Five topics pertaining to the unique chemistry of metalloporphyrins as observed in multi-metal complex systems are introduced. The topics include the following: (i) the unique chromatographic separation of cyclic porphyrins on modified silica gel; (ii) room temperature phosphorescence from the zinc porphyrin part in a zinc porphyrin/rhenium complex hetero dyad; (iii) the substituent effect, in the preparation of a readily soluble special-pair-type zinc porphyrin dimer/rhenium complex having efficient photocatalytic CO2 reduction ability; (iv) assessment of the excited triplet state of a special-pair-type zinc porphyrin dimer in macrocyclic multiporphyrin rings; and (v) solvation/desolvation indicators based on exclusive transformation between the head-head type and head-tail type of supramolecular co-ordination polymers composed of bis(zinc porphyrin)s.