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

Area of Science:

• Supramolecular Chemistry
• Organic Synthesis
• Coordination Chemistry

Background:

• Chiral BINOL derivatives are valuable building blocks in supramolecular chemistry.
• Controlling stereochemistry in self-assembly is crucial for creating functional molecular architectures.
• Understanding self-sorting behavior is key to designing complex multicomponent systems.

Purpose of the Study:

• To investigate how hydrogen-bonding ability and methylation of a BINOL-based dialdehyde influence self-assembly outcomes.
• To explore the impact of these modifications on self-sorting behavior with linear ligands.
• To prepare new stereochemically pure heteroleptic helicates by controlling chirality and assembly.

Main Methods:

• Synthesis of BINOL-based dialdehyde subcomponents with and without methyl groups.
• Self-assembly studies in the presence of metal ions (FeII, ZnII).
• Analysis of self-sorting behavior using techniques like NMR spectroscopy and mass spectrometry.

Main Results:

• Free hydroxy groups on the dialdehyde promote one diastereomeric helicate form, while methylation leads to another.
• Methylation switches self-sorting from narcissistic to integrative when mixed with a linear dialdehyde.
• Axial chirality of the BINOL unit consistently dictates helicate metal center handedness.
• New stereochemically pure heteroleptic helicates were successfully synthesized.
• Switching metal ions (FeII to ZnII) or using longer linear ligands favors heteroleptic helicate formation.

Conclusions:

• Hydrogen bonding and methylation are critical factors controlling stereochemistry and self-sorting in BINOL-based systems.
• Axial chirality transfer is a robust feature during stereospecific self-assembly.
• The findings enable the rational design and synthesis of novel stereochemically pure heteroleptic helicates.