Magnesium Tetra(phenylethynyl)porphyrin: Stepwise Synthetic Route, Crystal Structures, and Longer Singlet Excited-State Lifetime than Zinc Congener.

Magnesium tetra(arylethynyl)porphyrins (aryl=Ph or 4-CF C H ) were synthesized via 5,15-di(triisopropylsilylethynyl)-10,20-di(arylethynyl)porphyrin to ensure good solubility and high synthetic yields. Magnesium tetra(phenylethynyl)porphyrin was subjected to structural analyses and physico-chemical characterization. Single-crystal X-ray analysis revealed porous crystal structures featuring solvent molecules in their pores. From femtosecond transient absorption measurements we concluded that the singlet excited-state lifetime of magnesium tetra(phenylethynyl)porphyrin is with 7.4 ns substantially longer than that of its zinc congener with 2.8 ns; this is attributed to the lower atomic weight of magnesium compared with zinc.