Insights into the Anticorrosion Performance of Solanum lyratum Leaf Extract for Copper in Sulfuric Acid Medium.

In this paper, Solanum lyratum leaves were prepared into a corrosion inhibitor by a pure water extraction method. As a natural plant, S. lyratum leaf extract as a corrosion inhibitor has green features. S. lyratum leaf extract (SLLE) can effectively inhibit the corrosion of Cu in H2SO4 solution. The protective effect on copper in 0.5 mol/L H2SO4 solution was studied by electrochemical measurement, Fourier transform infrared spectrometry (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), atomic force microscopy (AFM), and theoretical calculation. These results showed that the maximum corrosion inhibition efficiency (η) of SLLE for copper obtained in the electrochemical measurement at different temperatures is more than 90%. The adsorption of SLLE on copper surfaces conforms to the Langmuir isotherm adsorption model. FTIR and XPS showed the bonding information. SEM and AFM proved that the SLLE can protect the copper from corrosion media. The interaction and inhibition mechanism between the SLLE and copper surface was further revealed at the molecular level by theoretical calculation.

A series of organic hybrid polyoxovanadate clusters incorporating tris(hydroxymethyl)methane derivatives.

A series of new organic hybrid polyoxovanadate clusters [V4O4(µ-OH)2(acac)2(Htri)2] (1, H3tri = tris(hydroxymethyl) aminomethane, acac = acetylacetone), [V4O4(acac)2(Htri)2(L)2] {HL = methanol (2), ethanol (3a and 3b), ethylene glycol (4) and benzyl alcohol (5)}, {V4O4(H2O)2(tri-acetamide)2(CH3COO)2} (6, H3tri-acetamide = N-(2-hydroxy-1,1-bis-hydroxymethyl-ethyl)-acetamide), [V6O8(µ-OH)2(Htri)3]·6H2O (7) and [V14O18(tri)2(Htri)6(HCOO)(CH3COO)]·2H2O (8) were prepared by hydro(solvo)thermal methods and characterized structurally. 1 contains [VO(OH)(acac)] and [VO2(Htri)] units, which are further interconnected via common edges to build a tetravanadyl cluster [V4O4(OH)2(acac)2(Htri)2] with the double-deficient cube [V4O6]. The tetravanadyl cluster frameworks of 2-5 can be derived from the tetravanadyl cluster of 1 by replacing two -OH groups with two deprotonated organic alcohol ligands, namely, CH3O- (2), CH3CH2O- (3a and 3b), HO(CH2)2O- (4) and C6H5CH2O- (5). Interestingly, both 3a and 3b have the same chemical structure, but they exhibit different conformational polymorphisms [denoted as α-type (3a) and ß-type (3b)]. Such conformational polymorphisms within the polyoxovanadate clusters incorporating tris(hydroxymethyl)methane derivatives emerged for the first time. 6 displays another tetravanadyl cluster {V4O4(H2O)2(tri-acetamide)2(CH3COO)2} with a [V4O16] fragment, where the tri-acetamide unit comes from the amidation reaction of H3tri and acetic acid and caps the tetrahedral void of the tetravanadyl cluster. The polyoxovanadate cluster of 7 can originate from the Lindqvist-type hexavanadyl cluster [V6O19] by replacing nine µ-oxides with nine alkoxides of three tri-acetamide3- ligands. 8 exhibits a fully reduced tetradecavanadyl cluster based on the linkage of two heptavanadyl clusters via two O bridges. The magnetic properties of 1-8 show typical antiferromagnetic interactions.