Solution ozonolysis of C70: stable products and chemiluminescence

Abstract

For the first time the total and relative contents of the stable ozonolysis products of fullerene C70 solutions were identified by IR spectroscopy and elemental and chemical analyses. At the 100% conversion of C70 a mixture of products corresponding to the empirical formula C70O14.3H0.21 (epoxides: polyketones: polyesters: secondary fullerene ozonides (SFOZ): acids = 1.07: 6: 6: 0.21: 1.02) is formed. The content of polyketones, polyesters, acids, and SFOZ increases during the whole ozonolysis time (1 h). The number of oxygen atoms in epoxides C70On (n = 1–4) is lower than that in epoxides C60On (n = 1–6) formed by the ozonolysis of fullerene C60. The kinetic curve of accumulation of epoxides C70On (n = 1–4) passes through a maximum, which is observed 0.5 min after the beginning of ozonolysis. No epoxides were identified among the products 3.5 min after the ozonolysis. The photoluminescence (PL) (λmax = 645 and 685 nm) of fullerene polyketones in glassy EtO2/EtOH solutions frozen at 77 K was observed. This PL is much brighter, than that of polyketones formed upon the ozonolysis of fullerenes C60. For the first time the chemiluminescence (CL) was detected and studied upon the ozonolysis of C70 solutions at 300 K. The CL emitters are excited states of fullerene polyketones. The CL spectrum is partially overlapped with the known CL spectrum appeared upon the ozonolysis of C60 (λmax = 685 nm) but contains the greater number of maxima (λmax = 645 and 685 nm), which is related to a lower symmetry of the C70 oxidation products.