WinPSSP: a revamp of the computer program PSSP and its performance solving the crystal structures of small organic compounds and solids of biological and pharmaceutical interest

Abstract

The direct-space methods software Powder Structure Solution Program (PSSP) [Pagola & Stephens (2010). J. Appl. Cryst. 43, 370–376] has been migrated to the Windows OS and the code has been optimized for fast runs. WinPSSP is a user-friendly graphical user interface that allows the input of preliminary crystal structure information, integrated intensities of the reflections and FWHM, the definition of structural parameters and a simulated annealing schedule, and the visualization of the calculated and experimental diffraction data overlaid for each individual solution. The solutions are reported as filename.cif files, which can be used to analyze packing motifs and chemical bonding, and to input the atomic coordinates into the Rietveld analysis software GSAS. WinPSSP performance in straightforward crystal structure determinations has been evaluated using 18 molecular solids with 6–20 degrees of freedom. The free-distribution program as well as multimedia tutorials can be accessed at http://users.uoi.gr/nkourkou/winpssp/.

Accessing New Charge-Transfer Complexes by Mechanochemistry: A Tetrathiafulvalene Chloranilic Acid Polymorph Containing Segregated Tetrathiafulvalene Stacks

“…The synchrotron PXRD data were indexed with the program McMaille . A preliminary crystallographic model was obtained with the program PSSP and later refined and checked with WinPSSP . The Rietveld refinement was carried out with the program GSAS, using soft bond length, angle, and planarity restraints, which target values were those of the orange TTF and CAH 2 .…”

“…“Green” mechanochemical syntheses using small quantities of liquids while grinding the reactants as powders, called liquid-assisted grinding (LAG), − are an effective approach to obtain materials of improved crystallinity compared with the products of neat grinding . The powder diffraction data of the former show generally less peak broadening effects and are often treatable toward crystal structure solution from powders, , avoiding the need for preparing single crystals by seeding . The small volumes of liquid added in mechanochemical reactions by LAG facilitate mass transport within the reaction mixtures.…”

Four interpenetrating hydrogen-bonded three-dimensional networks in divanillin

“…Crystal structure determination was simultaneously attempted using direct methods implemented in the software EXPO2013 (Altomare et al, 2013) and a direct-space approach using the software WinPSSP (Pagola et al, 2017) in the space group Pba2 and with Z 0 = 1 2 . The chemical formula and powder diffraction data were input into EXPO2013, allowing it to perform peak-search, indexing, space-group symmetry and crystal structure determination using the default calculation options.…”

Tetrathiafulvalene: A Gate to the Mechanochemical Mechanisms of Electron Transfer Reactions

“…[17]. In addition, our work using modern methods to solve crystal structures from powders [21,22] has led to the structural characterization of a few materials obtained by LAG as single phases: the black polymorph of tetrathiafulvalene chloranil [18]; the ionic form of tetrathiafulvalene 2,3-dichloro-5,6-dicyano-p-benzoquinone [19]; 2,5-dichloro-p-benzoquinone, tetrathiafulvalene chloranilic acid, form II [20]; and tetrathiafulvalene bromanilic acid. This is an advantage of LAG over neat mechanochemistry, which often leads to poorly crystalline materials, and the consequent diffraction peak broadening and background increase often makes difficult solving their crystal structures from powders.…”