Structural comparative studies on new Mn(II), Cr(III) and Ru(III) complexes derived from 2,4,6-tri-(2-pyridyl)-1,3,5-triazine (TPTZ)

Highly fluorescent hydroxyl groups functionalized graphitic carbon nitride for ultrasensitive and selective determination of mercury ions in water and fish samples

Heavy metal ion pollution is always a serious problem worldwide. Therefore, monitoring heavy metal ions in environmental water is a crucial and difficult step to ensure the safety of people and the environment. A mercury ion (Hg2+) fluorescence probe with excellent sensitivity and selectivity is described here. The functionalized graphitic carbon nitride nanosheets (T/G-C3N4) fluorescence probe was fabricated using melamine as a precursor by the pyrolysis technique, followed by a rapid KOH heat treatment method for 2 min. The chemical structure and morphology of the T/G-C3N4 probe were characterized using multiple analytical techniques including UV–Vis, SEM, XPS, XRD, and fluorometer spectroscopy. Geometry optimization of T/G-C3N4 as a modified probe was performed to assess its stability and interaction ability with Hg(II) via using the density function approach. The T/G-C3N4 probe showed a linear response based on quenching over the range 0–1.25 × 103 nM Hg(II); the detection limit was 27 nM. The remarkable sensitivity of T/G-C3N4 towards the Hg2+ ions was explained by the intense coordination and fast chelation kinetics of Hg2+ with the NH2, CN, C=N, and OH groups of T/G-C3N4 nanoprobe. The T/G-C3N4 probe demonstrates exceptional selectivity for Hg2+ ions among other metal ions including (Na+, Ag+, Mg2+, Fe2+, Fe3+, Co2+, Ni2+, Cd2+, K+, Ca2+, Cu2+, Pb2+, Mn2+ and Hg2+) and over a broad pH range (6–10), together with remarkable long-term fluorescence stability in water (> 30 days) and minimal toxicity. T/G-C3N4 was used to detect and quantify Hg2+ ions in tuna and mackerel fish and the results compared to ICP-AES. The results obtained offer a new simple and green technique for the design of multifunctional fluorescent probe appropriate for environmental applications.

Graphical Abstract

Crystal structure of aquadichlorido(2,4,6-tri-2-pyridyl-1,3,5-triazine-κ3 N,N′,N′′)nickel(II) monohydrate, C18H16Cl2N6NiO2

C18H16Cl2N6NiO2, monoclinic, P21/n (no. 14), a = 8.5737(6) Å, b = 11.4177(9) Å, c = 20.3031(16) Å, β = 99.309(3)°, V = 1961.3(3) Å3, Z = 4, R gt(F) = 0.0479, wR ref(F 2) = 0.0865, T = 293 K.

Interactions of atrazine with transition metal ions in aqueous media: experimental and computational approach

Transition metal ions have their own significances and utility. Externally applied pesticides may alter the bioavailability of these metal ions to plants through the coordinating ability of these pesticides with metal ions. In current study a series of metal complexes containing atrazine (Atr) group(s) attached to metal(II) (M) frame, with the formula; [M(Atr)_n.xH₂O.yCl] (where M = Mn, Fe, Co, Ni, Cu or Zn; n = 1 or 2; x = 1-4; y = 1-2), have been synthesized for the first time to check the interactions of atrazine with transition metal ions. More importantly, all the complexes were synthesized at neutral pH in aqueous medium. The major differences among the FTIR spectra were observed between 3,700-2,800 and 1,800-1,350 cm^-1. On the basis of FTIR, CHN and computational study, it was observed that Mn, Ni and Cu formed complexes in 1:2 and Fe, Co and Zn in 1:1. The obtained results were supported by 3D molecular modeling using GAMESS computations as a package of ChemBio3D Ultra14 program. The FTIR spectral analysis and 3D molecular modeling suggests that the Atr can show coordination through the nitrogen (in between two side chains) of ring as well as nitrogen (non steric amine) of side chain with different metal ions.

Comparative spectroscopic and DFT calculations of binary and ternary complexes derived from 4-allyl-1-(2-hydroxybenzoyl) thiosemicarbazide (L¹) and 2,2'-dipyridyl

Five metal complexes derived the reactions of 4-allyl-1-(2-hydroxybenzoyl) thiosemicarbazide (L(1)) with MX2 (M=Co(2+), Cu(2+) and Zn(2+) ions; X=Cl(-) in case of Co(2+) and Cu(2+) ions and Cl(-) and Ac(-) in case of Zn(2+) ion) in EtOH were synthesized and characterized. The results suggested that the binary and ternary complexes have the general formulae, [Cu(L(1)-2H)(EtOH)], [Co(L(1)-2H)(H₂O)₂]⋅H₂O and [Zn(L(1)-2H) (H₂O)1/2]⋅½EtOH, [Cu₂(dipy)(L(1)-2H)(OH)₂(H₂O)], [Co(dipy)(L(1)-2H)]⋅4H₂O and [Zn(dipy)(L(1)-2H)]. The binary and ternary complexes were characterized by elemental analyses, molar conductivities, spectral (IR, UV-vis; (1)H NMR, mass), thermal (TGA, DTG) and magnetic moments measurements. The mode of chelation is suggested using spectral data. The existence of OH group in the ternary complexes is confirmed from the results of IR, mass and (1)H NMR spectra. All the geometries of the ligands and the complexes are confirmed using DFT method from DMOL(3). The biological activity for the L(1) and two metal complexes were tested against DNA.

Spectroscopic, analytical and DFT calculation studies of two novel Al3+ complexes derived from 2,4,6-tri-(2-pyridyl)-1,3,5-triazine (TPTZ)

In this study TPTZ is used exclusively as an analytical reagent for the determination of micro amounts of Al3+ ions with high accuracy and lower detection limit, which reach 2.7 ppm. The developed blue color of Al3+-TPTZ complex was used selectivity to determine the concentration and the geometry of the Al3+ complex using continuous variation and molar ratio methods. Also, the novel Al3+ complexes derived from the reaction of TPTZ were synthesized. The solid complexes were characterized by elemental analyses, spectral (IR, UV-vis., 1H NMR, mass) and magnetic measurements. The isolated complexes have the general formulae, [Al(TPTZ)Cl3]·H2O·1½EtOH (1:1; M:L) and [Al2(TPTZ)Cl6(EtOH)2] (2:1; M:L). IR spectra indicate that TPTZ behaves in a bidentate manner in case of 1:1 and 2:1 (M:L). Elemental analyses and mass spectra of the complexes suggest the existence of an octahedral structure around the Al3+ ions. DFT calculations were used to determine the geometry of complexes.

Comparative studies and modeling structures of two new isomers containing binuclear PdII complexes derived from 2,4,6-tri-(2-pyridyl)-1,3,5-triazine (TPTZ)

The synthesis and comparative studies of two new binuclear PdII isomer complexes derived from TPTZ, [2,4,6-tri-(2-pyridyl)-1,3,5-triazine], have been synthesized and characterized. Their structures have been investigated by elemental analyses, spectral (IR, UV-vis, mass and 1H-NMR) and thermal measurements. Electronic and magnetic studies suggest a distorted square-planar around the two PdII ions. The HOMO, LUMO and DFT parameters on the atoms have been calculated to confirm the geometry of the ligand and their complexes. Kinetic parameters were determined using Coats-Redfern and Horowitz-Metzger methods. Also, the geometry of the two isomers is confirmed using DFT method from DMOL3 calculations. Moreover, the two PdII complexes have different specific optical rotation where the red PdII complex has dextrorotatory (+5.68) while the yellow PdII complex has levorotatory (-9.37). The results of biological activity for the two PdII complexes promised to be effective in tumor treatment.