Binding of 1,2,4-benzenetricarboxylate by open chain polyammonium cations.
The interaction of some open chain polyammonium cations with 1,2,4-benzenetricarboxylate was studied potentiometrically, at 25 degrees C. For all the investigated systems, the species ALHr(r-3) (r = 1,2 ... n + 2; n = number of aminogroups; A = amine; L = carboxylate) are formed. The stability of these complexes depends on charges in the polyammonium cation and in the carboxylic ligand, and for the reaction HiAi+ + HjL(j - 3) = ALHi + j(i + j - 3) we found a mean free energy contribution for salt bridge -delta G0 = 6.5 +/- 0.3 kJ mol-1 n-1 (n = number of possible salt bridges). The results of this investigation are compared with those of similar systems. By considering also the tricarboxylic ligands citrate and 1,2,3-propanetricarboxylate, we found for their complexes with polyammonium cations a fairly close stability. Calculations performed including complexes formed with these two ligands give -delta G0 = 6.6 +/- 0.4 kJ mol-1 n-1.
De Robertis
A
A
Dipartimento di Chimica Inorganica, Chimica Analitica e Chimica Fisica, Università di Messina, Salita Sperone 31, I-98166 Messina (Vill. S. Agata), Italy.
De Stefano
C
C
Foti
C
C
Sammartano
S
S
D001555:Benzene Derivatives / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D009994:Osmolar Concentration; D011073:Polyamines / Q000737:chemistry*; D011199:Potentiometry; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*; D014233:Tricarboxylic Acids / Q000737:chemistry*
D001555:Benzene Derivatives; D011073:Polyamines; D000644:Quaternary Ammonium Compounds; D014233:Tricarboxylic Acids