Scientists Crack the Code for Building Tiny Tubes from Molecules
Researchers have identified what determines whether molecules stack or fold when assembling into hollow nanotubes—a discovery that could accelerate manufacturing of nanomaterials for drug delivery and electronics. By understanding how molecular bonding preferences guide self-assembly, scientists can now predict and control the final structure, moving closer to reliable bottom-up production of engineered nanomaterials.
Originaltitel: Stacked or Folded? Impact of Chelate Cooperativity on the Self-Assembly Pathway to Helical Nanotubes from Dinucleobase Monomers
<p>Self-assembled nanotubesexhibit impressive biologicalfunctionsthat have always inspired supramolecular scientists in their effortsto develop strategies to build such structures from small moleculesthrough a bottom-up approach. One of these strategies employs moleculesendowed with self-recognizing motifs at the edges, which can undergoeither cyclization-stacking or folding-polymerizationprocesses that lead to tubular architectures. Which of these self-assemblypathways is ultimately selected by these molecules is, however, oftendifficult to predict and even to evaluate experimentally. We showhere a unique example of two structurally related molecules substitutedwith complementary nucleobases at the edges (i.e., G:C and A:U) for which the supramolecular pathway takenis determined by chelate cooperativity, that is, by their propensityto assemble in specific cyclic structures through Watson-Crickpairing. Because of chelate cooperativities that differ in severalorders of magnitude, these molecules exhibit distinct supramolecularscenarios prior to their polymerization that generate self-assemblednanotubes with different internal monomer arrangements, either stackedor coiled, which lead at the same time to opposite helicities andchiroptical properties.</p>