Urea as a New and Cheap Nitrogen Source for the Synthesis of Metal Nitride Clusterfullerenes: The Role of Decomposed Products on the Selectivity of Fullerenes

Abstract

By using urea as the new nitrogen source, for the first time, Sc-based metal nitride clusterfullerenes (NCFs), Sc(3)N@C(2n) (2n=80, 78, 70, 68), have been synthesized successfully. The optimum molar ratio of Sc(2)O(3)/CO(NH(2))(2)/C for the synthesis of Sc NCFs is 1:3:15. The yield of Sc(3)N@C(80)(I(h) +D(5h)) per gram of Sc(2)O(3), using CO(NH(2))(2) as the new nitrogen source, was quantitatively compared to those obtained when using the reported nitrogen sources, including N(2), NH(3), and guanidinium thiocyanate. We find that there is a clear difference on the selectivity of Sc-based NCFs within the extract mixture obtained from one rod and accumulative two rods. According to discharging experiments and XRD analysis, we conclude that NH(3) generated in situ from the decomposition of CO(NH(2))(2) is mainly responsible for the formation of Sc-based NCFs when using only one rod, whereas in the second rod CO(NH(2))(2) would decompose into melamine during discharging of the first rod. Thus, the selectivity of fullerenes is clearly dependent on the decomposed product of CO(NH(2))(2). Finally the difference in the decomposition behavior of CO(NH(2))(2) and melamine was studied in detail and a possible decomposition process of CO(NH(2))(2) during discharging was proposed. Accordingly, the difference in the selectivity and yield of Sc NCFs for CO(NH(2))(2) and melamine was interpreted.

A Platform for Specific Delivery of Lanthanide–Scandium Mixed‐Metal Cluster Fullerenes into Target Cells

“…Isolation of these mixed-metal nitride cluster fullerenes (NCFs) was accomplished by one-step HPLC. The analysis of the chromatogram and mass spectra proved the formation of NCFs as the major products of the reaction (Figure 1), which demonstrates the high selectivity of the synthesis using melamine as a nitrogen source (recently, similar selectivity was reported for urea[25]). The most abundant fraction eluting at a retention time ( t R ) of 29.8–32.0 min was collected and used for further synthesis of the modular contrast agent c-myc-antisense-Gd@BioShuttle (Figure 1 A).…”

Selective arc-discharge synthesis of Dy2S-clusterfullerenes and their isomer-dependent single molecule magnetism

“…The latter could be thus obtained with a high degree of selectivity. High selectivity of nitride clusterfullerene formation was also achieved with the use of solid nitrogen sources (such as guanidinium thiocyanate,49 inorganic salts,50 melamine,51 or urea52) or using NO x vapor from NO x -generating solid reagents and air (known as the CAPTEAR approach) 53. More recently, we have adapted a method for selective synthesis of carbide clusterfullerenes using methane as a reactive gas 42,54–57.…”

Gadolinium-containing endohedral fullerenes: structures and function as magnetic resonance imaging (MRI) agents

“…Additionally, the arc process may be modified with various dopants to inhibit the formation of C 60 and C 70 , which are usually the prevalent fullerenes, and to facilitate the incorporation of complex clusters such as Gd 3 N inside the cage. [13][14][15][16][17] Despite efforts to improve the arc generation process, the yields of endohedral fullerenes produced remain low.…”