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In the copper-mefenamate complex tetrakis[μ-2-(2,3-dimethylanilino)benzoato-κ²O:O']bis[aquacopper(II)]-1-methoxy-2-(2-methoxyethoxy)ethane (1/2), [Cu2(C15H14NO2)4(H2O)2]·2C6H14O3, the asymmetric unit comprises a CuII cation coordinated to two mefenamate ligands solvated with a water molecule and a diglyme molecule. The complex adopts a paddlewheel motif and is compared to structural analogues crystallized with dimethylformamide and dimethyl sulfoxide. [ABSTRACT FROM AUTHOR]

The ZrSiS family of compounds has garnered interest as Dirac nodal-line semimetals and offers an approach to study structural motifs coupled with electronic features, such as Dirac crossings. CeSbTe, of the ZrSiS/PbFCl structure type, is of interest due to its magnetically tunable topological states. The crystal structure consists of rare earth capped square nets separating the magnetic Ce–Te layers. In this work, we report the single crystal growth, magnetic properties, and electronic structures of LnSb1−xBixTe (Ln = La, Ce, Pr; x ∼ 0.2) and CeBiTe, adopting the CeSbTe crystal structure, and the implication of tuning the electronic properties by chemical substitution. [ABSTRACT FROM AUTHOR]

We review the polymorphism of p-aminobenzoic acid (pABA), a model drug compound whose crystallisation and polymorphic behaviour has been extensively studied in recent years. Beyond the well-known and characterised α and β forms, pABA also crystallises as a γ polymorph, which is structurally similar to the α form. In addition we also compare the newly reported δ form, obtained by high pressure crystallisation and through compression of the α-form. A structural analysis and comparison of all of the forms is presented, the conditions by which each of them is obtained summarised. Crystal structure prediction calculations have also been carried out in order to probe the solid form energy landscape of this compound. The overall picture of the polymorphism of pABA, reveals, surprisingly, the rarity of the β form. [ABSTRACT FROM AUTHOR]

The crystal structures of loxapine succinate [systematic name: 4-(2-chlorodibenzo[ b, f][1,4]oxazepin-11-yl)-1-methylpiperazin-1-ium 3-carboxypropanoate], C18H19ClN3O+·C4H5O4−, and loxapine succinate monohydrate {systematic name: bis[4-(2-chlorodibenzo[ b, f][1,4]oxazepin-11-yl)-1-methylpiperazin-1-ium] succinate succinic acid dihydrate}, 2C18H19ClN3O+·C4H4O42−·C4H6O4·2H2O, have been determined using X-ray powder diffraction and single-crystal X-ray diffraction, respectively. Fixed cell geometry optimization calculations using density functional theory confirmed that the global optimum powder diffraction derived structure also matches an energy minimum structure. The energy calculations proved to be an effective tool in locating the positions of the H atoms reliably and verifying the salt configuration of the structure determined from powder data. Crystal packing analysis of these structures revealed that the loxapine succinate structure is based on chains of protonated loxapine molecules while the monohydrate contains dispersion stabilized centrosymmetric dimers. Incorporation of water molecules within the crystal lattice significantly alters the molecular packing and protonation state of the succinic acid. [ABSTRACT FROM AUTHOR]

A new crystalline form of αβ‐d‐lactose prepared by oven drying a concentrated aqueous solution of d‐lactose is a lesson in the power of observation and the rigorous analysis of powder samples. [ABSTRACT FROM AUTHOR]

The crystal structure of the highly metastable β-form of RDX shows that the molecules adopt different conformations compared to the α-form and that, contrary to previous reports, the β-form obtained at ambient pressure is not the same form as that obtained at elevated temperatures and pressures. [ABSTRACT FROM AUTHOR]

Single crystal x-ray diffraction has been used to investigate the structures of six complexes containing O-atom protonated cations derived from the pharmaceutically relevant amides benzamide (BEN), paracetamol (PAR) and piperine (PIP). The structures of the salt forms [PAR(H)][SO 3 C 6 H 4 Cl], [BEN(H)][O 3 SC 6 H 4 Cl] and [BEN(H)][Br]·H 2 O are reported along with those of the hemi-halide salt forms [PAR(H)][I 3 ]. PAR, [PIP(H)][I 3 ]·PIP and [PIP(H)][I 3 ] 0·5 [I] 0.5 . PIP. The structure of the cocrystal BEN. HOOCCH 2 Cl is also presented for comparison. The geometry of the amide group is found to systematically change upon protonation, with the C O distance increasing and the C N distance decreasing. The hemi-halide species all feature strongly hydrogen bonded amide(H)/amide pairs. The amide group C O and C N distances for both elements of each such pair are intermediate between those found for simple neutral amide and protonated amide forms. It was found that crystallising paracetamol from aqueous solutions containing Ba 2+ ions gave orthorhombic paracetamol. [ABSTRACT FROM AUTHOR]

Four novel structurally analogous asymmetric, halogenated N-benzyl substituted diketopyrrolopyrroles (DPP) have been synthesized, and their crystal structures obtained. All four crystal structures exhibit π-π stacks with very small displacements along their short molecular axes, which based upon our previous studies involving symmetrical DPPs is a characteristic of N-benzyl substitution. Intermolecular interaction energies were computed for extracted crystal π-π dimer pairs by means of M06-2X density functional at the 6-311G(d) level to investigate the most energetically favored position of the halogen atoms in FBDPP and ClBDPP structures. In addition, effective stabilization energies arising from both benzyl and halogen substitution in these derivatives and in BrBDPP and IBDPP π-π dimer pairs were determined in order to probe the impact of these groups on the resulting dimer stability. Effects of the intermonomer displacements along the long molecular axis, which have been shown by us previously to significantly influence wavefunction overlap and effective electronic coupling, were investigated in detail using aligned and anti-aligned model systems of ClDPP and BrDPP. The predictions of these model systems are remarkably consistent with the observed displacements in their crystal derived π-π dimer pair equivalents, offering insight into the effective role of intermolecular contacts in crystal structures involving this molecular motif, particularly with a view toward crystal engineering in these systems. As a result, we believe that this study should be of significant interest to the growing DPP based materials community and in general to those investigating the detailed manner by which substituents can be employed in the supramolecular design of crystalline molecular architectures. [ABSTRACT FROM AUTHOR]

A breakthrough has been achieved in improving the efficiency of solid-state polymerization of acetylenedicarboxylic acid (ADCA). Traditional solid-state polymerization of ADCA is marked by long exposure times of ~-radiation (>10 days) and very low yields (around 5.5%). We have been able to perform a reaction to an n = 8 oligomer, as confirmed by matrix-assisted laser desorption/ionization-time of flight, in less than 2 min by employing ~6 GPa of pressure. We have determined the crystal structure of ADCA on increasing pressure to (5.2 GPa) to provide insight into the process of polymerization with Pixel calculations supporting our evaluation of the polymerization process. [ABSTRACT FROM AUTHOR]

An extensive experimental searchfor solid forms of the antipsychoticcompound olanzapine identified 60 distinct solid forms including threenonsolvated polymorphs, 56 crystalline solvates, and an amorphousphase. XPac analysis of the 35 experimental crystal structures (30from this work and 5 from the CSD) containing olanzapine show thatthey contain a specific, dispersion-bound, dimer structure which canadopt various arrangements and accommodate diverse solvents to producestructures with a similar moderate packing efficiency to form I. Thecrystal energy landscape confirms the inability of olanzapine to packwith an efficiency of more than 70%, explains the role of solventin stabilizing the solvate structures, and identifies a hypotheticalstructural type that offers an explanation for the inability to obtainthe metastable forms II and III separately. The calculations findthat structures that do not contain the observed dimer are thermodynamicallyfeasible, suggesting that kinetic effects are responsible for allthe observed structures being based on the dimer. Thus, this extensivescreen probably has not found all possible physical forms of olanzapine,and further form diversity could be targeted with a better understandingof the role of kinetics in its crystallization. [ABSTRACT FROM AUTHOR]