Theoretical study on aromatic and open-shell characteristics of carbon nanobelts composed of indeno[1,2-b]fluorene units: dependence on the number of units and charge states

Highly efficient charge transport across carbon nanobelts

Carbon nanobelts (CNBs) are a new form of nanocarbon that has promising applications in optoelectronics due to their unique belt-shaped π-conjugated systems. Recent synthetic breakthrough has led to the access to various CNBs, but their optoelectronic properties have not been explored yet. In this work, we study the electronic transport performance of a series of CNBs by incorporating them into molecular devices using the scanning tunneling microscope break junction technique. We show that, by tuning the bridging groups between the adjacent benzenes in the CNBs, we can achieve remarkably high conductance close to 0.1 G₀, nearly one order of magnitude higher than their nanoring counterpart cycloparaphenylene. Density functional theory-based calculations further elucidate the crucial role of the structural distortion played in facilitating the unique radial π-electron delocalization and charge transport across the belt-shaped carbon skeletons. These results develop a basic understanding of electronic transport properties of CNBs and lay the foundation for further exploration of CNB-based optoelectronic applications.

Indeno[2,1-a]fluorene-11,12-dione radical anions:synthesis,characterization and property

The one-electron reduction reactions of indeno[2,1-a]fluorene-11,12-dione ( IF ) with various alkali metals bring about the radical anion salts. The different structures and properties are characterized by single crystal X-ray diffraction, electron paramagnetic resonance (EPR) spectroscopy, superconducting quantum interference device (SQUID) measurements and physical property measurement system (PPMS). IF •- K + (18-c-6) is regarded as a one-dimensional magnetic chain through C-H-C interaction. Theoretical calculations and magnetic results prove that [ IF •- K + (15-c-5)] 2 is a dimer with an open-shell ground state. IF •- Na + (15-c-5) and IF •- K + (cryptand) are monoradical anion salts. IF 2 •- Li + possesses unique π-stack structure with an interplanar separation less than 3.46 Å, making it a semiconductor ( δ RT = 1.9 Χ 10 -4 S•cm -1 ). This work gives a wealth of insights into multifunctional radical anions, and makes the design and development of different functional radicals attractive.