Nitroxyde malonate methanofullerenes: interaction of Langmiur monolayers and thin films with radical antioxidants

I.V. Gulyaev*, N.B. Melnikova*, A.A. Volkov*, I.A. Nuretdinov**, V.P. Gubskaya**, and L.Sh. Berezhnaya**

*Nizhny Novgorod State Medical Academy, Minin and Pozharsky sq., 10/1, 603005 Nizhny Novgorod, Russia

** Arbuzov Institute of Organic and Physical Chemistry KSC RAS, Arbuzov str., 8, 420088 Kazan, Russia

Mono- and dinitroxyde malonate methanofullerenes (referred as I and II, respectively) are fullerene C60 derivatives which are applicable in the successful production of new materials and synthesis of biologically active compounds [1], for example, they are perspective compounds used as a photodynamic sensors in oncology therapy.

In the present work stable radical mono- and dinitroxyde methanofullerenes I and II were used to study monolayers and thin films properties in presence of polyphenolic flavonoid antioxidants such as dihydroquercetin (DHQ) and quercetin (Q) in subphase. Mixed Langmiur monolayers of nitroxyde methanofullerene and radical sponge such as three-2,4,6-tret-butylphenol (TTBP), 2-methyl-2-nitrosopropane (MNP), and 2,2,6,6-tetramethylpiperidine oxyl(TEMPO) were investigated too by measuring surface pressure-area isotherms. Thin films of mixed system with nitroxyde metrhanofullerenes after water treatment were examined through AFM images. The feature of isotherms depends on a composition of water subphase and on nature of radical sponge (acceptor or donor) in mixed monolayers. The limiting area per molecule A0 extrapolated to ?=0 in monolayers of methanofullerenes I or II is increased twice from 0.55 nm2 (subphase - water) to 1.00 nm2 (subphase - polyphenolic antioxidants Q and DHQ). The same increasing A0 was found when studying mixed monolayers of methanofullerenes and radical sponge (TTBP, MNP, and TEMPO). In both cases monolayers of I and II exhibit as condensed phases like liquid-solid films which are characterized by gently sloping rise of the isotherms upon compression.

AFM images show a looser and more regular structure of the films obtained in the presence of antioxidants and radical sponge.