New two-dimensional metal-organic networks constructed from 1,2,4,5-benzenetetracarboxylate and chelate ligands

Two novel nickel coordination polymers [Ni(2)(2,2'-bipy)(2)(OH)(2)(H(2)btec)](3)(n)(1) and [Ni(2)(1,10'-phen)(2)(H(2)O)(2)(btec)](n)(2) (btec = 1,2,4,5-benzenetetracarboxylate) have been hydrothermally synthesized and characterized by elemental analyses, IR and XPS spectra, TG analysis, X-ray powder diffraction, and single crystal X-ray diffraction. Crystal data for 1: C(90)H(66)N(12)O(30)Ni(6), monoclinic P2(1)/c, a = 10.905(2) A, b = 18.006(4) A, c = 20.551(4) A, beta = 94.91(3) degrees, Z = 2. Crystal data for 2: C(34)H(22)N(4)O(10)Ni(2), monoclinic P2(1)/n, a = 10.122(2) A, b = 9.3106(19) A, c = 15.690(3) A, beta = 92.03(3) degrees, Z = 2. Compound 1 exhibits a novel one-dimensional chainlike structure, in which the dinuclear Ni centers are linked by the btec ligands. Furthermore, the adjacent chains are linked into a 2-D wavelike layer via the strong OH.O hydrogen bonding interactions. Compound 2 possesses an unusual two-dimensional steplike network with interesting rhombic grids. Both compounds exhibit unprecedented metal-organic ligand construction modes in [M/btec/L] (M = transition metal; L = chelate ligands) systems. The magnetic behaviors of compounds 1 and 2 have been studied.     

Studies on the regio- and stereoselectivity of halohydroxylation of 1,2-allenyl sulfides or selenides

It was observed that the halohydroxylation of 1,2-allenyl sulfides or selenides with Br2 (CuBr2 or NBS) or I2 and water demonstrated a fairly good regioselectivity (i.e., the C=C bond that is remote from the S or Se atom was halohydroxylated with the halogen atom connecting to the middle carbon atom and the hydroxyl group connecting to the non-S terminal carbon or Se-substituted terminal carbon atom of the allene moiety), leading to the synthesis of synthetically important 3-organosulfur or seleno-2-haloallylic alcohols. The stereoselectivity depends on the nature of X+ and S or Se, showing a Z-selectivity with the matched Lewis acid-base pair.     

Computational study of the Stone-Wales transformation in C36

The transition of the D6h neutral and charged isomers to D2d isomers of C36 via Stone-Wales transformation has been studied by means of the hybrid density functional method (B3LYP). The results show that the transition state (TS) and reaction pathway could be identified for the rearrangement from C36-D6h to C36-D2d on the potential energy surface. We found that the neutral and charged transition states all have C2 molecular point group symmetry with the two migrating carbon atoms remaining close to the fullerene surface. The other kind of possible TS with a carbene-like structure along the stepwise reaction path does not exist as a stationary point with the density functionals utilized here. The classical barriers are 6.23 eV through the neutral TS, 6.37 eV through the anionic TS, and 6.29 eV through the cationic TS at the B3LYP/6-31G level of theory.     

Four new eremophilendiolides from Ligularia atroviolacea

From Ligularia atroviolacea, four new eremophilendiolides, 81$-hydroxy-eremophil-3,7 （11）-dien-12,8α（14,6α）-diolide （1）, 8β-methoxy-eremophil-3,7（11）-dien-12,8α（14,6α）-diolide （2）, 8α-hydroxy-eremophil-3,7（11）-dien-12,8lβ（14,6α）-diolide （3） and eremophil-3,7（11）,8-trien-12,8 （14,6α）-diolide （4）, as well as a known diolide （5） were isolated. Their structures were elucidated on the basis of 1D and 2D NMR as well as ESI-MS spectral data.     

A facile stereospecific synthesis of （Z）-2-sulfonyl-substituted 1,3-enynes via Sonogashira coupling of （E）-α-iodovinyl sulfones with 1-alkynes

(E)-a-Iodovinyl sulfones 1 underwent the Sonogashira coupling reactions with terminal alkynes 2 in piperidine at room temperature in the presence of 5 mol% of Pd(PPh3)4 and 10 mol% of CuI to stereospecifically afford the corresponding (Z)-2- sulfonyl-substituted 1,3-enynes 3 in high yields.     

New Subclasses of Biholomorphic Mappings and the Modified Roper-Suffridge Operator

The authors propose a new approach to construct subclasses of biholomorphic mappings with special geometric properties in several complex variables. The RoperSuffridge operator on the unit ball B~n in C~n is modified. By the analytical characteristics and the growth theorems of subclasses of spirallike mappings, it is proved that the modified Roper-Suffridge operator [Φ_(G,γ)(f)](z) preserves the properties of S_Ω~*(A, B), as well as strong and almost spirallikeness of type β and order α on B~n. Thus, the mappings in S_Ω~*(A, B), as well as strong and almost spirallike mappings, can be constructed through the corresponding functions in one complex variable. The conclusions follow some special cases and contain the elementary results.     

各向异性材料对二维六角晶格光子晶体中狄拉克点的影响EI北大核心CSCD

光子能带结构中的狄拉克点是目前光子晶体研究中新兴的热点。选用双轴材料,用六边形介质柱构成了六角晶格各向异性光子晶体。该光子晶体有三个各异的主介电常数εxx、εyy、εzz。依据麦克斯韦方程组,垂直极化(TE)波中的狄拉克点会受到εxx≠εyy的影响,即可以通过调制双轴材料中X、Y方向的主折射率Nx、Ny得到光子晶体中TE波的狄拉克速率,从而调节TE波中狄拉克点在能带结构图中的位置(即调节狄拉克点的归一化频率及其在布里渊区的位置)。研究了Nx、Ny(对应εxx、εyy)与TE波中狄拉克点的存在性的关系,并通过仿真实验验证了提出的观点。这些研究可为研发新型光学器件以及构建光子芯片提供更多的可能。     

Cu6S4 cluster based twelve-connected face-centered cubic and Cu19I4S12 cluster based fourteen-connected body-centered cubic topological coordination polymers

Hydrothermal reaction of Cu(MeCO2)2, (4-pyridylthio)acetic acid and NH4SCN resulted in a twelve-connected face-centered cubic topological metal-organic framework [Cu3(pdt)2(CN)] (pdt = pyridinethiolate) in which Cu6S4 clusters act as twelve-connected nodes and pyridine rings and cyanides act as connectors. As an extension, an unprecedented fourteen-connected body-centered cubic coordination polymer [Cu19I4(pdt)12(SH)3] has been synthesized by three methods, in which nanosized chiral Cu19I4S12 clusters act as fourteen-connected nodes and triple pyridine rings and hydrosulfides act as connectors. The in situ S-C(sp(3)), S-C(sp(2)), and S-C(sp) cleavage reactions have been observed in the work.     

Multiple-quantum-well perovskite for hole-transport-layer-free light-emitting diodes

We demonstrate hole-transport-layer-free light-emitting diodes(LEDs) based on solution-processed multiple-quantum-well(MQW) perovskite. The MQW perovskite can self-assemble to a unique structure of vertically graded distribution with two-dimensional layered perovskite covered by three-dimensionallike perovskite at top, which can naturally form a barrier of electron transporting to the anode interface,thereby enhancing the charge capture efficiency. This leads to hole-transport-layer-free MQW per...     

Light-guided tumor diagnosis and therapeutics: From nanoclusters to polyoxometalates

Malignant tumors, with the characteristics of easy metastasis and recurrence, are a serious threat to health of mankind. It is urgent to develop promising clinical cancer targeted agents with combination of rapid diagnosis and efficient therapies. Compared with the conventional photosensitizing agents, the recent advances of nanoagents based on transition metal-oxide clusters possess unique structural and electronic properties, greatly improving cancer survival rate, meanwhile, keeping high cont...