A new high-pressure benzocaine polymorph — towards understanding the molecular aggregation in crystals of an important active pharmaceutical ingredient (API)

2020 ◽  
Vol 76 (1) ◽  
pp. 56-64 ◽  
Author(s):  
Ewa Patyk-Kaźmierczak ◽  
Michał Kaźmierczak
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Ambient Pressure ◽  
Active Pharmaceutical Ingredient ◽  
Molecular Packing ◽  
Molecular Aggregation ◽  
Pressure Release ◽  
Hydrogen Bonding Pattern

Benzocaine (BZC), an efficient and highly permeable anaesthetic and an active pharmaceutical ingredient of many commercially available drugs, was studied under high pressure up to 0.78 GPa. As a result, new BZC polymorph (IV) was discovered. The crystallization of polymorph (IV) can be initiated by heating crystals of polymorph (I) at a pressure of at least 0.45 GPa or by their compression to 0.60 GPa. However, no phase transition from polymorph (I) to (IV) was observed. Although polymorph (IV) exhibits the same main aggregation motif as in previously reported BZC polymorphs (I)–(III), i.e. a hydrogen-bonded ribbon, its molecular packing and hydrogen-bonding pattern differ considerably. The N—H...N hydrogen bonds joining parallel BZC ribbons in crystals at ambient pressure are eliminated in polymorph (IV), and BZC ribbons become positioned at an angle of about 80°. Unfortunately, crystals of polymorph (IV) were not preserved on pressure release, and depending on the decompression protocol they transformed into polymorph (II) or (I).

Five pseudopolymorphs of 6-amino-2-thiouracil: absence of N—H...S hydrogen bonds

2012 ◽  
Vol 69 (1) ◽  
pp. 93-100 ◽  
Author(s):  
Wilhelm Maximilian Hützler ◽  
Michael Bolte
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Cambridge Structural Database ◽  
Hydrogen Bonding Pattern ◽  
Crystallization Experiments ◽  
Structural Database ◽  
Thiouracil Derivatives

In order to study the preferred hydrogen-bonding pattern of 6-amino-2-thiouracil, C4H5N3OS, (I), crystallization experiments yielded five different pseudopolymorphs of (I), namely the dimethylformamide disolvate, C4H5N3OS·2C3H7NO, (Ia), the dimethylacetamide monosolvate, C4H5N3OS·C4H9NO, (Ib), the dimethylacetamide sesquisolvate, C4H5N3OS·1.5C4H9NO, (Ic), and two different 1-methylpyrrolidin-2-one sesquisolvates, C4H5N3OS·1.5C5H9NO, (Id) and (Ie). All structures containR21(6) N—H...O hydrogen-bond motifs. In the latter four structures, additionalR22(8) N—H...O hydrogen-bond motifs are present stabilizing homodimers of (I). No type of hydrogen bond other than N—H...O is observed. According to a search of the Cambridge Structural Database, most 2-thiouracil derivatives form homodimers stabilized by anR22(8) hydrogen-bonding pattern, with (i) only N—H...O, (ii) only N—H...S or (iii) alternating pairs of N—H...O and N—H...S hydrogen bonds.

scholarly journals Crystal structures of butyl 2-amino-5-hydroxy-4-(4-nitrophenyl)benzofuran-3-carboxylate and 2-methoxyethyl 2-amino-5-hydroxy-4-(4-nitrophenyl)benzofuran-3-carboxylate

2019 ◽  
Vol 75 (6) ◽  
pp. 880-887 ◽  
Author(s):  
Rosita Diana ◽  
Angela Tuzi ◽  
Barbara Panunzi ◽  
Antonio Carella ◽  
Ugo Caruso
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Molecular Structures ◽  
Antitumoral Activity ◽  
Space Group ◽  
One Dimensional ◽  
Axis Direction ◽  
Hydrogen Bonding Pattern ◽  
Butyl Group

The title benzofuran derivatives 2-amino-5-hydroxy-4-(4-nitrophenyl)benzofuran-3-carboxylate (BF1), C19H18N2O6, and 2-methoxyethyl 2-amino-5-hydroxy-4-(4-nitrophenyl)benzofuran-3-carboxylate (BF2), C18H16N2O7, recently attracted attention because of their promising antitumoral activity. BF1 crystallizes in the space group P\overline{1}. BF2 in the space group P21/c. The nitrophenyl group is inclined to benzofuran moiety with a dihedral angle between their mean planes of 69.2 (2)° in BF1 and 60.20 (6)° in BF2. A common feature in the molecular structures of BF1 and BF2 is the intramolecular N—H...Ocarbonyl hydrogen bond. In the crystal of BF1, the molecules are linked head-to-tail into a one-dimensional hydrogen-bonding pattern along the a-axis direction. In BF2, pairs of head-to-tail hydrogen-bonded chains of molecules along the b-axis direction are linked by O—H...Omethoxy hydrogen bonds. In BF1, the butyl group is disordered over two orientations with occupancies of 0.557 (13) and 0.443 (13).

scholarly journals Effect of pressure on the crystal structure of L-serine-I and the crystal structure of L-serine-II at 5.4 GPa

2005 ◽  
Vol 61 (1) ◽  
pp. 58-68 ◽  
Author(s):  
Stephen A. Moggach ◽  
David R. Allan ◽  
Carole A. Morrison ◽  
Simon Parsons ◽  
Lindsay Sawyer
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
Hydrogen Bonds ◽  
Single Crystal ◽  
Ambient Pressure ◽  
Crystal Form ◽  
Hydroxyl Groups ◽  
Orthorhombic Space Group ◽  
Crystal Forms ◽  
Hydrogen Bonded

The crystal structure of L-serine has been determined at room temperature at pressures between 0.3 and 4.8 GPa. The structure of this phase (hereafter termed L-serine-I), which consists of the molecules in their zwitterionic tautomer, is orthorhombic, space group P212121. The least compressible cell dimension (c), corresponds to chains of head-to-tail NH...carboxylate hydrogen bonds. The most compressible direction is along b, and the pressure-induced distortion in this direction takes the form of closing up voids in the middle of R-type hydrogen-bonded ring motifs. This occurs by a change in the geometry of hydrogen-bonded chains connecting the hydroxyl groups of the —CH2OH side chains. These hydrogen bonds are the longest conventional hydrogen bonds in the system at ambient pressure, having an O...O separation of 2.918 (4) Å and an O...O...O angle of 148.5 (2)°; at 4.8 GPa these parameters are 2.781 (11) and 158.5 (7)°. Elsewhere in the structure one NH...O interaction reaches an N...O separation of 2.691 (13) Å at 4.8 GPa. This is amongst the shortest of this type of interaction to have been observed in an amino acid crystal structure. Above 4.8 GPa the structure undergoes a single-crystal-to-single-crystal phase transition to a hitherto uncharacterized polymorph, which we designate L-serine-II. The OH...OH hydrogen-bonded chains of L-serine-I are replaced in L-serine-II by shorter OH...carboxyl interactions, which have an O...O separation of 2.62 (2) Å. This phase transition occurs via a change from a gauche to an anti conformation of the OH group, and a change in the NCαCO torsion angle from −178.1 (2)° at 4.8 GPa to −156.3 (10)° at 5.4 GPa. Thus, the same topology appears in both crystal forms, which explains why it occurs from one single-crystal form to another. The transition to L-serine-II is also characterized by the closing-up of voids which occur in the centres of other R-type motifs elsewhere in the structure. There is a marked increase in CH...O hydrogen bonding in both phases relative to L-serine-I at ambient pressure.

scholarly journals High-pressure polymorphism in l-threonine between ambient pressure and 22 GPa

CrystEngComm ◽  
2019 ◽  
Vol 21 (30) ◽  
pp. 4444-4456 ◽  
Author(s):  
Nico Giordano ◽  
Christine M. Beavers ◽  
Konstantin V. Kamenev ◽  
William G. Marshall ◽  
Stephen A. Moggach ◽  
...  
Keyword(s):  
High Pressure ◽  
Hydrogen Bonding ◽  
Phase Transitions ◽  
Amino Acid ◽  
Molecular Conformation ◽  
Ambient Pressure ◽  
Three Phase

The amino acid l-threonine undergoes three phase transitions between ambient pressure and 22.3 GPa which modify both hydrogen bonding and the molecular conformation.

The influence of pressure on the infrared spectra of hydrogen bonded solids. II. Bihalide salts

1976 ◽  
Vol 29 (3) ◽  
pp. 479 ◽  
Author(s):  
SD Hamann ◽  
M Linton
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Hydrogen Bonds ◽  
High Pressure Phase Transition ◽  
Infrared Measurements ◽  
Normal Hydrogen ◽  
Combination Bands ◽  
Pressure Phase ◽  
Made In ◽  
Hydrogen Bonded

Infrared measurements have been made of the influence of pressures between 0 and 40 kbar on the asymmetrical stretching frequencies v3 and bending frequencies v2 of the hydrogen-bonded ions FHF- and ClHCl- in the solid salts NaHF2, KHF2, NH4HF2, (CH3)4NHCl2 and (C2H5)4NHCl2 at 25�C. The behaviour of the symmetrical stretching frequency v1 for FHF- in KHF2 has been deduced indirectly from the shifts of combination bands. Contrary to the behaviour of compounds with weaker, 'normal', hydrogen bonds, the v3 bands shift to higher frequencies and the v2 bands shift to lower frequencies with increasing pressure. The vl band of KHF2 shifts to higher frequencies. These trends are all in agreement with predictions made in Part I for a simple model of hydrogen bonds. A new high-pressure phase transition has been found to occur in NaHF2 at about 40 kbar.

High Pressure NQR Study of the Phase Transition in Anilinium Iodide

1986 ◽  
Vol 41 (1-2) ◽  
pp. 290-293
Author(s):  
Mariusz Maćkowiak ◽  
Maria Zdanowska-Fra̧zek ◽  
Piotr Kozioł ◽  
Jan Stankowski ◽  
Alarich Weiss
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Transition Temperature ◽  
Hydrogen Bonds ◽  
Transition Point ◽  
Pressure Coefficient ◽  
Coupling Constants ◽  
Quadrupole Coupling ◽  
Nuclear Quadrupole ◽  
Asymmetry Parameters

The 127I NQR frequency in anilinium iodide C6H5NH3⊕I⊖ was studied at pressures up to 300 MPa and within the temperature range 77 K - 290 K. With increasing pressure the order-disorder transition point Tc is shifted to higher temperatures. The pressure coefficient of the phase transition temperature amounts to dTc/dp = 4.2 x 10-2 deg MPa-1. The pressure coefficient of the NQR frequency is negative. In addition, the 12'I nuclear quadrupole coupling constants and the respective asymmetry parameters η were evaluated as a function of pressure. The results confirm the close connection between the mechanism of the phase transition and the dynamics of the N - H⊕ ...I⊖ hydrogen bonds.

A tetragonal polymorph of SrMn2P2made under high pressure – theory and experiment in harmony

2017 ◽  
Vol 46 (21) ◽  
pp. 6835-6838 ◽  
Author(s):  
Weiwei Xie ◽  
Michał J. Winiarski ◽  
Tomasz Klimczuk ◽  
R. J. Cava
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Tetragonal Phase ◽  
Ambient Pressure ◽  
Structure Type ◽  
Space Group ◽  
Type Space ◽  
Tetragonal Phase Transition ◽  
Theory And Experiment

A trigonal–tetragonal phase transition in SrMn2P2is proposed and confirmed experimentally under high pressure. At ambient pressure, SrMn2P2crystallizes in the primitive trigonal La2O3structure type (space groupP3̄m1) in blue. Under high pressure, the tetragonal ThCr2Si2structure type (space groupI4/mmm) in red is more stable.

More examples of the 15-crown-5...H2O—M—OH2...15-crown-5 motif, M = Al3+, Cr3+ and Pd2+

2010 ◽  
Vol 66 (2) ◽  
pp. 213-221 ◽  
Author(s):  
Maxime A. Siegler ◽  
Jacob H. Prewitt ◽  
Steven P. Kelley ◽  
Sean Parkin ◽  
John P. Selegue ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Water Molecule ◽  
Lattice Water Molecule ◽  
Literature Survey ◽  
The Other ◽  
Water Molecules ◽  
Lattice Water ◽  
Hydrogen Bonding Pattern ◽  
Hydrogen Bonded

Five structures of co-crystals grown from aqueous solutions equimolar in 15-crown-5 (or 15C5) and [M(H2O)6](NO3) n , M = Al3+, Cr3+ and Pd2+, are reported. The hydrogen-bonding patterns in all are similar: metal complexes including the fragment trans-H2O—M—OH2 alternate with 15C5 molecules, to which they are hydrogen bonded, to form stacks. A literature survey shows that this hydrogen-bonding pattern is very common. In each of the two polymorphs of the compound [Al(H2O)6](NO3)3·15C5·4H2O there are two independent cations; one forms hydrogen bonds directly to the 15C5 molecules adjacent in the stack, while the other cation is hydrogen-bonded to two water molecules that act as spacers in the stack. These stacks are then crosslinked by hydrogen bonds formed by the three nitrate counterions and the three lattice water molecules. The hydrogen-bonded stacks in [Cr(H2O)5(NO3)](NO3)2·1.5(15C5)·H2O are discrete rather than infinite; each unit contains two Cr3+ complex cations and three 15C5 molecules. These units are again crosslinked by the uncoordinated nitrate ions and a lattice water molecule. In [Pd(H2O)2(NO3)2]·15C5 the infinite stacks are electrically neutral and are not crosslinked. In [Pd(H2O)2(NO3)2]·2(15C5)·2H2O·2HNO3 a discrete, uncharged unit containing one Pd complex and two 15C5 molecules is `capped off' at either end by a lattice water molecule and an included nitric acid molecule. In all five structures the infinite stacks or discrete units form an array that is at least approximately hexagonal.

LEAD-CHALCOGENIDES UNDER PRESSURE: AB-INITIO STUDY

2013 ◽  
Vol 22 ◽  
pp. 612-618 ◽  
Author(s):  
DINESH C. GUPTA ◽  
IDRIS HAMID
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Ab Initio ◽  
Band Gap ◽  
Rock Salt ◽  
High Pressures ◽  
Ambient Pressure ◽  
High Pressure Phase ◽  
Lead Chalcogenides ◽  
Pressure Phase

ab-initio calculations using fully relativistic pseudo-potential have been performed to investigate the high pressure phase transition, elastic and electronic properties of lead-chalcogenides including the less known lead polonium. The calculated ground state parameters, for the rock-salt structure show good agreement with the experimental data. The enthalpy calculations show that these materials undergo a first-order phase transition from rock-salt to CsCl structure at 19.4, 15.5, 11.5 and 7.3 GPa for PbS, PbSe, PbTe and PbPo, respectively. Present calculations successfully predicted the location of the band gap at L-point of Brillouin zone as well as the value of the band gap in every case at ambient pressure. It is observed that unlike other lead-chalcogenides, PbPo is semi-metal at ambient pressure. The pressure variation of the energy gap indicates that these materials metalized under high pressures. For this purpose, the electronic structure of these materials has also been computed in parent as well as in high pressure phase.

High-pressure transformations of NbO2F

2000 ◽  
Vol 56 (2) ◽  
pp. 189-196 ◽  
Author(s):  
Stefan Carlson ◽  
Ann-Kristin Larsson ◽  
Franziska E. Rohrer
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
High Pressures ◽  
Ambient Pressure ◽  
Close Packing ◽  
Hexagonal Close Packing ◽  
Rietveld Refinements ◽  
X Ray ◽  
Anion Coordination ◽  
Diamond Anvil

The ReO3-type structure NbO2F, niobium dioxyfluoride, has been studied at high pressures using diamond anvil cells and synchrotron X-ray radiation. High-pressure powder diffraction measurements have been performed up to 40.1 GPa. A phase transition from the cubic (Pm3¯m) ambient pressure structure to a rhombohedral (R3¯c) structure at 0.47 GPa has been observed. Rietveld refinements at 1.38, 1.96, 3.20, 6.23, 9.00 and 10.5 GPa showed that the transition involves an a − a − a − tilting of the cation–anion coordination octahedra and a change of the anion–anion arrangement to approach hexagonal close packing. Compression and distortion of the Nb(O/F)6 octahedra is also revealed by the Rietveld refinements. At 17–18 GPa, the diffraction pattern disappears and the structure becomes X-ray amorphous.

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