Roles of Organic Fragments in Redirecting Crystal/Molecular Structures of Inorganic-Organic Hybrids Based on Lacunary Keggin-Type Polyoxometalates

Lacunary polyoxometalates (LPOMs) are key precursors for the synthesis of functional POMs. To date, reviews dedicated to behavioral studies of LPOMs often comprise the role of metal ions, including transition metal (TM) and rare earth (RE) ions, in extending and stability of high-nuclearity clusters. In contrast, the role of organic ligands in the structures and properties of lacunary-based hybrids has remained less explored. In this review, we focus on the role of organic fragments in the self-assembling process of POM-based architectures and discuss relationships between the nature and structure of organic ligand and properties such as the topology of hybrid inorganic–organic material in RE and TM-RE heterometallic derivatives of lacunary Keggin-type POMs. The effects of organic fragment in mixed ligand hybrids are also briefly reviewed.

Silver Cation Coordination Study to AsW9 Ligand – A Trilacunar Arsenotungstate Compound

Objective: The main objective of this research is to find the coordination ratio between AsW9and Ag+, as a preliminary study for synthesizing a new silver-arsenotungstate complex. Material and method: The ligand:cation molar ratio in complexes was determined by conductometric and potentiometric titrations of AsW9with silver salts: CH3COOAg, AgNO3. Results: The ratio was obtained from the inflexion points of the curves when molar ratio was plotted versus conductivity, or from the equivalence point when silver added volume was plotted versus pH value. Each graphic shows one point of inflexion corresponding to 1:1.54 ratio of AsW9:Ag+. In the same manner, the equivalent volumes determined by graphical method gave the ratio 1:1.53. The spectral results confirmed that a AsW9:Ag+complex was formed since the ligand absorption maxima values have been changed from 190 nm to 197 nm in the case of using AgNO3and 196 nm for CH3COOAg corresponding to the W=Odbond, and from 246.5 nm to 274 nm (AgNO3) and 270 nm (CH3COO-Ag+) for the W-Ob,c-W bond. Conclusions: Silver cation exhibit a preference for AsW9in a ratio of 3 to 2. This ratio can be associated to a sandwich type arrangement, with two trilacunary Keggin building blocks incorporating 3 metal cations in a tetrahedral geometry.

Two novel Co(ii) and Ni(ii) complexes of tebuconazole with enhanced antifungal activities

Controlled release studies and theoretical investigations on two complexes based on tebuconazole were carried out to explain their increased antifungal activities.

Two Cu(ii) complexes of triadimefon: crystal structure, antifungal activities and structure–activity relationship

Theoretical investigations of the electronic structures of Cu(ii) complexes carried out by DFT calculations partially explained the increased biocidal properties.

Synergistic actions between tebuconazole ligand and Cu(ii) cation: reasons for the enhanced antifungal activity of four Cu(ii) complexes based on the fungicide tebuconazole

The enhanced antifungal activity of four synthesized complexes is due to the synergistic actions of tebuconazole ligand and Cu(ii) cation.