Scanning tunneling microscopy (STM) has shown that template-free nanorings (c-PNs) with N > 8 form highly ordered arrays, on a graphite surface, with the porphyrins parallel to the surface. The larger nanorings (N = 24-40) also form stacked aggregates on a gold surface, if deposited in the absence of pyridine. 16 However, STM images of these species only provide information in two dimensions, and lack atomic resolution.