One-Pot Synthesis and AFM Imaging of a Triangular Aramide Macrocycle

• Published in: Journal of the American Chemical Society Vol. 136; no. 37; pp. 12832 - 12835
• Main Authors: Storz, Christof, Badoux, Michael, Hauke, Christopher M, Šolomek, Tomáš, Kühnle, Angelika, Bally, Thomas, Kilbinger, Andreas F. M
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 17-09-2014
• Subjects: Benzamides - chemical synthesis; Benzamides - chemistry; Bridged-Ring Compounds - chemical synthesis; Bridged-Ring Compounds - chemistry; Calcium Carbonate - chemistry; Combinatorial Chemistry Techniques; Cyclization; Dimerization; Hydrogen Bonding; Macrocyclic Compounds - chemical synthesis; Macrocyclic Compounds - chemistry; Microscopy, Atomic Force; Models, Molecular; Surface Properties
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja506646s

Macrocyclizations in exceptionally good yields were observed during the self-condensation of N-benzylated phenyl p-aminobenzoates in the presence of LiHMDS to yield three-membered cyclic aramides that adopt a triangular shape. An ortho-alkyloxy side chain on the N-benzyl protecting group is necessary for the macrocyclization to occur. Linear polymers are formed exclusively in the absence of this Li-chelating group. A model that explains the lack of formation of other cyclic congeners and the demand for an N-(o-alkoxybenzyl) protecting group is provided on the basis of DFT calculations. High-resolution AFM imaging of the prepared molecular triangles on a calcite(10.4) surface shows individual molecules arranged in groups of four due to strong surface templating effects and hydrogen bonding between the molecular triangles.