Thymine functionalised porphyrins, synthesis and heteromolecular surface-based self-assembly?

Chemical Science Pub Date: 2014-12-11 DOI: 10.1039/C4SC03531C

Abstract

The synthesis and surface-based self-assembly of thymine-functionalised porphyrins is described. Reaction of 1-formylphenyl-3-benzoyl-thymine with suitable pyrollic species leads to the formation of tetra-(phenylthymine)porphyrin (tetra-TP) or mono-thymine-tri-(3,5-di-tert-butylphenyl)porphyrin (mono-TP). Single crystal X-ray diffraction studies demonstrate the self-association of mono-TP in the solid state through thymine?thymine hydrogen-bonding interactions but in solution this interaction (Kd = 6.1 ± 3.0 M?1) is relatively weak in comparison to the heteromolecular interaction between mono-TP and 9-propyladenine (K = 91.8 ± 20.5 M?1). STM studies of the tetratopic hydrogen-bonding tecton, tetra-TP, deposited on an HOPG substrate reveal the formation of an almost perfectly square self-assembled lattice through thymine?thymine hydrogen-bonding. Co-deposition of tetra-TP with 9-propyladenine leads to the adoption of preferable thymine?adenine interactions leading to the formation of a heteromolecular tetra-TP?9-propyladenine hydrogen bonded array including both Watson–Crick thymine?adenine interactions and adenine?adenine hydrogen-bonding. The studies demonstrate a pathway for the self-assembly of tetratopic hydrogen-bonding tectons and the use of preferential heteromolecular thymine?adenine interactions for the disruption of the homomolecular tetra-TP array. Studies of the self-assembly of tetra-TP and 9-propyladenine demonstrate a strong dependence on overall concentration and molar ratio of components indicating the importance of kinetic effects in surface self-assembly processes.

Graphical abstract: Thymine functionalised porphyrins, synthesis and heteromolecular surface-based self-assembly
Recommended Literature