Fixation of Neutral Molecules in the Binding Cavity of Nonplanar Porphyrins Ð A Third Dodeca- phenylporphyrin Modification with NH-Solvent Hydrogen Bonding

A third crystalline modification of dodecaphenylporphyrin is described in which the pyrrole ni­ trogen atoms are hydrogen-bonded to two etha­ nol molecules. This is the first crystallographic proof for the accessibility of nitrogen atoms in saddle-distorted free base porphyrins for hy­ drogen bonding. No such coordination is possible in either planar or ruffled porphyrins. Thus, the possibility exists to utilize conformationally dis­ torted porphyrins for the binding of neutral mole­ cules.