Vernier‐Templated Synthesis,Crystal Structure,and Supramolecular Chemistry of a 12‐Porphyrin Nanoring |
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Authors: | Dr Dmitry V Kondratuk Dr Johannes K Sprafke Dr Melanie C O'Sullivan Dr Luis M A Perdigao Dr Alex Saywell Dr Marc Malfois Prof James N O'Shea Prof Peter H Beton Dr Amber L Thompson Prof Harry L Anderson |
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Institution: | 1. Department of Chemistry, University of Oxford, Chemistry Research Laboratory, Oxford, OX1 3TA (UK);2. School of Physics & Astronomy, University of Nottingham, Nottingham, NG7 2RD (UK);3. Diamond Light Source Ltd. Harwell Science and Innovation Campus, Didcot, OX11 0DE (UK) |
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Abstract: | Vernier templating exploits a mismatch between the number of binding sites in a template and a reactant to direct the formation of a product that is large enough to bind several template units. Here, we present a detailed study of the Vernier‐templated synthesis of a 12‐porphyrin nanoring. NMR and small‐angle X‐ray scattering (SAXS) analyses show that Vernier complexes are formed as intermediates in the cyclo‐oligomerization reaction. UV/Vis/NIR titrations show that the three‐component assembly of the 12‐porphyrin nanoring figure‐of‐eight template complex displays high allosteric cooperativity and chelate cooperativity. This nanoring–template 1:2 complex is among the largest synthetic molecules to have been characterized by single‐crystal analysis. It crystallizes as a racemate, with an angle of 27° between the planes of the two template units. The crystal structure reveals many unexpected intramolecular C?H???N contacts involving the tert‐butyl side chains. Scanning tunneling microscopy (STM) experiments show that molecules of the 12‐porphyrin template complex can remain intact on the gold surface, although the majority of the material unfolds into the free nanoring during electrospray deposition. |
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Keywords: | conjugation macrocycles porphyrinoids supramolecular chemistry template synthesis |
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