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Multiadditions of heteroaddends to C60are achieved via the oxazolination reaction of 1,4-(PhCH2)2C60with OH–and PhCN, which exhibit a unique regioselectivity regarding the addition sites of the heteroatoms. [ABSTRACT FROM AUTHOR]

Fixation CO2with microalgae is a potential promising technique to reduce CO2emission for its various advantages. In this work, we develop a microalgal fixation CO2system to capture CO2from actual flue gas. At first, we evolved a strain Scenedesmus obliquus, named S. obliquusWUST4, with a UV mutagenesis technique, which can endure actual flue gas. The S. obliquusWUST4 can tolerate high concentration CO2, and possesses high CO2fixation ability. Then, we developed a pilot scale microalgal fixation CO2system to capture CO2from actual flue gas with the evolved S. obliquusWUST4. The flue gas was discharged from the combustion chamber in a coke oven. A 100 L air-lift photobioreactor was built in this system. In the pilot scale system, CO2can be captured from the actual flue gas by the S. obliquusWUST4. The CO2removal ratio can reach 67% with the optimal operation conditions. This provides an efficient technique for CO2capture. [ABSTRACT FROM AUTHOR]

In this paper, four novel silver(I) sulfonate coordination polymers containing neutral ligands, namely, [Ag2L1(biim)2]·2H2O (1), AgL2(biim) (2), [Ag(HL3)(Pic)2]·H2O (3), and [Ag3(L3)(HL3)(4,4'-bipy)3(H2O)2]·4H2O (4), have been synthesized [L1 = 3-carboxy-4-hydroxybenzenesulfonate, L2 = p-aminobenzenesulfonate, H2L3 = p-hydroxybenzenesulfonic acid, biim = 1,1'-(1,4-butanediyl)-bis(imidazole), Pic = β-picoline, 4,4'-bipy = 4,4'-bipyridine]. For compounds 1 and 2, Ag(I) cations are bridged by biim ligands to form a one-dimensional (1D) "zigzag" chain, and L1 and L2 sulfonate ligands are not coordinated to the silver cation. Compound 3 has a dimeric structure in which two silver cations are bridged by two HL3 ligands. For compound 4, L3 ligand coordinates to a silver cation as a monodentate ligand, and Ag(I) cations are bridged by 4,4'-bipy ligands to form a 1D chain. Compound 1 contains water dimers, while compound 4 contains water trimers. Compounds 1−3 display room-temperature photoluminescence. Four coordination polymers of silver(I) sulfonates containing neutral ligand were synthesized and characterized. Three of them show one-dimensional polymeric structures that contain a polymeric chain of silver ions and neutral ligands, and one shows a discrete dimeric structure. Three compounds display photoluminescent properties. [ABSTRACT FROM AUTHOR]

A facile and green approach has been developed for synthesis of boron nitride quantum dots (BNQDs). The obtained BNQDs exhibit strong fluorescence and excellent stabilities, including high thermostability, good salt tolerance stability, pH-independence ability, and excellent antiphotobleaching capability. The strong inner filter effect between 2,4,6-trinitrophenol (TNP) and BNQDs resulted in fluorescence quenching of BNQDs. Thus, TNP can be selectively and sensitively detected in the concentration range of 0.25-200 μM, with a limit detection of 0.14 μM. The BNQD-based turn-off sensor shows potential prospects for rapidly and selectively detecting TNP in natural water samples without tedious sample pretreatment processes.

Although most of the M 2 C 2n -type metallofullerenes (EMFs) tend to form carbide cluster EMFs, we report herein that Lu-containing EMFs Lu 2 C 2n (2n = 82, 84, 86) are actually dimetallofullerenes (di-EMFs), namely, Lu 2 @C s (6)-C 82 , Lu 2 @C 3v (8)-C 82 , Lu 2 @D 2d (23)-C 84 , and Lu 2 @C 2v (9)-C 86 . Unambiguous X-ray results demonstrate the formation of a Lu-Lu single bond between two lutetium ions which transfers four electrons in total to the fullerene cages, thus resulting in a formal divalent state for each Lu ion. Population analysis indicates that each Lu atom formally donates a 5d electron and a 6s electron to the cage with the remaining 6s electron shared with the other Lu atom to form a Lu-Lu single bond so that only four electrons are transferred to the fullerene cages with the formal divalent valence for each lutetium ion. Accordingly, we confirmed both experimentally and theoretically that the dominating formation of di-EMFs is thermodynamically very favorable for Lu 2 C 2n isomers.

We herein demonstrate for the first time the unexpected oxygen-involving reaction between M 3 N@I h (7)-C 80 (M = Sc, Lu) and 1,3-bis(diisopropylphenyl)imidazol-2-ylene (1). By introducing a tiny amount of oxygen into the reaction, unprecedented products (2a for Sc 3 N@C 80 and 3a for Lu 3 N@C 80 ) with the normal carbene center C2 singly bonded to a triple hexagonal junction (THJ) cage carbon together with an oxygen atom bridging the same THJ carbon atom and a neighboring carbon atom forming an epoxy structure are obtained. In situ mechanism study, in combination with theoretical calculations, reveals that the bond-breaking peroxidation facilitates the formation of the unexpected products 2a and 3a, providing new insight into fullerene chemistry.

Tubular higher fullerenes are prototypes of finite-length end-capped carbon nanotubes (CNTs) whose structures can be accurately characterized by single-crystal X-ray diffraction crystallography. We present here the isolation and crystallographic characterization of two unprecedented higher fullerenes stabilized by the encapsulation of a La2C2 cluster, namely, La2C2@Cs(574)-C102, which has a perfect tubular cage corresponding to a short (10, 0) zigzag carbon nanotube, and La2C2@C2(816)-C104 which has a defective cage with a pyracylene motif inserting into the cage waist. Both cages provide sufficient spaces for the large La2C2 cluster to adopt a stretched and nearly planar configuration, departing from the common butterfly-like configuration which has been frequently observed in midsized carbide metallofullerenes (e.g., Sc2C2@C80-84), to achieve strong metal-cage interactions. More meaningfully, our crystallographic results demonstrate that the defective cage of C2(816)-C104 is a starting point to form the other three tubular cages known so far, i.e., D5(450)-C100, Cs(574)-C102, and D3d(822)-C104, presenting evidence for the top-down formation mechanism of fullerenes. The fact that only the large La2C2 cluster has been found in giant fullerene cages (C>100) and the small clusters M2C2 (M = Sc, Y, Er, etc.) are present in midsized fullerenes (C80-C86) indicates that geometrical matching between the cluster and the cage, which ensures strong metal-cage interactions, is an important factor controlling the stability of the resultant metallofullerenes, in addition to charge transfer.

Carbon nanofibers, CNFs, due to their superior strength, conductivity, flexibility, and durability have great potential as a material resource but still have limited use due to the cost intensive complexities of their synthesis. Herein, we report the high-yield and scalable electrolytic conversion of atmospheric CO2 dissolved in molten carbonates into CNFs. It is demonstrated that the conversion of CO2 → CCNF + O2 can be driven by efficient solar, as well as conventional, energy at inexpensive steel or nickel electrodes. The structure is tuned by controlling the electrolysis conditions, such as the addition of trace transition metals to act as CNF nucleation sites, the addition of zinc as an initiator and the control of current density. A less expensive source of CNFs will facilitate its adoption as a societal resource, and using carbon dioxide as a reactant to generate a value added product such as CNFs provides impetus to consume this greenhouse gas to mitigate climate change.

We report a mechanism of electrochemical ammonia (NH3) production via an iron intermediate in which H2 and NH3 are cogenerated by different electron-transfer pathways. Solar thermal can contribute to the energy to drive this synthesis, resulting in a STEP, solar thermal electrochemical process, for NH3. Enhancements are presented to this carbon dioxide (CO2)-free synthesis, which uses suspensions of nano-Fe2O3 in high-temperature hydroxide electrolytes at nickel and Monel electrodes. In a 200 °C molten eutectic Na(0.5)K(0.5)OH electrolyte, the 3 Faraday efficiency per mole of synthesized NH3, η(NH3), increases with decreasing current density, and at j(electrolysis) = 200, 25, 2, and 0.7 mA cm(-2), η(NH3) = 1%, 7%, 37%, and 71%, respectively. At 200 mA cm(-2), over 90% of applied current drives H2, rather than NH3, formation. Lower temperature supports greater electrolyte hydration. At 105 °C in the hydrated Na(0.5)K(0.5)OH electrolyte, η(NH3) increases and then is observed to be highly stable at η(NH3) = 24(+2)%.

The anion radicals of isomeric [5,6] and [6,6] Sc3N@C80 benzoadducts were studied by electron spin resonance spectroscopy, density functional theory computations, and molecular dynamics. In both compounds the rotation of the Sc3N cluster is frozen and the spin density distribution of the cluster is highly anisotropic, with hyperfine coupling constants of 9.1 and 2 × 33.3 G for the [5,6] adduct and ∼0.6 and 2 × 47.9 G for the [6,6] adduct. Remarkably, the subtle variation of the position of the exohedral group on the surface of the cage results in very pronounced changes in the spin density distribution and the dynamics of the encapsulated Sc3N cluster.

The electrosynthetic method has been used for the selective synthesis of fullerene derivatives that are otherwise not accessible by other procedures. Recent attempts to electrosynthesize Sc(3)N@I(h)-C(80) derivatives using the Sc(3)N@I(h)-C(80) dianion were unsuccessful because of its low nucleophilicity. Those results prompted us to prepare the Sc(3)N@C(80) trianion, which should be more nucleophilic and reactive with electrophilic reagents. The reaction between Sc(3)N@C(80) trianions and benzal bromide (PhCHBr(2)) was successful and yielded a methano derivative, Sc(3)N@I(h)-C(80)(CHPh) (1), in which the >CHPh addend is selectively attached to a [6,6] ring junction, as characterized by MALDI-TOF mass spectrometry and NMR and UV-vis-NIR spectroscopy. The electrochemistry of 1 was studied using cyclic voltammetry, which showed that 1 exhibits the typical irreversible cathodic behavior of pristine Sc(3)N@I(h)-C(80), resembling the behavior of other methano adducts of Sc(3)N@I(h)-C(80). The successful synthesis of endohedral metallofullerene derivatives using trianionic Sc(3)N@I(h)-C(80) and dianionic Lu(3)N@I(h)-C(80), but not dianionic Sc(3)N@I(h)-C(80), prompted us to probe the causes using theoretical calculations. The Sc(3)N@I(h)-C(80) trianion has a singly occupied molecular orbital with high spin density localized on the fullerene cage, in contrast to the highest occupied molecular orbital of the Sc(3)N@I(h)-C(80) dianion, which is mainly localized on the inside cluster. The calculations provide a clear explanation for the different reactivities observed for the dianions and trianions of these endohedral fullerenes., (© 2012 American Chemical Society)

Isomerization of an oxazoline cycle from a [6,6]- to [5,6]-junction on the C(60) sphere of dianionic [60]fullero-oxazoline (1(2-)) during a 1,4-addition is studied by electrochemistry and a stepwise addition of PhCH(2)Br and PhCD(2)Br. Cyclic voltammerty of the in situ generated 1(2-) shows a very unusual positive shift for the anodic peak corresponding to the oxidation of 1(2-), indicating that the C(60) cage of dianionic 1 bears only one unit negative charge due to the heterolytic cleavage of the C(60)-O bond. Further study with a stepwise addition of PhCH(2)Br and PhCD(2)Br, which are used to differentiate the aryl groups added at each step onto dianionic 1, shows explicitly there is an exclusive selectivity of the C-O bond for the ring-opening and ring-closure during the isomerization of the heterocycle. A reaction mechanism is proposed on the basis of the experimental results and computational calculations.

Electrochemically generated Lu(3)N@I(h)-C(80) dianions react with the electrophile, PhCHBr(2), to produce a methano derivative of Lu(3)N@I(h)-C(80)(CHC(6)H(5)) (1) with high regioselectivity. The compound was characterized by MALDI-TOF, NMR, and UV-vis-NIR absorption spectroscopy. Electrochemical characterization of this Lu(3)N@I(h)-C(80)(CHC(6)H(5)) derivative showed the typical irreversible reductive behavior of the pristine Lu(3)N@I(h)-C(80), similar to those observed for Bingel adducts of Lu(3)N@I(h)-C(80). Using the same conditions, the reaction between Sc(3)N@I(h)-C(80) dianions and PhCHBr(2) was conducted for comparison. Unexpectedly, no nucleophilic reaction was observed, indicating that Sc(3)N@I(h)-C(80) dianions are not reactive toward the electrophile. Theoretical studies for both dianionic Lu(3)N@I(h)-C(80) and Sc(3)N@I(h)-C(80) showed that the HOMO is more highly localized on the fullerene cage for [Lu(3)N@I(h)-C(80)](2-) and more localized on the inside cluster for [Sc(3)N@I(h)-C(80)](2-), providing an explanation for the drastically different reactivities observed.

The [2 + 2] cycloaddition reaction of Sc(3)N@I(h)-C(80) with benzyne was successfully conducted for the first time. The reaction affords both the [5,6]- and [6,6]-monoadducts with a four-membered ring attached to the cage surface on 5,6- and 6,6-ring fusions, respectively. The compounds were characterized by MALDI-TOF, NMR, UV-vis-NIR spectroscopy and single-crystal X-ray structure determination. The electrochemical behavior of both monoadducts was investigated. The [5,6]-regioisomer displays reversible cathodic behavior similar to that observed for the fulleropyrrolidines with a 5,6-addition pattern. Surprisingly, the [6,6]-regioisomer also exhibits reversible cathodic behavior. The interconversion reaction of the isomers was also explored, and the results showed that both monoadducts are thermally very stable.

The formation of fullerooxazoles from C(61)HPh(3-) has been examined in benzonitrile (PhCN), m-methoxybenzonitrile (m-OCH(3)PhCN), m-tolunitrile (m-CH(3)PhCN), and o-tolunitrile (o-CH(3)PhCN), where cis-1 bisadducts with Ph-, m-OCH(3)Ph-, m-CH(3)Ph-, and o-CH(3)Ph-substituted cyclic imidate next to the phenylmethano are formed as evidenced by various characterizations. Interestingly, only regioisomers 2a-d with the oxygen atom bonded to C4/C5 and the nitrogen atom bonded to C3/C6 are generated as demonstrated by heteronuclear multiple bond coherence (HMBC) NMR, while the alternative regioisomers 3a-d, which have the oxygen and nitrogen atoms at C3/C6 and C4/C5, respectively, are not formed from the reactions, even though the DFT (density functional theory) calculations have predicted that the energy differences between the two types of regioisomers are very small, with regioisomers 3a-d actually having lower energies than 2a-d. The results are rationalized by the charge distributions of C(61)HPh(3-), where computational calculations have shown that the negative charges on C4 and C5 are greater than those on C3 and C6, indicating that the exhibited site selectivity of heteroatoms is a result of the charge-directed addition process.

The electrochemical properties of a series of structurally related fullerooxazoles, [6,6] cyclic phenylimidate C(60) (1), 1,2-benzal-3-N-4-O-cyclic phenylimidate C(60) (2), and 1,4-dibenzyl-2,3-cyclic phenylimidate C(60) (3), are described, and the spectroscopic characterizations of their anionic species are reported. The results show that compounds 1 and 2 undergo retro-cycloaddition reactions that lead to the formation of C(60) and C(61)HPh, respectively, upon two-electron-transfer reduction. However, compound 3 demonstrates much more electrochemical stability as no retro-cycloaddition reaction occurs under similar conditions. Natural bond orbital (NBO) calculations on charge distribution show there is no significant difference among the dianions of 1, 2, and 3, indicating that the electrochemical stability of 3 is unlikely to be caused by the charge distribution difference of the dianions of three compounds. Examination on the crystal structure of compound 3 reveals close contacts of the C-H group with the heteroatoms (N and O) of cyclic phenylimidate, suggesting the existence of C-H...X (X = N, O) intramolecular hydrogen bonding among the addends, which is further confirmed by NBO analysis. The results thus suggest that intramolecular hydrogen bonding is responsible for the electrochemical stability of 3.

During the reaction of reduced C60 with benzyl bromide in benzonitrile, a novel cis-1 C60 adduct, 1,4-dibenzyl-2,3-cyclic phenylimidate C60 (1), was obtained rather than the expected product of 1,4-dibenzyl C60. The structure of compound 1 was analyzed by X-ray single-crystal diffraction, identifying the presence of a five-membered heterocycle at a [5,6] bond of C60. One of the heteroatoms is assigned as a nitrogen atom; however, the identity of the other heteroatom cannot be determined unambiguously by crystallography due to similarity between the nitrogen and oxygen atoms. A related compound (2) bearing the same heterocycle was obtained from anionic C60 benzonitrile solution when no benzyl bromide was added. The structure of compound 2 was determined by NMR, MALDI FT-ICR MS, and UV-vis. Results from MALDI FT-ICR MS for compound 2 show unambiguously that the second heteroatom is an oxygen atom, which is probably from traces of water in the solvent. Control experiments of the reactivity of the neutral, monoanionic, dianionic, and trianionic C60 have shown that the reactive species for the unexpected reaction is the C60 trianion.

This article represents a systematical examination of the structures of silver(I) sulfonates incorporating neutral ligands. To survey the influence of the properties of neutral ligands on the structures of silver(I) sulfonates, three kinds of sulfonate anions (L1=1-naphthalenesulfonate, L2=p-toluenesulfonate, and L3=1, 3, 6, 8-pyrenetetrasulfonate) and three kinds of neutral ligands (pyrazine, Pyr, a divergent bidentate ligand; hexamethylenetetramine, hmt, a divergent tetradentate ligand; and beta-picoline, Pic, a monodentate ligand) were selected for study, and five novel silver(I) sulfonates containing neutral ligands have been synthesized: [Ag(L1)(Pyr)].H2O, Ag(L2)(Pyr), Ag4(L3)(Pyr)4(H2O)2, [Ag(L1)(hmt)].H2O, and Ag(L1)(Pic)2. The crystal structures have been determined by single-crystal X-ray diffraction, and these compounds show a variety of structures with different dimensionalities. Moreover, the luminescent properties of compounds and are also discussed.