Determination of the rate constants of excited-complex formation and the diffusion rate constants for triplet-triplet annihilation kinetics for tetrapyrrole molecules in liquid solutions

1998 ◽  
Vol 65 (4) ◽  
pp. 541-547
Author(s):  
V. V. Sapunov
Keyword(s):  
Complex Formation ◽  
Rate Constants ◽  
Diffusion Rate ◽  
Excited Complex ◽  
Liquid Solutions ◽  
Triplet Triplet Annihilation

scholarly journals Examination of 2-Phenoxyaniline Fluorescence Quenching by Chloromethanes

2019 ◽  
Vol 9 (1S3) ◽  
pp. 257-259
Keyword(s):  
Complex Formation ◽  
Fluorescence Quenching ◽  
Electron Affinity ◽  
Rate Constants ◽  
Diffusion Rate ◽  
Solvent Polarity ◽  
Quenching Rate ◽  
Clear Cut ◽  
Donor Acceptor ◽  
Diffusion Rate Constant

The fluorescence quenching of 2-phenoxyaniline (2PAN) by chloromethanes were studied in hexane, dioxane, acetonitrile and methanol. The quenching rate constants (kq) are large with CCl4 and CHCl3 and close to diffusion rate constant (kdiff) and viscosity dependent, where with CH2Cl2 they are less. No clear cut variation of solvent polarity or viscosity is observed for CH2Cl2. Intermediate donor-acceptor complex formation is suggested for CH2Cl2 quenching. kq varies with electron affinity of quenchers suggesting the formation of non-emissive exciplex in quenching.

Colorimetric Determination of Fluoride in Drinking Groundwater using a Polymeric Zirconium Complex of 5-(2-Carboxyphenylazo)-8-Hydroxyquinoline

2013 ◽  
Vol 12 (7) ◽  
pp. 460-465
Author(s):  
Sameer Amereih ◽  
Zaher Barghouthi ◽  
Lamees Majjiad
Keyword(s):  
Drinking Water ◽  
Detection Limit ◽  
Complex Formation ◽  
Molar Absorptivity ◽  
Colorimetric Determination ◽  
Zirconium Complex ◽  
Reliable Determination ◽  
Percentage Recovery ◽  
Quantitation Limit

A sensitive colorimetric determination of fluoride in drinking water has been developed using a polymeric zirconium complex of 5-(2-Carboxyphenylazo)-8-Hydroxyquinoline as fluoride reagents. The method allowed a reliable determination of fluoride in range of (0.0-1.5) mg L-1. The molar absorptivity of the complex formation is 7695 ± 27 L mol-1 cm-1 at 460 nm. The sensitivity, detection limit, quantitation limit, and percentage recovery for 1.0 mg L-1 fluoride for the proposed method were found to be 0.353 ± 0.013 μg mL-1, 0.1 mg L-1, 0.3 mg L-1, and 101.7 ± 4.1, respectively.

Determination of rate constants of redox reactions of second order from current-less potential-time curves by a simplified graphical-numerical method

1983 ◽  
Vol 48 (5) ◽  
pp. 1358-1367 ◽  
Author(s):  
Antonín Tockstein ◽  
František Skopal
Keyword(s):  
Numerical Method ◽  
Explicit Form ◽  
Rate Constant ◽  
Optimization Algorithm ◽  
Rate Constants ◽  
Redox Reactions ◽  
Second Order ◽  
Wide Region ◽  
Recurrent Formula

A method for constructing curves is proposed that are linear in a wide region and from whose slopes it is possible to determine the rate constant, if a parameter, θ, is calculated numerically from a rapidly converging recurrent formula or from its explicit form. The values of rate constants and parameter θ thus simply found are compared with those found by an optimization algorithm on a computer; the deviations do not exceed ±10%.

Determination of the Accurate Values of the Rate Constant and Thermodynamic Parameters for the Rotation About the C(sp2)-C(aryl) Bond; Adamantan-1-yl 3-Bromo-2,4,6-trimethylphenyl Ketone

1998 ◽  
Vol 63 (7) ◽  
pp. 955-966
Author(s):  
Eva Přibylová ◽  
Miroslav Holík
Keyword(s):  
Thermodynamic Parameters ◽  
Shape Analysis ◽  
Rate Constants ◽  
Line Shape ◽  
Microsoft Excel ◽  
Hindered Rotation ◽  
H Nmr ◽  
Line Shape Analysis ◽  
Coalescence Temperature

Four programs for the 1H NMR line shape analysis: two commercial - Winkubo (Bruker) and DNMR5 (QCPE 165) and two written in our laboratory - Newton (in Microsoft Excel) and Simtex (in Matlab) have been tested in order to get highly accurate rate constants of the hindered rotation about a single bond. For this purpose four testing criteria were used, two of them were also developed by us. As supplementary determinations the rate constants obtained for the coalescence temperature and for the thermal racemization of chromatographically separated enantiomers were used which fitted well the temperature dependence of the rate constants determined by the line shape analysis. As a test compound adamantan-1-yl 3-bromo-2,4,6-trimethylphenyl ketone was prepared and studied. It was shown that supermodified simplex method used in our algorithm (Simtex), though time consuming, gives the most accurate values of the rate constants and consequently the calculated thermodynamic parameters Ea, ∆H≠, and ∆S≠ lay in relatively narrow confidence intervals.

Determination of the Nucleophilicity of Tricarbonyliron Coordinated Cyclohepta-1,3,5-triene

1999 ◽  
Vol 64 (11) ◽  
pp. 1770-1779 ◽  
Author(s):  
Herbert Mayr ◽  
Karl-Heinz Müller
Keyword(s):  
Gibbs Energy ◽  
Ambient Temperature ◽  
Rate Constants ◽  
Second Order ◽  
Order Rate ◽  
Electrophilic Additions ◽  
Kinetics Of

The kinetics of the electrophilic additions of four diarylcarbenium ions (4a-4d) to tricarbonyl(η4-cyclohepta-1,3,5-triene)iron (1) have been studied photometrically. The second-order rate constants match the linear Gibbs energy relationship log k20 °C = s(E + N) and yield the nucleophilicity parameter N(1) = 3.69. It is concluded that electrophiles with E ≥ -9 will react with complex 1 at ambient temperature.

Interfacial catalysis by phospholipase A2: determination of the interfacial kinetic rate constants

Biochemistry ◽  
1991 ◽  
Vol 30 (29) ◽  
pp. 7283-7297 ◽  
Author(s):  
Otto G. Berg ◽  
Bao Zhu Yu ◽  
Joe Rogers ◽  
Mahendra Kumar Jain
Keyword(s):  
Phospholipase A2 ◽  
Rate Constants ◽  
Kinetic Rate ◽  
Kinetic Rate Constants ◽  
Interfacial Catalysis
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