Theoretical Investigation On The Effect Of The Kinetic Stability On The Formation Of Fullerenes And Their Derivates

Because of the special geometric structure,chemical and physical properties,fullerenes and their exohedral derivatives have been widely investigated since the discovery of Ih-symmetric C60.At present,experimental synthesis and separation of the exohedral derivatives are mostly halogenated fullerenes,especially fullerene chlorides.Generally,there are two reaction pathways for the formation of the fullerene chlorides.The first pathway consists in addition of chlorine source(CCl4)involving arc-discharge of graphite.The second pathway involves the carbon soot from arc-discharge of graphite,followed in next step,by a chlorinated reaction under a low temperature via chlorinating agent such as VCl4 and SbCl5,and thus the formation of chlorinated fullerenes.In the second pathway,the pristine cages synthesized firstly should be previously regarded as to be thermodynamically favorable.However,several isolated fullerene chlorides via the second pathway were found that pristine cages are thermodynamically unfavorable.It is unclear about the formation mechanism of these fullerene chlorides.So it's important to perform theoretical study of these fullerene chlorides and the formation mechanism to help the understanding and design new fullerene materials.In this paper,by means of density functional theory(DFT)calculations,we firstly studied C100(417)Cl28 with a thermodynamically unfavorable pristine cage.Then we systematically studied the geometric structures and electronic properties of the tubular fullerenes with high kinetic stability.Finally,we investigated the role of kinetic stability for the growth pathway of fullerenes from C70 to C80.The results are summarized as follows:1.We proposed that C100(417)C128 had two reaction pathways:The first pathway was the chlorination of C100(417)directly.The second pathway was the reaction of the stable C102 isomer via chlorination,C2 and SW.2.We systematically studied the SPP tubular fullerene chlorides which pristine cages had a high kinetic stability.In addition,SPP tubular fullerene chlorides and(5,5)SWCNTs had similar geometric structures and electronic properties.3.Three growth pathways of C70-C80 were put forward for the first time.And the existence of chlorine sources can affect the growth pathways of fullerenes,leading to producing different products.These theoretical results provided a reliable elucidation on the obtained fullerenes and the exohedral derivatives.