The effect of selective metallation of free-base ionic porphyrin tectons on the structural, electronic, and optical properties of their crystalline self-assemblies is presented. Rod-like crystals were prepared by combining meso-tetra(N-methyl-pyridyl)porphyrin, H₂TMPyP, and meso-tetra(4-sulfonatophenyl)porphyrin, H₂TSPP, with either a nickel or copper ion contained in one of the synthons. These materials were characterized by optical microscopy, X-ray diffraction methods, thermogravimetric analysis, diffuse reflectance UV-visible and luminescence spectroscopies, and conductivity and photoconductivity measurements. All the porphyrin assemblies formed monoclinic P2_1/C crystals with pseudo-hexagonal cross sections. Thermogravimetric experiments indicate that water molecules associated with crystals desorb at two different rates. In addition, the temperature dependent XRD showed that the dehydration of the porphyrin solids causes modification in the crystals which is completely reversible (i.e., crystals return to their original structural geometry upon rehydration). All the metallated porphyrin crystals exhibit dark conductivity at moderately high temperatures and become more conducting upon photoexciation. The primary charge carriers in these solids upon photoexcitation are electrons and the charge recombination mechanism follows monomolecular kinetics. Quantum mechanical calculations provide the electronic band structure, the density of states and explain the experimental prompt photoconductivity measurements of the porphyrin self-assemblies.