Determination of the gas-phase value of the inductive effect parameter of the methyl group from solvatochromic study of the charge-transfer band maxima of complexes of tetracyanoethylene with methylbenzenes

1994 ◽  
Vol 106 (1) ◽  
Author(s):  
Mahadeb Roy ◽  
Bejoy K Seal
Keyword(s):  
Charge Transfer ◽  
Gas Phase ◽  
Inductive Effect ◽  
Charge Transfer Band ◽  
Methyl Group ◽  
Effect Parameter

Organometallic Rhodium(III) and -(I) Complexes with 1,3-Diniethyllumazine(DML). The Crystal Structure of [(η2- (O4,N5)DML)(η5-C5Me5)ClRh](PF6)

1994 ◽  
Vol 49 (11) ◽  
pp. 1554-1560 ◽  
Author(s):  
Oliver Heilmann ◽  
Hans-Dieter Hausen ◽  
Wolfgang Kaim
Keyword(s):  
Crystal Structure ◽  
Charge Transfer ◽  
Structure Determination ◽  
Charge Transfer Band ◽  
Crystal Structure Determination ◽  
Bond Lengths ◽  
Electron Reduction

The crystal structure determination of the new rhodium(III)-complex [(DML)(C5Me5)ClRh](PF6). DML = 1,3-dimethyllumazine, reveals O4,N5 coordination of the metal to DML with not very different bond lengths of 213.0(2) pm (Rh-N) and 219.2(2) pm (Rh-O). This result stands in contrast to the previously reported structure of a cationic dihydrobiopterin bound to [Mo(O)Cl3]- which exhibited a very unsymmetrical chelate ar­rangement. Chemical and electrochemical two-electron reduction of the Rh(III) complex led to a very labile Rh(I) species (DML)(C5Me5)Rh which is distinguished by an intense charge transfer band in the visible. The results confirm the characterization of DML as a weak σ donor/π acceptor ligand with a rather low-lying π* orbital.

scholarly journals The Use of Charge-Transfer Complexation in The Spectrophotometric Determination of Amlodipine Besylate

2000 ◽  
Vol 68 (3) ◽  
pp. 235-246 ◽  
Author(s):  
Ayșegül (Yardımcı) Gölcü ◽  
Cem Yücesoy ◽  
Selahattin Serin
Keyword(s):  
Charge Transfer ◽  
Charge Transfer Band ◽  
Amlodipine Besylate ◽  
Absorption Bands ◽  
Experimental Conditions ◽  
Maximum Charge ◽  
Experimental Parameters ◽  
A Charge ◽  
Charge Transfer Complexation

A simple and sensitive analytical method has been developed for the spectrophotometric assay of amlodipine besylate (ADB) in pure forms and tablets have been described. The method is based on the formation of a charge-transfer complex between the drug and tetrachloquinone (TCQ). This complex exhibit intense absorption bands in the electronic spectrum. The molecular ratio of the reactant in the complex was established and the experimental conditions leading to maximum charge-transfer band was also studied. The reaction proceeds quantitatively at pH 9 and 55°C for 10 min, the absorbance was measured at 346 nm. The method was applied to commercially available tablets and the results were statistically compared wrth those obtained by UV spectrophotometric method, using Newman-Keuls tests. In our method, Beer's Law limits to 5-25 µg/ml. The optimum experimental parameters for colour production with reagent were studied and incorporated into procedure.

scholarly journals Influence of chlorine substitution on the rate of oxidation of paraffin hydrocarbons

1949 ◽  
Vol 196 (1045) ◽  
pp. 160-171 ◽  
Keyword(s):  
Gas Phase ◽  
Inductive Effect ◽  
Methyl Groups ◽  
Direct Oxidation ◽  
Chlorine Atoms ◽  
Methyl Group ◽  
Chlorine Substitution ◽  
Stabilizing Effect ◽  
Branching Chains ◽  
Kinetics Of

In the kinetics of their gas phase oxidations primary and some secondary chloro-paraffins are generally similar to the corresponding hydrocarbons. The rate is strongly affected by the pressure of the organic reactant and nearly independent of oxygen. (With tertiary chloro-compounds an oxygen-catalyzed pyrolysis obscures the direct oxidation.) For the oxidation a mechanism analogous to that proposed for hydrocarbons is assumed, namely one in which the rate is governed by branching chains whose development depends upon the breaking of an unstable —O—O— link. Previous work on the influence of hydrocarbon structure is interpreted with the aid of the hypothesis that methyl groups exert a specific stabilizing effect (and that relatively rapid oxidation demands a point of attack in the molecule sufficiently remote from a methyl group). In the light of this hypothesis the influence of chlorine atoms is compared with that of methyl groups. The chlorine accelerates the oxidation ( a ) by impairing the symmetry of a methyl group into which it is introduced, and ( b ) by a direct inductive effect of its own. The opposite effects of chlorine and of methyl are consistent with the view that the —O—O— links are stabilized by electron accession and weakened by electron recession.

Determination of Epsilon Aminocaproic Acid Based on Charge Transfer Complexation with p-Nitrophenlol by Spectrophotometry

2020 ◽  
Vol 16 ◽  
Author(s):  
Sheng-Yun Li ◽  
Fang Tian
Keyword(s):  
Charge Transfer ◽  
Aminocaproic Acid ◽  
Concentration Limit ◽  
Official Method ◽  
Good Precision ◽  
Pharmaceutical Dosage Forms ◽  
Relative Standard ◽  
A Charge ◽  
Epsilon Aminocaproic Acid

: A spectrophotometry was investigated for the determination of epsilon aminocaproic acid (EACA) with p-nitrophenol (PNP). The method was based on a charge transfer (CT) complexation of this drug as n-electron donor with π-acceptor PNP. Experiment indicated that the CT complexation was carried out at room temperature for 10 minutes in dimethyl sulfoxide solvent. The spectrum obtained for EACA/PNP system showed the maximum absorption band at wavelength of 425 nm. The stoichiometry of the CT complex was found to be 1:1 ratio by Job’s method between the donor and the acceptor. Different variables affecting the complexation were carefully studied and optimized. At the optimum reaction conditions, Beer’s law was obeyed in a concentration limit of 1～6 µg mL-1. The relative standard deviation was less than 2.9%. The apparent molar absoptivity was determined to be 1.86×104 L mol-1cm-1 at 425 nm. The CT complexation was also confirmed by both FTIR and 1H NMR measurements. The thermodynamic properties and reaction mechanism of the CT complexation have been discussed. The developed method could be applied successfully for the determination of the studied compound in its pharmaceutical dosage forms with a good precision and accuracy compared to official method as revealed by t- and F-tests.

Polarizability and nonpolarizability of oil-water interfaces with relevance to a.c. impendance measurements

1991 ◽  
Vol 56 (1) ◽  
pp. 112-129 ◽  
Author(s):  
Takashi Kakiuchi ◽  
Mitsugi Senda
Keyword(s):  
Charge Transfer ◽  
Numerical Calculation ◽  
Supporting Electrolyte ◽  
Water Interface ◽  
Migration Effect ◽  
Ac Current ◽  
Stationary Interface ◽  
Oil Water ◽  
Anion Transfer

We have estimated the degree of polarizability of a polarized oil-water interface used as a working interface and that of the nonpolarizability of a nonpolarized interface used as a reference oil-water interface from the numerical calculation of dc and ac current vs potential behavior at both interfaces. Theoretical equations of dc and ac currents for simultaneous cation and anion transfer of supporting electrolytes have been derived for the planar stationary interface for reversible and quasi-reversible cases. In the derivation, the migration effect and the coupling of the cation and anion transfer have been incorporated. The transfer of ions constituting a supporting electrolyte contributes to the total admittance of the interface even in the region where the interface may be considered as polarized in dc sense, as pointed out first by Samec et al. (J. Electroanal. Chem. 126, 121 (1981)). Moreover, the reference oil-water interface is not ideally reversible, so that the contribution from this interface to the measured admittance cannot be negligible, unless the area of the reference oil-water interface is much larger than that of the working oil-water interface. The effect of non-ideality of the reference oil-water interface on the determination of double layer capacitances and kinetic parameters of charge transfer at the working oil-water interface has been estimated.

scholarly journals Charge Transfer Complexes of Ketotifen with 2,3-Dichloro-5,6-dicyano-p-benzoquinone and 7,7,8,8-Tetracyanoquodimethane: Spectroscopic Characterization Studies

Molecules ◽  
2021 ◽  
Vol 26 (7) ◽  
pp. 2039
Author(s):  
Gamal A. E. Mostafa ◽  
Ahmed Bakheit ◽  
Najla AlMasoud ◽  
Haitham AlRabiah
Keyword(s):  
Charge Transfer ◽  
Spectroscopic Characterization ◽  
Molar Ratio ◽  
Charge Transfer Complexes ◽  
Physical Parameters ◽  
Spectrophotometric Methods ◽  
Theoretical Approaches ◽  
The Stability ◽  
Ct Complexes

The reactions of ketotifen fumarate (KT) with 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) and 7,7,8,8-tetracyanoquinodimethane (TCNQ) as π acceptors to form charge transfer (CT) complexes were evaluated in this study. Experimental and theoretical approaches, including density function theory (DFT), were used to obtain the comprehensive, reliable, and accurate structure elucidation of the developed CT complexes. The CT complexes (KT-DDQ and KT-TCNQ) were monitored at 485 and 843 nm, respectively, and the calibration curve ranged from 10 to 100 ppm for KT-DDQ and 2.5 to 40 ppm for KT-TCNQ. The spectrophotometric methods were validated for the determination of KT, and the stability of the CT complexes was assessed by studying the corresponding spectroscopic physical parameters. The molar ratio of KT:DDQ and KT:TCNQ was estimated at 1:1 using Job’s method, which was compatible with the results obtained using the Benesi–Hildebrand equation. Using these complexes, the quantitative determination of KT in its dosage form was successful.

Sign in / Sign up

Export Citation Format

Share Document