Hierarchical\nSelf-Organization and Disorganization\nof Helical Supramolecular Columns Mediated by H‑Bonding and\nShape Complementarity

H-bonding, shape complementarity,\nand quasi-equivalence are widely\naccepted as some of the most influential molecular recognition events\nmediating biological and synthetic self-organizations. H-bonds are\nweaker than ionic but stronger than van der Waals forces. However,\nthe directionality of H-bonds makes them the most powerful among all\nnonbonding interactions. Here, we selected two taper-shaped self-assembling\ndendrons, one flexible and one rigid, and equipped them with −CO<sub>2</sub>CH<sub>3</sub>, −CH<sub>2</sub>OH, and −COOH\nat their apex. They demonstrated the hierarchical way in which shape-complementarity\nin the presence of −CO<sub>2</sub>CH<sub>3</sub> mediated highly\nordered helical self-organization for the case of the rigid building\nblock and less ordered helical arrays for the flexible one. Weak H-bonding\nby −CH<sub>2</sub>OH unwound the helix from the rigid dendron,\nyielding a porous column. Due to its quasi-equivalence, the flexible\ndendron tolerated better the H-bonding by −CH<sub>2</sub>OH\nself-organizing a different helical column. The rigid and the flexible\ndendrons yielded only disorganized nonhelical columns in the presence\nof −COOH at the apex. This balance between rigidity, flexibility,\nand tolerance or lack of it to diverse H-bonding architectures indicates\nthat mechanistic elucidation of the self-organization process helps\nendow it with the same building block, both helical organizations\napproaching biological precision, and disorganized nonhelical arrangements.