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991.
Chaoyang Wang Fang Zeng Xinxing Liu Shuizhu Wu Ping Liu 《European Polymer Journal》2005,41(1):185-191
The complexation between poly(ethylene imine) (PEI) and poly(2-acrylamido-2-methylpropanesulfonic acid) (PAMPS) or AMPS copolymers was investigated with the relative excimer emission intensity IE/IM of a cationic probe 1-pyrenemethylamine hydrochloride (PyMeA · HCl), fluorescence nonradiative energy transfer (NRET) IPy/INp of naphthalene to pyrene labels, the fluorescence anisotropy r and IE/IM of pyrene labels. PEI was a hyperbranched weak polycation in acid solution, which formed complex with anionic polyelectrolytes due to the electrostatic attraction. The IE/IM of PyMeA · HCl probe decreased to zero, the intra-, intermolecular NRET IPy/INp and IE/IM of pyrene labels on the AMPS copolymers reached their maxima when χ was increased from 0 to 2.4, which was defined as the mole ratio of the amino group in PEI to the AMPS group in the polyanion. These facts indicated the formation of nonstoichiometric complex of the oppositely charged polyelectrolytes when χ = 2.4 at the concentration much lower than their overlap concentrations. The intermolecular aggregate appeared as indicated by an increase in the intermolecular IPy/INp and r with χ up to 2.4 due to neutralizing and hydrophobizing the polyelectrolytes and the bridging effect of the PEI chain bound on different polyanion chains. At high pH, PEI became a neutral polymer and did not bind with the AMPS anion to form the complex as illustrated by the constant value of r for the pyrene labels attached to the AMPS polyanion as that without addition of PEI. The amino group in PEI quenched pyrene and naphthalene emission, resulting a decrease in both INp and IPy. 相似文献
992.
Man-Kit Lau Qian-Feng Zhang Wing-Tak Wong Wa-Hung Leung 《Journal of organometallic chemistry》2004,689(14):2401-2410
Treatment of [M(Buppy)2Cl]2 (M=Ir (1), Rh (2); BuppyH=2-(4′-tert-butylphenyl)pyridine) with Na(Et2NCS2), K[S2P(OMe)2], and K[N(Ph2PS)2]2 afforded monomeric [Ir(Buppy)2(S∧S)] (S∧S=Et2NCS2 (3), S2P(OMe)2 (4), N(PPh2S)2 (5)) and [Rh(Buppy)2(S∧S)] (S∧S=Et2NCS2 (6), S2P(OMe)2 (7), N(PPh2S)2 (8)), respectively. Reaction of 1 with Na[N(PPh2Se)2] gave [Ir(Buppy)2{N(PPh2Se)2}] (9). The crystal structures of 3, 4, 7, and 8 have been determined. Treatment of 1 or 2 with AgOTf (OTf=triflate) followed by reaction with KSCN gave dinuclear [{M(Buppy)2}2(μ-SCN)2] (M=Ir (10), Rh (11)), in which the SCN− ligands bind to the two metal centers in a μ-S,N fashion. Interaction of 1 and 2 with [Et4N]2[WQ4] gave trinuclear heterometallic complexes [{Ir(Buppy)2}2(μ-WQ4)] (Q=S (12), Se (13)) and [{Rh(Buppy)2}2{(μ-WQ)4}] (Q=S (14), Se (15)), respectively. Hydrolysis of 12 led to formation of [{Ir(Buppy)2}2{W(O)(μ-S)2(μ3-S)}] (16) that has been characterized by X-ray diffraction. 相似文献
993.
Synthesis,structure and catalytic polymerization activity of half‐sandwich cyclometallated iridium complexes 下载免费PDF全文
A series of mononuclear half‐sandwich cyclometallated iridium complexes with Schiff base ligands were synthesized in good yields. Five air‐stable C,N‐chelate mode complexes were obtained smoothly through metal‐mediated C─H bond activation. Treatments of dimeric metal complexes [Cp*IrCl2]2 with ligands L1–L5 afforded the corresponding C,N‐chelate mononuclear half‐sandwich iridium(III) complexes 1 – 5 . These iridium complexes exhibit high catalytic activity for norbornene polymerization. Both steric and electronic effects of the substituted groups have influences on the behaviors of the polymerization process. All complexes were characterized using infrared and NMR spectroscopies and elemental analysis. Molecular structures of complexes 1 , 2 and 5 were further confirmed using single‐crystal X‐ray analysis. 相似文献
994.
《Journal of Coordination Chemistry》2012,65(2):165-173
The title complex has been synthesized and characterized by elemental and thermal analysis, IR and electronic spectroscopy, conductivity studies and X-ray crystallography. In the crystal, the complex has two-fold symmetry and the copper atom adopts square pyramidal coordination. Bond valences for Cu were computed. Cu–O(propionate) bonds are slightly stronger than the Cu–N bonds, and the Cu–O(water) bond is distinctly weaker. Molecules are linked by O–H···O hydrogen bonds to form infinite hydrogen-bonded chains along the y axis. 相似文献
995.
《Journal of Coordination Chemistry》2012,65(19):3157-3167
Reaction of FeCl3 with one equivalent of acac (acac = pentane-2,4-dionate) and KTpMe2 (TpMe2 = hydrotris(3,5-dimethyl-pyrazol-1-yl)borate) yielded TpMe2Fe(acac)Cl (3), which upon reaction with methanolic solution of sodium azide resulted in the formation of a six coordinate compound TpMe2Fe(acac)N3 (4) with a single azide. When the reaction of FeCl3 and KTpMe2 was performed with two equivalents of sodium azide and one equivalent of 3,5-dimethylpyrazole (PzMe2H), a six coordinate cis azide compound [TpMe2Fe(PzMe2H)(N3)2] (5) was obtained. These compounds were characterized by spectroscopic methods and single crystal X-ray crystallography. Electrochemical studies of 5 show that it can be irreversibly reduced at relatively lower potential than 4. The photolysis of 5 was performed at 77 K at different wavelengths (480, 419, and 330 nm) showing that 5 was photoreduced to a high-spin Fe(II) species instead of photooxidized to Fe(V). 相似文献
996.
The host–guest complex of a proline–thiourea bipyridine trifluoromethanesulfonic acid salt can catalyze organocatalytic asymmetric reactions such as aldol, Michael, and Mannich in polar protic medium with high stereoselectivities. The privileged bipyridine backbone and the thiourea motif are essential to the activity and enantioselectivity through hydrogen bonding interactions. 相似文献
997.
《Analytical letters》2012,45(1):57-61
Abstract A new method for the determination of the titre of ascorbic acid standard solutions employing potassium dichromate as a primary standard has been developed. In a pyrophosphate medium, the pyrophosphate complex of divalent manganese is oxidized by dichromate to the pyrophosphate complex of tervalent manganese; the latter oxidizes o-tolidine reversibly with formation of the corresponding quinonediimine, which is visually titrated by the ascorbic acid standard solution. 相似文献
998.
Rosenani A. Haque Abbas Washeel Salman Srinivasa Budagumpi Amirul Al‐Ashraf Abdullah Zena A. Abdul Hameed Al‐Mudaris Amin M. S. Abdul Majid 《应用有机金属化学》2013,27(8):465-473
A series of Ag(I) complexes ( 6 , 7 , 8 , 9 ) derived from imidazol‐2‐ylidenes was synthesized by reacting Ag2O with an o‐, m‐, p‐xylyl or 1,3,5‐triazine‐linked imidazolium salts ( 1 , 2 , 3 , 4 ) and then characterizing these using various spectro‐analytical techniques. Additionally, triazine‐linked bis‐imidazolium salt 5 was characterized using the single‐crystal X‐ray diffraction method. Complexes 6–9 were formed from the N‐heterocyclic carbene ligand precursors 1–3 as PF6‐ salts in good yields. Conversely, salt 5 does not form Ag(I) complex even under various reaction conditions. Using ampicillin as a standard, complexes 6–9 were tested against bacteria strains Escherichia coli and Staphylococcus aureus as Gram‐negative and Gram‐positive bacteria, respectively, showing potent antimicrobial activities against the tested bacteria even at minimum inhibition concentration and bacterial concentration levels. Furthermore, the potential anticancer activities of the reported complexes were evaluated against the human colorectal cancer (HCT 116) cell lines, using 5‐fluorouracil as a standard drug. The highest anticancer activities were observed for complex 8 with an IC50 value of 3.4 μm , whereas the lowest was observed for complex 9 with an IC50 value of 18.1 μm . Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
999.
A new nickel(II) σ‐aryl complex, trans‐chloro(9‐phenanthrenyl)bis(triphenylphosphine)nickel(II), was used as a precatalyst for the Suzuki–Miyaura coupling reactions of aryl chlorides. The catalytic conditions were optimized by investigating the cross‐coupling of p‐chloroanisole with phenylboronic acid. The results show that this complex is efficient for both electron‐rich and electron‐deficient aryl chlorides, though it gives better yields for activated arylboronic acids than deactivated ones. All isolated cross‐coupled biaryl products have been characterized by 1H and 13C NMR, and their spectral data are consistent with those reported. Side products from the coupling of arylboronic acid with the precatalyst complex have also been isolated and characterized, which is helpful for understanding the coupling mechanism. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
1000.
A new metal complex[MnL2](NO3)2·CH3CN(1) was synthesized by reaction of 4’-4-(l,2,4-triazol-l-yl)phenyl -2,2’:6’,2"-terpyridine(L) with manganese nitrate.The structure of the complex was determined by X-ray crystallography.The results of UV-vis studies showed that the complex exhibits colorimetric sensing ability for Fe3+,which can be observed by naked eye. 相似文献