[reaction: see text] The crystal and molecular structures of two six-coordinate tin(IV)porphyrin phenolate complexes show that infinite cylindrical channels of uniform pore dimension are formed along the crystallographic c-direction. The underlying recognition event responsible for the porosity is an extremely tight intermeshing of the meso-tolyl units between layers which is a result of Sn-O...H interactions. Thermogravimetric analysis and differential scanning calorimetry have been used to characterize the sieve-like materials.