Plotting 1/(A0-A) according to 1/[Dt] gives the
binding constant K according to the slope.
In this case, CH signals were used to calculate the
binding constant. However, for [I.sup.-], N[O.sub.3.sup.-] and Cl[O.sub.4.sup.-], a negligible change in the NMR signals was observed.
As the double reciprocal plot of 1/[DELTA]A versus 1/[L] is linear, the
binding constant can be estimated from the following equation:
The intrinsic
binding constants ([K.sub.b]) were calculated at [[lambda].sub.max] for each charge transfer band; 364.7, 366.4, 365.1, and 458 nm attributing to the binding yields of silver complexes (1-4) and DNA.
where [[K.sub.a]] and [Q] are the total concentration of HSA and coumarin drug, respectively, and the
binding constant and number of binding sites were obtained and tabulated in Table 1 using the least-square fitting algorithm (Figure 2(c)).
However, the presence of SY in the formed CB7/luteolin or CB7/EGCG complex enabled the replacement of luteolin or EGCG in the CB7 by SY because CB7/SY complex possessed a higher
binding constant than CB7/luteolin or CB7/EGCG complex, leading to a "switch-off" fluorescence emission response.
The
binding constant ([K.sub.b]) and number of binding sites (n) can be determined from emission spectra with (3).
K is the
binding constant of Tm(III)-ASA complex with DNA and [c.sub.DNA] is the concentration of DNA.
The
binding constant of complex formation was computed from the change in the intensity to the absorption peak at 280nm, according to Benesi-Hildebrand relation,
Sw and Sm are substrates in aqueous and micellar pseudo phase respectable; K'w and K'm are the related first order rate constants and Ks is the
binding constant (Domingos et al., 2003).
Table 1
Binding constant and thermodynamic parameters for the interaction of 6-shogaol with HSA, obtained from fluorescence quench titration experiments at different temperatures, pH 7.4.