Amino acid modified calixarenes as crystal growth modifiers

Amino acid functionalized calixarenes, incorporating aspartic acid 1, alanine 2, and sarcosine 3, have been synthesized and studied as crystal growth modifiers. Calixarene 1 was found to alter the morphology of calcite significantly, elongating crystals in the c direction, and inducing chiral morphologies and growth features on the crystal surface. Additive 2, a secondary amide, was more efficacious than tertiary amide 3, suggesting a role for hydrogen bonding of the amide proton in crystal growth modification. The aspartic acid derivative 1 was also found to control the crystal growth of calcium oxalate, inducing crystallization of the dihydrate rather than the monohydrate produced in the control system.