Host‐Guest Interactions Facilitated by Chalcogen Bonding within Selenadiazole Functionalised Porphyrin Nanotubes

Abstract

The structural rigidity of tetrakis(4‐pyridyl)porphyrin (TPyP) has been utilised to prepare a robust novel porous coordination polymer of composition Cd2(TPyP)(sez)2 (TPyP = 5,10,15,20‐tetra(4‐pyridyl)porphyrin, sez = 1,2,5‐benzoselenadiazole‐5‐carboxylate). The coordination polymer may be described as a hexagonal porphyrin nanotube (PNT) and has the potential to bind guest molecules through chalcogen bonding. Single crystal X‐ray diffraction (SCXRD) data indicate an internal pore diameter ~9 Å which represents ~35% of the crystal volume. Immersion of the PNTs in solvents such as DMSO and CS2 result in the incorporation of these molecules within the nanotubes with chalcogen bonding between host and guest. The crystallographic guest‐inclusion investigations are complemented by solid‐state 77Se, 13C, 113Cd and 2H NMR studies which provide insights into dynamic behaviour. The porosity of the crystals was further explored using gas adsorption experiments, indicating the reversible uptake of CO2, CH4, H2 and N2. Structure‐function relationships are clearly established from complementary crystallographic, NMR and adsorption investigations.