Fluorination pattern-dependent control of electronic properties in Zn(II)-porphyrins: A combined experimental and theoretical investigation

Fluorination is a powerful strategy for tuning the electronic structure and photophysical properties of porphyrins, thereby improving performance in sensing, catalysis, and biomedical applications. In this work, we present a combined experimental and computational investigation of how mesophenyl versus βpyrrolic fluorination pattern modulates the optical and redox properties of Zn(II) porphyrins. Commercially available ZnTPP is used as a benchmark, and compared to its mesoperfluorinated analog ZnTPPF20, and βoctafluorinated derivative ZnTPPβF8. UV–Vis absorption and emission measurements, and electrochemical data reveal progressive hypsochromic shifts and systematic stabilization of frontier orbitals upon fluorination, with βsubstitution producing the largest optical gap and strongest electrochemical LUMO stabilization. Population analyses and geometry optimizations performed at the M06-2X level, together with TD-DFT calculations using B3LYP, M06-2X, and CAM-B3LYP, consistently reproduce the experimental trends. The results show that mesoperfluorination primarily induces inductive electronic effects transmitted through the phenyl rings, whereas βfluorination combines strong electron withdrawal with steric distortion of the macrocycle, reducing conjugation and amplifying its impact on excitedstate energies. Overall, this study establishes clear structure–property relationships for fluorinated Zn(II) porphyrins and identifies β-fluorination as a particularly effective strategy for tuning LUMO energies, electron affinities, and photophysical responses.