title: Binding of polyanions by biogenic amines. II. Formation and stability of protonated putrescine and cadaverine complexes with carboxylic ligands.
abstract: The formation and stability of protonated diamines-carboxylic ligand complexes was studied potentiometrically (H(+)-glass electrode). Species formed are ALH(r) (A=cadaverine, putrescine, L=acetate, malate, tartrate, malonate, citrate, 1,2,3-propanetricarboxylate, 1,2,3,4-butanetetracarboxylate and glutamate; r=1...m+1, where m is the maximum degree of protonation of the carboxylic ligand), and their stability is a function of charges involved in the formation reaction. For the equilibrium H(i)A(i+)+H(j)L((j-z))=ALH((i+j-z))(i+j) the following linear relationships can be written: logK(1j)=-0.25+0.75 |j-z|, logK(2j)=0.50+0.90 |j-z| (by also considering some ethylenediamine and 1,2-diaminopropane complexes). Medium effects were considered. Comparison was made with analogous inorganic polyanion complexes. The simplest relationships -DeltaG(0)=6.5+/-0.3 and -DeltaG(0)=7.9+/-0.6 kJ mol(-1)n(-1) (n=number of possible salt bridges) were found for carboxylic and inorganic anions, respectively.
authors.affiliation: Dipartimento di Chimica Inorganica, Chimica Analitica e Chimica Fisica dell'Università, Salita Sperone 31, I-98166, Messina, Vill. S. Agata, Italy.
authors.forename: C
authors.initials: C
authors.lastname: De Stefano
authors.forename: A
authors.initials: A
authors.lastname: Gianguzza
authors.forename: R
authors.initials: R
authors.lastname: Maniaci
authors.lastname: Daniela Piazzese
authors.forename: S
authors.initials: S
authors.lastname: Sammartano