Solvatomorphism of a 2,6-pyridyldicarboxamide-based foldamer

Area of Science:

• Supramolecular Chemistry
• Materials Science
• Crystal Engineering

Background:

• Foldamers are oligomers that mimic biological macromolecules.
• Solvatomorphism, the phenomenon where a compound crystallizes in different forms depending on the solvent, is crucial for solid-state properties.
• Understanding solvent effects on foldamer conformation and packing is key for designing functional materials.

Purpose of the Study:

• To investigate the solvatomorphism of a diamine-terminated 2,6-pyridyldicarboxamide-based foldamer.
• To determine the influence of various polar and non-polar solvents on the foldamer's solid-state conformation and crystal packing.
• To explore the formation of solvent-mediated supramolecular aggregates and their stabilizing interactions.

Main Methods:

• Single-crystal X-ray diffraction analysis of seven solvatomorphs.
• Solid-state analysis to identify intermolecular non-covalent interactions.
• Systematic variation of solvents including chloroform, trifluorotoluene/dichloromethane, dimethylformamide/diethyl ether, tetrahydrofuran, butanone, dichloromethane, methanol/dichloromethane, and dimethylsulfoxide.

Main Results:

• Seven solvatomorphs of the foldamer were identified (1A, 1B, 1·DCM, 1·THF, 1·butanone, 1·MeOH, 1·DMSO).
• Solvents like DCM, THF, butanone, MeOH, and DMSO were incorporated into supramolecular aggregates (channels/cavities) with dimensions ranging from 3.5 to 9.0 Å.
• Intermolecular interactions, including N-H⋯O, N-H⋯Cl, O-H⋯O, and C-H⋯O hydrogen bonds, stabilized these solvent-mediated structures.

Conclusions:

• Solvent choice significantly impacts the solid-state structure and packing of the studied foldamer.
• The formation of solvent-mediated channels offers potential for crystal engineering and the uptake of small molecules.
• These findings provide insights for the future design of foldamers for applications in energy storage and materials chemistry.