Thermodynamic Investigation and Mixed Ligand Complex Formation of 1,4-Bis-(3-aminopropyl)-piperazine and Biorelevant Ligands

Table 4

Thermodynamic parameters for the stepwise protonation of (BAPP) in aqueous solution (at 0.01 M ionic strength)^a.

Equilibrium^b	Δ𝐻^∘	Δ𝑆^∘	Δ𝐺^∘
	kJMol^−1	JK^−1 Mol^−1	kJMol^−1
(1) L + H^+⇌ LH^+log𝐾^𝐻1	−48.8 (0.8)	32.7 (0.7)	−58.5 (0.8)
(2) LH^+ + H^+⇌ LH2^2+ log𝐾^𝐻2	−47.4 (0.7)	30.1 (0.6)	−56.3 (0.8)
(3) LH2^2+ + H^+⇌ LH3^3+ log𝐾^𝐻3	−31.8 (0.6)	27.3 (0.5)	−39.9 (0.8)
(4) LH3^3+ + H^+⇌ LH4^4+log𝐾^𝐻4	−13.5 (0.3)	7.31 (0.12)	−15.6 (0.3)

^aStandard deviations are given in parentheses; ^b must be under Table 4 refer to L, where L denotes 1,4-bis(3-aminopropyl)-piperazine (BAPP)