The NOE experiments for the under- and super-saturated Boc-Asn solutions were carried out to investigate the behaviors of solute molecules in the pre-step of homogeneous nucleationand crystal growth. First, the conformation of Boc-Asn molecules assembled in the crystal was determined by X-ray analysis and compared with the molecular structure estimated from the NOE data obtained for the solutions. THe conformation of Boc-Asn molecules approached to that in crystal beyond the saturation from the undersaturation. The conformational change occurred within at least 1 h after the solution was adjusted to given supersaturation (saturation ratio: 1.62). However, the solute molecules did not aggregate immediately after the change of the conformation, but suddenly aggregated after 120h-incubation. The formation of aggregates played an important role for a synchronized nucleation and crystal growth.
展开▼
