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Molecular and Carbon Nanoelectronics
Published in Sergey Edward Lyshevski, Nano- and Micro-Electromechanical Systems, 2018
It is possible to substitute carbon with the heteroatoms (alkali, alkaline earth metals, transition metals, etc.) in the exterior surface of fullerenes. For example, silicon can be doped, and three-dimensional SixCxx complexes result. Silicon-doped fullerenes have been fabricated utilizing laser ablation processes (using Si/C composite rods), direct growth, photofragmentation, chemical vapor deposition, etc. Considering SiCxx (xx = 58−61) and Si2Cxx (xx = 58, 60, …), it is evident that complex bridge-, edge-, and other SixCxx topological configurations result. This allows one to synthesize complex three-dimensional nano-IC functional topologies. In addition to the silicon-doped fullerenes, boron/nitrogen-doped heterofullerenes C60−2x(BN)x are another important inroad for fullerene-centered nanoelectronics. Replacing one carbon on the fullerene cage with nitrogen leads to C59N, and one electron is added to the π-system of C60. The modified anions of C60 exhibit distinct properties. The C59N heterofullerene is a radical with an unpaired electron localized on the carbon atom C1 closest to the nitrogen. In this doped fullerene, C1 becomes fourfold coordinated as C59HN or (C59N)2. Among other heterofullerenes, C48N12 and C48B12 are very promising for nanoelectronics. Those and other doped fullerenes can be uniquely utilized.
Transition metals doped fullerenes: structures – NLO property relationships
Published in Molecular Physics, 2019
Shuo Liu, Feng-Wei Gao, Hong-Liang Xu, Zhong-Min Su
The heterofullerene, in which at least one carbon atom that forms the fullerene carbon cage is replaced by a heteroatom. Since Smalley and co-workers reported on the gas phase formation and mass spectrometric detection of borafullerenes in 1992, C60-nBn(n = 1–6), generated by laser vaporisation of graphite/boron nitride composites [51], heterofullerene became the third fundamental group of modified fullerenes. In the same year, later, the preparation of CnNm clusters formed by contact-arc vaporisation in a partial N2 or NH3 atmosphere was reported [52]. In 1995, Wudl carried out the first synthesis of heterofullerenes in mass quantities with the preparation of azafullerene(C59N) [53]. At the same time, a group of Mattay [52] and Hirsch [54], respectively revealed that certain N-substituted fullerenes and azahomofullerenes are suitable precursors for forming positively charged heterofullerens such as C59N+ and C69N+. From then on, the real preparative heterofullerene chemistry began and reached a mature state, at the same time, metal-doped fullerene also got some achievements, in 1992 group of Farid observed electron spin resonance (ESR) signals in Na3C60, K3C6, Rb3C60 and Cs3C60, they found near transition temperatures the ESR susceptibility changed from antiferromagnetic to paramagnetic behaviour [55]. In 1999, Billas and his co-researchers synthesised C60Mx and C70Mx clusters where M═Fe, Co, Ni, Rh, Ir and Si, they complemented their study with ab-initio calculations on C59Si and C58Si2 [56]. Then Akari Hayashi obtained C58Pt- and C58Pt+ by laser ablation and analysed with DFT calculations in 2004 [57]. Up to now, compared with non-metal-doped fullerenes, reports on the development of metal-doped fullerenes are kind of limited.