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1.
The infrared spectra of the complexes [Cu(bipy) 3] (C10 4) 2′ [Cu(bipy) 2] (C10 4) 2, [Cu(bipy) 2I]I, [cu(bipy) 2I] C10 4 and [Cu(bipy)(C10 4) 2] (bipy - 2,2′-bipyridine) are discussed in relation to their known or probable structures. Evidence for tetragonal distortion of [Cu(bipy) 3] 2+ but not [Cu(phen) 3] 2+ (phen = 1, 10-phenanthroline) is adduced. 相似文献
2.
A novel chromogenic and fluorogenic chemosensor RhB-pMOSal comprising a rhodamine fluorophore and a salicylaldehyde receptor being connected by an iminohydrazine link was synthesized and fully characterized. Its sensing behavior toward various metal ions in neutral aqueous solution was investigated by absorption and fluorescence spectroscopy. RhB-pMOSal exhibited a reversible and sensitive ??turn-on?? response of absorption and fluorescence toward Cu 2+ in aqueous acetonitrile solution. Approximate 65 and 6-fold enhancement in the absorbance at 556 nm and fluorescence intensity at 573 nm were estimated when equivalent Cu 2+ was added to the RhB-pMOSal solution. Under the same conditions, RhB-pMOSal displayed more sensitive than a reported analogue RhB-Sal to Cu 2+ ion. The competition experiments for Cu 2+ mixed with common metal ions exhibited no obvious change in absorption and emission except Cr 3+ ion that can induce the fluorescence quenching of RhB-pMOSal to some extent. 相似文献
3.
The absorption and fluorescence spectra of α-carboline, 9H-pyrido[2,3-b]indole, AC, in organic aprotic solvents containing different water proportions and in acid/base aqueous solutions inside and outside the pH range have been examined. In the organic aprotic solvents, the addition of increasing concentrations of water sequentially quenches and shifts to the red the fluorescence spectra of AC. These spectral changes have been rationalized assuming the formation, at the lower water concentrations, of a discrete ground state non-cyclic weakly fluorescent AC hydrate emitting at 376 nm that, upon increasing the water concentrations, evolves to a higher order AC poly hydrate emitting at 397 nm. The changes of the AC absorption spectra in aqueous acid/basic solutions indicate the existence of three ground state prototropic species; the pyridinic protonated cation, C (pK a?=?4.10?±?0.05), the neutral, N (pK a?=?14.5?±?0.2), and the pyrrolic deprotonated anion, A. Conversely, the changes of the AC fluorescence spectra in these media indicate the existence of four excited state species emitting at 376 nm, 397 nm, 460 nm and 465 nm. Since the emissions at 376 nm and 397 nm satisfactorily match those of the hydrates observed in the organic-water mixtures, they were consistently assigned to two differently hydrated ground state N species. The remaining emissions at 460 nm and 465 nm have been assigned without ambiguity, on the basis of their excitation spectra, to the C and A species, respectively. The excited-state pK as of the prototropic species of AC have been estimated by using the Förster-Weller cycle. 相似文献
4.
DOPA–melanin (DOPA = 3,4-dihydroxyphenyl-alanine) complexes with Cu(II) cations were studied by electron paramagnetic resonance
(EPR) spectroscopy. After the addition of metal cations to the melanin polymer, the EPR spectra parameters were measured.
The axial g-factor values are g
|| = 2.20 and g ^ = 2.0 5 g_{ \bot } = 2.0 5 . Since $ g_{||} > g_{ \bot } > 2 $ g_{||} > g_{ \bot } > 2 , the ground state orbital of the unpaired electron of the Cu(II) complex is | x 2 - y 2
ñ \left| {{{x}}^{ 2} } \right. \, - \, \left. {{{y}}^{ 2} } \right\rangle . Square coordination of these cations in melanin is proposed. The influence of the Cu(II) concentration in solution used
during synthesis on the concentration of melanin radicals was investigated. Cu(II) cations causes the decrease in the paramagnetic
center concentration in melanin. The Cu(II) EPR spectra are not saturated within the microwave power range of 0.7–70 mW used
in our experiment. 相似文献
5.
A Fluorescent chemosensor based on pyrene scaffold, 5-diethylamino-2-(pyren-1-yliminomethyl)-phenol (PDS) is synthesized using condensation method. It displays novel aggregation-induced emission (AIE) phenomena in its aggregated/solid state. The AIE characteristic of PDS is studied in CH3CN/H2O mixtures at different volume percentage of water and morphology of the aggregated particles are investigated by DLS and optical fluorescence microscopic study. The probe is aggregated into ordered one-dimensional (1-D) rod like microcrystals and exhibit high efficiency of solid-state emission with green colour. By taking advantage of its interesting AIE feature, the aggregated hydrosol has been utilized as ‘off–on’ type fluorescence switching chemosensor with superb selectivity and sensitivity towards Cu2+ions and the limit of detection (LOD) was calculated as low as 6.3 µM. A high Stern–Volmer quenching constant was estimated to be 2.88?×?105 M?1. The proposed chemosensor with AIE feature reveals a prospective view for the on-site visual recognition of Cu2+ ions in fluorescent paper strips and the synthesized probe is also exploited to find out the concentration of Cu2+ions in real water samples. 相似文献
6.
A highly selective and sensitive fluorescent Zn 2+ sensor N-(2-(benzo[d]thiazol-2-yl)phenyl)-2-((pyridin-2-ylmethyl)amino)acetamide ( 1) that derived from 2-(2′-aminophenyl)benzothiazole has been developed. In aqueous solution (HEPES/CH 3CN=4/6, v/v, HEPES 20 mM, pH?=?7.4), sensor 1 displays highly selective recognition to Zn 2+ over other metal ions with a distinct longer-wavelength emission enhancement. Sensor 1 binds Zn 2+ through its amide form with a 1:1 binding stoichiometry, which switched on the excited-state intramolecular proton transfer (ESIPT). Graphical Abstract A simple 2-(2′-aminophenyl)benzothiazole-based fluorescent “off-on” sensor for Zn2+ recognition in HEPES/CH3CN(4/6, v/v, HEPES 20 mM, pH?=?7.4) solution through switching on ESIPT has been developed. 相似文献
7.
For the first time, the nuclear magnetic resonance method of “stationary coaxial ampoule” was used to study the temperature dependence of the paramagnetic contribution of iron-containing complex molecules to the volume magnetic susceptibility of a solution of this complex. It was found that when the complex [Fe(salten)Cl] is dissolved in the chloroform/toluene mixture (1:1), this dependence obeys the Curie–Weiss law. On the basis of the obtained dependence the value of the effective spin of the Fe(III) ion was calculated with high accuracy. The obtained value of S eff for the Fe(III) ion agrees with the value found in the EPR study of the vitrified solution of this complex. 相似文献
8.
ESR studies were conducted on Cu 2+-doped bis-(5,5′-diethylbarbiturato)bis picoline Zn(II). Two Cu 2+ lattice sites, Cu 2+(I) and Cu 2+(II), were identified. These sites exhibit two sets of four hyperfine lines in all directions. The g factor and hyperfine splitting were calculated from ESR absorption spectra: gx ?=?2.0201?±?0.002, gy ?=?2.0900?±?0.002, gz ?=?2.1634?±?0.002, Ax ?=?(30?±?2)?×?10 ?4?cm ?1, Ay ?=?(40?±?2)?×?10 ?4?cm ?1 and Az ?=?(154?±?2)?×?10 ?4?cm ?1. It was found that Cu 2+ enters the lattice substitutionally. The ground-state wavefunction of the Cu 2+ ion in this lattice was determined from the spin Hamiltonian constants obtained from the ESR studies. With the help of an optical absorption study, the nature of the bonding in the complex is also discussed. 相似文献
9.
Commercially available CdSe–ZnS Quantum Dots (QDs) have been modified by exchanging the hydrophobic surface ligands with (2-mercaptoethyl)-trimethylammonium
chloride. The resulting water soluble conjugate was titrated with solutions of adenosine triphosphate (ATP), adenosine diphosphate,
adenosine monophosphate, guanosine triphosphate (GTP), guanosine diphosphate and guanosine monophosphate in 0.01 M 4-(2-hydroxyethyl)-1-piperazineethanesulfonic
acid buffer (pH 7.4). A strong fluorescence quench of about 80% was observed for ATP, a quench of 25% was observed for GTP
while the others had virtually no effect. The quenching effect of ATP and GTP was attributed to the high negative charge density
associated with these substrate’s resulting in a strong attraction to the QD surface enabling them to engage in electron transfer
with the excited QD. The lack of fluorescence quenching associated with the other nucleotides was most likely due to their
reduced charge density resulting in a lower affinity for the QD surface. 相似文献
10.
In this article the solution of dynamical equation of motion of IBM-Ⅱ in continuous variable representation is discussed.With appropriate transformation and approximation,the on-phase part of system manifests the vibration-rotation mode and the off-phase part the 'scissor mode',ect.In the last section the energy spectrum of 156Gd is calculated.The result can well reproduce the algebraic result of IBM-Ⅱ. 相似文献
11.
The heterogeneous exchange reaction between cobalt ions in solution and Co 3Co(CN) 6 2 · 12 H 2O has been studied. It is found that the exchange rate increases as the concentration of Co 2+ ions in solution decreases. The results show that the exchange rate is controlled by the surface reaction at the solid-liquid interface. The activation parameters E a, ΔH #, ΔS #, and ΔG # are calculated. 相似文献
12.
It has been shown 1–3 that the exchange interactions in the dimeric 4 complex di-μ-(pyridine N-oxide) bis [bisnitrato(pyridine N-oxide) copper(II)], [Cu(pyO) 2] 2 lead to a triplet ground state for the copper(II) pairs. The triplet state epr spectrum has been observed 1,3,5,6 for a powdered sample of the complex coprecipitated with the corresponding zinc(II) complex, and the computer simulation of this spectrum has been carried out by two different groups 3,5,6. As is often the case when dealing with spectra of powdered samples, there exist ambiguities with the spectrum of [Cu(pyO) 2-(NO 3) 2] 2 since all of the resonances were not observed, and consequently, the interpretation and values of the parameters remain in question. It was felt that examination of the epr spectra of single crystal samples should permit a rigorous analysis of this problem. 相似文献
13.
The effect of optical limitation of laser radiation in 2-cyclooctylamino-5-nitropyridine (COANP-C 70) doped with fullerene is experimentally studied. The energy density of the incident beam is measured to be ~4–4.5 J cm ?2 and the attenuation coefficients and the absorption spectrum of a new structure are determined. The photoinduced variation of the refractive index of the COANP-fullerene system and its influence on the optical limitation is studied in the visible range upon irradiation by nanosecond laser pulses. The mechanisms of optical limitation of radiation in these structures are specified. The nonlinear optical coefficients n 2 and χ (3) of the fullerene-doped π-conjugated COANP system are measured for the first time by the methods of dynamic holography. 相似文献
14.
Cu(L-glu)(bpy)(L-glu = L-glutamato; bpy = 2, 2′-bipyridine) was prepared. Its electronic absorption spectrum and photoacoustic spectrum were recorded at room temperature. They were compared with each other and compared quantitatively with ligand field theory(LFT) and the radical wave function of non-free ions [1–3]. Therefore, the electronic structure was also investigated with its spectrum behaviors and PLFT [1–3]. 相似文献
15.
In this report, the properties of triglycine sulfate (TGS) crystals doped with urea and L--alanine were studied. Urea and L--alanine have successfully entered into TGS crystal, demonstrated by infrared transmission spectrum and pyroelectric study. Figures of merit and Curie temperature are increased due to these two additions. UrLATGS is more suitable for infrared detectors than pure TGS crystals. 相似文献
16.
Effect of p-cyclodextrin (β-CD) on micellization of cetyltrimethylammonium bromide (CTAB) in aqueous solution was investigated by twisted intramolecular charge transfer (TICT) dual fluorescence of sodium p-dimethylaminobenzoate (SDMAB). It was shown that β-CD induces the micellization of CTAB and the aggregation of CTAB below CMC as well. A reduced charge density at CTAB micelle interface in the presence of β-CD, due to the incorporation of 1:1 CTAB-β-CD inclusion complex in micelle, was concluded to be the reason for β-CD induced micellization of CTAB. 相似文献
17.
The electron transitions in manganese(II)-doped II–VI compounds have been assigned by the Angular Overlap Model (AOM). The extracted AOM and electron repulsion parameters are applied to assess the covalency of the respective manganese-ligand bonds. A comparison with Crystal Field Theory (CFT) is made in order to demonstrate the advantages offered by the AOM. The Dq values for Mn(II) in CdS and CdSe were found by interpolation from the Dq vs R−5ml relation. 相似文献
18.
We prove that any gauged WZNW model has a Lax pair representation, and give explicitly the general solution of the classical
equations of motion of the SL(2,ℝ/U(1) theory. We calculate the symplectic structure of this solution by solving a differential
equation of the Gelfand–Dikii type with initial state conditions at infinity, and transform the canonical physical fields
non-locally onto canonical free fields. The results will, finally, be collected in a local B?cklund transformation. These
calculations prepare the theory for an exact canonical quantization.
Received: 9 June 1998 / Accepted: 7 March 1999 相似文献
19.
A Fourier Transform Infrared (FTIR) analysis using Fresnel Attenuated Total Reflectance (ATR) was performed on silica-filled cis-1,4-polyisoprene. Silica filler's detrimental effects on zinc-activated cure systems has been well documented. The silane coupling agent bis-(y-triethoxysilylpropyl)-tetrasulfide (Si-69) and polyethylene glycol (PEG) are industry standards used to offset the interactions caused by reaction between silica and the zinc-activated cure system. By adding PEG, it was found that the interaction peaks at 1040 and 1017 cm -1 caused by the adsorption of natural rubber (NR) onto the surface of the silica were not formed. Also, by monitoring the zinc stearate peak at 1540 cm -1, both Si-69 and PEG were found to reduce the soluble zinc ion reaction with the silica surface. Supporting evidence from the rheometer curves also shows that the additives reduce the cure retardation effects of the silica filler. 相似文献
20.
1 Introduction Inrecentyears,boththetheoreticalandexperimentalinvestigationsonlasercoolingandtrappinghavebecomeoneofthemajorfieldsinatomic,molecularandoptical physics[1~ 8] .Thedevelopmentoflasercoolingandtrappingtechnologyisimportantfortheapplicationssu… 相似文献
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