Time-resolved ESR study on photochemical formation of radical pair in cyclodextrin cavities

1991 ◽  
Vol 69 (11) ◽  
pp. 1643-1648 ◽  
Author(s):  
Hisao Murai ◽  
Yoshinori Yamamoto ◽  
Yasumasa J. I'Haya
Keyword(s):  
Aqueous Solution ◽  
Aqueous Solutions ◽  
Spin Polarization ◽  
Room Temperature ◽  
Radical Pair ◽  
Ion Pair ◽  
Time Resolved ◽  
Excited Triplet ◽  
Photochemical Formation ◽  
Fixed Orientation

The photoreduction of xanthone with diethylaniline in cyclodextrin cavities was studied at 77 K and room temperature by a time-resolved ESR technique. The radical pair observed in β- and γ-cyclodextrins showed inverted spin polarization compared to that of precursor excited triplet xanthone. This result is rationalized by taking account of the fixed orientation of the radical ion pair in the cyclodextrins. Frozen aqueous solutions and dried powder-like samples provided similar results. The spectrum of the radical pair was also detected in an aqueous solution of β-cyclodextrin at room temperature. Key words: cyclodextrins, xanthone, spin polarization, radical ion-pair, time-resolved ESR.

scholarly journals Time-Resolved Resonance Raman Spectroscopy of Excited Triplet State All-Trans-Retinal: Excitation Profiles, Intersystem Crossing Kinetics, and O2 Quenching

1983 ◽  
Vol 3 (1-6) ◽  
pp. 321-332 ◽  
Author(s):  
G. H. Atkinson ◽  
J. B. Pallix
Keyword(s):  
Raman Spectroscopy ◽  
Triplet State ◽  
Room Temperature ◽  
Resonance Raman Spectroscopy ◽  
Resonance Raman ◽  
Excited Triplet State ◽  
Intersystem Crossing ◽  
Time Resolved ◽  
Excited Triplet

The time-resolved resonance Raman (TR3) spectra of excited triplet state all-trans-retinal (ATR (T1)) are analyzed with respect to (1) time-resolved excitation profiles (TREP), (2) T1 → S0 intersystem crossing rates, and (3) O2 quenching kinetics. These TR3 data are used to comment on the electronic characteristics and kinetic decay of the excited triplet state of a specific retinal isomer in room temperature solutions.

scholarly journals Two-dimensional monolayer salt nanostructures can spontaneously aggregate rather than dissolve in dilute aqueous solutions

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Wenhui Zhao ◽  
Yunxiang Sun ◽  
Weiduo Zhu ◽  
Jian Jiang ◽  
Xiaorong Zhao ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Aqueous Solutions ◽  
Room Temperature ◽  
Md Simulations ◽  
Free Energy Calculations ◽  
Zigzag Chain ◽  
Two Dimensional ◽  
Nucleation Behavior ◽  
Dilute Aqueous Solution ◽  
Dilute Aqueous Solutions

AbstractIt is well known that NaCl salt crystals can easily dissolve in dilute aqueous solutions at room temperature. Herein, we reported the first computational evidence of a novel salt nucleation behavior at room temperature, i.e., the spontaneous formation of two-dimensional (2D) alkali chloride crystalline/non-crystalline nanostructures in dilute aqueous solution under nanoscale confinement. Microsecond-scale classical molecular dynamics (MD) simulations showed that NaCl or LiCl, initially fully dissolved in confined water, can spontaneously nucleate into 2D monolayer nanostructures with either ordered or disordered morphologies. Notably, the NaCl nanostructures exhibited a 2D crystalline square-unit pattern, whereas the LiCl nanostructures adopted non-crystalline 2D hexagonal ring and/or zigzag chain patterns. These structural patterns appeared to be quite generic, regardless of the water and ion models used in the MD simulations. The generic patterns formed by 2D monolayer NaCl and LiCl nanostructures were also confirmed by ab initio MD simulations. The formation of 2D salt structures in dilute aqueous solution at room temperature is counterintuitive. Free energy calculations indicated that the unexpected spontaneous salt nucleation behavior can be attributed to the nanoscale confinement and strongly compressed hydration shells of ions.

Radiation Chemistry of DNA Model Compounds, IX. Carbohydrate Products in the γ-Radiolysis of Thymidine in Aqueous Solution. The Radical-Induced Scission of the N-Glycosidic Bond

1976 ◽  
Vol 31 (2) ◽  
pp. 227-233 ◽  
Author(s):  
Miral Dizdaroglu ◽  
Klaus Neuwald ◽  
Clemens Von Sonntag
Keyword(s):  
Aqueous Solution ◽  
Aqueous Solutions ◽  
Room Temperature ◽  
Radiation Chemistry ◽  
Oh Radical ◽  
Glycosidic Linkage ◽  
Model Compounds ◽  
Sugar Moiety ◽  
G Value ◽  
Radical Attack

In the γ-radiolysis of deoxygenated N2O-saturated aqueous solutions of thymidine (10-3 M, room temperature, dose rate 4· 1018 eV/g.h., dose 6.7 1017-3.3 • 1018 eV/g) the following products (G-values in parentheses) have been identified : 2,5-dideoxy-pentos-4-ulose (1) (0.01), 2,4-dideoxy-pentodialdose (2) (0.02), 2,4-dideoxy-pentos-3-ulose (3) (0.03), 2,3-dideoxy-pentos-4-ulose (4) (0.01), 2-deoxy-pentos-4-ulose (5) (0.1), 2-deoxyribonic acid (6) (0.02) and thymine (8) ( ≤ 0.2). In the presence of oxygen (N2O/O2 80/20 v/v saturated) products 1-4 are absent, G (5) = 0.2, G (6) = 0.07 and G (8) ≤ 0.4. Furthermore, 2-deoxy-tetrodialdose (7) which is absent in deoxygenated solution is formed with a G-value of 0.03. Mechanisms are proposed to account for the scission of the N-glycosidic linkage. Product 6 is thought to be due to a primary OH radical attack at C-1′ of the sugar moiety, 8 arises from an attack at C-3′, 1, 4 and 5 from an attack at C-4′, and 2 and 7 from an attack at C-5′.

Direct homogeneous phosphoroimmunoassay for carbamazepine in serum.

1986 ◽  
Vol 32 (1) ◽  
pp. 53-56 ◽  
Author(s):  
A M Sidki ◽  
D S Smith ◽  
J Landon
Keyword(s):  
Room Temperature ◽  
Biological Fluids ◽  
Liquid Solution ◽  
Oxygen Quenching ◽  
Time Resolved ◽  
Excited Triplet ◽  
Complete Rejection ◽  
Pre Treatment ◽  
Development And Validation

Abstract In this "phosphoroimmunoassay," a phosphorescent label is used: erythrosin (tetraiodofluorescein). Its long-lived phosphorescence was detected after pulsed excitation in a time-resolved luminescence spectrometer. To achieve convenient open-atmosphere phosphorimetry in liquid solution at room temperature, we used sodium sulfite as an "in situ" chemical deoxygenator, to eliminate oxygen quenching of the excited triplet state. Time-resolved detection allows for complete rejection of short-lived background signals, including those from fluorescent or light-scattering components of biological fluids that can interfere in fluoroimmunoassays. We chose the antiepileptic drug carbamazepine (CBZ) and its active metabolite CBZ-10, 11-epoxide (CBZE) to demonstrate the development and validation of nonseparation assays based on quenching the phosphorescence of erythrosin-labeled drug upon binding to antibody. These two compounds cross reacted equally with the antiserum used; hence, we measured the activity of both in patients' sera. Alternatively, simple pre-treatment of the sample with acid destroys CBZE immunoreactivity and enables specific assay of CBZ.

Electron spin polarization in an excited triplet-radical pair system: Generation and decay of the state

2006 ◽  
Vol 30 (3-4) ◽  
pp. 619-636 ◽  
Author(s):  
V. F. Tarasov ◽  
I. S. M. Saiful ◽  
Y. Iwasaki ◽  
Y. Ohba ◽  
A. Savitsky ◽  
...  
Keyword(s):  
Spin Polarization ◽  
Electron Spin ◽  
Radical Pair ◽  
The State ◽  
Electron Spin Polarization ◽  
Excited Triplet ◽  
System Generation ◽  
Triplet Radical Pair

scholarly journals New Insights on the Self-Assembly of Bio-sourced Block Copolymer MH-b-PS in Aqueous Solutions: Nanocorals, Cubosomes & Nanocubes

2021 ◽  
Author(s):  
Yomen Atassi ◽  
Redouane Borsali
Keyword(s):  
Aqueous Solution ◽  
Block Copolymer ◽  
Aqueous Solutions ◽  
Self Assembly ◽  
Room Temperature ◽  
Linear Structure ◽  
The Self ◽  
Fine Tuning ◽  
Experimental Parameters ◽  
First Time

Polymer self-assembly in solution still constitutes a simple methodology for the preparation of elegant yet sophisticated nanomaterials. This work aims at presenting how the fine tuning of the experimental parameters of the nanoprecipitation process can lead to a variety of novel morphologies ranging from nanocorals through cubosomes to nanocubes. A carbohydrate dibloc copolymer with a simple and linear structure MH1.2k-b-PS2.3 has been used as a model to illustrate the formation of these new self-assemblies. This is the first time that nanocube morphology has been generated using this type of bio-sourced co-polymer in aqueous solution and at room temperature.

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