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Orthorhombic Form (orthorhombic + form)
Selected AbstractsTwo new paracetamol/dioxane solvates,a system exhibiting a reversible solid-state phase transformationJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 10 2003Ranko M. Vrcelj Abstract This work reports on the crystal structures of two dioxane solvates of paracetamol that are true polymorphs. The high temperature phase is an orthorhombic form, space group Pbca, Z,=,8, a,=,12.6078(3) Å, b,=,12.1129(2) Å, c,=,13.4138(3) Å, V,=,2048.52(7) Å3, (at 295 K) and the low temperature form is monoclinic, space group P21/c, Z,=,4, a,=,12.325(6) Å, b,=,11.965(4) Å, c,=,13.384(6) Å, ,,=,92.01°, V,=,1972.6(14)Å3 (at 123 K). The structures of these polymorphs are described as is the interrelationship between the two structures. In addition to the structural interrelationship, it is shown that the two forms undergo a reversible phase transformation. Desolvation of either form generates the stable monoclinic phase of paracetamol. © 2003 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 92:2069,2073, 2003 [source] Crystallization conditions and formation of orthorhombic paracetamol from ethanolic solutionJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 3 2002N. Al-Zoubi Orthorhombic paracetamol exhibits far better tabletability than the monoclinic form and its bulk crystallization from solution attracts much interest. In this study, temperature changes in supersaturated ethanolic solution have been recorded after seeding with orthorhombic crystals under different cooling temperatures (TC) and agitation rates (AR). Average cooling rate (CR), time for maximum temperature deviation (tmax) and area confined between curves of measured and reference temperature plots (AUC) were calculated and correlated with crystal yield (Y). The micromeritic (size and shape) and the compression properties, the density and the orthorhombic content of the crystalline product were evaluated and related to the main crystallization conditions applied (TC and AR). Conditions for optimal crystal yield and orthorhombic content were elucidated. It was found that crystal yield (Y) increased with AR and decreased with TC. The ratio tmax/CR provided good prediction of crystal yield (Y = 58.92 ,1.386 tmax/CR, r2 = 0.964 and P = 0.0001). TC and AR linearly affected crystal size and the size distribution, probably due to alterations in supersaturation, but they did not affect the crystal shape significantly. Density and compression properties (yield pressure and elastic recovery) were determined by the content of the orthorhombic form, which increased linearly with AR (P = 0.009) and with TC (P = 0.039) when agitation was between 300 and 500 rev min,1, while tmax decreased. At 700 rev min,1 orthorhombic content was maximized and became independent to TC. Higher orthorhombic content and crystal yield was expected for lower TC and for lower tmax, which corresponded to higher AR and might have also been affected by alteration of seeding and harvesting procedure. [source] Three isomeric 1-(2-chloronicotinoyl)-2-(nitrophenyl)hydrazines, including three polymorphs of 1-(2-chloronicotinoyl)-2-(2-nitrophenyl)hydrazine: hydrogen-bonded supramolecular structures in two and three dimensionsACTA CRYSTALLOGRAPHICA SECTION B, Issue 1 2007Solange M. S. V. Wardell 1-(2-Chloronicotinoyl)-2-(2-nitrophenyl)hydrazine, C12H9ClN4O3, crystallizes in three polymorphic forms, two monoclinic forms in space groups Cc (Ia) and P21 (Ib), and an orthorhombic form in space group Pbcn (Ic). In the Cc polymorph (Ia) the molecules are linked into sheets by combinations of one N,H,O and two C,H,O hydrogen bonds, while in the P21 polymorph (Ib) the molecules are linked into sheets by combinations of three hydrogen bonds, one each of N,H,O, C,H,N and C,H,O types. In the orthorhombic polymorph (Ic) the molecules are linked into a complex three-dimensional framework structure by a combination of one N,H,O, one N,H,N and three C,H,O hydrogen bonds, and an aromatic ,,, stacking interaction. In the isomeric compound 1-(2-chloronicotinoyl)-2-(3-nitrophenyl)hydrazine (II) the molecules are again linked into a three-dimensional framework, this time by a combination of three hydrogen bonds, one each of N,H,O, N,H,N and C,H,O types, weakly augmented by a ,,, stacking interaction. The molecules of 1-(2-chloronicotinoyl)-2-(4-nitrophenyl)hydrazine (III) are linked into sheets by a combination of three hydrogen bonds, one each of N,H,O, N,H,N and C,H,O types. [source] Crystallographic rationalization of the reactivity and spectroscopic properties of (2R)- S -(2,5-dihydroxyphenyl)cysteineACTA CRYSTALLOGRAPHICA SECTION C, Issue 4 2010Gabriele Kociok-Köhn At 150,K, the title compound, C9H11NO4S, crystallizes in the orthorhombic form as a zwitterion and has a low gauche conformation [, = ,46.23,(16)°] for an acyclic cysteine derivative. A difference in bond length is observed for the alkyl C,S bond [1.8299,(15),Å] and the aryl C,S bond [1.7760,(15),Å]. The ,NH3+ group is involved in four hydrogen bonds, two of which are intermolecular and two intramolecular. The compound forms an infinite three-dimensional network constructed from four intermolecular hydrogen bonds. Characterization data (13C NMR, IR and optical rotation) are reported to supplement the incomplete data disclosed previously in the literature. [source] A new polymorph of benzene-1,2-diamine: isomorphism with 2-aminophenol and two-dimensional isostructurality of polymorphsACTA CRYSTALLOGRAPHICA SECTION C, Issue 4 2010Agnieszka Czapik A new crystalline form of benzene-1,2-diamine, C6H8N2, crystallizing in the space group Pbca, has been identified during screening for cocrystals. The crystals are constructed from molecular bilayers parallel to (001) that have the polar amino groups directed to the inside and the aromatic groups, showing a herringbone arrangement, directed to the outside. The known monoclinic form and the new orthorhombic polymorph exhibit two-dimensional isostructurality as the crystals consist of nearly identical bilayers. In the monoclinic form, neighbouring bilayers are generated by a unit translation along the a axis, whereas in the orthorhombic form they are generated by a c -glide. Moreover, the new form of benzene-1,2-diamine is essentially isomorphous with the only known form of 2-aminophenol. [source] Two polymorphs of morpholin-4-ium 2-(5-methyl-1H -1,2,4-triazol-3-ylsulfanyl)acetateACTA CRYSTALLOGRAPHICA SECTION C, Issue 1 2009Svetlana V. Shishkina Two polymorphs of the title organic salt (a very effective medicinal preparation with the commercial name thiotriazoline), C4H10NO+·C5H6N3O2S,, were obtained. The cations and anions are connected by hydrogen bonds and extend into two-dimensional networks. The main packing motifs are an R44(12) cluster in the monoclinic form and a chain in the orthorhombic form. [source] Surface-entropy reduction approaches to manipulate crystal forms of ,-ketoacyl acyl carrier protein synthase II from Streptococcus pneumoniaeACTA CRYSTALLOGRAPHICA SECTION D, Issue 2 2008Gopalakrishnan Parthasarathy A series of experiments with ,-ketoacyl acyl carrier protein synthase II (FabF) from Streptococcus pneumonia (spFabF) were undertaken to evaluate the capability of surface-entropy reduction (SER) to manipulate protein crystallization. Previous work has shown that this protein crystallizes in two forms. The triclinic form contains four molecules in the asymmetric unit (a.u.) and diffracts to 2.1,Å resolution, while the more desirable primitive orthorhombic form contains one molecule in the a.u. and diffracts to 1.3,Å. The aim was to evaluate the effect of SER mutations that were specifically engineered to avoid perturbing the crystal-packing interfaces employed by the favorable primitive orthorhombic crystal form while potentially disrupting a surface of the protein employed by the less desirable triclinic crystal form. Two mutant proteins were engineered, each of which harbored five SER mutations. Extensive crystallization screening produced crystals of the two mutants, but only under conditions that differed from those used for the native protein. One of the mutant proteins yielded crystals that were of a new form (centered orthorhombic), despite the fact that the interfaces employed by the primitive orthorhombic form of the native protein were specifically unaltered. Structure determination at 1.75,Å resolution reveals that one of the mutations, E383A, appears to play a key role in disfavouring the less desirable triclinic crystal form and in generating a new surface for a packing interaction that stabilizes the new crystal form. [source] Expression, crystallization and preliminary structural analysis of the ectoplasmic region of apical membrane antigen 1 from Plasmodium vivax, a malaria-vaccine candidateACTA CRYSTALLOGRAPHICA SECTION D, Issue 11 2004Brigitte Vulliez-Le Normand Apical membrane antigen 1 (AMA1), a type 1 transmembrane protein present in the microneme organelles of Plasmodium, is a leading malaria-vaccine candidate. The ectoplasmic region of AMA1 from P. vivax has been expressed in Pichia pastoris and crystallized in two different forms: an orthorhombic form (space group P212121, unit-cell parameters a = 54.1, b = 76.1, c = 103.9,Å) and a monoclinic form (space group C2, unit-cell parameters a = 150.0, b = 53.8, c = 60.3,Å, , = 113.2°). Native data have been collected to 2.0,Å resolution for the orthorhombic form and 1.8,Å for the monoclinic form. A platinum derivative was prepared for the orthorhombic and monoclinic crystals using K2PtCl4 and data were collected at several wavelengths to obtain phases by the MAD technique. A partial model has been built from the electron-density maps of both forms and refinement is in progress. [source] An orthorhombic form of Escherichia coli aminopeptidase P at 2.4,Å resolutionACTA CRYSTALLOGRAPHICA SECTION D, Issue 5 2003Stephen C. Graham Aminopeptidase P (AMPP) from Escherichia coli cleaves the N-terminal residue from an oligopeptide if the second residue is proline. The active site contains a dinuclear metal centre. Following earlier structural analyses of crystals in space groups P6422 and I4122, the structure of AMPP has been solved and refined in the orthorhombic space group C2221 at 2.4,Å resolution. There are six subunits in the asymmetric unit. These are arranged in two types of tetramer. One tetramer comprises four crystallographically independent subunits, while the other comprises two pairs of subunits related by a crystallographic twofold axis. The final model of 20,994 protein atoms, 1618 water molecules and 12 metal atoms refined to residuals R = 0.195 and Rfree = 0.215. The molecular structure confirms most of the previously reported features, including the subunit,subunit interfaces in the tetramer and persistent disorder at some residues. The metal,ligand bond lengths at the active site suggest that one of the two Mn atoms is five-coordinate rather than six-coordinate. [source] Crystallization and preliminary crystallographic studies of a new crystal form of Escherichia colil -asparaginase II (Ser58Ala mutant)ACTA CRYSTALLOGRAPHICA SECTION D, Issue 4 2000Maciej Kozak Periplasmic Escherichia colil -asparaginase II with an Ser58Ala mutation in the active-site cavity has been crystallized in a new orthorhombic form (space group P21212). Crystals of this polymorph suitable for X-ray diffraction have been obtained by vapour diffusion using two sets of conditions: (i) 1% agarose gel using MPD as precipitant (pH 4.8) and (ii) liquid droplets using PEG-MME 550 (pH 9.0). The crystals grown in agarose gel are characterized by unit-cell parameters a = 226.9, b = 128.4, c = 61.9,Å and diffract to 2.3,Å resolution. The asymmetric unit contains six protein molecules arranged into one pseudo-222-symmetric homotetramer and an active-site competent dimer from which another homotetramer is generated by crystallographic symmetry. [source] Comparison between the orthorhombic and tetragonal forms of the heptamer sequence d[GCG(xT)GCG]/d(CGCACGC)ACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 9 2010Koen Robeyns Cyclohexene nucleic acid (CeNA) building blocks can be introduced into natural DNA sequences without a large conformational influence because of the ability of the six-membered sugar ring to mimic both the C2,- endo and C3,- endo conformations of the naturally occurring ribofuranose sugar ring. The non-self-complementary DNA sequence d[GCG(xT)GCG]/d(CGCACGC) with one incorporated CeNA (xT) moiety crystallizes in two forms: orthorhombic and tetragonal. The tetragonal form, which diffracts to 3,Å resolution, is a kinetically stable polymorph of the orthorhombic form [Robeyns et al. (2010), Artificial DNA, 1, 1,7], which diffracts to 1.17,Å resolution and is the thermodynamically stable form of the CeNA-incorporated duplex. Here, the two structures are compared, with special emphasis on the differences in crystal packing and the irreversible conversion of the kinetic form into the high-resolution diffracting thermodynamic form. [source] Crystallization and preliminary X-ray diffraction analysis of the N-terminal domain of Mrs2, a magnesium ion transporter from yeast inner mitochondrial membraneACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 6 2010Muhammad Bashir Khan Mrs2 transporters are distantly related to the major bacterial Mg2+ transporter CorA and to Alr1, which is found in the plasma membranes of lower eukaryotes. Common features of all Mrs2 proteins are the presence of an N-terminal soluble domain followed by two adjacent transmembrane helices (TM1 and TM2) near the C-terminus and of the highly conserved F/Y-G-M-N sequence motif at the end of TM1. The inner mitochondrial domain of the Mrs2 from Saccharomyces cerevisae was overexpressed, purified and crystallized in two different crystal forms corresponding to an orthorhombic and a hexagonal space group. The crystals diffracted X-rays to 1.83 and 4.16,Å resolution, respectively. Matthews volume calculations suggested the presence of one molecule per asymmetric unit in the orthorhombic crystal form and of five or six molecules per asymmetric unit in the hexagonal crystal form. The phase problem was solved for the orthorhombic form by a single-wavelength anomalous dispersion experiment exploiting the sulfur anomalous signal. [source] Crystallization and preliminary X-ray analysis of Leishmania major glyoxalase IACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 8 2005Antonio Ariza Glyoxalase I (GLO1) is a putative drug target for trypanosomatids, which are pathogenic protozoa that include the causative agents of leishmaniasis. Significant sequence and functional differences between Leishmania major and human GLO1 suggest that it may make a suitable template for rational inhibitor design. L. major GLO1 was crystallized in two forms: the first is extremely disordered and does not diffract, while the second, an orthorhombic form, produces diffraction to 2.0,Å. Molecular-replacement calculations indicate that there are three GLO1 dimers in the asymmetric unit, which take up a helical arrangement with their molecular dyads arranged approximately perpendicular to the c axis. Further analysis of these data are under way. [source] Crystallization and preliminary characterization of the Thermus thermophilus RNA helicase Hera C-terminal domainACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 3 2009Markus G. Rudolph Heat-resistant RNA-dependent ATPase (Hera) from Thermus thermophilus is a DEAD-box RNA helicase. Two constructs encompassing the second RecA-like domain and the C-terminal domain of Hera were overproduced in Escherichia coli and purified to homogeneity. Single crystals of both Hera constructs were obtained in three crystal forms. A tetragonal crystal form belonged to space group P41212, with unit-cell parameters a = 65.5, c = 153.0,Å, and contained one molecule per asymmetric unit. Two orthorhombic forms belonged to space group P212121, with unit-cell parameters a = 62.8, b = 70.9, c = 102.3,Å (form I) and a = 41.6, b = 67.6, c = 183.5,Å (form II). Both orthorhombic forms contained two molecules per asymmetric unit. All crystals diffracted X-rays to beyond 3,Å resolution, but the tetragonal data sets displayed high Wilson B values and high mean |E2, 1| values, indicating potential disorder and anisotropy. The tetragonal crystal was phased by MAD using a single selenium site. [source] | ||||||||||