A series of polynuclear assemblies based on ligand L (1,4,7-tris[hydrogen (6-methylpyridin-2-yl)phosphonate]-1,4,7-triazacyclononane) has been developed. The coordination properties of ligand L with Ln (Ln = La, Eu, Tb, Yb, Lu) have been studied in water (pH = 7.0) and in DO (pD = 7.0) by UV-absorption spectrometry, spectrofluorimetry, H andP NMR, DOSY, ESI-mass spectrometry, and X-ray diffraction. This nonadentate ligand forms highly stable mononuclear complexes in water and provides a very efficient shielding of the Ln cations, as emphasized by the very good luminescence properties of the Yb complex in DO, especially regarding its lifetime (τ = 10.2 μs) and quantum yield (ϕ = 0.42%). In the presence of excess Ln cation, polynuclar complexes of [(LnL)Ln ] stoichiometry (x = 1 and x = 2) are observed in solution. In the solid state, a dinuclear complex of La could be isolated and structurally characterized by X-ray diffraction, unraveling the presence of strong hydrogen bonding interactions between a La(HO) cation and the [LaL] complex.
The adsorption behavior and inhibition mechanism of (1, 4, 7-Tris [hydrogen (6-methylpyridin-2-yl) phosphonate] -1, 4, 7-triazacyclononane) (TPP) on the corrosion of mild steel in 1 M HCl were investigated by weight loss technique, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS) methods for different concentrations at 25°C. The results show that the inhibition efficiency values depend on the amount of immersion times and the concentration. A 90% efficiency is found at the highest concentration of the studied compound according to weight loss measurements. The adsorption of the investigated inhibitor on the mild steel surface was well supported using an AFM study. For the assignment of the absorption sites, we performed quantum chemical calculations with (DFT) method. The interaction between the inhibitor and iron surface were performed by molecular dynamic (MD) simulations. In this paper, experimental methods and results used to assess the efficiency of the studied compound are presented.
The electrochemical behavior of dibutyl methyl ester p-tert-butylcalix [4] arene compound 1 was studied by cyclic voltammetry. At25°C and scan rate of 20 mVs−1. The anodic peak is affected by scanrate, concentration and temperature is a totally irreversible process.The result shows that there is an irreversible electrochemicaloxidative wave when the potential is more 1.3 V versus Ag/AgCl inan acetonitrile.
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