A new crystal form of the NSAID dexketoprofen

Dexketoprofen [(2S)‐2‐(3‐benzoylphenyl)propanoic acid], C₁₆H₁₄O₃, is the S‐enantiomer of ketoprofen, a nonsteroidal anti‐inflammatory drug (NSAID) that has analgesic, antipyretic and anti‐inflammatory properties, and finds applications for the short‐term treatment of mild to moderate pain. A new crystalline phase of dexketoprofen is reported. Its solid‐state structure was determined by single‐crystal X‐ray diffraction (SCXRD). The molecular structure of the two independent molecules found in the asymmetric unit of this new phase ( DXKP‐β ) were compared to those of the already known crystal form of dexketoprofen ( DXKP‐α ) and with the S‐enantiomer of the racemic compound. The three different conformers of dexketoprofen found in DXKP‐α and DXKP‐β were then investigated by computational methods. The optimized structures are very close to the corresponding starting geometries and do not differ significantly in energy. The crystal packing of DXKP‐β was studied by means of Hirshfeld surface (HS) analysis; interaction energies were also calculated. A comparison with DXKP‐α shows close similarities between the two crystal forms, i.e. in both cases, molecules assemble through the catemer O—H…O synthon of the carboxylic acid stabilized by additional C—H…O contacts and, accordingly, the interaction energies, as well as the contributions to the HS area, are very similar. Finally, the thermal behaviour of the two polymorphs of dexketoprofen was assessed by means of XRD (both from single crystal and microcrystalline powder) and differential scanning calorimetry (DSC); both crystal forms are stable under the experimental conditions adopted (air, 300–350 K for DXKP‐α and 300–340 K DXKP‐β ) and no solid–solid phase transition occurs between the two crystal forms in the investigated temperature range (from 100 K up to ca 350 K).     

Inelastic scattering of fast electrons from metastable states of helium

Inelastic scattering cross sections for collisions of electrons with helium atoms in metastable 2 ^1,3 S states are calculated for some final states of S and P symmetry by using the First Born Approximation and the Random Phase Approximation. The results for the total cross sections compare reasonably well with previous accurate values in the case of singlet-singlet transitions.     

“One pot” synthesis of 2,9-disubstituted 8-azaadenines (3,5-disubstituted 7-amino-3H-1,2,3-triazolo[4,5-d]pyrimidines)

A new simple method for the synthesis of title compounds is described starting from malononitrile, benzyl-azide and an aliphatic or aromatic nitrile.     

First measurement of the (Ξ−→∑−γ)/(Ξ−→Λπ−) branching ratio

In an experiment performed at the CERN SPS charged hyperon beam, we have observed the radiative decay Ξ^?→∑^?γ. From a sample of 11 candidates, containing an estimated background of 1.6 events, the branching ratio is found to be: $$\Gamma (\Xi ^ - \to \Sigma ^ - \gamma )/(\Xi ^ - \to \Lambda \pi ^ - ) = (2.3 \pm 1.0) \times 10^{ - 4} .$$      

Ξ− and Ξ− inclusive production in Ξ− Be interactions at 116 GeV/c

The cross sections for Ξ^? and Ω^? inclusive production in Ξ^? Be collisions at 116 GeV/c have been measured in the kinematic domain [0.1<x _F <0.9, 0<p _T <1.7 GeV/c]. The integrated cross sections per nucleon are found to be about twice as large as in Ξ^? p collisions. The invariant cross sections increase by a factor of 70 for the Ξ^? s and of 100 for the Ω^? s between the central region (x _F ～0.2) and the projectile fragmentation region (x _F ～0.8). In the central region, they have about the same magnitude as the ones for Ξ^? and Ω^? inclusive production inp nucleon collisions. The Ξ^? and Ω^? polarisations have been measured over the same kinematic domain and are found to be compatible with zero.     

Measurement of theΞ - p elastic cross section at 102 and 135 GeV/c

TheΞ ^- p differential elastic cross section has been measured in the SPS hyperon beam at 102 and 135 GeV/c. In the range 0.012, thet distributions are found to be compatible with the formA exp(Bt) whereB is 7.7±0.4(GeV/c)^?2 at 102 GeV/c and 8.2 ±0.5(GeV/c)^?2 at 135 GeV/c. The corresponding total elastic cross sections areσ _el=4.9±0.7 mb andσ _el=5.6±0.9 mb, respectively. These results are compared with the predictions of phenomenological models.     

Measurement of strong interaction effects in kaonic atoms

X-rays produced by kaons stopping in targets of O, Mg, Al, Si, S, Co, Ni, Cu, Ag, Cd, In and Sn have been observed. The shifts, widths and yields of the last observed mesic X-ray due to the effects of the strong interaction have been measured. The results are compared with optical-model predictions.