Molecular tweezers with a rotationally restricted linker and freely rotating porphyrin moieties. Issue 34 (14th August 2018)

• Record Type: Journal Article
• Authors: Murphy, Rhys B.; Pham, Duc-Truc; White, Jonathan M.; Lincoln, Stephen F.; Johnston, Martin R.
• Is Part Of: Organic & biomolecular chemistry. Volume 16:Issue 34(2018)
• Page Start: 6206
• Page End: 6223
• Publication Date: 2018-08-14
• Subjects: Chemistry, Organic -- Periodicals; Bioorganic chemistry -- Periodicals; Chemistry, Physical organic -- Periodicals; 547
• DOI: 10.1039/c8ob00944a
• Languages: English
• ISSNs: 1477-0520

Abstract

Abstract : The different host–guest behaviour of non-interconvertible bis-porphyrin tweezer isomers was examined, contributing to ongoing discussions regarding rigidity/flexibility and preorganisation in synthetic receptors. Abstract : The effect of the degree of conformational rigidity and/or flexibility on preorganisation in artificial molecular receptors continues to be actively explored by supramolecular chemists. This work describes a bis-porphyrin architecture, linked via a rigid polycyclic backbone, in which a sterically bulky 2, 3, 5, 6-tetramethylphenyl diimide core restricts rotation to afford two non-interconvertible tweezer conformations; syn - and anti -. After separation, the host–guest chemistry of each conformation was studied independently. The difference in host geometry allows only the syn -conformation to form a strong 1 : 1 bis-porphyrin complex with the diamino ligand 1, 4-diazabicyclo[2.2.2]octane (DABCO) ( K 11 = 1.25 × 10 8 M −1 ), with the anti -conformation adopting a 2 : 2 sandwich complex with DABCO ( K 22 = 5.57 × 10 17 M −3 ).