text: Porphyrin complexes consist of a square planar MN core.  The periphery of the porphyrins, consisting of sp-hybridized carbons, generally display small deviations from planarity.  "Ruffled" or saddle-shaped porphyrins is attributed to interactions of the system with its environment.  Additionally, the metal is often not centered in the N plane.  For free porphyrins, the two pyrrole protons are mutually trans and project out of the N plane. These nonplanar distortions are associated with altered chemical and physical properties. Chlorophyll-rings are more distinctly nonplanar, but they are more saturated than porphyrins.