Energetic and Topological Supramolecular Study and Nucleation Proposal of Halogenated Aryl Amides

A supramolecular study of 12 halogenated aryl amides (F, Cl, Br, I) in the ortho, meta, or para positions was realized. From mono crystal X-ray diffraction data and theoretical calculations...

de Oliveira JP, A. Vasconcellos MLA, Zanatta N, G. Bonacorso H, Martins MAP. Substituent effects on the crystallization mechanisms of 7-chloro-4-substituted-quinolines

The crystallization mechanisms of a series of fourteen 7-chloro-4-substituted-quinolines were proposed based on a retrocrystallization approach using the supramolecular cluster as demarcation.

Review and Modeling of Crystal Growth of Atropisomers from Solutions

In this paper, theories on anisotropic crystal growth and crystallization of atropisomers are reviewed and a model for anisotropic crystal growth from solution containing slow inter-converting conformers is presented. The model applies to systems with growth-dominated crystallization from solutions and assumes that only one conformation participates in the solute integration step and is present in the crystal lattice. Other conformers, defined as the wrong conformers, must convert to the right conformer before they can assemble to the crystal lattice. The model presents a simple implicit method for evaluating the growth inhibition effect by the wrong conformers. The crystal growth model applies to anisotropic growth in two main directions, namely a slow-growing face and a fast-growing face and requires the knowledge of solute crystal face integration coefficients in both directions. A parameter estimation algorithm was derived to extract those coefficients from data about temporal concentration and crystal size during crystallization and was designed to have a short run time, while providing a high-resolution estimation. The model predicts a size-dependent growth rate and simulations indicated that for a given seed size and solvent system and for an isothermal anti-solvent addition crystallization, the seed loading and the supersaturation at seeding are the main factors impacting the final aspect ratio. The model predicts a decrease of the growth inhibition effect by the wrong conformer with increasing temperature, likely due to faster equilibration between conformers and/or a decrease of the population of the wrong conformer, if of low energy, at elevated temperatures. Finally, the model predicts that solute surface integration becomes the rate-limiting mechanism for high solute integration activation energies, resulting in no impact of the WC on the overall crystal growth process.

Supramolecular Similarity in Polymorphs: Use of Similarity Indices (IX)

A systematic investigation to assess the degree of similarity between polymorphs was carried out. A similarity indices (I^X) approach was applied in ten series of polymorphs with different characteristics and number of molecules in the asymmetric unit. Geometric (I^D), contact area (I^C), and stabilization energy (I^G) parameters were used. It was possible to situate each comparison in different regions of similarity within the polymorphism phenomenon and determine the boundaries between quasi-isostructural polymorphs and polymorphs of low similarity. The multiparameter I^DCG index was used as a robust tool to determine the total similarity within the polymorphism phenomenon. The highest contribution of the stabilization energy parameter (45%) toward the final value of similarity (I^DCG) was observed, followed by the contact area index (32%). The geometric index contributed approximately 23% to the final value of I^DCG. This information reinforces the importance of the contact area and stabilization energy in assessing the degree of similarity between crystalline structures. A new descriptor (I^Q) based on the comparison of the energetic contribution of intermolecular interaction types present in each crystal structure is presented. I^Q can be a versatile tool and applicable even for systems that do not share any similarity.