The single-bonded fullerene dimer RC 60 ÀC 60 R, which has a direct covalent bond between two C 60 cages, is an interesting and unusual structure that is expected to display interesting optical and electronic properties through the interaction of two adjacent fullerene cages.[1] Since the pioneering work by Krusic and co-workers, [2] studies on ESR and X-ray crystalstructure analysis revealed that singly bonded fullerene dimers consist of racemic and meso isomers, which are in equilibrium with the monomer radical (RC 60 C) in solution. [3] Some experimental and theoretical studies on these singlebonded fullerene dimers demonstrated that they were usually formed by dimerization of RC 60 C radicals, which were generated by various radical reactions; [4] for example, the photoirradiation of C 60 with perfluoroalkyl iodides in the presence of (R 3 Sn) 2 , [3a] Mn(OAc) 3 -mediated radical reaction of C 60 with phosphonate esters [3c] or dialkyl malonates, [5a] and one-electron oxidation of the monoanion RC 60 À by oxidants.[3b, 5b-d] However, their application to the elaborated fullerene dimers is generally limited by low functional-group tolerance, low yield, and the use of large excess amounts of reagents. Functionalization of fullerene by transition-metal catalysis has recently been considered to be a promising and innovative strategy in fullerene chemistry, which offers advantages for high chemical yield, selectivity control, and high functional-group compatibility under mild reaction conditions.[6] However, examples of catalytic dimerization for the synthesis of single-bonded fullerene dimers have never been reported.[6f]Recently, we developed the cobalt-catalyzed hydroalkylation of C 60 with active alkyl bromides at ambient temperature to give monoalkylated hydrofullerenes in good to high yields. [7] Our interest in catalytic CÀH bond activation led us to consider the possibility of catalytic CÀH bond functionalization of the monosubstituted hydrofullerenes toward the construction of fullerene dimers.[8] A study by Komatsu and co-workers revealed that RC 60 C could be formed from fullerenyl radical cation (RHC 60 C + ), which in turn was generated from monofunctionalized hydrofullerene by one-electron oxidation in sulfuric and sulfonic acids.[9] In addition, Yu and co-workers reported the Cu II -catalyzed aryl CÀH bond functionalization by using O 2 ;[10] the reaction was proposed to proceed through the formation of an aryl radical cation (ArC + ) species by one electron transfer from the aryl ring to the Cu II catalyst followed by formation of an aryl radical (ArC). Taking these results into consideration, we turned our attention to metal oxidants as catalysts. Herein, we report a novel and efficient Cu(OAc) 2 -catalyzed homo-dimerization of various monofunctionalized hydrofullerenes that affords the singlebonded fullerene dimers 2 as a mixture of racemic and meso isomers in excellent yields in the presence of a small amount of dimethylformamide (DMF) at room temperature under air [Eq. (1); ODCB = 1,2-di...

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The brominated and/or chlorinated organic compounds (referred to as organohalogens) are frequently detected in natural and engineered environments. However, the ultrahigh resolution mass spectrometry (UHR-MS)-based non-target identification of the organohalogens remains challenging due to the presence of vast number of halogenated and non-halogenated organic molecules in the same aqueous sample. In this study, a new algorithm, namely NOMDBP Code, was developed, based on natural organic matter (NOM) chemistry, to simultaneously identify organohalogens and non-organohalogens from the UHR-MS spectra of natural and engineered waters. In addition to isotopic pattern extraction, for the first time, three optional filter rules (namely selection of minimum non oxygen heteroatoms, inspection of newly formed halogenated disinfection byproducts [X23 DBPs] and precursors) were incorporated in our code, which can accurately identify DBPs associated peaks and further elucidate the X-DBPs generation and transformation mechanisms. The formulae assignment rate against previously reported 2,815 unique organohalogens and their 11,583 isotopologues was determined to be >97%. Application of our algorithm to disinfected NOM indicated that oxygen-containing X-DBPs species accounted for a majority of X-DBPs. Further, brominated X-DBPs (Br-DBPs) during disinfection process were characterized by higher degree of unsaturation compared to chlorinated X-DBPs (Cl-DBPs). Our algorithm also suggested that, in addition to electrophilic substitution and electrophilic addition reactions, the decomposition/transformation is another important mechanism in Br-DBPs formation. Results of this study highlight the superior potential of this code to efficiently detect yet-unknown organohalogens (including organohalogens with non-oxygen heteroatoms) in a non-target manner and identify their generation mechanism during the disinfection process File list (3) download file view on ChemRxiv DBP paper.pdf (1.10 MiB) download file view on ChemRxiv DBP paper_SI.pdf (2.69 MiB) download file view on ChemRxiv Supporting Information SI1 DBP list.xls (523.00 KiB)

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We report a novel method of producing monodispersed polycyclic aromatic hydrocarbon nanocrystals as a result of crystal growth in a stabilizer-free oil-in-water emulsion. The emulsion was prepared by dispersing a hot organic solvent including target molecules into an aqueous medium at the same temperature as the solvent, and nucleation and crystal growth were then induced in the emulsion by decreasing the temperature. The emulsifier of the organic solvents was easily removed from the dispersion medium, and we were able to obtain π-conjugated organic nanocrystals such as tetracene, C 60 fullerene, and anthracene at high dispersion concentrations.

The formation of amides and peptides often necessitates powerful yet mild reagent systems. The reagents used, however, are often expensive and highly elaborate. New atom-economical and practical methods that achieve such goals are highly desirable. Ideally, the methods should start with substrates that are readily available in both chiral and non-chiral forms and utilize cheap reagents that are compatible with a wide variety of functional groups, steric encumberance, and epimerizable stereocenters. A direct oxidative method was developed to form amide and peptide bonds between amines and primary nitroalkanes simply by using I2 and K2 CO3 under O2 . Contrary to expectations, a 1:1 halogen-bonded complex forms between the iodonium source and the amine, which reacts with nitronates to form α-iodo nitroalkanes as precursors to the amides.

By stepwise catenation of bicyclo[1.1.1]pentasilane units persila[n]staffanes (n=1, 2, and 3) were synthesized as air‐stable colorless crystals. A remarkable red‐shift of the UV/Vis absorption bands with increasing number of bicyclo[1.1.1]pentasilane units suggests remarkable interactions between bridgehead SiSi σ orbitals and between cage SiSi σ orbitals (see picture).

The development and characterization of enantioselective organocatalytic oxidative kinetic resolution (OKR) of racemic secondary alcohols using chiral alkoxyamines as precatalysts are described. A number of chiral alkoxyamines have been synthesized, and their structure-enantioselectivity correlation study in OKR has led us to identify a promising precatalyst, namely, 7-benzyl-3-n-butyl-4-oxa-5-azahomoadamantane, which affords various chiral aliphatic secondary alcohols (ee up to >99%, k(rel) up to 296). In a mechanistic study, chlorine-containing oxoammonium species were identified as the active species generated in situ from the alkoxyamine precatalyst, and it was revealed that the chlorine atom is crucial for high reactivity and enantioselectivity. The present OKR is the first successful example applicable to various unactivated aliphatic secondary alcohols, including heterocyclic alcohols with high enantioselectivity, the synthetic application of which is demonstrated by the synthesis of a bioactive compound.