We report the quantum yields for singlet oxygen production by a series of porphyrazines (pz) of the form M[pz(A_n;B_4−n)] (^{Scheme 1}), where the peripheral substituent A is [S–R]₂ with R = (CH₂CH₂O)₃H, B is a fused α,α′-dialkoxybenzo group and M = 2H, Mg or Zn. These compounds show intense near-IR absorbance/emission (longest wavelength emission, ∼830 nm). Their solubilities vary with R, whereas their optical properties do not. We show that singlet oxygen sensitization by these luminescent compounds can be “tuned” from essentially off to on by varying n and selection among M = 2H, Mg or Zn. The quantum yields vary ca 60-fold within the set of compounds studied, from ϕ_Δ = 0.007 for compound 3 to ϕ_Δ = ∼0.4 for compound 11.