Studying the impact of the pre-exponential factor on templated nucleation

Traditionally, the enhancement of nucleation rates in the presence of heterogeneous surfaces in crystallisation processes has been attributed to the modification of the interfacial energy of the system according to the classical nucleation theory. However, recent developments have shown that heterogeneous surfaces instead alter the pre-exponential factor of nucleation. In this work, the nucleation kinetics of glycine and diglycine in aqueous solutions have been explored in the presence and absence of a heterogeneous surface. Results from induction time experiments show that the presence of a heterogeneous surface increases the pre-exponential factor by 2-fold or more for both glycine and diglycine, while the interfacial energy remains unchanged for both species. This study suggests that the heterogeneous surface enhances the nucleation rate via hydrogen bond formation with both glycine and diglycine. This is verified by hydrogen bond propensity calculations, molecular functionality analysis, and calculation of the time taken for a solute molecule to attach to the growing nucleus, which is an order of magnitude shorter than the estimated lifetime of the hydrogen bond. The effect of the heterosurface is of greater magnitude for diglycine than for glycine, which may be due to the heightened molecular complementarity between the hydrogen bond donor and acceptor sites on diglycine and the heterosurface.

Computational investigation, comparative approaches, molecular structural, vibrational spectral, non-covalent interaction (NCI), and electron excitations analysis of benzodiazepine derivatives

The present work explores the structural parameters and vibrational frequencies as well as molecular interactions of benzodiazepine derivatives, such as clothiapine (CT), clozapine (CZ), and loxapine (LX). Employing fitting experimental data to theoretical results is used to assess the structural parameters of heading composites. The main assignment is passed out according to the overall distribution of energy of the vibrational modes. From the hyper-conjugative interaction, the permanency of the structure had been predicted through natural bond orbital analysis; it is also used to identify the bonding and antibonding regions of the molecules. Moreover, electrostatic potential (ESP), density of states (DOS), and charge transfer occurring of the molecule among HOMO as well as LUMO energy were calculated and presented; utilizing electron localized field (ELF), localized orbital locator (LOL), and reduced density gradient (RDG), the chemical interactive regions are found. Additionally, mean polarizability (α_tot), the first-order hyperpolarizability (β_tot), and softness and hardness of the entitled compounds were also performed. The interaction between protein-ligand was also predicted by docking studies.

Antipsychotic clozapine binding to alpha-2-macroglobulin protects interacting partners against oxidation and preserves the anti-proteinase activity of the protein

In this study, the interaction between clozapine, an atypical antipsychotic drug, and alpha-2-macroglobulin (α₂M), a multipurpose anti-proteinase, was investigated under simulated (patho) physiological conditions using multiple spectroscopic techniques and molecular modeling. It was found that α₂M binds clozapine with a moderate affinity (the binding constant of 0.9 × 10⁵ M^-1 at 37 °C). The preferable binding site for both clozapine's atropisomers was revealed to be a large pocket at the interface of C and D monomer subunits of the protein. Hydrogen bonds and the hydrophobic effect were proposed as dominant forces in complex formation. The binding of clozapine did not induce significant conformational change of the protein, as confirmed by virtually unaltered α₂M secondary structure and anti-proteinase activity. However, both clozapine and α₂M shielded each other from the deleterious influence of strong oxidants: sodium hypochlorite and 2,2'-azobis-2-methyl-propanimidamide dihydrochloride (AAPH). Moreover, clozapine in a concentration range that is usually targeted in the plasma during patients' treatment effectively protected the anti-proteinase activity of α₂M under AAPH-induced free radical overproduction. Our results suggest that the cooperation between α₂M and clozapine may be a path by which these two molecules synergistically protect neural tissue against injury caused by disturbed proteostasis or oxidative stress.

A very short O-H⋯O hydrogen bond in the structure of clozapinium hydrogen bis-(3,5-di-nitro-benzoate)

In the title salt {systematic name: 4-[6-chloro-2,9-di-aza-tri-cyclo-[9.4.0.03,8]penta-deca-1(15),3(8),4,6,9,11,13-heptaen-10-yl]-1-methyl-piperazin-1-ium 3,5-di-nitro-benzoate-3,5-di-nitro-benzic acid (1/1)}, C18H20ClN4 +·C7H3N2O6 -·C7H4N2O6, there is a very short, asymmetric, O-H⋯O hydrogen bond [O⋯O = 2.453 (3) Å] within the anion. The oxygen atoms of one of the nitro groups of the anion are disordered over two sets of sites having occupancies of 0.56 (3) and 0.44 (3). The fused tricyclic portion of the cation adopts a butterfly conformation, with a dihedral angle of 45.59 (6)° between the planes of the two aryl rings. In the crystal, a combination of O-H⋯O, N-H⋯O and C-H⋯O hydrogen bonds links the component species into a three-dimensional framework. Comparisons are made with the structures of some related compounds.

Crystal nucleation of salicylamide and a comparison with salicylic acid

Nucleation behaviour of salicylamide in different solvents was determined and compared with salicylic acid, attempting to progress the rationalization of the influence of the solvent and solute on crystal nucleation of organic compounds in solution.

Nanocellulose-assisted construction of hydrophilic 3D hierarchical stereocomplex meshworks in enantiomeric polylactides: towards thermotolerant biocomposites with enhanced environmental degradation

A hydrophilic and hierarchical 3D stereocomplexed crystalline meshwork was in situ constructed in fully bio-derived enantiomeric polylactide/cellulose nanocrystal nanocomposites.