Hydrazine-Modified Topology-Dependent Conductivity of Cyclic NDI as a Molecular Circuit

Significant conductance enhancement can be achieved by topology modification of n-type semiconducting naphthalenediimide (NDI) as a molecular circuit. Hydrazine not only reduces electron-deficient NDI to NDI^•–radical anions but also modifies the topology by selectively replacing the amino acid methyl esters from NDI 1 and forms a cyclic NDI nanorim. On treatment with hydrazine, the NDI 1 emission band at 525 nm gradually disappears, and a new band appears at 607 nm, presumably due to NDI oligomer formation. Eventually, a shiny black, almost insoluble precipitate of the NDI nanorim appeared. The cyclic NDI nanorim was characterized by powder X-ray diffraction, high-resolution mass spectrometry, Fourier transform infrared, and ¹³C CP-MAS NMR spectroscopy. Cyclic voltammetry (CV) of NDI 1 possesses two sequential one-electron cathodic waves at −0.4661 and −0.9456 V versus Ag/Ag⁺ due to NDI^•– and NDI^2– formation. However, CV of the NDI nanorim reveals four distinct reversible one-electron waves due to electronic communication between the four NDI redox centers within the nanorim. The I–V measurements show sevenfold conductance enhancements by topology modification from linear NDI to a nanorim.