Crystal Growth & Design最新文献

A family of discrete dinuclear complexes [M^IILn^III] (M = Cu, Ni and Ln = Ce, Gd, Tb, Dy, Er, Yb) has been synthesized from the use of the compartmental Schiff base ligand H₄L (3,3′-((1E,1′E)-(ethane-1,2-diylbis(azaneylylidene)) bis(methaneylylidene))bis(benzene-1,2-diol)), obtained from the condensation of ethylenediamine and 2,3-dihydroxybenzaldehyde. All of the complexes have been structurally and magnetically characterized. The dynamic magnetic measurements show that the [Cu^IILn^III] and [Ni^IILn^III] derivatives exhibit ac response as a function of the d-cation. Noteworthily, the isotropic Gd^III complexes exhibit a slow relaxation of magnetization.

A family of discrete dinuclear complexes [M^IILn^III] (M = Cu, Ni, and Ln = Ce, Gd, Tb, Dy, Er, Yb) has been synthesized from the use of the compartmental Schiff base ligand H₄L (3,3′-((1E,1′E)-(ethane-1,2-diylbis(azaneylylidene)) bis(methaneylylidene))bis(benzene-1,2-diol)), obtained from the condensation of ethylenediamine and 2,3-dihydroxybenzaldehyde.

A workflow for the digital design of crystallization processes starting from the chemical structure of the active pharmaceutical ingredient (API) is a multistep, multidisciplinary process. A simple version would be to first predict the API crystal structure and, from it, the corresponding properties of solubility, morphology, and growth rates, assuming that the nucleation would be controlled by seeding, and then use these parameters to design the crystallization process. This is usually an oversimplification as most APIs are polymorphic, and the most stable crystal of the API alone may not have the required properties for development into a drug product. This perspective, from the experience of a Lilly Digital Design project, considers the fundamental theoretical basis of crystal structure prediction (CSP), free energy, solubility, morphology, and growth rate prediction, and the current state of nucleation simulation. This is illustrated by applying the modeling techniques to real examples, olanzapine and succinic acid. We demonstrate the promise of using ab initio computer modeling for solid form selection and process design in pharmaceutical development. We also identify open problems in the application of current computational modeling and achieving the accuracy required for immediate implementation that currently limit the applicability of the approach.

This work considers the theoretical basis of crystal structure prediction (CSP), free energy, solubility, morphology, and growth rate prediction, and the current state of nucleation simulation to provide the conceptual process design for industrial crystallizations of pharmaceutical compounds. This is illustrated by applying the modeling techniques to real examples, olanzapine and succinic acid. We describe and demonstrate the promise of using ab initio computer modeling for solid form selection and process design in pharmaceutical development from only a molecular structure.

Oxadiazoles are the satisfactory structural units of energetic materials due to high densities. However, the practical use of most oxadiazole compounds in energetic materials is limited by their low thermal decomposition temperature (<180 °C). In this work, 3-(3-nitro-1H-pyrazol-4-yl)-1,2,4-oxadiazol-5(4H)-one (6) with relatively high detonation performance (D_v = 8315 m s^–1; P = 29.22 GPa) and good thermal stability (T_d = 275.9 °C) has been successfully synthesized by the introduction of a pyrazole backbone into the oxadiazole skeleton, which is better than HNS (D_v = 7612 m·s ^–1; P = 24.3 GPa). In addition, compound 6 was synthesized using a green, low-toxicity three-step process (cyclization, amination, and hydrolysis) rather than highly toxic cyanogen bromide. To investigate the correlation between the structure and stability of compound 6, calculations of Hirshfeld surface analysis, 2D-fingerprint plots, and electrostatic potentials were performed. This provides a guide to synthesizing energetic materials with high detonation and good thermal stability.

The perovskite oxide SrMoO₃ has attracted significant attention for its potential applications in ultraviolet (UV) transparent conductors. Thus far, synthesizing high-quality epitaxial SrMoO₃ thin films by pulsed laser deposition (PLD) is usually under highly reducing (Ar or Ar-H₂ gas mixture) atmospheres. Here, we grew SrMoO₃ epitaxial films using the PLD technique at a base pressure below 1 × 10^–5 Pa without any gas supply to optimize their optical and electrical properties. By depositing these films on the (001) SrTiO₃, (001) LaAlO₃, and (001) MgO substrates, the as-grown SrMoO₃ films, with a nominal lattice mismatch in the range of −4.8 to +5.7% and a thickness of 20–60 nm, show prominent transparent conductivity in both visible and UV wavelengths. All the films exhibit metallic-like conductivity, with a room-temperature resistivity varying from 10 to 60 μΩ·cm. The resistivity increases with decreasing thickness. Notably, we can achieve extremely high transmittance, exceeding 80% for wavelengths ranging from 300 to 500 nm, and a low resistivity of approximately 20 μΩ·cm in SrMoO₃ films as thin as 20 nm. The excellent UV transparent conducting properties that are insensitive to the substrate type and film thickness make SrMoO₃ films a promising material for various photoelectronic devices and energy-harvesting applications.

We report herein, by means of structural and computational analyses, a comprehensive study of the capability of differently substituted haloalkenes to behave as electron density acceptors in noncovalent interactions. The nature of these interactions between haloalkenes and Lewis bases highly depends on the number and nature of the halogen atoms bound to the carbon–carbon double bond. When hydrogen bonds, which generally dominate for mono- and dihaloalkenes, cannot be formed, we observe the establishment of attractive interactions in which an sp² carbon atom, belonging to an acyclic C═C double bond, plays the role of the Lewis acid via its π* antibonding orbital.

By means of a computational study, we have evaluated the capability of halogenated ethene systems to engage in noncovalent interactions as the electron-deficient species, involving different interaction modes depending on the halogen atom present and the nature of the Lewis base.

Crystallographic analysis of solvate structures formed by 3,5-dihydrohybenzoic acid demonstrates that the high propensity of this compound to form solvate-hydrates is a result of the highly efficient crystal structure framework obtained by the inclusion of water molecules. On the contrary, pure solvates can be obtained with a limited number of organic solvents, only with relatively small solvents providing efficient hydrogen bonding. The crystal structure analysis shows that the steric characteristics of the solvent molecules notably affect the crystal structure framework. In all of the cases where the formation of alternative crystal forms is possible, the water content present in the crystallization medium directly influences the obtained crystal form. Exploration of the formation of two ethyl acetate solvate-hydrates indicates that the water content present in the crystallization medium and packing characteristics in the crystal structure mostly influence the phase appearance frequency.