Adducts Formation at Fullerenes С60 and С70 Dissolution in Essential Oils

It was established by the method HPLC-MS with electrospray ionization that in solutions of fullerenes С60 and С70 in some essential oils a chemical reaction occurred leading to adducts of fullerenes with unsaturated terpenes. In the course of time the quantity of the adduct in solution increased and a component originating from addition of two molecules of terpene to a molecule of fullerene is formed. This can be the reason of abnormally high solubility of light fullerenes in mixtures of terpene hydrocarbons. . Solubility of fullerenes in organic solvents attracts attention both due to its theoretical interest (determination of thermodynamic characteristics and prediction of retention data in the chromatographic analysis [1, 2]) and practical opportunities of applying these solutions. A number of studies was carried out up till now investigating various theoretical aspects of solubility of light fullerenes and their mixtures in pure or mixed solvents [1–5]. Among the practical applications of fullerenes cosmetology, pharmacology, and medicine should be mentioned. For this reason the selection of solvents for fullerenes introduction in cosmetic, pharmaceutical, and medical complex mixtures should be regarded as a challenge. It is well known that aromatic hydrocarbons and their derivatives (toluene, o-xylene, and chlorobenzenes) [3, 6] are efficient solvents of light fullerenes С60 and С70. Solubility of fullerenes and their mixtures in oils had been studied [4, 5]. The application of these solutions is of certain potential in cosmetology [7, 8] and pharmacology [9]. These processes require monitoring, hence building devices for calibration of measuring instruments for such monitoring [10]. For the safety reasons the most desirable solvents of fullerenes for medical and pharmaceutical purposes are those of natural oils i.e., of animal and plant origin. In the studies on the solubility of light fullerenes in certain plant and essential oils (olive, sunflower, juniper, clove, etc.) [5] it is presumed in explicit or implicit form that the solutions of fullerenes are true ones. In many cases of application of traditional solvents such statement is correct, though in some instances the solvent acts not entirely as a solution medium. Due to relatively high reactivity of fullerenes [6] it is impossible to rule out the likelihood of chemical processes between fullerenes and thea solvent or its components. This is particularly true in the case of applying complex mixtures like fats, essential oils etc. Just this phenomenon we detected in the course of development of standard samples of fullerenes solutions in oils. We prepared solutions of fullerenes in some essential oils (tangerine, lemon, orange, clove, rosemary, lavender, eucalyptus) and subjected them to HPLC and HPLC-MS procedures to determine their qualitative composition. Mass chromatograms of fullerene С60 solutions in essential oils are presented in Fig. 1. The mass chromatograms of fullerene С60 solutions in essential oils besides the peak characteristic of genuine fullerene С60 (m/z 720), contain also the peaks m/z (720 + 136) and m/z (720 + 136 + 136). Similar data are registered also for the solutions of fullerene С70 : С70 (m/z 840), and satellite components m/z (840 + 136), (840 + 136 + 136). Based on the fact that the majority of terpenes are components of the essential oils under study (pinenes, DOI: 10.1134/S1070363214020078