Bridging [8]cyclo-para-phenylene with carbonyl and dicyanovinylene functionalities to access electron-deficient...

Despite the fantastic developments in the last fifteen years, nanohoops still remain rarely incorporated in organic electronic devices. In particular, electron-poor nanohoops for n-type Organic Field-Effect Transistors (OFETs) are almost completely absent from the literature. In this work, by bridging [8]cyclo-para-phenylene ([8]CPP) with four carbonyl or dicyanovinylene functional junctions, we managed to significantly depress the LUMO energy levels of CPP-like molecules, rendering the corresponding nanohoops compatible with an incorporation into n-type OFETs. We discuss herein the synthesis and the electrochemical and photophysical properties of two electron-deficient nanohoops, namely [8]CPP(CO)₄ and [8]CPP(DCV)₄. Although no FE mobility was recorded for the benchmark [8]CPP, an n-type saturated FE mobility of 4.4 × 10^-5 cm² V^-1 s^-1 was measured for the dicyanovinylene nanohoop [8]CPP(DCV)₄. Other OFET parameters (such as threshold voltage V _TH = 13.7 V and subthreshold slope SS = 1.86 V dec^-1) are the most efficient among those reported for n-type OFETs based on a nanohoop, revealing the potential of this class of materials. The OFET output characteristics are also presented, demonstrating the possibility of integrating this type of device into an electronic circuit.