Charge-Transfer Complexes Between Iodine and Substituted Thioureas: Determination of Thermodynamic and Spectroscopic Properties

1996 ◽  
Vol 51 (1-2) ◽  
pp. 116-122 ◽  
Author(s):  
Cornelia Fooken ◽  
Wolfram Baumann
Keyword(s):  
Equilibrium Constants ◽  
Spectroscopic Properties ◽  
Critical Discussion ◽  
Charge Transfer Complexes ◽  
Published Data ◽  
Visible Spectroscopy ◽  
Dichloromethane Solution ◽  
Uv Visible ◽  
Iodine Complexes

Abstract 15 iodine complexes with substituted thioureas were investigated in dichloromethane solution by UV-visible spectroscopy, and their equilibrium constants, reaction enthalpies and molar absorption coefficients were determined. The influence of the substituents on the properties of the charge-trans-fer complexes is examined. A critical discussion of previously published data is given, where comparable data are available.

Free-base corroles: determination of deprotonation constants in non-aqueous media

2007 ◽  
Vol 11 (04) ◽  
pp. 269-276 ◽  
Author(s):  
Jing Shen ◽  
Zhongping Ou ◽  
Jianguo Shao ◽  
Michał Gałęzowski ◽  
Daniel T. Gryko ◽  
...  
Keyword(s):  
Equilibrium Constants ◽  
Aqueous Media ◽  
Free Base ◽  
Organic Base ◽  
Experimental Conditions ◽  
Spectral Changes ◽  
Base Analysis ◽  
Uv Visible ◽  
The Given

A series of free-base corroles with different electron-donating or electron-withdrawing substituents were reacted with piperidine, 4-aminopyridine, 2-methylimidazole, 2-aminopyridine or pyridine in PhCN and the UV-visible spectral changes monitored during conversion of ( Cor ) H 3 to [( Cor ) H 2]- as a function of the concentration and strength of the added organic base. Analysis of the UV-visible spectral changes as a function of the added base concentration enabled calculation of equilibrium constants ( logK ) for deprotonation of each corrole under the given experimental conditions. Relationships are examined between the experimentally measured logK values and previously published spectroscopic and structural properties of the compounds.

The use of UV-visible spectroscopy for the determination of hydrophobic interactions between neuropeptides and membrane model systems

Biopolymers ◽  
1992 ◽  
Vol 32 (8) ◽  
pp. 1061-1064 ◽  
Author(s):  
John K. Young ◽  
William H. Graham ◽  
Debbie J. Beard ◽  
Rickey P. Hicks
Keyword(s):  
Hydrophobic Interactions ◽  
Model Systems ◽  
Membrane Model ◽  
Visible Spectroscopy ◽  
Uv Visible

Determination of pKa of felodipine using UV–Visible spectroscopy

2013 ◽  
Vol 115 ◽  
pp. 887-890 ◽  
Author(s):  
M.M. Pandey ◽  
A. Jaipal ◽  
A. Kumar ◽  
R. Malik ◽  
S.Y. Charde
Keyword(s):  
Visible Spectroscopy ◽  
Uv Visible

scholarly journals Analytical Determination of the Bending Stiffness of a Five-Layer Corrugated Cardboard with Imperfections

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 663
Author(s):  
Tomasz Garbowski ◽  
Anna Knitter-Piątkowska
Keyword(s):  
Load Capacity ◽  
Element Model ◽  
Critical Discussion ◽  
Bending Stiffness ◽  
Analytical Determination ◽  
Published Data ◽  
Corrugated Board ◽  
Correct Determination ◽  
Corrugated Cardboard

Bending stiffness (BS) is one of the two most important mechanical parameters of corrugated board. The second is edge crush resistance (ECT). Both are used in many analytical formulas to assess the load capacity of corrugated cardboard packaging. Therefore, the correct determination of bending stiffness is crucial in the design of corrugated board structures. This paper focuses on the analytical determination of BS based on the known parameters of the constituent papers and the geometry of the corrugated layers. The work analyzes in detail the dependence of the bending stiffness of an asymmetric, five-layer corrugated cardboard on the sample arrangement. A specimen bent so that the layers on the lower wave side are compressed has approximately 10% higher stiffness value. This is due to imperfections, which are particularly important in the case of compression of very thin liners. The study showed that imperfection at the level of a few microns causes noticeable drops in bending stiffness. The method has also been validated by means of experimental data from the literature and simple numerical finite element model (FEM). The obtained compliance of the computational model with the experimental model is very satisfactory. The work also included a critical discussion of the already published data and observations of other scientists in the field.

Determination of Rate Constants in Second-Order Kinetics Using UV-Visible Spectroscopy

2001 ◽  
Vol 55 (1) ◽  
pp. 77-83 ◽  
Author(s):  
Sabina Bijlsma ◽  
Hans F. M. Boelens ◽  
Age K. Smilde
Keyword(s):  
Rate Constants ◽  
Second Order ◽  
Visible Spectroscopy ◽  
Uv Visible

scholarly journals DEVELOPMENT AND VALIDATION OF UV-SPECTROPHOTOMETRIC METHODS FOR DETERMINATION OF GEMCITABINE HYDROCHLORIDE IN BULK AND POLYMERIC NANOPARTICLES

2017 ◽  
Vol 9 (5) ◽  
pp. 60 ◽  
Author(s):  
Taranjit Kaur ◽  
Sukhjinder Kaur ◽  
Parminderjit Kaur
Keyword(s):  
Polymeric Nanoparticles ◽  
Visible Spectroscopy ◽  
International Conference ◽  
Spectrophotometric Methods ◽  
Gemcitabine Hydrochloride ◽  
Double Beam ◽  
Uv Visible ◽  
Formulation Analysis ◽  
Development And Validation

Objective: The objective of the present work was to develop and validate a novel, specific, precise and reliable method for estimation of gemcitabine hydrochloride in bulk and polymeric nanoparticles using UV-visible spectroscopy method.Methods: The UV-Visible spectrophotometric determination was performed with double beam Systronics UV-visible spectrophotometer; model UV-2201 (India). The proposed methods were validated for various parameters like linearity, precision, accuracy, robustness, ruggedness, detection, quantification limits, and formulation analysis as per international conference on harmonization (ICH) guidelines.Results: The method was based on measurement of absorbance at wavelength maxima i.e. 267.2 nm, λmax of the drug in distilled water, phosphate buffer pH 6.8 and 7.4. The method obeyed Beer Lambert’s law in the concentration range of 5-30 µg/ml andR2-value was found to be 0.999. Moreover, the % drug recovered from polymeric nanoparticles was found to be 97.97%.Conclusion: According to results, the currently developed method shows compliance with acceptance criteria with Q2 (R1) and international conference on harmonization (2005) guidelines, because the % RSD was found to be less than 2%. The developed method was simple, accurate and précised.

CHARGE-TRANSFER COMPLEXES OF BIPHENYLENE

1966 ◽  
Vol 44 (1) ◽  
pp. 9-12 ◽  
Author(s):  
P. H. Emslie ◽  
R. Foster ◽  
R. Pickles
Keyword(s):  
Charge Transfer ◽  
Charge Transfer Complex ◽  
Equilibrium Constants ◽  
Charge Transfer Complexes ◽  
Kcal Mole ◽  
Dichloromethane Solution ◽  
Entropy Of Formation ◽  
Charge Transfer Transitions ◽  
Different Temperatures ◽  
Enthalpy And Entropy

An attempt has been made to redetermine the enthalpy and entropy of formation of the charge-transfer complex between tetracyanoethylene and biphenylene in dichloromethane solution from measurements of the equilibrium constant at different temperatures. The results obtained under conditions where biphenylene is in excess differ from those previously published in which tetracyanoethylene was in excess. It is argued that the optimum condition for determining equilibrium constants of a 1:1 complex is when the reactants are mixed in solution in this ratio. Determinations under this condition yield ΔH = −2.6 kcal mole−1 and ΔS = −4.1 e.u.The energies of the intermolecular charge-transfer transitions of biphenylene with several different acceptors suggest that the ionization potential of biphenylene is ~7.4 eV.

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