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A new utility for multipurpose analysis, SOLVERSTAT, taking advantage of the versatility of spreadsheets is here described. By means of this tool advanced statistical tests have introduced in Microsoft Excel Solver thus allowing regression diagnostic and discrimination between different models. The utility is here applied to the determination, by UV-Vis spectroscopy, of the stability constant for the uptake of molecular dioxygen by the 1:2 complex of Co(II) with N,N′-dimethylethylenediamine (dmen) in the aprotic solvent dimethylsulfoxide (dmso) at 298 K and in a medium adjusted to 0.1 mol dm−3 with Et4NClO4. The reliability of the model and parameters obtained are discussed and the results compared with those obtained by Dynafit, a different software package, and by independent voltammetric measurements. The validity of SOLVERSTAT has been also examined applying it to the discrimination between different models already discussed in the literature. 相似文献
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Andrea Melchior Martina Sanadar Rosita Cappai Marilena Tolazzi 《Entropy (Basel, Switzerland)》2022,24(9)
Access to the enthalpy and entropy of the formation of metal complexes in solution is essential for understanding the factors determining their thermodynamic stability and speciation. As a case study, in this report we systematically examine the complexation of silver(I) in acetonitrile (AN) with the following monoamines: n-propylamine (n-pr), n-butylamine (n-but), hexylamine (hexyl), diethylamine (di-et), dipropylamine (di-pr), dibutylamine (di-but), triethylamine (tri-et) and tripropylamine (tri-pr). The study shows that the complex stabilities are quite independent of the length of the substitution chain on the N atom and demonstrates that, in general, the overall enthalpy terms associated with the complex formation are strongly exothermic, whereas the entropy values oppose the complex formations. In addition, we examined the similarity of the formation constants of AgL complexes of the primary monoamines in AN, dimethylsulfoxide (DMSO) and water, which were unexpected on the basis of the difference between the donor properties of solvents. 相似文献
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Polese Pierluigi Tolazzi Marilena Melchior Andrea 《Journal of Thermal Analysis and Calorimetry》2018,132(2):1317-1323
Journal of Thermal Analysis and Calorimetry - The pyrolysis characteristics and kinetics of lignocellulosic biomass (cotton stalk) and seaweed (Gracilaria lemaneiformis) were studied comparatively.... 相似文献
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Melchior Andrea Lanas Sara Gràcia Valiente Manuel Tolazzi Marilena 《Journal of Thermal Analysis and Calorimetry》2018,134(2):1261-1266
Journal of Thermal Analysis and Calorimetry - The adsorption of Pt(IV) by iron oxide (Fe3O4) superparamagnetic nanoparticles (SPION) functionalized with 3-mercaptopropionic acid (3-MPA) is... 相似文献
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Andrea Melchior Marilena Tolazzi Silvia Del Piero 《Journal of Thermal Analysis and Calorimetry》2011,103(1):35-40
The complex formation of Cd(II) with N-donor ligands in dimethylsulfoxide (DMSO) is investigated by means of potentiometry
and titration calorimetry. The ligands considered in this work are tripodal polyamines and polypyridines: 2,2′,2″-triaminotriethylamine
(TREN), tris(2-(methylamino)ethyl)amine (Me3TREN), tris(2-(dimethylamino)ethyl)amine (Me6TREN), tris[(2-pyridyl)methyl]amine (TPA) and 6,6′-bis-[bis-(2-pyridylmethyl)aminomethyl]-2,2′-bipyridine (BTPA). These ligands
are characterized by a systematic modification of the donor groups to relate their structure to the thermodynamics of the
complexes formed. The TREN and Me3TREN ligands form highly stable species. The stability of the complex formed with the fully methylated Me6TREN is much lower than with other polyamines and the enthalpic and entropic terms suggest an incomplete coordination to the
metal ion. In general, the TPA ligand forms complexes less stable than TREN and Me3TREN as a result of the combination of higher structural rigidity of TPA and lower basicity of pyridine moiety with respect
to primary and secondary amines. Pyridine-containing ligands display, in general, a less unfavorable formation entropy than
tripodal polyamines here considered. In particular, TPA forms a more stable 1:1 species with respect to Me6TREN due to the entropic term, being the enthalpy less negative. The ligand BTPA is able to form only a monometallic complex,
where the metal ion is likely to be encapsulated as indicated by the obtained thermodynamic parameters. 相似文献
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Silvia Del Piero Andrea Melchior Davide Menotti Marilena Tolazzi Anders Døssing 《Journal of Thermal Analysis and Calorimetry》2009,97(3):845-851
An investigation on the thermodynamics of complex formation between Ag(I) ion and two 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 dimethylformamide (DMF) by means of potentiometry and titration calorimetry. The results for
TPA are compared with those already obtained for other aliphatic tripodal polyamines. In general, the TPA ligand forms complexes
less stable than 2,2′,2″-triaminotriethylamine (TREN) and tris(2-(methylamino)ethyl)amine (Me3TREN) as a result of the combination of higher structural rigidity of TPA and lower σ-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 σ-donor effects. The ligand
BTPA is able to form bimetallic species whose relative stability is largely influenced by the different solvation of Ag(I)
ion in DMSO and DMF rather than by the difference in the dielectric constants of these two media. 相似文献
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Silvia Del Piero Rosalisa Fedele Andrea Melchior Pierluigi Polese Roberto Portanova Marilena Tolazzi 《Journal of solution chemistry》2008,37(4):543-551
The thermodynamic functions of the complexation of Ag(I) by the tripodal ligands, tris(2-(methylamino)ethyl)amine (Me3tren) and tris(2-(dimethylamino)ethyl)amine (Me6tren) (L), are determined in dimethyl sulfoxide (DMSO) by potentiometric and calorimetric techniques at 298.0 K and 0.1 mol⋅dm−3 ionic strength (Et4NClO4). A comparison is made between previous data concerning Ag(I) complex formation with the non-alkylated tripodal 2,2′,2″-triaminotriethylamine
(tren), in order to analyze the influence of N-methylation on this type of branched donor, and with those relative to the
linear triethylenetetramine (trien) and 1,1,4,7,10,10-hexamethyltriethylenetetramine (Me6trien). The results are discussed taking into account different σ-donating properties, geometric arrangement of the ligands, steric repulsions and solvation effects. 相似文献
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L. Cavallo J. -M. Ducéré Rosalisa Fedele A. Melchior Maria Chiara Mimmi G. Morini F. Piemontesi Marilena Tolazzi 《Journal of Thermal Analysis and Calorimetry》2008,91(1):101-106
A calorimetric investigation on the reactions of TiCl4 with phthalates in 1,1,2,2-tetrachloroethane (TCE) is presented in order to better understand the complex interactions present
in Ziegler-Natta catalytic systems. The Lewis bases diethyl isophthalate (L1), diethyl terephthalate (L2) and the ortho-isomer diethylphthalate (L3), have been chosen to study how the substituent positions could influence the energy and the stoichiometry of the complexation
reactions.
FTIR spectroscopy was used to obtain information on the coordination mode of the ligands and diffusion measurements by NMR
was carried out to verify the presence of oligo-or polymeric species. Experimental results were compared with theoretical
calculations based on Density Functional Theory (DFT). 相似文献