A comparison of electron density from Hirshfeld-atomrefinement, X-ray wavefunction refinement andmultipole refinement on three urea derivatives

Electron density distributions of three urea derivatives N-methylurea, N-phenylurea and N,N′-diphenylurea were determined by single-crystal X-ray diffraction. High-resolution data were measured with synchrotron radiation. Data were subjected to a multipole refinement using the Hansen–Coppens multipole model, to Hirshfeld-atom refinement with and without a surrounding cluster of point charges/dipoles and to X-ray wavefunction refinement. Electron density distributions were evaluated in terms of deformation and residual electron density plots as well as bond critical points, atomic volumes and charges as defined in Bader's Theory of Atoms In Molecules. Given a sufficiently extended basis-set Hirshfeld-atom refinement yields results superior to multipole model refinements; best figures of merit were achieved by X-ray wavefunction refinement. Results indicate how conventional crystallographic studies can be systematically improved

Correction: Sankaranarayanan et al. Auger Emitter Conjugated PARP Inhibitor for Therapy in Triple Negative Breast Cancers: A Comparative In-Vitro Study. <i>Cancers</i> 2022, <i>14</i>, 230

The authors wish to replace the ‘Author Contributions’ statement and the affiliation for Jochen Maurer of this article [...

Evidence for Point Transformations in Photoactive Molecular Crystals by the Photoinduced Creation of Diffuse Diffraction Patterns

Time-resolved diffuse X-ray scattering is one powerful method for monitoring the progression from the creation of local structural changes inside a crystalline material up to the transformation of the whole crystalline bulk. In this work, we study the mechanism of phototransformation of a molecular crystal by time-resolved diffuse X-ray scattering. Here, an optical excitation source, like a pulsed laser, initiates structural transformations which are monitored by X-ray scattering techniques. We have studied the dimerization process of the molecular switch α-styrylpyrylium (trifluoromethanesulfonate) TFMS, in particular for understanding whether cooperative effects influence the changes of the structure in the bulk and its periodicity. Upon illumination with optical light, α-styrylpyrylium TFMS instantaneously photoswitches. Depending on the optical fluence, X-ray diffuse planes are observed prior to phototransformation of the bulk. In the early stages of transformation, the analysis reveals systems of randomly distributed islands of product clusters with gradual growth in size and amount. The degree of transformation follows the optical excitation profile, i.e., the spatial absorption of the laser beam. In the present studies, no influence of cooperativity on the photodimerization process has been found