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81.
Daron E. Janzen Michael Juchum Shaun R. Presow Tanya K. Ronson Wolfgang Mohr Rodolphe Clérac 《Supramolecular chemistry》2016,28(1-2):125-140
Sandwich coordination complexes, [LnIII(H3L)2]X3?solvents, of Tb(III), Eu(III), Dy(III), Ho(III) and Er(III) were prepared with two new zwitterionic ester-substituted tripodal amine ligands, tris((2-hydroxy-5-n-butyl benzoate)aminoethyl)-amine (H3L1) and tris((2-hydroxy-5-methyl benzoate)aminoethyl)-amine (H3L2). These ligands were synthesised by condensation of the appropriately substituted salicylaldehyde with tris(2-aminoethyl)amine (tren) followed by in situ reduction of the tris-imine to tris-amine. Subsequent 2:1 reaction with lanthanide(III) ions yields [LnIII(H3L)2]X3?solvents (L = L1, L2; X = Cl?, NO3?; solvents = MeOH or H2O). All complexes were characterised by microanalysis, infrared spectroscopy, high resolution mass spectrometry and solid-state photoluminescence measurements. The crystal structures of [TbIII(H3L1)2]Cl3·6MeOH, [Dy(H3L1)2]Cl3·6MeOH, [EuIII(H3L1)2]Cl3·6MeOH and [TbIII(H3L1)2](NO3)3 reveal high-crystallographic ?3 symmetry at the O6-coordinated octahedral lanthanide(III) ions and that the tripodal ligands are bound in zwitterionic form: the protons from the phenolic oxygens have migrated to the amino nitrogens. Photoluminescence measurements indicate various degrees of energy transfer of the ligand chromophore to the lanthanide ions, as both ligand and lanthanide emission features are observed. Despite the high-crystallographic symmetry and the likely small transverse magnetic anisotropy of the complexes, no evidence of slow relaxation of the magnetisation, characteristic of a single-molecule magnet, was observed for [TbIII(H3L1)2]Cl3·MeOH·3H2O, [DyIII(H3L1)2]Cl3·6H2O, [HoIII(H3L1)2](NO3)3·2H2O, [ErIII(H3L1)2]·H2O and [TbIII(H3L1)2](NO3)3 down to 2.0 K. 相似文献
82.
Titanium dioxide (TiO2) is one of the best semiconductor photocatalysts with optical band gap of 3.2 eV. The optical band gap and photocatalytic properties could be further tuned by tailoring shape, size, composition, and morphology of the nanostructures. Hydrothermal synthesis methods have been applied to produce well-controlled nanostructured TiO2 materials with different morphologies and improved optoelectronic properties. Among various morphologies, one-dimensional (1D) TiO2 nanostructures are of great importance in the field of energy, environmental, and biomedical because of the directional transmission properties resulting from their 1D geometry. Particularly, TiO2 nanorods (NRs) have gained special attention because of their densely packed structure, quantum confinement effect, high aspect ratio, and large specific surface area that could specially improve the directional charge transmission efficiency. This results in the effective photogenerated charge separation and light absorption, which are really important for potential applications of TiO2-based materials for photocatalytic and other important applications. In this review, hydrothermal syntheses of TiO2 NRs including the formation chemistry and the growth mechanism of NRs under different chemical environments and effects of various synthesis parameters (pH, reaction temperature, reaction time, precursors, solvents etc.) on morphology and optoelectronic properties have been discussed. Recent developments in the hydrothermal synthesis of TiO2 NRs and tailoring of their surface properties through various modification strategies such as defect creation, doping, sensitization, surface coating, and heterojunction formation with various functional nanomaterials (plasmonic, oxide, quantum dots, graphene-based nanomaterials, etc.) have been reported to improve the photocatalytic activities. Furthermore, applications of TiO2 NRs/tailored TiO2 NRs as superior photocatalysts in degradation of organic pollutants and bacterial disinfection have been discussed with emphasis on mechanisms of action and recent advances in the fields. 相似文献
83.
84.
Selective Endo and Exo Binding of Mono‐ and Ditopic Ligands to a Rhomboidal Diporphyrin Prism 下载免费PDF全文
Dr. Govindasamy Jayamurugan Derrick A. Roberts Dr. Tanya K. Ronson Prof. Jonathan R. Nitschke 《Angewandte Chemie (International ed. in English)》2015,54(26):7539-7543
Copper(I) can preferentially form heteroleptic complexes containing two phosphine and two nitrogen donors due to steric factors. This preference was employed to direct the self‐assembly of a porphyrin‐faced rhomboidal prism having two parallel tetrakis(4‐iminopyridyl)porphyrinatozinc(II) faces linked by eight 1,4‐bis(diphenylphosphino)benzene pillars. The coordination preferences of the CuI ions and geometries of the ligands come together to generate a slipped‐cofacial orientation of the porphyrinatozinc(II) faces. This orientation enables selective encapsulation of 3,3′‐bipyridine (bipy), which bridges the ZnII ions of the parallel porphyrins, whereas 4,4′‐bipy exhibits weaker external coordination to the porphyrin faces. Reaction with 2,2′‐bipy, by contrast, results in the displacement of the tetratopic porphyrin ligand and formation of [{(2,2′‐bipy)CuI}2(diphosphine)2]. The differing strengths of interactions of bipyridine isomers with the system allows for a hierarchy to be deciphered, whereby 4,4′‐bipy may be displaced by 3,3′‐bipy, which in turn is displaced by 2,2′‐bipy. 相似文献
85.
The present study aims at developing an extraction protocol for efficient ginsenoside recovery from cell suspensions of Panax quinquefolius and P. sikkimensis. Methanol (100%, 70% and 30%), water (40°C, 90°C), water-saturated butanol and butanol-saturated water were compared for their ultrasonication-assisted ginsenoside retrieval efficacy. HPLC and HP-TLC analysis revealed 100% methanol as the best solvent for maximum retrieval of Rb (diol) and Rg (triol) ginsenosides (P. quinquefolius: Rb: 0.189, Rg: 3.163 mg/g DW; P. sikkimensis: Rb: 0.245, Rg: 4.073 mg/g DW), followed by water (90°C). Methanolic solutions, especially 70%, proved to be significant retrievers of Rg1 (1.812 and 1.327 mg/g DW in P. quinquefolius and P. sikkimensis), with poor Re recovery (0.328 and 0.342 mg/g DW). Water-saturated butanol also led to significant ginsenoside extraction (72.4% of content extracted by methanol), selectively in P. quinquefolius, with a less than 50% of total content extracted by methanol, in P. sikkimensis. 相似文献
86.
Peptide mimics with constrained backbone and side-chain geometry are important tools for studying structure activity relationships of biologically active candidates. A general method for creating β-turn mimics possessing side-chain diversity has been developed featuring diastereoselective S(N)1 displacements of an iodide precursor. In particular, 6-iodo-pyrroloazepin-2-one amino ester 10 has served as a common precursor in reactions with a variety of alcohol, phenol, nitrate, and azide nucleophiles to provide an array of constrained peptide mimics. 相似文献
87.
Low cost and scalable manufacture of lab-on-chip devices for applications such as point-of-care testing is an urgent need. Weaving is presented as a unified, scalable and low-cost platform for the manufacture of fabric chips that can be used to perform such testing. Silk yarns with different properties are first selected, treated with the appropriate reagent solutions, dried and handloom-woven in one step into an integrated fabric chip. This platform has the unique advantage of scaling up production using existing and low cost physical infrastructure. We have demonstrated the ability to create pre-defined flow paths in fabric by using wetting and non-wetting silk yarns and a Jacquard attachment in the loom. Further, we show that yarn parameters such as the yarn twist frequency and weaving coverage area may be conveniently used to tune both the wicking rate and the absorptive capacity of the fabric. Yarns optimized for their final function were used to create an integrated fabric chip containing reagent-coated yarns. Strips of this fabric were then used to perform a proof-of-concept immunoassay with sample flow taking place by capillary action and detection being performed by a visual readout. 相似文献
88.
Fluorescence-based aluminum ion sensing using a surface-functionalized microstructured optical fiber
Warren-Smith SC Heng S Ebendorff-Heidepriem H Abell AD Monro TM 《Langmuir : the ACS journal of surfaces and colloids》2011,27(9):5680-5685
The first microstructured optical fiber-based sensor platform for aluminum ions using a surface-attached derivative of lumogallion (3), a known fluorescence-based indicator, has been fabricated. These fibers allow for strong evanescent field interactions with the surrounding media because of the small core size while also providing the potential for real-time and distributed measurements. The fluorescence response to aluminum ions was first demonstrated by applying the procedure to glass slides. This was achieved through the covalent attachment of the fluorophore to a polyelectrolyte-coated glass surface and then to the internal holes of a suspended-core microstructured optical fiber to give an effective aluminum sensor. Whereas the sensor platform reported is fabricated for aluminum, the approach is versatile, with applicability to the detection of other ions. 相似文献
89.
90.
Maass JS Zeller M Breault TM Bartlett BM Sakiyama H Luck RL 《Inorganic chemistry》2012,51(9):4903-4905
The syntheses and structural properties of three dinuclear complexes [L(3)Co(μ(2)-O(2)P(Bn)(2))(3)CoL'][L"] [one ionic L(3) = py(3), L' = py, L" = ClO(4)(-) (1) and two molecular L(3) = py(3), L' = Cl (2) and L(3) = py, μ(2)-NO(3)(-), L' = py (3)] are reported. Complexes feature octahedral Co(II) sites bridged by three dibenzylphosphinate ligands to a tetrahedrally ligated Co(II) site, with the remaining coordination sites occupied by py, nitrato, and Cl ligands. The Co-Co distances are 4.248 ? at 291 K and 4.265 ? at 100 K for 1 and 4.278 and 4.0313(7) ? for 2 and 3, respectively at 100 K. A fit of the low-temperature magnetic susceptibility data was derived for complex 1 with g = 2.25, TIP = 700 × 10(-6) cm(3) mol (-1), λ = -173 cm(-1), κ = 0.93, ν = -3.9, Δ = 630 cm(-1), J = 0.15 cm(-1), and θ = -1.8 resulting in R(χ(M)) = 2.5 × 10(-5) and R(χ(M)T) = 5.8 × 10(-5). 相似文献