Carla Tadini

Structure and solid-state chemistry of anhydrous and hydrated crystal forms of the trimethoprim-sulfamethoxypyridazine 1:1 molecular complex

The crystal structure of the equimolar trimethoprim (TMP) and sulfamethoxypyridazine (SMPD) complex in the anhydrous form (TMP. SMPD) and that of the species with 1.5 molecules of water of crystallization (TMP.SMPD.W) are reported in this article. X-ray powder diffraction patterns (both computer generated and experimental) and thermal analytical data from differential scanning calorimetry (DSC) and thermogravimetry useful for the characterization of TMP.SMPD and TMP.SMPD.W are provided. The stability of TMP.SMPD.W, which retains its crystallographic order under 0% relative humidity (RH) conditions at room temperature (22 degrees C) and 20 mmHg, is accounted for in terms of crystal structure and hydrogen bonding. Transformation of TMP.SMPD to the hydrate complex by exposure to approximately 100% RH, suspension in water, and wet granulation, and dehydration of TMP.SMPD.W by thermal treatment and by desiccation with methanol were investigated and tentatively interpreted in terms of crystal properties. Interactions in the physical mixture of TMP and SMPD by grinding, compression, heating, and contact with water were also studied. Water-mediated formation of TMP.SMPD.W by wetting and metastable eutectic melting-mediated formation of TMP.SMPD by heating was demonstrated. Mechanical activation by milling makes the physical mixture prone to solid-state transformation into dimorphic anhydrous cocrystals by supply of thermal energy during a DSC scan.

The crystal structure of eudialyte

As a result of the present paper, the most probable formula unit of eudialyte is: (Fe2+, Fe3+, Mn, Mg)3Zr3(Zr, Nb) x (Ca, R.E.)6Na12[Si9O27−y (OH) y ]2[Si3O9]2Cl z withx=0.1−0.9;y=1−3;z=0.7−1.4. Space group:R

PREPARATION AND CONFIGURATION OF RACEMIC AND OPTICALLY ACTIVE ANALGESIC CYCLOAMINOALKYLNAPHTHALENES

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Refinement of the crystal structure of fluoborite, Mg3(F,OH)3(BO3)

a;a=14.244 A,c=30.080 A,Z=3. The crystal structure was determined from 3-dimensional Weissenberg data by Patterson- and electron density-syntheses, and refined by the least squares method:R=0.075 for 831 obs. reflections. Eudialyte is a cyclosilicate with both threefold and ninefold rings of SiO4-tetrahedra. Si−O distances measure 1.62–1.65 A (for shared oxygens) and 1.58–1.60 A (for unshared oxygens). Zirconium has a practically regular octahedral coordination (Zr−O=2.07–2.08 A), whereas iron is surrounded by only four oxygens in a square arrangement (Fe−O=2.04 A); the coordination polyhedron of calcium is a distorted octahedron (Ca−O=2.33–2.38 A). Two non equivalent sodium atoms have rather irregular coordinations: Na(1) is bound to six oxygens which form a fairly distorted hexagonal ring (Na−O=2.53–2.66 A), whereas Na(2) has four shorter distances to three oxygens (Na−O=2.53–2.57 A) and one chlorine (Na−Cl=2.98 A), and three longer distances to oxygens (Na−O=2.74–2.77 A) in a sort of distorted octahedron with a centered face. Some of the most reliable chemical analyses are reexamined in order to derive a formula unit consistent with the crystal structure and to confirm some of its peculiar features, e.g. the presence of two sets of crystallographic sites only partially occupied by chlorine and zirconium atoms respectively.

Modular aspects of the crystal structures of kurchatovite and clinokurchatovite

The crystal structure of weberite, Na2MgAlF7, was redetermined from 3-dim. X-ray data and refined by least squares methods in space groupImma to a conventional reliability factorR=0.036. Mg and Al have octahedral 6-coordination. Two crystallographically independent kinds of Na atoms form different NaF8-polyhedra with the F atoms at the corners of a flattened hexagonal bipyramid and of a square prism, respectively.

Reexamination of the crystal structure of phosgenite, Pb2Cl2(CO3)

Cycloaminoalkylnaphthalene 3 shows interesting opioid-like analgesic properties. It possesses two chiral centers and can exist as two racemic pairs and four diastereomers. Since the binding of opioids with receptors is stereoselective, it was important to have the two racemic pairs as well as the four diastereomers. In this paper the synthesis of the (2R,3S/2S,3R) racemate and the (2R,3S) and (2S,3R) enantiomers of the 1,2-dimethyl-3-[2-(6-hydroxynaphthyl)]-3-hydroxypyrrolidine 3 is considered and the determination of absolute configuration is described. The (2R,3S/2S,3R)-3 racemate and the (2R,3S)-3 and (2S,3R)-3 enantiomers were prepared by reaction of the racemic and optically active 1,2-dimethyl-3-pyrrolidone 2, respectively, with the lithiation product obtained from 2-bromo-6-tetrahydropyranyloxy-naphthalene 1 and acidic hydrolysis. The above-mentioned enantiomers of 3 were also obtained by optical resolution via fractional crystallization of the salts with D- and L-tartaric acids. The configuration of the optically active compounds was determined by X-ray analysis of a crystal of (-)-(2S,3R)-3.HCl.H2O. The pharmacological test HPT showed that (-)-(2S,3R)-3.HCl.H2O enantiomer is able to induce opioid-like analgesia with a relative potency 1.5 times that of (2R,3S/2S,3R)-3 and approximately 1.5 times that of morphine.

Chiral resolution and absolute configuration of the enantiomers of 5-acetyl-2-methyl-4-methylsulfinyl-6-phenyl-3(2H)-pyridazinone and evaluation of their platelet aggregation inhibitory activity

The refined lattice parameters of beryllonite are:a=8.178 (3) A,b=7.818 (2) A,c=14.114 (6) A, β=90.00° (2); space groupP21/n,Z=12. Integrated Weissenberg photographs were taken by using CuK α radiation and multiple film packs. The anisotropic refinement of the crystal structure by means of least-square methods gave a finalR value of 0.063 for the 1388 observed reflections. In the crystal structure PO4 and BeO4 tetrahedra, linked by shared oxygen atoms in a three-dimensional network, form pseudo-ditrigonal rings perpendicular to theb axis. The independent Na atoms lying in the channels formed by the rings are coordinated as an irregular “nine-cornered” polyhedron and as distorted octahedra.

Refinement of the crystal structure of northupite: Na3Mg(CO3)2Cl

The crystal structure of fluoborite, Mg3(F, OH)3(BO3), has been refined using X-ray data collected on an automatic diffractometer. The anisotropic refinement converged to a conventionalR of 0.029. The structural model proposed byTakeuchi as well as the space groupP 63/m have been confirmed.