Structural study of the novel deuterated calix[4]pyrrole complex d12‐meso‐tetrakis(4‐methoxyphenyl)‐meso‐tetramethylcalix[4]pyrrole–pyridine N‐oxide–acetonitrile (1/1/1)

Calix[4]pyrroles act as powerful receptors for electron-rich neutral guests and anionic guests in organic solvents. For the electron-rich neutral guest pyridine N-oxide, calix[4]pyrrole, with a deep cavity, provides an appropriate environment. The ability of calix[4]pyrrole to host binding guest mol­ecules is the result of hydrogen bonding, π–π, C—H⋯π and hydro­phobic inter­actions of the cavity. The novel title complex, C52H40D12N4O4·C5H5NO·C2H3N, based on d12-meso-tetra­kis­(4-meth­oxy­phen­yl)-meso-tetra­methyl­calix[4]pyrrole, has been assembled using an excess of pyridine N-oxide and is the first deuterated com­plex of calix[4]pyrrole. A single-crystal X-ray study shows that the receptor adopts a cone conformation with the N-oxide fragment encapsulated deep within the cavity. 1H NMR spectroscopy was used to probe the mol­ecular binding formation in CD3CN. The results are consistent with the single-crystal X-ray study in identifying that the pyridine N-oxide mol­ecule occupies the cavity of the calix[4]pyrrole mol­ecule. UV–vis spectroscopy revealed that the calix[4]pyrrole receptor molecules are able to form 1:1 inclusion complexes in CH3CN.