Drastic solid-state fluorescence enhancement behaviour of imidazo[4,5-a]naphthalene-type fluorescent hosts upon inclusion of polyethers and tert-butyl alcohol

As one of the most promising materials for the construction of desirable solid-state fluorescent system, new solid-state fluorescent host-guest system, which consists of the imidazo[4,5-a]naphthalene-type fluorescent hosts 2 and sterically hindered guest molecules were designed and prepared. The crystals of 2 exhibit sensitive colour change and drastic fluorescence enhancement behaviour upon polyethers (diethylene glycol dimethyl ether (DGDM), diethylene glycol diethyl ether (DGDE) and diethylene glycol dibutyl ether (DGDB)) or tert-butyl alcohol. A comparison of the X-ray crystal structures of the guest-free and polyether- and tert-butyl alcohol-inclusion compounds indicates that the enclathrated polyether or tert-butyl alcohol molecule decrease the π-stacking between hosts and enlarge the distance between the host-host aromatic planes. On the bases of the spectral data and the crystal structures, the effects of the enclathrated sterically hindered guest on the drastic solid-state fluorescence enhancement behaviour of the host-guest crystals are discussed.     

Reaction of 2,3-diaminomaleonitrile with diones

2,3-Diaminomaleonitrile (DAMN) was allowed to react with 2,6-heptanedione to produce (2Z)-2-amino-3-[(1E)-3-methylcyclohex-2-enylideneamino]but-2-enedinitrile and (2Z)-2-amino-3-[(1Z)-3-methylcyclohex-2-enylideneamino]but-2-enedinitrile. The reaction of DAMN with 2,7-octanedione yielded trans-5,8a-dimethyl-1,5a,6,7,8,8a-hexahydrocyclopenta[e]-1,4-diazepine-2,3-dicarbonitrile. DAMN reacted with 2,8-nonanedione to afford trans- and cis-5,9a-dimethyl-5a,6,7,8,9,9a-hexahydro-1H-benzo[e]-1,4-diazepine-2,3-dicarbonitrile. These compounds were characterized by X-ray crystallography, NMR spectroscopy, and DFT calculations.     

Control of Duplex Formation and Columnar Self‐Assembly with Heterogeneous Amide/Urea Macrocycles

The perfect blend : A new class of self‐assembling cyclooligomers with mixed urea/amide backbone is described (see figure). A high level of hierarchical and directional control is achieved: depending on the level of backbone preorganization, columnar or tubular arrangements with either parallel or antiparallel growing modes can be selected.

     

The supramolecular chemistry of metal complexes with heavily substituted imidazoles as ligands: Cobalt(II) and zinc(II) complexes of 1-methyl-4,5-diphenylimidazole

An investigation of the M^II/X⁻/L [M^II = Co, Ni, Cu, Zn; X⁻ = Cl⁻, Br⁻, I⁻, NCS⁻, NO₃⁻, N₃⁻, CH₃COO⁻; L = 1-methyl-4,5-diphenylimidazole] general reaction system towards the detailed study of the intermolecular interactions utilized for controlling the supramolecular organization and the structural consequences on the structures produced has been initiated. Three representative complexes with the formulae [Co(NO₃)₂(L)₂] (1), [Zn(NO₃)₂(L)₂] (2) and [Co(NCS)₂(L)₂]·EtOH (3·EtOH) have been synthesized and characterized by spectroscopic methods and single-crystal X-ray analysis. Compounds 1 and 2 are isomorphous (tetragonal, I4₁cd) with their metal ions in a severely distorted octahedral Co/ZnN₂O₄ environment, while 3·EtOH crystallizes in P2₁/c with a tetrahedral CoN₄ coordination. The structural analysis of 1, 2 and 3·EtOH reveals a common mode of packing among neighbouring ligands (expressed through intramolecular π–π interactions between the 4,5-diphenylimidazole moieties), enhancing thus the rigidity and stability of the complexes. The bent coordination of the two isothiocyanates in 3 [Co–NCS angles of 173.8(2) and 160.8(2)°] seems to be caused by intermolecular hydrogen bonding and crystal packing effects.     

FAAS法测定三种中药材中的微量元素

采用V（浓硝酸）＋V（高氯酸）=4＋1混酸溶解消化样品。用火焰原子吸收光谱法（FAAS）测定了红芪、黄芪、板蓝根中K、ca、Na、Mg、Fe、Mn、Zn、Cu8种微量元素的含量。结果表明,红芪中钙的含量最高,铜的含量最低;黄芪和板蓝根中镁的含量最高,铜的含量最低。各元素回收率（n=7）在96．07％～101．26％之间,RSD值（n=7）在0．60％～2．99％之间。     

M@B<Subscript>9</Subscript> and M@B<Subscript>10</Subscript> molecular wheels containing planar nona- and deca-coordinate heavy group 11, 12, and 13 metals (M=Ag,Au, Cd,Hg, In,Tl)

A density functional and ab initio theory investigation on M@B₉ and M@B₁₀ molecular wheels containing planar nona- and deca-coordinate heavy group 11, 12 and 13 metals (M=Ag, Au, Cd, Hg, In, Ti) has been performed. These unusual clusters all prove to be true minima on the potential energy surfaces of the systems and σ+π double aromatic in nature. The first two vertical one-electron detachment energies of M@B₁₀⁻ (M=Ag, Au) anions and first two ionization potentials of M@B₉ (M=Ag, Au) and M@B₁₀ (M=Cd, Hg) neutrals were calculated to aid future experiments. The cluster complexes designed in this work may expend the domain of planar hyper-coordinate elements to include heavy group 11, 12, and 13 metals and serve as interesting candidates to be targeted in experiments. Electronic Supplementary Material  Supplementary material is available for this article at and is accessible for authorized users. Supported by the National Natural Science Foundation of China (Grant No. 20873117)