Structure and Coordination Modes in the Interaction between Cd2+ and 3-Mercaptopropionic Acid

Green-emitting functionalized silicon nanoparticles as an "off-on" fluorescence bio-probe for the sensitive and selective detection of mercury (II) and 3-mercaptopropionic acid

Herein, we developed a class of functionalized silicon nanoparticles (F-SiNPs) bio-probes named thiol-conjugated F-SiNPs. They combine excellent biocompatibility with small dimensions (<10 nm) and biological usefulness with sustained and robust fluorescence (3.32% photoluminescent quantum yield). Identifying 3-Mercaptopropionic acid (3-MPA), which lowers the quantity of gamma-aminobutyric acid in the brain, and mercury (Hg²⁺) was a crucially important step since their excessive levels are a sign of several disorders. Using F-SiNPs as a fluorescent bio-probe, we provided an "off-on" technique for sensitively and selectively determining Hg²⁺ and 3-MPA in this study. The 3-(2-aminoethylamino) propyl (dimethoxymethylsilane) and basic fuchsin as precursors were hydrothermally treated to produce the F-SiNPs exhibiting green fluorescence. Our results suggest that Hg²⁺ reduced the fluorescence of F-SiNPs because of strong ionic interactions and metal-ligand binding among many thiols and carboxyl groupings at the surface of Hg²⁺ and F-SiNPs. Additionally, the resultants demonstrated that after being quenched by Hg²⁺, the produced F-SiNPs led to the distinctive "off-on" response to 3-MPA. Moreover, the method could detect Hg²⁺ and 3-MPA with limits of detection of 0.065 μM and 0.017 μM, respectively. The technique employed is quick, easy, affordable, and environmentally friendly. The sensing platform has successfully determined Hg²⁺ and 3-MPA in urine, water, and human serum samples.

Probing the coordination properties of glutathione with transition metal ions (Cr2+, Mn2+, Fe2+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Hg2+) by density functional theory

Complexes formed by reduced glutathione (GSH) with metal cations (Cr(2+), Mn(2+),Fe(2+),Co(2+),Ni(2+),Cu(2+),Zn(2+),Cd(2+),Hg(2+)) were systematically investigated by the density functional theory (DFT). The results showed that the interactions of the metal cations with GSH resulted in nine different stable complexes and many factors had an effect on the binding energy. Generally, for the same period of metal ions, the binding energies ranked in the order of Cu(2+)>Ni(2+)>Co(2+)>Fe(2+)>Cr(2+)>Zn(2+)>Mn(2+); and for the same group of metal ions, the general trend of binding energies was Zn(2+)>Hg(2+)>Cd(2+). Moreover, the amounts of charge transferred from S or N to transition metal cations are greater than that of O atoms. For Fe(2+),Co(2+),Ni(2+),Cu(2+),Zn(2+),Cd(2+) and Hg(2+) complexes, the values of the Wiberg bond indices (WBIs) of M-S (M denotes metal cations) were larger than that of M-N and M-O; for Cr(2+) complexes, most of the WBIs of M-O in complexes were higher than that of M-S and M-N. Furthermore, the changes in the electron configuration of the metal cations before and after chelate reaction revealed that Cu(2+), Ni(2+),Co(2+) and Hg(2+) had obvious tendencies to be reduced to Cu(+),Ni(+),Co(+) and Hg(+) during the coordination process.

Complexation of Bi(iii) with 3-mercaptopropionic acid in aqueous solutions: a combined experimental and theoretical study

The coordination mode for interactions between Bi(iii) and 3-mercaptopropionic acid has been established by combined experimental and theoretical investigation.

Structural and Electronic Characterization of the Complexes Obtained by the Interaction between Bare and Hydrated First-Row Transition-Metal Ions (Mn2+, Fe2+, Co2+, Ni2+, Cu2+, Zn2+) and Glycine

The complexes formed by the simplest amino acid, glycine, with different bare and hydrated metal ions (Mn(2+), Fe(2+), Co(2+), Ni(2+), Cu(2+), Zn(2+)) were studied in the gas phase and in solvent in order to give better insight into the field of the metal ion-biological ligand interactions. The effects of the size and charge of each cation on the organization of the surrounding water molecules were analyzed. Results in the gas phase showed that the zwitterion of glycine is the form present in the most stable complexes of all ions and that it usually gives rise to an eta(2)O,O coordination type. After the addition of solvation sphere, a resulting octahedral arrangement was found around Ni(2+), Co(2+), and Fe(2+), ions in their high-spin states, whereas the bipyramidal-trigonal (Mn(2+) and Zn(2+)) or square-pyramidal (Cu(2+)) geometries were observed for the other metal species, according to glycine behaves as bi- or monodentate ligand. Despite the fact that the zwitterionic structure is in the ground conformation in solution, its complexes in water are less stable than those obtained from the canonical form. Binding energy values decrease in the order Cu(2+) > Ni(2+) > Zn(2+) approximately Co(2+) > Fe(2+) > Mn(2+) and Cu(2+) > Ni(2+) > Mn(2+) approximately Zn(2+) > Fe(2+) > Co(2+) for M(2+)-Gly and Gly-M(2+) (H(2)O)(n) complexes, respectively. The nature of the metal ion-ligand bonds was examined by using natural bond order and charge decomposition analyses.