Engineering Oriented Gases: The Mechanism of Dyeing Potassium Sulfate

✍ Scribed by Loyd D Bastin; Bart Kahr

• Publisher: Elsevier Science
• Year: 2000
• Tongue: French
• Weight: 279 KB
• Volume: 56
• Category: Article
• ISSN: 0040-4020
• DOI: 10.1016/s0040-4020(00)00464-6

✦ Synopsis

AbstractÐPotassium sulfate was crystallized from solutions containing mM quantities of a variety of sulfonated dye molecules that became encapsulated within particular growth sectors. Linear dichroism measurements of the crystals coupled with a knowledge of the absorption anisotropy of the dyes obtained from semi-empirical molecular orbital theory, enabled the determination of the orientation of at least one dye molecule within each of the principal growth sectors ({010}, {021}, {110}, {001}, {111}) of K 2 SO 4 . The ensemble of orientations suggested a general mechanism of mixed crystal formation in which the dye's sulfonate groups matched the separation between sulfate ions in the lattice. The corresponding experiments with K 2 SO 4 isomorphs as well as the habit modi®cation accompanying dye inclusion crystal (DIC) formation are discussed. We further demonstrate how sector speci®c recognition enables growing crystals to separate molecules from complex solutions.