Sterics and Hydrogen Bonding Control Stereochemistry and Self-Sorting in BINOL-Based Assemblies

Here we demonstrate how the hydrogen-bonding ability of a BINOL-based dialdehyde subcomponent dictated the stereochemical outcome of its subsequent self-assembly into one diastereomeric helicate form when bearing free hydroxy groups, and another in the case of its methylated congener. The presence of methyl groups also altered the self-sorting behavior when mixed with another, short linear dialdehyde subcomponent, switching the outcome of the system from narcissistic to integrative self-sorting. In all cases, the axial chirality of the BINOL building block also dictated helicate metal center handedness during stereospecific self-assembly. A new family of stereochemically pure heteroleptic helicates were thus prepared using the new knowledge gained. We also found that switching from Fe-II to Zn-II, or the incorporation of a longer linear ligand, favored heteroleptic structure formation.

Automated summary

This study demonstrates how the hydrogen-bonding ability of a BINOL-based dialdehyde subcomponent influences the stereochemical outcome of self-assembly. The presence of methyl groups alters the self-sorting behavior, while the axial chirality of the BINOL building block affects the handedness of the helicate metal center.