A 2D perchlorinated sp2-carbon framework

Abstract

Two-dimensional (2D) π-conjugated polymers are promising electronic materials with diverse properties controlled by varying the structure of organic building blocks. We here report an organic framework with perchlorotriphenylmethyl (PTM) radical nodes, synthesized through dehalogenative thermolysis polymerization of tris(iodotetrachlorophenyl)methane. The resulting C-C-linked P2PTM is characterized by X-ray photoelectron, NMR, Raman, and FTIR spectroscopies and X-ray diffraction. Exfoliated, layered 2D sheets can be imaged with TEM and AFM. N2 adsorption experiment indicates a permanent porosity with a surface area of 150 m2/g, and dynamic vapor sorption shows a specific adsorption of one chloroform molecule per P2PTM unit cell, in line with modeling. DFT calculations predict degenerate Mott-insulating antiferromagnetic and ferromagnetic states, while the semi-metallic closed-shell configuration is less stable by ∼1 eV. Experimentally, P2PTM is a low-bandgap black solid with moderate electrical conductivity (∼4 × 10−4 S cm−1), gate-modulated ambipolar charge transport and paramagnetic behavior down to 1.9 K.