Peripherally mixed halogenated boron subphthalocyanines

Abstract

The goal of this study was to develop mixtures of peripherally halogenated boron subphthalocyanines (BsubPcs) to explore these macrocycles as mixed alloys for applications within the organic electronic space. These halogenated BsubPc mixtures were synthesized by reacting mixtures of commercially available phthalonitriles, namely 4,5-dichlorophthalonitrile (Cl2-pn), 4,5-difluorophthalonitrile (F2-pn), tetrachlorophthalonitrile (Cl4-pn), and tetrafluorophthalonitrile (F4-pn), with boron trichloride (BCl[Formula: see text] to achieve mixed halogenation upon formation of the BsubPcs. More specifically, as named, Cl2-pn + F2-pn and Cl4-pn + F4-pn mixtures were used to form Cl-Cl[Formula: see text]F[Formula: see text]BsubPc and Cl-Cl[Formula: see text]F[Formula: see text]BsubPc, respectively. To establish a firm synthetic methodology, the reaction kinetics of forming the BsubPc mixtures from their respective phthalonitrile mixtures were compared to the kinetics of the standard procedures forming the individual BsubPcs, for example, Cl-Cl[Formula: see text]BsubPc from Cl4-pn. As we use BCl3 to form the BsubPcs, the axial bond is in general chloride, but we observed again random fluoride axial exchange, and therefore moved to the second step to have complete axial fluorination. Crude mixed halogenated BsubPcs were sublimed at high purities to enable physical characterization, including a study of UV-Vis absorption spectra differentiation, and cyclic (CV) and differential pulse voltammograms (DPV) electrochemical differentiation. We also did density functional theory (DFT) calculations for points of physical properties comparison. The comparison points are together with fully peripherally chlorinated Cl[Formula: see text]BsubPcs and fluorinated F[Formula: see text]BsubPcs. Given the outcomes, we foresee in future studies the ability to tune different ratios of peripherally halogenated BsubPc mixtures via synthetic tools, to enable tuning of the HOMO LUMO energy levels, which could consequently tune their application and performance in organic electronics.