Important progress has been made in the synthesis of long conjugated single chiral carbon nanotubes by USTC

Carbon nanotubes (CNTs) can be regarded as all carbon based tubular conjugated polymers containing only SP 2 bonding atoms However, up to now, there is no report on the diameter specific CNT segment long conjugated polymers Recently, Du Pingwu, Professor of University of science and technology of China, has synthesized the first long conjugated chain segment of single chiral index single wall carbon nanotubes in the world through precise molecular design, and studied its electron transport and hole transport properties This work was published in J am Chem SOC (DOI: 10.1021 / JACS 9b10358) with the title of "a long π - converged poly para phenylene based polymer segment of single walled carbon nanotubles" Pure carbon nanotubes with single diameter and chirality have important application potential in the field of nanotechnology and electronics, but the synthesis of such carbon nanotubes is an important challenge in the field of synthetic chemistry and material chemistry The catalyst surface mediated growth method has great potential in the preparation of carbon nanotubes, but the purity of nanotubes is always a difficult problem to overcome From the perspective of precise structure control, the bottom-up method is one of the ideal strategies for the preparation of single chiral high-purity carbon nanotubes The typical ring-p-phenylene structure can be regarded as the shortest segment of armchair type carbon nanotubes The long conjugated extension of its structure is expected to obtain a new type of functional material similar to carbon nanotubes in structure In this work, based on a series of previous work on the synthesis and physical properties of new structures of carbon nanotubes, the researchers cleverly introduced the bifunctional structure into the curved conjugated small molecular carbon rings Subsequently, through the nickel catalyzed coupling reaction, the fragment was extended in one direction, and the diameter of the [8,8] single walled carbon nanotube long conjugated segment was constructed (Figure 1 a) The long conjugated polymer of CNTs was successfully synthesized by means of gel permeation chromatography, nuclear magnetic resonance, infrared spectroscopy and Raman spectroscopy (Fig 1 b-2d) It is found that the polymer film has obvious diffraction ring and certain crystallinity by wide angle X-ray diffraction Comparing the absorption, fluorescence, and fluorescence decay curves of monomers and conjugated polymers, it is found that the increase of conjugation degree also greatly improves the photophysical properties of polymers The carrier mobility test results show that the polymer has the ability to transport electrons and holes at the same time (Fig 1e-1f) The long conjugated chain segment is the first conjugated polymer in the world that is close to armchair type single wall carbon nanotubes in structure The results reported in this paper have achieved a new long conjugated structure for the synthesis of SWNTs with specific diameter, which provides a corresponding conjugated polymer template for the preparation of ultrapure SWNTs, and also provides an important reference for the preparation and property research of single chiral carbon nanotubes by solution method Fig 1 Study on the long conjugated segment structure PS1 and its properties of single chiral carbon nanotubes (a) PS1 structure and its luminescence in solution; (B-D) PS1 gel permeation chromatography, infrared and Raman spectroscopy characterization and comparison with monomer 8; (E-F) PS1 carrier transport properties, both electron transport and hole transport properties (source: J am Chem SOC) Huang Qiang, Ph.D student, Department of materials science and engineering, School of chemistry and materials science, University of science and technology of China, is the first author of the paper, Professor Du Pingwu is the only corresponding author of the paper, the theoretical calculation part is completed by Zhuang Guilin, associate professor of Zhejiang University of technology, and the carrier transport property is completed in cooperation with Professor Yang Shangfeng, University of science and technology of China The research was supported by NSFC, the Ministry of science and technology, Hefei National Research Center for micro scale material science, and the Collaborative Innovation Center for energy and material chemistry.