Naphthalene-1-sulfonic acid acidity constant

In contrast to this, the improved host structure 30 in the complexed state exists in the syn-conformation and is able to complex 2,7-naphthalene sulfonic acid. This was also shown by NMR studies in D O/DCl. With 1,8-ANS a complex constant of pK = 2.8 was determined... 

Salts of diazonium ions with certain arenesulfonate ions also have a relatively high stability in the solid state. They are also used for inhibiting the decomposition of diazonium ions in solution. The most recent experimental data (Roller and Zollinger, 1970 Kampar et al., 1977) point to the formation of molecular complexes of the diazonium ions with the arenesulfonates rather than to diazosulfonates (ArN2 —0S02Ar ) as previously thought. For a diazonium ion in acetic acid/water (4 1) solutions of naphthalene derivatives, the complex equilibrium constants are found to increase in the order naphthalene < 1-methylnaphthalene < naphthalene-1-sulfonic acid < 1-naphthylmethanesulfonic acid. The sequence reflects the combined effects of the electron donor properties of these compounds and the Coulomb attraction between the diazonium cation and the sulfonate anions (where present). Arenediazonium salt solutions are also stabilized by crown ethers (see Sec. 11.2). 

However maquettes for the design of redox proteins were proposed, based on a three helix bundle with a capping Co(III) (bipyridine)3 electron acceptor at the N-terminus and an electron donor at the C-terminus (199, 200). These proteins were tested for LRET. The a-helical percent was adjusted by addition of urea or trifluoroethanol (201, 202). Intriguingly, studies of one of the proteins (l6-mer-three helix bundle) shows a 2-fold higher LRET rate constant when the percent of helicity is 77% than when it is 0% (denatured in urea). However authors indicate that the kinetics is not a simple first-order one in the presence of urea. They interprete these data as coming from different donor-acceptor distances. The distribution of distances was determined by fluorescence lifetimes fit. Both when helicity is 0% or 77%, distributions peak around 18 A for the Ru(II) (16-mer)3-A (where A=5-((((2-acetyl)amino]ethyl)amino)-naphthalene-l sulfonic acid). Actually the distance appears 0.7A shorter for a-helix which is found consistent with the increased rate constant, by the authors. 

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