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Fullerenes
Published in Mihai V. Putz, New Frontiers in Nanochemistry, 2020
Fullerenes are a family of molecules composed exclusively by elemental carbon. In the fullerene molecules, the carbon atoms are sp2 hybridized and closed in a polyhedral cage structure (Kroto et al., 1991). The sp2 hybridization is typical of the carbon atoms disposed in a graphene sheet (a single layer of carbon atoms in graphite). In a graphene sheet, the sp2 hybridized carbon atoms are arranged in a series of condensed hexagonal rings without strain. The introduction of a single pentagonal ring in such a graphene plane causes a curvature in the plane (Cataldo, 2002). With 12 pentagons, the entire graphene sheet undergoes a closure into a fullerenic polyhedron. In this situation, the sp2 hybridized carbon atoms undergo a considerable strain and distortions that the pure aromatic character of a graphene plane is lost. Thus, the π electrons which are delocalized over the entire graphene plane become localized and weakly cross-conjugated in a fullerene cage (Haddon et al., 1986).
Optimization for the extraction of polyphenols from Inonotus obliquus and its antioxidation activity
Published in Preparative Biochemistry & Biotechnology, 2021
Yu Wang, Fengju Ouyang, Chunying Teng, Juanjuan Qu
The main absorption peaks of IOP were determined by UV-vis spectrum at 275 nm and 380 nm (Figure S2). The absorption peak at 275 nm indicated that there were benzene rings. The absorption peak at 380 nm suggested that a double bond structure containing heteroatoms might exist. The cross-conjugated system consisting of cinnamoyl and benzoyl groups in most flavonoid molecules generally had two main absorption peak bands, at 220–280 nm and 300–400 nm.[24] Thus, it is consistent with adsorption characteristics flavonoids UV absorption peak and maybe initially identified as the polyphenols.