Chemiluminescence during thermolysis of fullerene C60 derivatives containing reactive oxygen

Abstract

Chemiluminescence (CL) of fullerenes was first de tected in the ozonolysis of C60 solutions 1,2 and later in the oxidation of sodium fullerides with a CeIV complex.3 In this work, a new type of the CL of fullerenes was observed during the thermolysis of complex C60 oxides (1) formed by the ozonolysis of C60 solutions and containing reac tive oxygen (RO)4 and epoxide,5 carbonyl,6,7 and ester groups.7 Earlier,8,9 chemiluminescence in the thermoly sis of organic peroxides was reported. Chemiluminescence was measured by a known method.2 The starting oxide 1 was prepared as a brown precipitate according to a known procedure7 by the ozonolysis of C60 solutions in CCl4 (1.4 mmol of O3 h –1, [C60]0 = 1.6•10 –4 mol L–1, V = 20 mL). Heating of the suspension of 1 in CCl4 (20 mL) results in CL with a kinetic peak at the fifth minute (Imax = 2.5•10 9 photon s–1 mL–1) (Fig. 1). From the excitation of CL to its complete disappearance, the content of RO in the sample (determined by iodometric titration2) decreases from 1.6•10–4 mol to zero, while the contents of epoxide, carbonyl, and ester groups (deter mined according to a procedure7) do not change notice ably. The energy of activation calculated from the linear plot of logI vs. 1/T is 17.3±1.4 kcal mol–1. Thus, CL can be attributed to thermal cleavage of the O—O groups bound to the ozonolysis transformed framework of C60. 7 The CL spectrum is the same as the known2 CL spectrum recorded during the ozonolysis of C60 solutions (see Fig. 1); i.e., in the thermolysis of 1, the emitter of CL is also the >C=O* group bound to the framework of C60. The CL excitation scheme can be represented only in the most general form