UDP-Galactose 4-Epimerase:  NAD+Content and a Charge-Transfer Band Associated with the Substrate-Induced Conformational Transition†

Biochemistry ◽  
1996 ◽  
Vol 35 (23) ◽  
pp. 7615-7620 ◽  
Author(s):  
Yijeng Liu ◽  
Janeen L. Vanhooke ◽  
Perry A. Frey
Keyword(s):  
Charge Transfer ◽  
Conformational Transition ◽  
Charge Transfer Band ◽  
A Charge

Spectra of the 1:1 and 3:1 solid complexes of coronene-TCNQ

1977 ◽  
Vol 55 (21) ◽  
pp. 3712-3716 ◽  
Author(s):  
Kim Doan Truong ◽  
André D. Bandrauk
Keyword(s):  
Charge Transfer ◽  
Absorption Spectra ◽  
Electronic Absorption ◽  
Ground State ◽  
Electronic Absorption Spectra ◽  
Charge Transfer Band ◽  
Out Of Plane ◽  
The Individual ◽  
A Charge ◽  
Solid Complexes

Two new solid TCNQ complexes have been isolated, coronene–TCNQ 1:1 and 3:1. The infrared and electronic absorption spectra are presented for the two different stoichiometries. From these spectra we infer that the complexes are covalent in the ground state with a charge transfer band appearing at 730 nm. The out of plane vibrations of the individual molecules are noticeably perturbed upon complexation.

Charge transfer complexes of diquat and paraquat with halide anions

1987 ◽  
Vol 65 (10) ◽  
pp. 2425-2427 ◽  
Author(s):  
S. G. Bertolotti ◽  
J. J. Cosa ◽  
H. E. Gsponer ◽  
C. M. Previtali
Keyword(s):  
Charge Transfer ◽  
Charge Transfer Band ◽  
Association Constants ◽  
Charge Transfer Complexes ◽  
Ion Selective Electrodes ◽  
Halide Ions ◽  
Ultraviolet Spectrophotometry ◽  
A Charge ◽  
Difference Absorption ◽  
Absorption Measurements

The association of methylviologen, 1,1′-dimethyl-4,4′-bipyridynium (PQ2+), with halide and pseudo-halide ions was studied in water at 25 °C by ultraviolet spectrophotometry. A charge transfer band could be observed in the region around 300 nm. From difference absorption measurements the first association constant (K1,) was obtained as 1.7 (Cl−), 3.3 (Br−), 3.9 (I−), 0.7 (CN−), and 2.0(SCN−) M−1. Similar results were obtained for the dication, 6,7-dihydrodipyrido[1,2-a:2′,1′-c]pyrazinium (DQ2+), with first association constants 3.3 (Cl−), 4.1 (Br−) and 4.6 (I−) M−1. First and second (K2) association constants were also determined by a potentiometric technique using ion selective electrodes: K1 = 2.0 M−1; K2 = 0.4 M−1 for the system PQ2+–Cl− and K1 = 5.3 M−1; K2 = 0.3 M−1 for DQ2+Br−.

A SPECTROPHOTOMETRIC STUDY OF HEXA-, PENTA-, AND TETRA- COORDINATED HALOGENOCOPPER(II) COMPLEXES IN ACETONE – HYDROHALIC ACID MIXTURES

1966 ◽  
Vol 44 (14) ◽  
pp. 1643-1653 ◽  
Author(s):  
G. H. Faye
Keyword(s):  
Charge Transfer ◽  
Absorption Spectra ◽  
Hydrobromic Acid ◽  
Charge Transfer Band ◽  
Visible Region ◽  
Spectrophotometric Study ◽  
Ligand Field ◽  
A Charge ◽  
Hydrohalic Acid

A spectrophotometric study of the Cu(II) – acetone – hydrochloric (hydrobromic) acid systems has revealed that at relatively high ratios of halide: copper there is a probable equilibrium between four-, five-, and six-coordinate halogenocopper(II) complexes. A distorted tetrahedral species is favored at the highest ratios. Ligand field bands of pseudo-octahedral monohalogenocopper(II) complexes and, in the visible region, a charge transfer band of the six-coordinate complex, [CuCl4(ac)2]2−, have been identified. The results of the present work point to the important role of the solvent in determining the geometries and absorption spectra of the complexes, a factor that seems to have been misinterpreted by some previous workers.

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.

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