Electron‐Deficient Phenazines: Synthesis, Structures, Redox, and Optoelectronic Properties in the Gas Phase, in Solution, and in the Solid State

High-temperature gas-phase reactions of 1,4-C₄F₈I₂ with phenazine (PHNZ) afforded new thermally- and air-stable derivatives with cyclo-C₄F₈ substituents, viz. 1,2-PHNZ(C₄F₈), 2,3-PHNZ(C₄F₈), 1,2:6,7-PHNZ(C₄F₈)₂, 1,2:7,8-PHNZ(C₄F₈)₂, and 1,2:8,9-PHNZ(C₄F₈)₂. Reactions in the presence of Cu powder resulted in reductive-defluorination/aromatization of some of the cyclo-C₄F₈ substituents to produce 2,3-PHNZ(C₄F₄), 2,3-PHNZ(C₄HF₃), and 1,2:6,7-PHNZ(C₄F₈)(C₄F₄), which are formally tri- or tetrafluoro derivatives of benzo[a]phenazine. Single-crystal x-ray diffraction structures of these compounds demonstrate the planarity of 2,3-PHNZ(C₄F₄) and 2,3-PHNZ(C₄HF₃) and ordered π-stacking in 1,2-PHNZ(C₄HF₃), 1,2-PHNZ(C₄F₄), 1,2-PHNZ(C₄F₈), and 2,3-PHNZ(C₄F₈). Low-temperature gas-phase photoelectron spectra of the PHNZ(C₄F₈)_1,2 compounds show that they are strong electron acceptors, with the three PHNZ(C₄F₈)₂ isomers having electron affinities exceeding that of C₆₀. Cyclic voltammetry in acetonitrile shows that the five PHNZ(C₄F₈)_1,2 compounds exhibit reversible one-electron reductions with large positive shifts in their reduction potentials relative to unsubstituted PHNZ. Spectroelectrochemical absorption and EPR spectra of PHNZ(C₄F₈)_1,2 ^{- •} anion radicals and extensive DFT calculations revealed the significant role that the different substitution patterns have on determining the optoelectronic properties of the PHNZ(C₄F₈)_1,2 derivatives and PHNZ(C₄F₈)_1,2 ^{- •} anion radicals. Time-resolved microwave conductivity (TRMC) measurements and photoluminescence spectra of blends of the PHNZ(C₄F₈)_1,2 derivatives with the donor poly(3-hexylthiophene) (P3HT) were recorded to assess the possible use of the new compounds in optoelectronic devices.