A host-guest optical sensor for the determination of aliphatic amines as exemplified by octylamine is proposed. It is based
on the reversible fluorescence enhancement of heptakis(2,6-di-O-isobutyl)-β-cyclodextrin(DOB-β-CD) hosting tetraphenylporphyrin
(TPP) immobilized in poly(vinyl chloride) (PVC) membrane by aliphatic amine extracted from aqueous phase into membrane phase.
The optimum membrane contained 1.15 wt % TPP, 6.15 wt % DOB-β-CD as sensing reagent and other membrane materials. The fluorescence
enhancement of the membrane resulted from the formation of a stable three-component complex among DOB-β-CD, TPP, and aliphatic
amines. With the optimum conditions described, the fluorescence response of the sensor to octylamine shows a good correlation
with the theoretically derived equation in the range 1.0 × 10–6 to 8.0 × 10–4 mol/L. The response characteristics including reversibility, response time, reproducibility and lifetime and selectivity
of this optical device are also discussed in detail. This sensor has also been applied for the determination of octylamine
in water samples containing interferents with satisfactory recovery.
Received: 21 November 1999 / Revised: 10 January 2000 / Accepted: 15 January 2000 相似文献
A theory of dissociative recombination of slow electrons and molecular ions in a strong monochromatic light field is developed. The theory takes into account interference between various reaction channels and is constructed in a rigid basis adiabatic with respect to rotation (the approximation of a fixed molecular axis). The mathematical apparatus of the theory is based on the stationary formalism of the matrix of radiation collisions, whose poles correspond to “quasi-energy” states of a composite system. Along with transitions into dissociative configurations, field-induced nonadiabatic transitions into bound intermediate states of valence (non-Rydberg) configurations are considered. As a particular application of the theory, the e? + O2+(2Πg) → $ O(^{2s_1 + 1} l_1 ) + O(^{2s_2 + 1} l_2 ) A theory of dissociative recombination of slow electrons and molecular ions in a strong monochromatic light field is developed.
The theory takes into account interference between various reaction channels and is constructed in a rigid basis adiabatic
with respect to rotation (the approximation of a fixed molecular axis). The mathematical apparatus of the theory is based
on the stationary formalism of the matrix of radiation collisions, whose poles correspond to “quasi-energy” states of a composite
system. Along with transitions into dissociative configurations, field-induced nonadiabatic transitions into bound intermediate
states of valence (non-Rydberg) configurations are considered. As a particular application of the theory, the e− + O2+(2Πg) → reaction is analyzed. A study of this reaction requires detailed information about the potential curves of the states participating
in it with taking into account the external electromagnetic field (l and s are the electronic angular momenta and reaction product spins). For this purpose, the general problem is divided into three
stages. At the first stage, the theoretical approach is formulated, and at the second stage, the corresponding potential curves
are calculated and the main reaction mechanisms are determined. The third stage should include calculations of the total and
differential cross sections. This work is concerned with the first two stages; that is, the adiabatic potential curves of
the singlet and triplet dissociative states of the O2** oxygen molecule are calculated, a classification of all possible transition types is given, and reaction mechanisms in the
presence of monochromatic laser radiation are determined. The frequency regions of external radiation in which these mechanisms
are most effective are found.
Original Russian Text ? S.O. Adamson, R.J. Buenker, G.V. Golubkov, M.G. Golubkov, A.I. Dement’ev, 2009, published in Khimicheskaya
Fizika, 2009, Vol. 28, No. 4, pp. 26–42. 相似文献
The endothermic associative ionization reaction N(2D) + O(3P) → NO** → NO(1Σ+) +e- in slow collisions of the atoms has been considered in terms of the multichannel quantum defect theory. The dependences of the partial and total cross sections of the reaction on the energy of the colliding atoms in the range of 0–0.3 eV have been calculated. It has been shown that the cross sections have a pronounced resonance structure, which is formed as a result of the multichannel interaction of autoionization states of the intermediate Rydberg complex NO** with dissociative states. The temperature dependence of the reaction rate constant is presented. The results are compared with those of other calculations and available experimental data. 相似文献
A cationic degradation product, formed in solution from retinal Schiff base (RSB), is examined in the gas phase using ion mobility spectrometry, photoisomerization action spectroscopy, and collision induced dissociation (CID). The degradation product is found to be N-n-butyl-2-(β-ionylidene)-4-methylpyridinium (BIP) produced through 6π electrocyclization of RSB followed by protonation and loss of dihydrogen. Ion mobility measurements show that BIP exists as trans and cis isomers that can be interconverted through buffer gas collisions and by exposure to light, with a maximum response at λ = 420 nm.
The diluted aerosols from a cigarette (3R4F) and an e-cigarette (Vype ePen) were compared in two commercially available in vitro exposure systems: the Borgwaldt RM20S and Vitrocell VC10. Dosimetry was assessed by measuring deposited aerosol mass in the exposure chambers via quartz crystal microbalances, followed by quantification of deposited nicotine on their surface. The two exposure systems were shown to generate the same aerosols (pre-dilution) within analytically quantified nicotine concentration levels (p = 0.105). The dosimetry methods employed enabled assessment of the diluted aerosol at the exposure interface. At a common dilution, the per puff e-cigarette aerosol deposited mass was greater than cigarette smoke. At four dilutions, the RM20S produced deposited mass ranging 0.1–0.5 µg/cm2/puff for cigarette and 0.1–0.9 µg/cm2/puff for e-cigarette; the VC10 ranged 0.4–2.1 µg/cm2/puff for cigarette and 0.3–3.3 µg/cm2/puff for e-cigarette. In contrast nicotine delivery was much greater from the cigarette than from the e-cigarette at a common dilution, but consistent with the differing nicotine percentages in the respective aerosols. On the RM20S, nicotine ranged 2.5–16.8 ng/cm2/puff for the cigarette and 1.2–5.6 ng/cm2/puff for the e-cigarette. On the VC10, nicotine concentration ranged 10.0–93.9 ng/cm2/puff for the cigarette and 4.0–12.3 ng/cm2/puff for the e-cigarette. The deposited aerosol from a conventional cigarette and an e-cigarette in vitro are compositionally different; this emphasises the importance of understanding and characterising different product aerosols using dosimetry tools. This will enable easier extrapolation and comparison of pre-clinical data and consumer use studies, to help further explore the reduced risk potential of next generation nicotine products.
Graphical abstract A cigarette and an e-cigarette (top left) were assessed on two different in vitro exposure systems, the Borgwaldt RM20S (top right) and the VC 10 (bottom right). Compositionally the product aerosols were different, but there was no difference between the same product on different machines (bottom left).
In order to investigate the ability of bis(zinc octaethylporphyrin) (bis–ZnOEP) to discriminate cyclohexanohemicucurbit[n]urils (cycHC[n]) of different shapes and sizes, the self-assembly of barrel-shaped chiral cycHC[n] with bis–ZnOEP was studied by various spectroscopic methods (absorption, fluorescence, circular dichroism (CD), and NMR). While the binding of 6-membered cycHC[6] induced a tweezer-like conformation followed by the formation of anti-form of bis–ZnOEP upon further addition of cycHC[6], the interaction of 8-membered cycHC[8] is more complex and proceeds through the featured syn-to-anti conformational change of bis–ZnOEP and further intermolecular self-assembly via multiple noncovalent associations between cycHC[8] and bis–ZnOEP. Whilst bis–porphyrins are known to be effective chemical sensors able to differentiate various guests based on their chirality via induced CD, their ability to sense small differences in the shape and size of relatively large macrocycles, such as chiral cycHC[6] and cycHC[8], is scarcely examined. Both studied complexes exhibited characteristic induced CD signals in the region of porphyrin absorption upon complexation. 相似文献
Biacetyl and acridinium ion but not Michler's ketone sensitize the aquation of Cr(NH35(NCS)2+ in 0.1 N sulfuric acid solution. Phosphorescence quenching occurs in first system, and the kinetics of this and of the sensitized reaction in the presence and absence of oxygen indicate that transfer of excitation energy occurs from the biacetyl first triplet state. The reaction is entirely one of ammonia aquation, indicating that the first quartet excited state of the complex is populated.Acridinium ion sensitizes both ammonia and thiocyanate aquation, the presence of oxygen affecting the latter but not the former mode. The kinetics of the fluorescence quenching by the complex and that of the sensitized ammonia aquation indicate that the latter process is induced by the first singlet excited state of acridinium ion, along with a small component of thiocyanate aquation. The oxygen dependence results indicate that the remainder of the thiocyanate aquation is induced by the first triplet excited state of the donor. It is concluded that, in this system, the singlet excited state of acridinium ion populates the first quartet excited state of the complex ion while the triplet state populates the doublet excited state of the complex. Some of the complexities of excited state processes of Cr(III) complexes are discussed.
Zusammenfassung Das Biacetyl und das Acridinium, nicht aber Michler's Keton sensibilisieren die Aquotisierung von Cr(NH35(NCS)2+ in 0,1 n-Schwefelsäure-Lösung. Phosphoreszenzlöschung tritt im erstgenannten System auf und seine Kinetik, sowie die der sensibilisierten Reaktion, in Gegenwart sowie unter Ausschluß von Sauerstoff weist darauf hin, daß der Übergang der Anregungsenergie vom ersten Triplettzustand des Biacetyls stattfindet. Die Reaktion führt anschließend zur Aquotisierung von Ammoniak. Diese Tatsache weist darauf hin, daß der erste angeregte Quartettzustand des Komplexes besetzt wird. Das Acridinium sensibilisiert sowohl die Ammoniakals auch die Thiocyanat-Aquotisierung, wobei die Gegenwart von Sauerstoff zwar letztere, jedoch nicht erstere beeinflußt. Die Kinetik der Fluoreszenzlöschung durch den Komplex sowie die der sensibilisierten Ammoniak-Aquotisierung deuten darauf hin, daß letzterer Prozeß durch den ersten angeregten Singulettzustand des Acridiniums induziert wird, zusammen mit einem kleinen Teil der Thiocyanat-Aquotisierung. Die Sauerstoffabhängigkeit zeigt, daß der Rest der Thiocyanat-Aquotisierung durch den ersten angeregten Triplettzustand des Donors induziert wird. Daraus wird der Schluß gezogen, daß in diesem System der angeregte Singlettzustand des Acridiniums zur Besetzung des ersten angeregten Quartettzustands des Komplexes führt, wohingegen die Energie des Triplettzustands auf den angeregten Dublettzustand des Komplexes übertragen wird. Einige Probleme der Prozesse zwischen angeregten Zuständen von Cr(III)-Komplexen werden diskutiert.
Résumé Les ions biacétyle et acridinium, mais non pas la cétone de Michler, sensibilisent l'hydratation de Cr(NH3)5(NCS)2+ dans une solution d'acide sulforique 0,1 N. L'extinction de la phosphorescence se produit dans le premier système; sa cinétique ainsi que celle de la réaction sensibilisée en présence et en l'absence d'oxygène indiquent que le transfert d'énergie d'excitation se produit à partir du premier état triplet du biacétyle. La réaction est totalement celle de l'hydratation de l'ammoniac, ce qui indique que le premier quartet excité du complexe se trouve peuplé.L'ion acridinium sensibilise l'hydratation de l'ammoniac et du thiocyanate seule cette dernière réaction étant sensible à l'oxygène. La cinétique de l'extinction de fluorescence par le complexe ainse que celle de l'hydratation sensibilisée de l'ammoniac indiquent que ce dernier processus est induit par le premier état excité singulet de l'ion acridinium, avec parallèlement une faible hydratation du thiocyanate. Les résultats sur le rôle de l'oxygène montrent que le restant de l'hydratation du thiocyanate est induit par le premier triplet excité du donneur. On en conclue que dans ce système l'état excité singulet de l'ion acridinium peuple le premier quartet excité de l'ion complexe tandis que l'état triplet peuple l'état excité doublet du complexe. On discute certains détails complexes des processus d'excitation des complexes de Cr (III).
Dedicated to the memory of Professor Hans-Ludwig Schläfer. 相似文献
