Tube-shaped molecular structures built from acylphloroglucinols: an ab initio and DFT study

Molecular structures containing a cavity encounter a variety of applications, from hosts to ions or to smaller molecules to building units for nanomaterials. Previous computational studies of bowl-shaped structures built from acylphloroglucinol (ACPL) units had shown that ACPLs can form the deepest cavities among hydroxybenzenes. The current work considers tube-shaped structures built from ACPL units. To ensure that the two rims have equal size, the orientations of the even-number units are alternated, so that each rim contains alternating RCO and OH-only groups from neighbouring units. Tubes with 4 and 6 units and different R chains have been calculated at the HF/6-31G(d,p) and DFT/B3LYP/6-31+G(d,p) levels. In each rim, the space between two consecutive RCO groups contains three consecutive intramolecular hydrogen bonds (IHBs). The computable properties of the calculated tubes are analysed in detail, with particular attention to the tubes’ geometric features (including the size of the hollow inner part) and to the characteristics and roles of the IHBs. It is inferred that the characteristics of these tubes (including the tight texture of their ‘walls’, the electron-richness of their cavities, and the possibility of expanding their size through the addition of more monomeric units) suggest potential interest for practical applications.