,

: The title compound was synthesized in near-quantitative yield using nucleophilic aromatic substitution of 4,4 (cid:48) -(hexaﬂuoroisopropylidene)diphenol ( BPAF ) with perﬂuoropyridine ( PFP ). The purity and structure were determined by NMR ( 1 H, 13 C, 19 F), GC–EIMS, and single-crystal X-ray crystallography.


Introduction
Perfluoropyridine (PFP) is a versatile starting material for nucleophilic aromatic substitution (SNAr), reacting with a broad range of O-, N-, S, and C-nucleophiles via exclusive attack at the 4-para-position [1,2] (Scheme 1). Sequential addition to the 2,6-ortho-positions can also be accomplished leaving the 3,5-meta-fluorines intact. Furthermore, PFP has demonstrated utility as a protecting group for phenols [3,4], fluorinating reagent [5,6] and can also be defluorinated via site-selective catalysis [7,8]. Motivation for incorporating PFP into polymer frameworks led to the development of a pool of new fluoropolymer architectures, including highly processable polyarylethers, fluorosilicones, dendrimers, and high-char-yield resins for demanding aerospace applications [9], in addition to expanding the utility of hydrofluoroethers (HFEs) [10]. These unique materials have shown marked improvement over conventional state-of-the-art polymers in processabilty, mechanical strength, and compatibility with hybrid composites, while retaining high-temperature resistance. More recently, PFP was used for the mechanochemical synthesis of perfluoropolyether oligomers, which expands its utility for solvent-free polymerizations [11]. As an extension of this work, herein, we detail the synthesis and structural characterization of a PFP end-capped bisphenol, a new type of monomer for SNAr polymerizations.

Introduction
Perfluoropyridine (PFP) is a versatile starting material for nucleophilic aromatic substitution (SNAr), reacting with a broad range of O-, N-, S, and C-nucleophiles via exclusive attack at the 4-para-position [1,2] (Scheme 1). Sequential addition to the 2,6-ortho-positions can also be accomplished leaving the 3,5-meta-fluorines intact. Furthermore, PFP has demonstrated utility as a protecting group for phenols [3,4], fluorinating reagent [5,6] and can also be defluorinated via site-selective catalysis [7,8]. Motivation for incorporating PFP into polymer frameworks led to the development of a pool of new fluoropolymer architectures, including highly processable polyarylethers, fluorosilicones, dendrimers, and high-char-yield resins for demanding aerospace applications [9], in addition to expanding the utility of hydrofluoroethers (HFEs) [10]. These unique materials have shown marked improvement over conventional state-of-the-art polymers in processabilty, mechanical strength, and compatibility with hybrid composites, while retaining high-temperature resistance. More recently, PFP was used for the mechanochemical synthesis of perfluoropolyether oligomers, which expands its utility for solvent-free polymerizations [11]. As an extension of this work, herein, we detail the synthesis and structural characterization of a PFP end-capped bisphenol, a new type of monomer for SNAr polymerizations.

Materials and Methods
Chemicals and solvents were purchased as reagent grade through commercial suppliers. 1 H-, 13 C{ 1 H}-, and 19 F-NMR spectra were recorded on a Jeol 500 MHz spectrometer. Chemical shifts are reported in parts per million (ppm), and the residual solvent peak was used as an internal reference: proton (chloroform δ 7.26), carbon (chloroform, C{D} triplet, δ 77.0 ppm), and fluorine (CFCl3 δ 0.00). NMR data are reported as follows: chemical shift, multiplicity, coupling constants (Hz), and integration. Gas chromatography/mass spec-

Materials and Methods
Chemicals and solvents were purchased as reagent grade through commercial suppliers. 1 H-, 13 C{ 1 H}-, and 19 F-NMR spectra were recorded on a Jeol 500 MHz spectrometer. Chemical shifts are reported in parts per million (ppm), and the residual solvent peak was used as an internal reference: proton (chloroform δ 7.26), carbon (chloroform, C{D} triplet, δ 77.0 ppm), and fluorine (CFCl3 δ 0.00). NMR data are reported as follows: chemical shift, multiplicity, coupling constants (Hz), and integration. Gas chromatography/mass spec-

Materials and Methods
Chemicals and solvents were purchased as reagent grade through commercial suppliers. 1 H-, 13 C{ 1 H}-, and 19 F-NMR spectra were recorded on a Jeol 500 MHz spectrometer. Chemical shifts are reported in parts per million (ppm), and the residual solvent peak was used as an internal reference: proton (chloroform δ 7.26), carbon (chloroform, C{D} triplet, δ 77.0 ppm), and fluorine (CFCl 3 δ 0.00). NMR data are reported as follows: chemical shift, multiplicity, coupling constants (Hz), and integration. Gas chromatography/mass spectrometry (GC-MS) analysis was performed on an Agilent 7890 gas chromatograph coupled to an Agilent 5975C electron impact mass spectrometer with initial 2 min temperature hold at 80 • C, followed by a temperature gradient of 80 to 250 • C at 15 • C/min.

Single-Crystal XRD Determination
The single crystal X-ray diffraction studies were carried out on a Rigaku Synergy-i single-crystal diffractometer equipped with a Mo K α radiation source (λ = 0.71073) and a Bantam HyPIX-3000 direct photon-counting detector. A 0.379 × 0.298 × 0.242 mm 3 translucent colorless prism crystal was mounted on a Cryoloop with Paratone-N oil. Data were collected in a nitrogen gas stream at 100.00(15) K using scans. The crystal-todetector distance was 40 mm using an exposure time of 10 s with a scan width of 0.50 • . Data collection was 100.0% complete to 25.242 • in θ. A total of 81,813 reflections were collected. Of these, 5176 reflections were found to be symmetry-independent, with an R int of 0.0340. Indexing and unit cell refinement indicated a primitive orthorhombic lattice. The space group was found to be Pbca. The data were integrated using the CrysAlisPro software program (Rigaku Oxford Diffraction, 2020, 1.171.42.49) and scaled using an empirical absorption correction implemented in the SCALE 3 ABSPACK software program, as well as a numerical absorption correction based on Gaussian integration over a multifaceted crystal model. Solution by direct methods (SHELXT-2014) produced a complete phasing model consistent with the proposed structure. All non-hydrogen atoms were refined anisotropically by full-matrix least squares (SHELXL-2008). All carbon bonded hydrogen atoms were placed using a riding model with their positions constrained relative to their parent atom using the appropriate HFIX command in SHELXL.