Vernier templating and synthesis of a 12-porphyrin nano-ring

Vernier templates cut complex molecular synthesis down to size Chemists use template-directed synthesis to position molecular components so that they can be covalently linked into complex molecules that are not readily accessible by classical synthetic methods. But as larger structures are targeted, the synthesis of the templates themselves becomes challenging. O'Sullivan et al . now show that 'molecular Verniers', based on the principle of moiré pattern formation, can solve this problem. Using a Vernier template with six binding sites and molecular building blocks with four porphyrins acting as binding sites, the authors create a 12-porphyrin nano-ring with a diameter of 4.7 nanometres. The ease and efficiency of this synthesis establishes Vernier templating as a powerful new strategy for producing large monodisperse macromolecules. Templates are widely used to arrange molecular components so they can be covalently linked into complex molecules that are not readily accessible by classical synthetic methods. But, as larger structures are targeted, the synthesis of the templates themselves becomes challenging. It is now shown that 'molecular Verniers' can solve this problem: using a template with six binding sites and molecular building blocks with four porphyrins acting as binding sites, a 12-porphyrin nano-ring with a diameter of 4.7 nm is created. The ease and efficiency of this synthesis establishes Vernier templating as a powerful new strategy for producing large monodisperse macromolecules. Templates are widely used to arrange molecular components so they can be covalently linked into complex molecules that are not readily accessible by classical synthetic methods 1 , 2 , 3 , 4 , 5 , 6 , 7 . Nature uses sophisticated templates such as the ribosome, whereas chemists use simple ions or small molecules. But as we tackle the synthesis of larger targets, we require larger templates—which themselves become synthetically challenging. Here we show that Vernier complexes can solve this problem: if the number of binding sites on the template, n T , is not a multiple of the number of binding sites on the molecular building blocks, n B , then small templates can direct the assembly of relatively large Vernier complexes where the number of binding sites in the product, n P , is the lowest common multiple of n B and n T (refs 8 , 9 ). We illustrate the value of this concept for the covalent synthesis of challenging targets by using a simple six-site template to dir