An investigation on the thermodynamics of complex formation between Ag(I) ion and different tripodal ligands (tris[(2-pyridyl)methyl]amine) (TPA) and 6,6'-bis[bis(2-pyridylmethyl)aminomethyl]-2,2'-bipyridine (BTPA) has been carried out in the aprotic solvents dimethylsulfoxide (DMSO) and dimethylformammide (DMF) by means of potentiometry and titration calorimetry. The results presented for TPA are also compared with those already obtained for other tripodal polyamines: as a general trend the TPA ligand forms complexes less stable than 2,2',2''-triaminotriethylamine (TREN) and tris(2-(methylamino)ethyl)amine  (Me₃TREN) as a result of  combination of structural rigidity of TPA and lower s-donor ability of pyridinic moieties with respect to primary and secondary amines. The same trend is found if the stability of Ag(I) complex with TPA is compared with that of tris(2-(dimethylamino)ethyl)amine  (ME₆TREN), despite the pyridinic nitrogen is formally a tertiary one. Theoretical calculations run to explain the reasons of this weaker interaction indicate that this difference is due to solvation, rather than to steric or donor effects.

The ligand BTPA is able to form bimetallic species whose relative stability is largely influenced by the different solvational properties of the solvents towards Ag(I) ion rather than by the significative difference in the dielectric constants.