Fluorinated meso-tetraaryl Pt(ii)-porphyrins: structure, photophysical, electrochemical, and phosphorescent oxygen sensing studies

Abstract

Fluorinated Pt(II)-porphyrins (F1–F8) were synthesized, characterized; photophysical and electrochemical studies were conducted. The electronic absorption spectra of the complexes exhibited an intense Soret band (392–402 nm) and two hypsochromically shifted visible (Q) bands (508–510 and 538–541 nm). They also exhibited two emission bands (701–721 nm and 651–658 nm), corresponding to the T → S₀ transition. The cyclic voltammetric studies of the porphyrins revealed the order of electron deficiency is as follows; F2 > F7 ≈ F8 > F5 > F4 > F3. The crystals of F3, F4, and F7 were structurally characterized and the crystal packing was mainly controlled by F⋯H, O⋯H, O⋯O, C⋯H close contacts. The oxygen sensing studies of the synthesized Pt(II)-porphyrins demonstrate that the highest sensitivity was observed for F8 compared to other complexes. The modified Stern–Volmer or two-site model provides the highest weighted quenching constant (K_SV) of 0.068 Torr⁻¹ for F8, which is twofold of the reference compound F1.