Thymine functionalised porphyrins, synthesis and heteromolecular surface-based self-assembly
Slater, Anna G. and Hu, Ya and Yang, Lixu and Argent, Stephen P. and Lewis, William and Blunt, Matthew O. and Champness, Neil R. (2014) Thymine functionalised porphyrins, synthesis and heteromolecular surface-based self-assembly. Chemical Science, 6 . pp. 1562-1569. ISSN 2046-2069
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.
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