The interaction of sulfate with some open chain polyammonium cations was quantitatively studied b... more The interaction of sulfate with some open chain polyammonium cations was quantitatively studied by potentiometric (H(+)-glass electrode) measurements. Enthalpy changes, for some systems, were determined calorimetrically. Some literature data were also considered in the discussion of results. In all the systems, A(SO4)Hi(i-2) species are formed (i = 1, ...m; m = maximum protonation degree of amine), and, for i > or = 4, also A(SO4)2Hi(i-4) species were found. Both the stability and the formation enthalpies, for these complexes, are a direct function of the charges of reactants, and some empirical relationships are reported. A small, but significant, difference was found between the stability of unsubstituted and N-alkylsubstituted polyammonium cation-sulfate complexes.
Acid - base properties of Halloysite clay nanotubes in NaCl medium S. Cataldo, A. Gianguzza, A. P... more Acid - base properties of Halloysite clay nanotubes in NaCl medium S. Cataldo, A. Gianguzza, A. Pettignano, S. Sammartano Dipartimento di Fisica e Chimica, Università di Palermo, Viale delle Scienze, edificio 17 , Cap 90128, Palermo, Italia Dipartimento di Scienze Chimiche, Università degli Studi di Messina, Viale Ferdinando Stagno d’Alcontres, 31, Cap-98166 Messina (Vill. S. Agata), Italy Halloysite clay nanotubes (HNTs) have a series of important properties that make this kind of material very useful for different purposes in several fields. Among the various applications, worth of mention are: i) their use as additive for devices in the capture tumor cells in blood; ii) nanoparticles for the entrapment and controlled release of active molecules; ii) additive agents in wound and personal care; iv) sorbents for water contaminants etc [1,2]. In all these applications, the knowledge of acid-base properties of HNTs is very important and gives useful information on the behaviour of the...
The interaction of sulfate with some open chain polyammonium cations was quantitatively studied b... more The interaction of sulfate with some open chain polyammonium cations was quantitatively studied by potentiometric (H(+)-glass electrode) measurements. Enthalpy changes, for some systems, were determined calorimetrically. Some literature data were also considered in the discussion of results. In all the systems, A(SO4)Hi(i-2) species are formed (i = 1, ...m; m = maximum protonation degree of amine), and, for i > or = 4, also A(SO4)2Hi(i-4) species were found. Both the stability and the formation enthalpies, for these complexes, are a direct function of the charges of reactants, and some empirical relationships are reported. A small, but significant, difference was found between the stability of unsubstituted and N-alkylsubstituted polyammonium cation-sulfate complexes.
Enthalpy changes for the binding of malonate, citrate, 1,2,3-propanetricarboxylate and 1,2,3,4-bu... more Enthalpy changes for the binding of malonate, citrate, 1,2,3-propanetricarboxylate and 1,2,3,4-butanetetracarboxylate by fully methyl substituted linear polyammonium cations (with the general formula C3nNnH(8n + 2)n+, with n = 1,2,3) were determined calorimetrically. Enthalpy changes were also determined for the binding of malonate by unsubstituted polyammonium cations (with the general formula C2(n - 1)NnH(6n - 2)n+, n = 1...6). delta H0/kJ mol-1 values are always positive and strongly dependent on the charges involved in the formation reaction. Mean values for delta G0 and T delta S0 were obtained as a function of the charge product zeta = Zanion/ Zcation: -delta G0/kJmol-1 = (4.0 +/- 0.4) zeta, T delta S0/kJmol-1 = (5.9 +/- 0.1) zeta (substituted polyamines), and -delta G0/kJmol-1 = (3.5 +/- 0.2) zeta, T delta S0/kJmol-1 = (5.0 +/- 0.4) zeta (unsubstituted polyamines). For both classes of amines it was found that T delta S0 vs. delta G0 is linear with a correlation coefficient of r = 0.9618. Crude approximation gives -delta G0/kJmol-1 = (7.0 +/- 0.4) n-1, T delta S0/kJmol-1 = (10.0 +/- 0.8) n-1 for unsubstituted amines and -delta G0/kJmol-1 = (8.0 +/- 0.8) n-1, T delta S0/kJmol-1 = (11.8 +/- 2.0) n-1 (n = number of possible salt bridges, or single interactions) for substituted amines.
The interaction of sulfate with some open chain polyammonium cations was quantitatively studied b... more The interaction of sulfate with some open chain polyammonium cations was quantitatively studied by potentiometric (H(+)-glass electrode) measurements. Enthalpy changes, for some systems, were determined calorimetrically. Some literature data were also considered in the discussion of results. In all the systems, A(SO4)Hi(i-2) species are formed (i = 1, ...m; m = maximum protonation degree of amine), and, for i > or = 4, also A(SO4)2Hi(i-4) species were found. Both the stability and the formation enthalpies, for these complexes, are a direct function of the charges of reactants, and some empirical relationships are reported. A small, but significant, difference was found between the stability of unsubstituted and N-alkylsubstituted polyammonium cation-sulfate complexes.
Acid - base properties of Halloysite clay nanotubes in NaCl medium S. Cataldo, A. Gianguzza, A. P... more Acid - base properties of Halloysite clay nanotubes in NaCl medium S. Cataldo, A. Gianguzza, A. Pettignano, S. Sammartano Dipartimento di Fisica e Chimica, Università di Palermo, Viale delle Scienze, edificio 17 , Cap 90128, Palermo, Italia Dipartimento di Scienze Chimiche, Università degli Studi di Messina, Viale Ferdinando Stagno d’Alcontres, 31, Cap-98166 Messina (Vill. S. Agata), Italy Halloysite clay nanotubes (HNTs) have a series of important properties that make this kind of material very useful for different purposes in several fields. Among the various applications, worth of mention are: i) their use as additive for devices in the capture tumor cells in blood; ii) nanoparticles for the entrapment and controlled release of active molecules; ii) additive agents in wound and personal care; iv) sorbents for water contaminants etc [1,2]. In all these applications, the knowledge of acid-base properties of HNTs is very important and gives useful information on the behaviour of the...
The interaction of sulfate with some open chain polyammonium cations was quantitatively studied b... more The interaction of sulfate with some open chain polyammonium cations was quantitatively studied by potentiometric (H(+)-glass electrode) measurements. Enthalpy changes, for some systems, were determined calorimetrically. Some literature data were also considered in the discussion of results. In all the systems, A(SO4)Hi(i-2) species are formed (i = 1, ...m; m = maximum protonation degree of amine), and, for i > or = 4, also A(SO4)2Hi(i-4) species were found. Both the stability and the formation enthalpies, for these complexes, are a direct function of the charges of reactants, and some empirical relationships are reported. A small, but significant, difference was found between the stability of unsubstituted and N-alkylsubstituted polyammonium cation-sulfate complexes.
Enthalpy changes for the binding of malonate, citrate, 1,2,3-propanetricarboxylate and 1,2,3,4-bu... more Enthalpy changes for the binding of malonate, citrate, 1,2,3-propanetricarboxylate and 1,2,3,4-butanetetracarboxylate by fully methyl substituted linear polyammonium cations (with the general formula C3nNnH(8n + 2)n+, with n = 1,2,3) were determined calorimetrically. Enthalpy changes were also determined for the binding of malonate by unsubstituted polyammonium cations (with the general formula C2(n - 1)NnH(6n - 2)n+, n = 1...6). delta H0/kJ mol-1 values are always positive and strongly dependent on the charges involved in the formation reaction. Mean values for delta G0 and T delta S0 were obtained as a function of the charge product zeta = Zanion/ Zcation: -delta G0/kJmol-1 = (4.0 +/- 0.4) zeta, T delta S0/kJmol-1 = (5.9 +/- 0.1) zeta (substituted polyamines), and -delta G0/kJmol-1 = (3.5 +/- 0.2) zeta, T delta S0/kJmol-1 = (5.0 +/- 0.4) zeta (unsubstituted polyamines). For both classes of amines it was found that T delta S0 vs. delta G0 is linear with a correlation coefficient of r = 0.9618. Crude approximation gives -delta G0/kJmol-1 = (7.0 +/- 0.4) n-1, T delta S0/kJmol-1 = (10.0 +/- 0.8) n-1 for unsubstituted amines and -delta G0/kJmol-1 = (8.0 +/- 0.8) n-1, T delta S0/kJmol-1 = (11.8 +/- 2.0) n-1 (n = number of possible salt bridges, or single interactions) for substituted amines.
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Papers by Alberto Pettignano