Molecular recognition controls the organization of mixed self-organized bis-urea based mineralization templates for CaCO3

To investigate the role and importance of nondirectional electrostatic interactions in mineralization, we explored the use of Langmuir monolayers in which the charge d. can be tuned using supramol. interactions. It is demonstrated that, in mixed Langmuir monolayers of bis-ureido surfactants contg. oligo(ethylene oxide) and ammonium head groups assocd. with matching or nonmatching spacers between the two urea groups, the organization is controlled by mol. recognition. These different organizations of the mols. lead to different nucleation behavior in the mineralization of calcium carbonate. The formation of modified calcite and vaterite crystals was induced selectively by different phases of mixed monolayers, and they were characterized by SEM, TEM, and SAED. To understand the influence of the mixed Langmuir monolayers on the crystn. process, we studied the mixts. by means of (pi-A) isotherms and Brewster angle microscopy observations. IR reflection-absorption spectroscopy expts. were also performed on Langmuir-Schaefer films. From these results, we conclude that the local organization of the two systems discussed here gives rise to differences in both charge d. and flexibility that together det. not only polymorph selection and the nucleation face but also the morphol. of the resulting crystals. [on SciFinder (R)]