The synthesis of a borylated Ni2+ porphyrin and its application as a versatile precursor for building up functional ortho-substituted tetraaryl porphyrin architectures is reported. This precursor porphyrin provides the basis for efficient modular syntheses of porphyrin compounds with covalently attached axial ligands which are important as enzyme model complexes, electron transfer dyads, and many other applications. In the present study, the precursor porphyrin was used for the synthesis of molecular spin switches which previously showed high potential as photoresponsive contrast agents for magnetic resonance imaging.