Applications of Low Temperature Gradient Sublimation in Vacuo: Rapid Production of High Quality Crystals. The First Solvent-Free Crystals of Ethinyl Estradiol

Abstract

A sublimation method based on the use of a conventional vacuum oven has been developed to extend the method's range of applications. The use of a small, externally controlled heater has increased the temperature range from 80− 200 to 80−500 °C and provides high-quality crystals of compounds ranging from oxalic acid to metal-free phthalocyanine. Some unique benefits of the method are relatively rapid crystal production, provision of crystals of compounds that are known only as solvates, simple optical detection of crystals that are likely to bend, and crystal habit control. The inability of ethynyl estradiol (EE) to form solvent-free crystals is explained on the basis of the structure of vapor-grown crystals, and three new solvate structures are reported. The visual detection of bending crystals of naftazone and 1,3-dinitrobenzene is described. The crystal morphologies of 1,4-naphthaquinone, metal-free phthalocyanine, and benzoic acid are controlled by the temperature gradient in the oven.

Conversion of Gel-Forming Crystal Needles To Easily Processable More Equant Crystals Using High-Shear Ultralow Attrition Agitation: Accelerated Ostwald Ripening without Crystal Attrition

“…17,18 The Monte Carlo based methods give the best results for anisotropic crystal growth in stacked systems and the prediction that the aspect ratio is inversely proportional to the gas phase crystallization driving force for -phthalocyanine has been confirmed for other stacked systems which exhibit needle growth. 17,19 It is likely that the systems most likely to benefit from the HSULAA process are those which exhibit vdW contact stacking. This type of stacking can be detected in crystal structures in an automated procedure using a molecular centroid distance matrix analysis which counts the fraction of atoms in a molecule that are in contact with their neighbours above and below them in a stack.…”

Investigation into solid and solution properties of quinizarin

“…The needle growth direction in the FI crystal structure is along the b axis, as predicted, coinciding with the direction of π-stacking of ribbons. 37 Notably, in the present case, when agitation was suspended upon nucleation needles were observed (Fig. 35 The high growth rate in the needle direction of β-phthalocyanine has been associated with the low activation energy required to generate a new View Article Online step in the stacking direction.…”

How Substitution Combines with Non-Covalent Interactions to Modulate 1,4-Naphthoquinone and Its Derivatives Molecular Features—Multifactor Studies

“…The models of 1,4-naphthoquinone and its derivatives were constructed on the basis of experimental data available in the Cambridge Crystallographic Data Centre (CCDC) [ 56 ] (CCDC Database Identifier: NAPHQU01; Deposition Number 939729) [ 21 ]. For the crystallographic data visualization the Mercury 3.1 program was used [ 77 ].…”

“…In the history of science, much spectacular evidence of SE can be found. One example could be considered in the current study, e.g., 1,4-naphthoquinone [ 21 ] substituted by two hydroxyl groups introduced a new compound—naphthazarin [ 22 ]—which can be obtained experimentally or from natural sources. 1,4-Naphthoquinone and its derivatives have been of significant interest to the scientific community in recent years due to their various molecular features [ 23 , 24 , 25 ].…”