共查询到20条相似文献,搜索用时 15 毫秒
1.
Leila Tarazi Nara Narayanan John Sowell Gabor Patonay Lucjan Strekowski 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2002,58(2):257-264
The spectral features of the squarylium dye NN525 in different solutions and its complexation with several metal ions were investigated. The absorbance maximum of the dye is at 669 nm in tetrahydrofuran. This value matches the output of a commercially available laser diode (650 nm), thus making use of such a source practical for excitation. The emission maximum of the dye in tetrahydrofuran is at 676 nm. The addition of either Fe(III) ion or Co(II) ion resulted in fluorescence quenching of the dye. The detection limit is 6.24 x 10(-8) M for Fe(III) ion and 1.55 x 10(-8) M for Co(II) ion. The molar ratio of the metal to the dye was established to be 1:1 for both metal ions. The stability constant Ks of the metal-dye complex was calculated to be 3.14 x 10(6) M(-1) for the Fe-dye complex and 2.64 x 10(5) M(-1) for the Co-dye complex. 相似文献
2.
The spectral features of the near-infrared (NIR) dye TG-170 in different solutions and its complexation with several metal ions were investigated. The absorbance maxima of the dye are at λ=819, 805, and 791 nm in dimethyl sulfoxide (DMSO), methanol, and a buffer of pH 5.9, respectively. These values match the output of a commercially available laser diode (780 nm), thus making use of such a source practical for excitation. The emission wavelengths of the dye are at λem =822, 812, and 803 nm in DMSO, methanol, and the buffer, respectively. The molar absorptivity and fluorescence quantum yield increase accordingly. The addition of either an Al(III) ion or Be(II) ion resulted in fluorescence quenching of the dye. The Stern–Volmer quenching constant, KSV, was calculated from the Stern–Volmer plot to be KSV=3.11×105 M−1 for the Al(III) ion and KSV=1.17×106 M−1 for the Be(II) ion. The molar ratio of the metal to the dye was established to be 1:1 for both metal ions. The stability constant, KS, of the metal–dye complex was calculated to be 4.37×104 M−1 for the Al–dye complex and 1.94×106 M−1 for the Be–dye complex. 相似文献
3.
《Journal of Coordination Chemistry》2012,65(22):3915-3925
Two new complexes, [Co(L1)(Py)3]Cl0.75Br0.25 (L1=4-hydroxy salicylaldehyde S-allyl-isothiosemicarbazonato-N,N′,O) and [Fe(L2)Cl]·C2H5OH (L2=S-allyl-N1-(4-hydroxy salicylaldehyde)-N4-(salicylaldehyde)isothiosemicarbazide-N,N′,O,O′), have been synthesized and characterized by elemental analysis, FT-IR and UV–vis spectroscopy, and molar conductivity. The solid-state structures of the complexes were also determined by single crystal X-ray diffraction. The iron(III) and cobalt(III) complexes adopt distorted square-pyramidal and octahedral geometries, respectively. The strength of the bonding in these complexes was investigated by thermogravimetric studies with both exhibiting stability with complete decomposition not occurring until ca. 600?°C. 相似文献
4.
报导了四个单核Co(Ⅱ)和Fe(Ⅱ)的配合物[Co(L1)2](ClO4)2·(CH3CN)(1),[Fe(L1)2](ClO4)2·(H2O)(2),[Co(L2)](ClO4)2(3),以及[Fe(L2)](ClO4)2·2H2O(4),(其中L1=4’-苯基-2,2’:6’,2”-三联吡啶,L2=N,N,N-三-(2-(2-吡啶甲叉氨基)乙基)胺)的合成和性质,以及配合物1、3的晶体结构.配合物1和3的晶体都属于单斜晶系.它们的晶胞参数分别为:1a=1.0855(4)nm,b=1.6201(5)nm,c=2.5236(5)nm,β=92.63(2)°,V=4.433(1)nm3;3a=2.8351(8)nm,b=1.0670(3)nm,c=1.9255(5)m,β=101.03(4)°,V=5717(2)nm3.2和4的氧化还原电位分别为E=0.78V和0.63V‘它们的d-d跃迁吸收最大值分别位于565和521nm处. 相似文献
5.
The syn-isomer of 1,8-bis(4,4′-diisopropyl-9,9′-diacridyl)naphthalene, 1, has been prepared by two consecutive Pd(PPh3)4-catalyzed Stille cross-coupling steps. This highly congested sensor undergoes Fe(III)-selective fluorescence quenching in water/acetonitrile even in the presence of excess of other metal ions. 相似文献
6.
M. A. El-Taher 《中国化学会会志》1998,45(6):815-820
The kinetics of hydrolysis of ortho- or para-hydroxybenzylidene-4-benzidine Schiff bases have been examined in the pH range 1.70–11.90, in aqueous media containing 20wt% dioxane, at 20 °C. In basic media, pH > 8.47, a slight increase in the hydrolysis reaction rate of the Schiff bases is observed. In such basic media, the rate-controlling step is the attack of hydroxide ion on the ionized Schiff base. Below pH 6.82, the rate-determining step is ascribed to be the attack of water molecules on the protonated substrate. The effects of Fe(II), Co(II), Ni(II) and Cu(II) ions on the hydrolysis reaction rate of the Schiff bases have been studied and discussed on the basis of formation of a monocyclic chelate rings. The various thermodynamic parameters have also been evaluated and discussed. 相似文献
7.
《Journal of Coordination Chemistry》2012,65(7):1132-1141
In this work, 2,3-dichlorophenoxy substituted cobalt and iron phthalocyanines have been synthesized and used as efficient catalysts for aerobic oxidation of nitrophenols. Co(II) and Fe(II) phthalocyanines have been characterized by IR, 1H NMR, 13C NMR, UV–vis, and mass spectroscopies. tert-butyl hydroperoxide (TBHP), m-chloroperoxybenzoic acid, hydrogen peroxide, and air oxygen have been used as oxygen source. These catalysts offered the highest activity on 4-nitrophenol oxidation in 3 h. In order to achieve the best reaction conditions, oxidant ratio, temperature, and oxidant type have been investigated with different nitrophenols in 3 h. 相似文献
8.
Complexes of three related 1-azapentadienyl ligands [N(SiMe2R1)C(But)(CH)3SiMe2R]−, abbreviated as L (R = But, R1 = Me), L′ (R = Me = R1), and L″ (R = But = R1), are described. The crystalline compounds Sn(L)2 (1), Sn(L′)2 (2), [Sn(L′)(μ-Cl)]2 (3) and [Sn(L″)(μ-Cl)]2 (4) were prepared from SnCl2 and 2 K(L), 2 K(L′), K(L′) and K(L″), respectively, in thf. Treatment of the appropriate lithium 1-azapentadienyl with Si(Cl)Me3 yielded the yellow crystalline Me3Si(L) (5) and the volatile liquid Me3Si(L′) (6) and Me3Si(L″) (7), each being an N,N,C-trisilyldieneamine. The red, crystalline Fe(L)2 (8) and Co(L′)2 (9) were obtained from thf solutions of FeCl2 with 2 Li(L)(tmeda) and CoCl2 with 2 K(L′), respectively. Each of 1-9 gave satisfactory C, H, N analyses; 6 and 7 (GC-MS) and 1, 2, 8 and 9 (MS) showed molecular cations and appropriate fragments (also 3 and 4). The 1H, 13C and 119Sn NMR (1-4) and IR spectra support the assignment of 1-4 as containing Sn-N(SiMe2R1)-C(But)(CH)3SiMe2R moieties and 5-7 as N(SiMe3)(SiMe2R1)C(But)(CH)3SiMe2R molecules; for 1-4 this is confirmed by their X-ray structures. The magnetic moments for 8 (5.56 μB) and 9 (2.75 μB) are remarkably close to the appropriate Fe and Co complex [M{η3-N(SiMe3)C(But)C(H)SiMe3}2]; hence it is proposed that 8 and 9 have similar metal-centred, centrosymmetric, distorted octahedral structures. 相似文献
9.
《中国化学快报》2020,31(5):1342-1344
The limited knowledge on low-coordinate zero-valent transition-metal species has intrigued great synthetic efforts in developing ligand sets for their stabilization. While the combined ligand set of N-heterocyclic carbene (NHC) with vinylsilanes was the only known ligand system amenable to the stabilization of three-coordinate formal zero-valent cobalt, iron, and manganese complexes, the exploration on other ligands has proved that the ligand set of NHCs with styrene is equally effective in stabilizing three-coordinate formal zero-valent metal complexes in the form of (NHC)M(η2-CH2CHPh)2 (NHC = IPr, IMes; M = Co, Fe, Mn). These styrene complexes can be prepared by the one-pot reactions of MCl2 with styrene, NHC and KC8, and have been characterized by various spectroscopic methods. Preliminary reactivity study indicated that the interaction of [(IMes)Fe(η2-CH2CHPh)2] with DippN3 produces the iron(IV) bisimido complex [(IMes)Fe(NDipp)2] and styrene, which hints at the utility of these zero-valent metal styene complexes as synthons of the mono-coordinate species (NHC)M(0). 相似文献
10.
An optimized flow-injection manifold for the chemiluminescence determination of cobalt(II), copper(II), iron(II) and chromium(III) by their catalytic effect on the luminol reaction is described. Detection limits are 0.0006, 0.08, 0.3 and 0.1 ng ml?1, respectively. The suppression effect of several carboxylic acids on the emission intensity is discussed. A procedure for the separation of cobalt(II), copper(II) and iron(II) on a low-capacity, silica-based cation-exchange column, using 5 mM oxalic acid at pH 4.2 as the mobile phase and post-column detection via the luminol reaction, is also described. Detection limits for cobalt(II) and copper(II) are 0.01 and 5 ng ml?1, respectively. 相似文献
11.
A potentiometric titration for cobalt(II) determination in the presence of Co(III) based on the oxidation of Co(II) with Na2CrO4 in ethylenediamine medium and back-titration of the oxidant excess with (NH4)2Fe(SO4)2 in acid medium is described. The titration is monitored with a Pt indicator electrode and carried out until the greatest jump of potential from one drop of titrant appears. A RSD smaller than 1.5% has been obtained for 50–300 μmol Co(II). The method proposed was applied in the analysis of a new type electroless copper plating solutions containing Co(II)-ethylenediamine complex compounds as reducing agents. Cu(II), Co(III) and Cr(III) do not interfere in the determination of Co(II). 相似文献
12.
13.
A series of 2,6-bis(imino)pyridyl iron(II) and cobalt(II) complexes [2,6-(ArNCMe)2C5H3N]MCl2 (Ar = 2,6-i-Pr2C6H3, M = Fe: 3a, M = Co: 4a; Ar = 2,4,6-i-Pr3C6H2, M = Fe: 3b, M = Co: 4b; Ar = 2,6-i-Pr2-4-BrC6H2, M = Fe: 3c, M = Co: 4c; Ar = 2,4-i-Pr2-6-BrC6H2, M = Fe: 3d, M = Co: 4d) has been synthesized, characterized, and investigated as precatalysts for the polymerization of ethylene in the presence of modified methylaluminoxane (MMAO). The substituents of pyridinebisimine ligands and their positions located significantly influence catalyst activity and polymer property. It is found that the catalytic activities of the iron complexes/MMAO systems are mainly dominated by electronical effect, while those of the cobalt complexes/MMAO systems are primarily controlled by hindering effect. 相似文献
14.
Zhengzhou Liu Zheng Lu Weifeng Peng Yang Liu Jianghuai Hu Ke Zeng Gang Yang 《Tetrahedron》2019,75(22):3008-3014
In this paper, an adenine-derived fluorescent chromophore (HCC-APA) was synthesized to detect its interaction with iron ions. The results showed that a large stokes shift (υ = 10981.5 cm?1) fluorescence of the HCC-APA was appeared. The fluorescence quantum yields of HCC-APA in DMF and THF were 3.49% and 17.54%, respectively, demonstrating its higher fluorescence performance than unmodified adenine. Besides, the fluorescence quenching of HCC-APA with iron ions was further detected. Fluorescence titration experiments confirmed that the detection limit of HCC-APA for Fe3+ was 3.69 μM. The interaction between iron ions and HCC-APA was investigated by continuous variable method, indicating that the binding ratio is 1:1. And the interaction site was deeply explored by 1H NMR and molecular simulation. 相似文献
15.
Tatiyana V. Serebryanskaya Ludmila S. IvashkevichAlexander S. Lyakhov Pavel N. GaponikOleg A. Ivashkevich 《Polyhedron》2010
Complexes ML12 and ML22, with M = FeII, CoII, NiII, and 1,3-bis(2-R-tetrazol-5-yl)triazenide ligands L1 (R = Me) and L2 (R = tBu), have been synthesized by the reaction of corresponding 1,3-bis(2-R-tetrazol-5-yl)triazenes with metal(II) salts in basic media and characterized by IR, UV–Vis spectroscopy, thermal and X-ray diffraction analyses. Both 1,3-bis(2-R-tetrazol-5-yl)triazenes were found to deprotonate on coordination and act as tridentate chelating ligands forming distorted MN6 octahedra around metal(II) cations. 相似文献
16.
《Journal of Coordination Chemistry》2012,65(3):328-340
The Co(II) and Cu(II) complexes of 2,4-diamino-5-(3,4,5-trimethoxybenzyl)pyrimidine (trimethoprim) were synthesized and characterized by elemental analysis, UV-Vis and IR spectroscopy, magnetic susceptibility measurements, EPR (Cu complexes) and single crystal X-ray studies. The molecular structures of the compounds consist of dimeric metal ions in distorted octahedral environments, bridged with four acetate ions and each metal ion coordinated to one trimethoprim through the pyrimidinyl nitrogen atom. 相似文献
17.
对Fe(Ⅱ/Ⅲ)离子在Nafion膜中的电荷传输以及在溶液扩散层中的传质过程进行了理论上的分析, 利用小幅度阶跃电位作为激励信号的阻抗测量法测定了该体系的阻抗并求出了Fe(Ⅱ/Ⅲ)离子在膜中的扩散系数和标准速度常数。同时讨论了电极电位和支持电解质浓度对体系阻抗的影响。实验的结果与理论推导的结果相一致。 相似文献
18.
《Analytical letters》2012,45(14):2555-2563
Abstract The coordination of the anticancer drug mithramycin to Tb(III), Fe(III) and Cu(II) was studied in aqueous solution using absorption measurements. The stability constants were calculated from equilibrium competition experiments by means of the SQUAD program. For both first ions, the competitor was oxalic acid and for the latter the competitor was the Cu(II) ions. Cu(II) at pH 7.5, Fe(III) at pH 3.5 and Tb(III) at pH 5.5 formed respectively 1:2, 1:3 and 1:4 metal-to-ligand species. 相似文献
19.
Chang Yi Bo Song Wenwen Tian Xia Cui Qi Qi Wei Jiang Zhengjian Qi Yueming Sun 《Tetrahedron letters》2014
A series of novel fluorene derivatives containing –PO(OH)2 (1, 2), –HS (3), and –N+ (CH3)3 (4) were synthesized and only phosphonic-functionalized fluorene derivatives can detect Fe3+ with high selectivity over other metal ions. The fluorescence quenching of 1 and 2 with titration Fe3+ in water–DMF solution fits the Perrin model of static quenching. Spectral analysis showed that Fe3+ bound with fluorene-based chemosensor through the O-atoms at the phosphonic group to form nonfluorescent complexes. The binding ratio was estimated by the Job plot and the trace levels of iron in samples were successfully monitored. 相似文献
20.
《Journal of Coordination Chemistry》2012,65(1):38-54
Four cobalt(II) coordination polymers, {[Co(HO-BDC)(bbp)]}n (1), {[Co(HO-BDC)(bmbp)2]·(H2O)2}n (2), {[Co(HO-BDC)(bbb)]}n (3), and {[Co2(HO-BDC)2(bmbb)2]·(H2O)3}n (4), where HO-H2BDC?=?5-hydroxyisophthalic acid, bbp = 1,3-bis(benzimidazol-1-yl)propane, bmbp = 1,3-bis(2-methyl-benzimidazol-1-yl)propane, bbb = 1,4-bis(benzimidazol-1-yl)butane, and bmbb = 1,4-bis(2-methyl-benzimidazol-1-yl)butane, have been synthesized and characterized by elemental analyses, IR spectra, single-crystal X-ray diffraction, thermogravimetric analyses, and fluorescence properties. Compounds 1 and 3 are 4-connected 2-D networks with (44·62) topology. Compound 2 is a 1-D chain, while 4 features a 1-D ladder. These 1-D and 2-D complexes are further connected by hydrogen bonds to form 3-D supramolecular architectures. Complexes 1–4 showed very strong yellow luminescence emission. 相似文献