Conformational variation of ligands in mercury halide complexes; high and low Z′ structures

Abstract

Small changes in the ligand resulted in a conformational variation of LPy to LPz which led to high and low Z′ structures in the corresponding metal complexes.

Polymorphism in carboxamide compounds with high-Z′ crystal structures

“…According to the results of rmsd, molecules in asymmetric unit are divided into four categories: (I) rmsd ≤ 0.1 for molecular shake, (II) 0.1 < rmsd ≤ 0.225 for partial conformational adjustment, (III) 0.225 < rmsd ≤ 0.375 for essential conformational adjustment, and (IV) 0.375 > rmsd for conformational change. 7 The rmsd for I , II , and III was calculated as 0.203, 0.135, and 0.088, respectively. Therefore, it is expected that I and II , belong to class II (partial conformational adjustment) and III belongs to class I (molecular shake).…”

“…3 Several factors have been investigated as the possible reasons for the occurrence of packing problems in the structures: (a) synthon frustration 4 (b) awkwardness in molecular geometry 5 (c) the existence of multiple functional groups on the molecule which lead to strong directional interactions and competition among them during nucleation process 6 (d) conformational variability. 7 It is shown that the propensity for high Z ′ compounds can be enhanced via strong hydrogen bond motifs and other interactions in packing, as well. 8 The high Z ′ in compounds can be ascribed to hydrogen bond interactions between the symmetry independent (SI) molecules which are effective in stabilizing high Z ′ polymorphs.…”

Accelerated Wound Healing with a Diminutive Scar through Cocrystal Engineered Curcumin

“…As fundamental sciences merge to create privileged interdisciplinary ones, integration of pharmaceutical cocrystals with wide range of disciplines have been extensively progressed during the last years. − A cocrystal is defined as a composition of two or more stoichiometric molecular/ionic entities in a homogeneous singular crystalline phase. , Cocrystal engineering utilizes the understanding of intermolecular interactions in the design of cocrystals with desired physicochemical properties and biological activities. − In 2018, European Medical Agency (EMA) and US-FDA announced a general guideline for cocrystals as a group of new molecular solids. The crystal structure of cocrystals should be characterized by different spectroscopy techniques and dissociated before reaching the active pharmacological site .…”