Synthesis and Properties of Energy-Rich Methanofullerenes Containing Norbornadiene and Quadricyclane Moieties

Abstract

The energy-rich methanofullerenes were synthesized for the first time by the reaction of fullerene C with mono- and bisquadricyclane esters of malonic acid. The C-C bond cleavage in the quadricyclane moieties of new hybrid molecules takes place in the presence of catalytic amounts of Cu, Pd, and Pt salts or complexes or SiO and is accompanied by heat evolution.

Photoswitchable Norbornadiene–Quadricyclane Interconversion Mediated by Covalently Linked C60

“…[13] During the early stage of our research, the work of Tuktarov and co-workers on the "Synthesis andProperties of Energy-Rich Methanofullerenes Containing Norbornadiene and QuadricyclaneM oieties" was published;t herefore, NBD/QC-fullerene monoadducts no longer presented an ew class of hybrid compounds. [14] Nevertheless,w ed ecidedt o continueo ur investigations because some of our observations did not coincide with the reportedo nes.H erein, we describe the synthesis and properties of variousNBD-fullerene monoadducts as wella su nprecedented NBD-fullerene hexakisadducts. By careful analysis of this small library of hybrid molecules, it was possible to establish synthetic strategies towards both QC-fullerene monoadducts as well as afirst QC-fullerene hexakisadduct.…”

“…Again, acetophenone was used as at riplet photosensitizer.T uktarov et al reported on the formation of ap oorly soluble precipitate during the irradiationo ft oluene solutions of NBD-fullereneh ybridsa nd acetophenone. [14] Although we were able to circumvent this problemb yw orking under the strict exclusion of oxygen,w ew ere not able to obtain the corresponding QC derivatives of compound 9, 10, 11, 13, 14 or 16.M ost likely the triplet sensitizer is more efficiently quenched by the fullerene core than by the NBD scaffold and, therefore, no isomerization can occur.C onsidering that our attempts towards the QC-fullerene hybrids carrying alkyl-mono-functionalizedN BD scaffolds failed, we investigated the two "push-pull" substituted NBD fullereneh ybrids 12 and 15.A s describedp reviously, [9] the "push-pull" NBD system which is implemented in the hybrid molecules 12 and 15 undergoes clean and quantitative photoisomerization to its QC species upon direct irradiation with light of 310 nm. To test whether this also works when the system is linked to the fullerene core, aq uartz glass cuvette was charged with 10 mg of compound 12 dissolved in 2.5 mL of properlyd egassed CDCl 3 .T he solution was irradiated by using aU VLED with an emission wavelength of 310 nm, the reaction was followed by 1 HNMR analysis (Figure 4).…”

“…The synthesis of QC-fullerene monoadducts from QC malonates and C 60 has been reported previously. [14] Therefore, we were confident,t hat the Bingel-Hirsch reaction with QC malonate 22 and C 60 would give the desired QC-fullerene hybrid 20.…”

Synthesis of C60 fullerene-quadricyclane hybrid compound and its preliminary in vitro antitumor activity in combination with cisplatin

“…The 1 Н NMR spectrum of methanofullerene 5, unlike that of norbornadiene isomer 4, exhibits a set of high-field signals at about 1.5-2.7 ppm corresponding to the cage hydrogen atoms, which is in full agreement with the published data for the quadricyclane adducts. 23 In the next stage of our research, we have investigated the in vitro antitumor activity of the norbornadiene and quadricyclane derivatives of fullerene С60 4 and 5 on the human T-lymphoblastic leukemia cells (Jurkat cells).…”

Synthesis of C60 Fullerene–Quadricyclane Hybrid Compound and Its Preliminary In Vitro Antitumor Activity in Combination with Cisplatin

“…Recently, 21 we have synthesized cyclopropane fullerene C 60 derivatives containing norbornadiene and quadricyclane moieties. It was found that in the presence of a catalytic amount of cisplatin, quadricyclane-containing methanofullerenes are quantitatively isomerized to the corresponding norbornadienes with heat generation.…”