Syntheses, structures and luminescence of silver(I) sulfonate complexes with nitrogen-containing ligands

Coordination Polymers Based on Rhenium Octahedral Chalcocyanide Cluster Anions and Ag+ Cations with Bipyridine Analogs

A series of six coordination polymers based on octahedral cluster anions [Re₆Q₈(CN)₆]^4- (Q = S or Se) and Ag⁺ cations coordinated by bipyridine analogs were synthesized under solvothermal conditions. Their structures have been characterized by single crystal X-ray diffraction. Compounds 1 and 2 described by the general formula [{Ag(phen)}₄Re₆Q₈(CN)₆] (Q = Se (1), S (2); phen = 1,10-phenanthroline) exhibit layered structures assembled into a supramolecular network by CH…π contacts. At the same time, compounds [{Ag(bipym)}₂Ag₂Re₆Se₈(CN)₆] (bipym = 2,2'-bipyrimidine) (3), [{Ag₂(bipy)}Ag₂Re₆Se₈(CN)₆]·CH₃CN (bipy = 4,4'-bipyridine) (4) and [{Ag(dpbp)}₄Re₆Q₈(CN)₆]·2H₂O·2CH₃CN (Q = Se (5), S (6); dpbp = 4,4'-Di(4-pyridyl)biphenyl)) evince framework structures. In 1, 2, 5 and 6 weak Ag⋯Ag interactions are observed. All the compounds show luminescence in the red region. The luminescence quantum yields and lifetimes were found to be notably higher than those for most of the coordination polymers based on the octahedral rhenium cluster complexes.

Synthesis and antioxidant properties of 2-(3-(hydroxyimino)methyl)-1H-indol-1-yl)acetamide derivatives

Background

The main aim of this work was to synthesise a novel N-(substituted phenyl)-2-(3-(hydroxyimino) methyl)-1H-indol-1-yl) acetamide derivatives and evaluate their antioxidant activity. These compounds were prepared by a condensation reaction between 1H-indole carbaldehyde oxime and 2-chloro acetamide derivatives. The newly synthesised compound structures were characterised by FT-IR, 1H-NMR, mass spectroscopy and elemental analysis. Furthermore, the above-mentioned compounds were screened for antioxidant activity by using ferric reducing antioxidant power (FRAP) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) methods.

Result

The antioxidant activity result reveals that most of the compounds were exhibiting considerable activity in both methods and the values are very closer to the standards. Among the synthesised compounds, compound 3j, 3a and 3k were shown remarkable activity at low concentration.

Conclusion

Compounds 3j, 3a and 3k were shown highest activity among the prepared analogues due to the attachment of halogens connected at the appropriate place in the phenyl ring. Hence, these substituted phenyl rings considered as a perfect side chain for the indole nucleus for the development of the new antioxidant agents.

How the Coordinated Structures of Ag(I) Catalysts Affect the Outcomes of Carbon Dioxide Incorporation into Propargylic Amine: A DFT Study

Density functional theory calculations have been carried out to explore the detailed mechanisms for carbon dioxide incorporation of N-unsubstituted propargylic amine catalyzed by Ag(I) catalysts. We show that the reaction undergoes substrate adsorption or displacement, isomerization from amine-coordinated species to the alkyne-coordinated species, CO₂ attack, and proton transfer, giving the carbamate intermediate. Subsequently, the reaction would bifurcate at the intermolecular ring-closing step, which produces five-membered ring (5MR) and six-membered ring (6MR) products at the same time, thus raising a regioselectivity issue. Our calculations reveal that the outcomes of the reaction critically depend on the coordination number and the basicity of the ligands. Higher coordinate number and stronger basicity of the ligands would stabilize the 5MR transition state over the 6MR counterpart. Such a preference can be rationalized by using transition state energy decomposition. All of these results could promote the rational design of noble metal/organic base combined catalysts with higher selectivity.

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.