of one of these compounds (10b) was obtained. The aromatase inhibition potency was evaluated in vitro and no activity was found.