A non-metal system for nitrogen fixation

Abstract

In all nitrogen-fixation processes known so far--including the industrial Haber-Bosch process, biological fixation by nitrogenase enzymes and previously described homogeneous synthetic systems--the direct transformation of the stable, inert dinitrogen molecule (N2) into ammonia (NH3) relies on the powerful redox properties of metals. Here we show that nitrogen fixation can also be achieved by using a non-metallic buckminsterfullerene (C60) molecule, in the form of a water-soluble C60:gamma-cyclodextrin (1:2) complex, and light under nitrogen at atmospheric pressure. This metal-free system efficiently fixes nitrogen under mild conditions by making use of the redox properties of the fullerene derivative.

Recent progress towards the electrosynthesis of ammonia from sustainable resources

“…To this end, Pospíšil and co-workers used C 60 encapsulated in γ-cyclodextrin as an electron relay for ammonia electrosynthesis in 0.1 M KCl at 60 °C, 50 building on earlier work showing that C 60 was able to mediate the photochemical reduction of N 2 to NH 3 in the presence of chemical reductants. 51 In Pospíšil's electrochemical system, potentials of -1.2 V vs. Ag/AgCl were applied using a mercury pool cathode, which reduced the C 60 -γ-cyclodextrin complexes by two electrons in two successive one-electron steps. This reduced relay species was then postulated to react with N 2 to produce N 2 H 2 , which was then reduced to ammonia either by direct electron transfers from the electrode or by electron transfers from other reduced relay complexes.…”

Pristine (C60) and Hydroxylated [C60(OH)24] Fullerene Phototoxicity towards HaCaT Keratinocytes: Type I vs Type II Mechanisms

“…Preparation of γ-Cyclodextrin Bicapped C 60 [(γ-CyD) 2 /C 60 ] and C 60 (OH) 24 Solution γ-Cyclodextrin bicapped C 60 [(γ-CyD) 2 /C 60 ] was prepared by the method of Yoshida et al (28,29) with some modification. Briefly, a mixture of C 60 (40.0 mg; 55.6 μmol) and γ-cyclodextrin (120.0 mg; 92.5 μmol) was stirred in a water/toluene (16/6 v/v) mixture at 118 °C for 48 h, and then, γ-cyclodextrin (60.0 mg; 46.3 μmol) was added twice more at 48 h intervals.…”

Antioxidant Activity of Supramolecular Water-Soluble Fullerenes Evaluated by β-Carotene Bleaching Assay

“…20) Despite numerous studies on the radical scavenging activity of water-soluble fullerenes, little is known about the comparative assay of fullerenes versus -carotene, the latter of which has frequently served as a reference compound in determining antioxidant activity. [21][22][23][24] In the present study, the antioxidant activity of supramolecular water-soluble fullerenes, viz., polyvinylpyrrolidone (PVP)-entrapped C 60 25) and -cyclodextrin (CD)-bicapped C 60 , [26][27][28][29] as shown in Fig. 1, was kinetically evaluated by means of coupled autoxidation of linoleic acid and -carotene.…”