Search

Thus far, all the stable singlet carbenes consist of a center carbon atom, and electron donor or withdrawing substituents with heteroatoms, such as, N, P, O, and S. Herein, carbene was generated by the lithium–bromine exchange reaction and used to functionalize C60. The reaction mechanisms, including the lithium–bromine exchange and carbene addition reactions, were studied in detail with ab initio density functional theory. The interaction between LiBr and the carbon atom was first characterized as a mainly ionic interaction, combined with the coordinate interaction and hyperconjugation. Then, a novel stable singlet fullerene carbene without the heteroatom, was primitively generated via lithium–bromine exchange and carbene addition reactions; it exhibited a remarkable stability with high singlet–triplet energy gap and HOMO–LUMO energy gap. This computational survey indicates that fullerene carbene will be a potential ligand in the coordinated compounds, and is useful for further functionalization and applications of fullerenes. Furthermore, theoretical results show that the lithium–bromine exchange reaction would be a powerful and feasible tool to functionalize the double bonds in some aliphatic and aromatic olefins, including anthracene, benzene, propylene, ethylene, 1-butene, propanal, and 3-pentanone. Based on the carbene reaction mechanisms and nature of corresponding bonds in their products, two indexes, bond length and the hybridization state of atoms, were suggested to distinguish the carbene addition and insertion to the double bond.

Four-electron transfer from U to the fullerene cage commonly exists in U@C2n (2n < 82) so far, while four- and three-electron transfers, which depend on the cage isomers, simultaneously occur in U@...

Thermodynamically stable La@C2v(24 107)-C78, La@D3h(24 109)-C78, La@C1(22 595)-C78, Ce@D3h(24 109)-C78, Sm@C2v(24 107)-C78, and Sm@D3h(24 109)-C78 based on density functional theory and statistical thermodynamic analysis are studied in theory. C1(22 595)-C78, violating the isolated pentagon rule, is a second novel isomer stabilized by encaging a La atom. In addition, three- and two-electron transfers occur in M@C78 (M = La and Ce) and Sm@C78, respectively. Although there are two electrons transferred from Sm to C78, these electrons transferred to the surface of C2v(24 107)-C78 are unpaired. Thus, the surface of the endohedral metallofullerene, Sm@C2v(24 107)-C78, firstly displays diradical characteristics. Notably, the spin states of the two electrons transferred from Sm to D3h(24 109)-C78 are different from those on C2v(24 107)-C78, leading to different spin ground states. Furthermore, the natural bond orders and bond critical point analyses on thermodynamically stable M@C78 (M = La, Ce, and Sm) reveal that the distance between the metal and carbon atom plays an important role in the covalent interaction between the inner metal atoms and C78. Because of the strong ionic interaction, the studies on the magnetic character of M@C78 (M = La, Ce, and Sm) show that Sm@C78 is a promising candidate for single-molecule magnets with high isotropic susceptibility. The infrared spectra were simulated to facilitate further experimental study on the stable M@C78 (M = La, Ce, and Sm). We believe that this work will provide good guidance and assistance for the further study of mono-metallofullerenes and coordination compounds in both experiment and theory.

Fullerenes are important zero-dimensional materials in photoelectric, antioxidant, pharmaceutical, and single-molecular-magnet fields, but the fullerene-formation mechanism has been elusive since t...

The successful isolation of cyclo-C18 in the experiment means the ground-breaking epoch of carbon rings. Herein, we studied the thermodynamic stabilities of cyclo-Cn (4 $\leq$ n $\leq$ 34) with density functional theory. When n = 4N + 2 (N is integer), cyclo-Cn (10 $\leq$ n $\leq$ 34) were thermodynamically stable. Especially, cyclo-C10 and cyclo-C14 were thermodynamically, kinetically, dynamically, and optically preferred to cyclo-C18, and were the candidates of zero-dimension carbon rings. The carbon atoms were sp hybridization in cyclo-C10, cyclo-C14 and cyclo-C18. Cyclo-C14 and cyclo-C18 had alternating abnormal single and triple bonds, but cyclo-C10 had equal bonds. Cyclo-C10, cyclo-C14, and cyclo-C18 with large aromaticities had out-plane and in-plane pi systems, which were perpendicular to each other. The number of pi electrons in out-plane and in-plane pi systems followed the Huckel rule. Simulated UV-vis-NIR spectra indicated the similar electronic structures of cyclo-C14 and cyclo-C18., Comment: 23 pages, 6 figures, 1 table

The effects of different electromagnetic field and technological parameters on the microstructure and composition segregation of Pb-80%Sn alloy were studied. The results show that, both rotating and spiral magnetic field can improve the composition segregation ,refine grains of alloy. Moreover,the spiral magnetic field is more effective on improving composition homogenization and grain refining. The electromagnetic force distribution of spiral magnetic field is more helpful to form a well stirring in a larger zone and promote the formation of equiaxed grains, and the direction of the grain arrangement is much smaller. The technical parameters of spiral magnetic field have been optimized. It is found that, under the spiral magnetic field condition, when stirring time and exciting current exceeded a critical value, the size of the primary phase became larger. Therefore, there existed an optimum value of magnetic stirring parameters for the homogenization of component and refinement of grains.

The Second International Workshop on Service and Cloud Based Data Integration (SCDI 2014) intends to bring researchers, practitioners and vendors together to discuss and share ideas and experiences. It fosters novel models, methodologies, and solution patterns that address the data integration issue and fit in the service and cloud based settings. This workshop will focus on the use of service and/or cloud based technologies to meet the new data integration challenges that are not well served by the current approaches.

In this work, two eutectic solders: 80Au20Sn and 52In48Sn were chosen for fiber bonding through laser soldering, and scanning electronic microscope (SEM) equipped with energy dispersive x-ray detector (EDX) was used to investigate the microstructures of at four interfaces between two solders and two metallizations: Au-Sn/(Au/Ti), Au-Sn/( Au/Ni), In-Sn/ (Au/Ti), In-Sn/(Au/Ni). Results show that as for the Au-Sn solder joint a large amount of zeta-phase was formed at the Au-Sn/(Au/Ti) interface with its morphology closely related with laser input energy; while at the Au-Sn/(Au/Ni) interface scallop-like (Au,Ni)Sn appeared with a low input energy and irregular-shaped (Au,Ni) 3Sn2 emerged with a high input energy. As for the In-Sn solder, the IMCs at the In-Sn/ (Au/Ti) interface transformed from a Au(In,Sn)2 layer to isolated Auln2 cubes with the increase of input energy while at the In-Sn/(Au/Ni) interface a thin layer of Au(In,Sn)2 was formed. As the connecting layer, Ti did not react in the soldering process