Work

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

Year: 2026

Type: article

Abstract: ABSTRACT High‐temperature gas‐phase reactions of 1,4‐C 4 F 8 I 2 with phenazine (PHNZ) afforded new thermally‐ and air‐stable derivatives with cyclo ‐C 4 F 8 substituents, viz. 1,2‐PHNZ(C 4 F 8 ), 2,3‐PHNZ(C 4 F 8 ), 1,2:6,7‐PHNZ(C 4 F 8 ) 2 , 1,2:7,8‐PHNZ(C 4 F 8 ) 2 , and 1,2:8,9‐PHNZ(C 4 F 8 ) 2 . Reactions in the presence of Cu powder resulted in reductive‐defluorination/aromatization of some of the cyclo ‐C 4 F 8 substituents to produce 2,3‐PHNZ(C 4 F 4 ), 2,3‐PHNZ(C 4 HF 3 ), and 1,2:6,7‐PHNZ(C 4 F 8 )(C 4 F 4 ), 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(C 4 F 4 ) and 2,3‐PHNZ(C 4 HF 3 ) and ordered π‐stacking in 1,2‐PHNZ(C 4 HF 3 ), 1,2‐PHNZ(C 4 F 4 ), 1,2‐PHNZ(C 4 F 8 ), and 2,3‐PHNZ(C 4 F 8 ). Low‐temperature gas‐phase photoelectron spectra of the PHNZ(C 4 F 8 ) 1,2 compounds show that they are strong electron acceptors, with the three PHNZ(C 4 F 8 ) 2 isomers having electron affinities exceeding that of C 60 . Cyclic voltammetry in acetonitrile shows that the five PHNZ(C 4 F 8 ) 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(C 4 F 8 ) 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(C 4 F 8 ) 1,2 derivatives and PHNZ(C 4 F 8 ) 1,2 − • anion radicals. Time‐resolved microwave conductivity (TRMC) measurements and photoluminescence spectra of blends of the PHNZ(C 4 F 8 ) 1,2 derivatives with the donor poly(3‐hexylthiophene) (P3HT) were recorded to assess the possible use of the new compounds in optoelectronic devices.

Source: Chemistry - A European Journal

DOI: 10.1002/chem.70921