Molecular complexes: effects of multiple equilibria on calculated absorptivities and association constants

1969 ◽  
Vol 47 (14) ◽  
pp. 2605-2611 ◽  
Author(s):  
C. C. Thompson Jr.
Keyword(s):  
Multiple Equilibria ◽  
Molecular Complexes ◽  
Formation Constants ◽  
Association Constants ◽  
Complex Species ◽  
Donor Acceptor ◽  
Order Complexes ◽  
High Degree ◽  
Absorbance Data ◽  
Stoichiometric Complex

Simulated absorbance data have been used to demonstrate the effects of 2:1 molecular complexes on formation constants and absorptivities calculated for 1:1 donor–acceptor interactions. By systematic variation of associated spectral, thermodynamic, and concentration parameters for these systems, it is found that previous attempts to describe effects produced by the presence of more than one stoichiometric complex species are inadequate. Formation constants and absorptivities calculated with the assumption of a simple 1:1 interaction may be increased or decreased by the occurrence of higher order complexes. These variations depend largely on the ratios of complex absorptivities, relative formation constants, and the range of donor concentrations. Equations incorporating 5 of the experimental variables permit the prediction of formation constants and absorptivities to a high degree of accuracy.

Formation Constants of Copper(II) and Zinc(II) with N-salicylideneanthranilic Acid in 50–50 Water–dioxane

1972 ◽  
Vol 50 (10) ◽  
pp. 1609-1611
Author(s):  
R. K. Mehta ◽  
R K Gupta
Keyword(s):  
Sodium Perchlorate ◽  
Formation Constants ◽  
Protonation Constants ◽  
Fair Agreement ◽  
Complex Species ◽  
Color Changes

Protonation constants of N-salicylideneanthranilic acid and formation constants of its Cu(II) and Zn(II)complexes have been studied potentiometrically in 50% dioxane (vol/vol) solutions (μ = 0.1 sodium perchlorate) at 30 ± 0.2 °C. The color changes observed during titrations have been related to the formation of different complex species in solution. The formation constants are in fair agreement with the Irving and Williams rule.

scholarly journals Random amplified polymorphic DNA (RAPD) finger prints evidencing high genetic variability among marine angiosperms of India

2016 ◽  
Vol 97 (6) ◽  
pp. 1307-1315 ◽  
Author(s):  
Elangovan Dilipan ◽  
Jutta Papenbrock ◽  
Thirunavakkarasu Thangaradjou
Keyword(s):  
Genetic Variability ◽  
Rapd Analysis ◽  
Random Amplified Polymorphic Dna ◽  
Rapd Marker ◽  
Seagrass Species ◽  
Complex Species ◽  
Marine Angiosperms ◽  
Different Populations ◽  
High Degree ◽  
Identification Tool

In India 14 seagrass species can be found with monospecific genera (Enhalus, ThalassiaandSyringodium),Cymodoceawith two species andHalophilaandHalodulerepresented by more than two taxonomically complex species. Considering this, the present study was made to understand the level and pattern of genetic variability among these species collected from Tamilnadu coast, India. Random amplified polymorphic DNA (RAPD) analysis was used to evaluate the level of polymorphism existing between the species. Out of the 12 primers tested, 10 primers amplified 415 DNA fragments with an average of 41.5 fragments per primer. Of the total 415 amplified fragments only 123 (29.7%) were monomorphic and the remaining 292 (70.3%) were polymorphic for Indian seagrass species. Among the 10 primers used four are identified as the key primers capable of distinguishing all the Indian seagrasses with a high degree of polymorphism and bringing representative polymorphic alleles in all the tested seagrasses. From the present investigation, this study shows that the RAPD marker technique can be used not only as a tool to analyse genetic diversity but also to resolve the taxonomic uncertainties existing in the Indian seagrasses. The efficiency of these primers in bringing out the genetic polymorphism or homogeneity among different populations of theHalophilaandHalodulecomplex still has to be tested before recommending these primers as an identification tool for Indian seagrasses.

Donor-acceptor complexes formed by perfluoro-organo bromides and iodides with nitrogenous and other bases. II. Band shapes and widths in the absorption spectrum of gaseous CF3I-N(CH3)3

1971 ◽  
Vol 24 (12) ◽  
pp. 2493 ◽  
Author(s):  
A Mishra ◽  
ADE Pullin
Keyword(s):  
Vibrational Mode ◽  
Low Frequency ◽  
Molecular Complexes ◽  
Wave Number ◽  
Centrifugal Distortion ◽  
Band Shape ◽  
Gaseous Mixtures ◽  
Factors Affecting ◽  
Donor Acceptor ◽  
Vibration Rotation

The absorption band centred at c. 77 cm-1 in gaseous mixtures of CF3I and N(CH3)3 previously reported and attributed to the N-I stretching mode of the complex CF3I-N(CH3)3 has been carefully re-examined. This band is of interest as an example of a low frequency ?dissociative type? vibrational mode of a weak molecular complex. The band is asymmetric and apparently structureless with a half intensity width at room temperature of 28-30 cm-1. The width of the band may be accounted for as arising from transitions vi + vi+1 where vi is the vibrational quantum number of the N-I stretching mode with vi up to c. 10 making appreciable contribution to the intensity on the low wave-number side. Centrifugal distortion in the complex is considered. Centrifugal stretching and consequent weakening of the bond may shift the band envelope 2-3 cm-1 to lower wave numbers. Assessment of these and other factors affecting the band shape suggest that the fundamental frequency is probably c. 90 cm-1. The band shape of the vibrational mode of the complex at c. 272 cm-1 is briefly discussed. Many of the considerations presented in this paper should apply to vibration-rotation band shapes in other weak molecular complexes. Some general consequences of anharmonicity for the interpretation of the spectra of weak molecular complexes are discussed.

Charge Transfer Molecular Complexes of 4-(Dimethylamino)pyridine with Some Conventional and Unconventional Acceptors Involving Fluoroarenes

2006 ◽  
Vol 71 (9) ◽  
pp. 1359-1370 ◽  
Author(s):  
Usama M. Rabie
Keyword(s):  
Charge Transfer ◽  
Nmr Spectra ◽  
Molecular Complexes ◽  
Outer Sphere ◽  
Formation Constants ◽  
Stoichiometric Ratio ◽  
Spectral Bands ◽  
Elemental Analyses ◽  
Ct Complexes ◽  
Solid Complexes

Charge transfer (CT) complexes of 4-(dimethylamino)pyridine (DMAP) with iodine as a typical σ-type acceptor and with typical π-type acceptor, 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), have been synthesized and characterized. Octafluorotoluene (OFT), octafluoronaphthalene (OFN), perfluorophenanthrene (PFP), and 2,3,5,6-tetrafluoropyridine-4-carbonitrile (TFP) were also used as acceptors for interaction with DMAP. Properties of such CT complexes were investigated by UV/VIS and IR spectra, and elemental analyses of the isolated complexes. The systems DMAP-iodine and DMAP-DDQ are characterized by formation of triiodide ions (I3-) and DDQ•- anion radicals, respectively, which is proposed to occur via initial formation of outer-sphere CT complexes. The systems (DMAP-OFT, DMAP-OFN, DMAP-PFP and DMAP-TFP) are characterized by the appearance of new UV/VIS spectral bands assigned as CT bands; they also furnished the corresponding solid complexes with the stoichiometric ratio 1:1. 1H and 19F NMR spectra were used on confirming the formation of the DMAP-PFP CT complexes. The formation constants (KCT) and molar absorption coefficients (εCT) of the latter complex were obtained.

Multi-mode ground state interaction terms in C60-based electron donor-acceptor complexes

Open Physics ◽  
2004 ◽  
Vol 2 (2) ◽  
Author(s):  
Elena Sheka
Keyword(s):  
Ground State ◽  
Singlet State ◽  
Molecular Complexes ◽  
Suggested Approach ◽  
Interaction Terms ◽  
Binary Complexes ◽  
Avoided Crossing ◽  
Donor Acceptor ◽  
Multi Mode ◽  
Chemical Testing

AbstractQuantum-chemical testing of donor-acceptor properties of binary molecular complexes, related to the singlet state, is suggested as QCh calculations of studied systems and their constituents by using both spin-nondependent (RHF) and spindependent (UHF) versions of the exploited computational tool. The avoided crossing of intermolecular interaction terms of neutral moleculesE int(A 0 B 0) and molecular ionsE int(A + B −) causes a multi-mode character of the ground state term. The dependence of D-A complex properties on the type of the term, space positions of the term minimum, and the interrelation of the corresponding energies are discussed. The suggested approach has been applied to binary complexes C60+X (X=TAE, TDAE, DMMA, COANP, 2Li, Mg).

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