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31.
32.
Lu W Mi BX Chan MC Hui Z Che CM Zhu N Lee ST 《Journal of the American Chemical Society》2004,126(15):4958-4971
The synthesis and structural, photophysical, electrochemical, and electroluminescent properties of a class of platinum(II) complexes bearing sigma-alkynyl ancillary ligands, namely [(C/N/N)Pt(C[triple bond]C]nR] [H(C/N/N) = 6-aryl-2,2'-bipyridine; n = 1-4; R = aryl, alkyl, or trimethylsilyl], have been studied. Substituents with different steric and electronic properties were introduced into the tridentate cyclometalating and arylacetylide ligands, and the pi-conjugation length of the oligoynyl moiety was homologously extended from ethynyl to octatetraynyl. The X-ray crystal structures of several derivatives confirm the Pt-(CC) ligation and reveal various intermolecular interactions, such as pi-pi, Pt...Pt, and C-H...F-C. The complexes display good thermal stability and intense phosphorescence in fluid and glassy solutions with high quantum yields and microsecond lifetimes. Their emission energies are sensitive to solvent polarity, the electronic affinities of the substituents on both the cyclometalating and arylacetylide groups, and the length of the oligoynyl ligand. By choosing appropriate cyclometalating and sigma-alkynyl ligands, the emission color of this class of platinum(II) complexes can be tuned from green-yellow to saturated red. In addition to (3)MLCT [Pt(5d) --> pi*(C/N/N)] and (3)IL(C/N/N), intriguing (3)IL(alkynyl) excited states localized on -(C[triple bond]C)(4)- and -(C[triple bond]Cpyrenyl-1) moieties that afford narrow-bandwidth emissions have been observed. Selected Pt(II) complexes were doped into the emissive region of multilayer, vapor-deposited organic light-emitting diodes. The tunable electrophosphorescence energy resembles that recorded in fluid solutions for these emitters, and the devices exhibit high luminance and efficiencies (up to 4.2 cd A(-1)). 相似文献
33.
The interactions of [Pt(CNN)(4-dpt)]PF(6), (1; 4-dpt=2,4-diamino-6-(4-pyridyl)-1,3,5-triazine, HCNN=6-phenyl-2,2'-bipyridine) with double-stranded DNA, poly(dA-dT)(2), and poly(dG-dC)(2) were examined by spectroscopic, electrophoretic, and hydrodynamic methods. The spectroscopic data were analyzed with McGhee, van't Hoff, and Gibbs-Helmholtz equations. In a comparative study, [Pt(CNN)(py)]PF(6) (2; py=pyridine) was prepared and the nature of its binding towards DNA was investigated [preliminary results: ChemBioChem 2003, 4, 62-68]. For reactions with calf thymus DNA at 20 degrees C, the intrinsic binding constants for 1 and 2 are (4.6+/-0.2)x10(5) and (2.3+/-0.3)x10(4) mol(-1) dm(3), respectively. Results of DNA-binding reactions revealed that 1 and 2 preferentially bind to the AT sequence of duplex DNA. Intercalation is the preferred binding mode for 2, whereas both intercalation and minor-groove binding are observed for 1. Complex 1 is cytotoxic against a number of carcinoma cell lines, including KB-3-1, CNE-3, and HepG2, and remains potent against multidrug- or cisplatin-resistant KB-V-1 and CNE1 cell lines, for which the resistance ratios are 1.6 and 1.5, respectively. Importantly, 1 is almost an order of magnitude less toxic to the normal cell line CCD-19Lu (IC(50)=176+/-1.7 microM) and it selectively induced apoptosis leading to cancer cell death with less than 5 % detectable necrosis. 相似文献
34.
Shanru He Yuanyuan Chen Lulu Wang Xue Bai Tingting Bu Jie Zhang Ming Lu Nam-Chul Ha Chunshan Quan Ki Hyun Nam Yongbin Xu 《Molecules (Basel, Switzerland)》2022,27(15)
Pyridoxal 5′-phosphate (PLP) is the active form of vitamin B6, but it is highly reactive and poisonous in its free form. YggS is a PLP-binding protein found in bacteria and humans that mediates PLP homeostasis by delivering PLP to target enzymes or by performing a protective function. Several biochemical and structural studies of YggS have been reported, but the mechanism by which YggS recognizes PLP has not been fully elucidated. Here, we report a functional and structural analysis of YggS from Fusobacterium nucleatum (FnYggS). The PLP molecule could bind to native FnYggS, but no PLP binding was observed for selenomethionine (SeMet)-derivatized FnYggS. The crystal structure of FnYggS showed a type III TIM barrel fold, exhibiting structural homology with several other PLP-dependent enzymes. Although FnYggS exhibited low (<35%) amino acid sequence similarity with previously studied YggS proteins, its overall structure and PLP-binding site were highly conserved. In the PLP-binding site of FnYggS, the sulfate ion was coordinated by the conserved residues Ser201, Gly218, and Thr219, which were positioned to provide the binding moiety for the phosphate group of PLP. The mutagenesis study showed that the conserved Ser201 residue in FnYggS was the key residue for PLP binding. These results will expand the knowledge of the molecular properties and function of the YggS family. 相似文献
35.
Du Yongbo Yu Pengfei Wang Junxiong Zhang Jinping Wang Chang’an Che Defu 《Journal of Thermal Analysis and Calorimetry》2021,143(1):327-334
Journal of Thermal Analysis and Calorimetry - Coal O2/CO2 combustion is a promising carbon capture and storage technology for coal-fired power plant. Char consumption rate prediction is essential... 相似文献
36.
Harun Muhammad Arif Bin Gunnasegaran Prem A./L. Sidik Nor Azwadi Che Beriache M’hamed Ghaderian Javad 《Journal of Thermal Analysis and Calorimetry》2021,144(4):1435-1449
Journal of Thermal Analysis and Calorimetry - High heat generation from electronic devices needs to cool down properly to prevent overheating. Loop heat pipe (LHP) is one of the excellent cooling... 相似文献
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38.
Hsu‐Feng Lee Po‐Hsun Wang Yi‐Chiang Huang Wen‐Hung Su Ram Gopal Chun Che Lee Steven Holdcroft Wen‐Yao Huang 《Journal of polymer science. Part A, Polymer chemistry》2014,52(18):2579-2587
A series of sterically‐encumbered, sulfonated, poly(arylene ether) copolymers were synthesized and their proton conductivity examined. The series was prepared by copolymerizing a novel monomer, 2″,3″,5″,6″‐tetraphenyl‐[1,1′:4',1″:4″,1″':4″',1″″‐quinquephenyl]‐4,4″″‐diol, with 4,4'‐difluorobenzophenone and bisphenol A. Subsequent sulfonation and solution casting provided membranes possessing ion exchange capacities of 1.9 to 2.7 mmol/g and excellent mechanical properties (Young's modulus, 0.2–1.2 GPa; tensile strength, 35–70 MPa; elongation at break, 62–231%). Water uptake ranged from 34 to 98 wt% at 80 °C/100% RH. Proton conductivities ranged between 0.24 to 16 mS/cm at 80 °C/60% RH, and 3 to 167 mS/cm at 80 °C/95% RH. TEM analysis of the polymers, in the dehydrated state, revealed isolated spherical aggregates of ions, which presumably coalesce when hydrated to provide highly conductive pathways. The strategy of using highly‐encumbered polymer frameworks for the design of mechanically‐robust and dimensionally‐stable proton conducting membranes is demonstrated. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2579‐2587 相似文献
39.