A rod- and tessellation-based comparative analysis of polymorphic and structurally-invariant molecular crystals: application to sulfathiazole and 2-benzyl-5-benzylidenecyclopentanones.

A rationalization of the alternative crystal structures adopted by a given molecular compound or by a set of substitutionally related molecular compounds is provided by reference to the five known polymorphs of sulfathiazole and 16 substituted 2-benzyl-5-benzylidene cyclopentanones (BBCPs), respectively. Two-dimensional (2D) packing fractions (ϕ) take space-group symmetry into account, with a clear demarcation of closed-packed zones (CPZ) and molecular junction zones (JZ) in all Z' = 1 structures. Representation of the molecules as two linked rods allows a concise treatment of conformation and rapid visualization of crystal packing.

Structural studies of crystalline forms of triamterene with carboxylic acid, GRAS and API molecules.

Pharmaceutical salt solvates (dimethyl sulfoxide, DMSO) of the drug triamterene with the coformers acetic, succinic, adipic, pimelic, azelaic and nicotinic acid and ibuprofen are prepared by liquid-assisted grinding and solvent-evaporative crystallization. The modified Δp rule as proposed by Cruz-Cabeza [(2012 ▸). , , 6362-6365] is in close agreement with the results of this study.

Using crystallography, topology and graph set analysis for the description of the hydrogen bond network of triamterene: a rational approach to solid form selection.

This study has demonstrated the use of crystallography, topology and graph set analysis in the description and classification of the complex hydrogen bonded network of triamterene. The aim is to give a brief overview of the methodology used to discuss the crystal structure of triamterene with a view to extending the study to include the solvates, cocrystals and salts of this compound. Graphical abstract One of the structurally significant dimers (supramolecular synthons) of triamterene identified by this study.

Describing hydrogen-bonded structures; topology graphs, nodal symbols and connectivity tables, exemplified by five polymorphs of each of sulfathiazole and sulfapyridine.

Background: Structural systematics is the comparison of sets of chemically related crystal structures with the aim to establish and describe relevant similarities and relationships. An important topic in this context is the comparison of hydrogen-bonded structures (HBSs) and their representation by suitable descriptors.

Results: Three different description methods for HBSs are proposed, a graphical representation, a symbolic representation and connectivity tables.

A mechanophysical phase transition provides a dramatic example of colour polymorphism: the tribochromism of a substituted tri(methylene)tetrahydrofuran-2-one.

Background: Derivatives of fulgides have been shown to have interesting photochromic properties. We have synthesised a number of such derivatives and have found, in some cases, that crystals can be made to change colour on crushing, a phenomenon we have termed "tribochromism". We have studied a number of derivatives by X-ray crystallography, to see if the colour is linked to molecular structure or crystal packing, or both, and our structural results have been supported by calculation of molecular and lattice energies.

Lateral rectus palsy following coronary angiography and percutaneous coronary intervention.

We present a rare case of unilateral lateral rectus palsy following an elective coronary angiography and percutaneous coronary intervention in a 78-year-old woman. Ophthalmoplegia following coronary angiography is extremely rare and this is the first case of a unilateral lateral rectus palsy following the procedure.

Further errors in polymorph identification: furosemide and finasteride.

Reassessment of the reported single-crystal X-ray diffraction characterization of polymorphs of furosemide and finasteride shows that, in each case, incomplete data collections have resulted in the mistaken identification of two forms that are, in fact, identical.