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 C 70 solutions were identified by IR spectroscopy and elemental and chemical analy ses. At the 100% conversion of С 70 a mixture of products corresponding to the empirical formula С 70 О 14.3 Н 0.21 (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 С 70 О n (n = 1-4) is lower than that in epoxides С 60 О n (n = 1-6) formed by the ozonolysis of fullerene С 60 . The kinetic curve of accumulation of epoxides С 70 О n (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) (λ max = 645 and 685 nm) of fullerene polyketones in glassy EtO 2 /EtOH solutions frozen at 77 K was observed. This PL is much brighter, than that of polyketones formed upon the ozonolysis of fullerenes С 60 . For the first time the chemilumines cence (CL) was detected and studied upon the ozonolysis of С 70 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 С 60 (λ max = 685 nm) but contains the greater number of maxima (λ max = 645 and 685 nm), which is related to a lower symmetry of the С 70 oxidation products.Key words: С 70 fullerene, ozonolisys of solutions, chemiluminescence, photoluminescence of fullerene polyketones.Studies of the mechanism and reaction products of fullerene oxidation with ozone is important from the view point of both investigation of fundamental chemical prop erties of fullerenes and development of the new, "oxida tion approach" to the synthesis of water soluble fullerene derivatives promising for medicine and pharmacology. An analysis of publications 1-8 on the study of С 70 ozo nolysis indicates that the total composition of stable products of this reaction has not been established up to presently. 1-8 For example, the most intense band in the IR spectra of the oxidation products was assigned simul taneously to the absorption of a wide range of various carbonyl containing compounds: aldehydes, ketones, acids, and lactones. 3 Fullerene С 70 usually is only men tioned in the title of an article, 1-8 whereas the experimen tal data are given only for С 60 , although the authors mention in the summary that analogous results were obtained for С 70 . Meanwhile, a comparative study of ozonolysis of these fullerenes can provide fruitful information on the influ ence of different structures of С 60 (I h ) and С 70 (D 5h ) on the reactivity of these molecules toward ozone 9,10 and on the composition of the reaction products. The purpose of this work is to determine the total composition of stable products of С 70 oxidation with ozone in solutions, to...

Reactivity of carbonyl oxides generated by the ozonolysis of C60 and C70 fullerenes: a chemiluminescence study and quantum-topological analysis

“…9 The ozonolysis of both C 60 4 and C 70 6 is accompanied by CL. Recently, 6 it was declared that differences in the CL properties of C 60 + O 3 and C 70 + O 3 systems are brighter than differences in the contents of the stable products of C 60 and C 70 ozonolysis and the CL emitters in the case of C 70 (C 70 polyketones) are generated in the reactions of carbonyl oxide intermediates (analogously to C 60 ozonolysis).…”