In situ generated polysiloxanes stabilizing μ3-oxo bridged Sb3 triangles

Discrete Molecular Aggregates Based on ZnII and SbIII/V Ions Displaying Efficient Antibacterial and Antioxidant Properties

The reactions of [Zn₃Cl₂(3,5-Me₂PzH)₄(t-BuPO₃)₂] with organostibonic acid in varying reaction conditions have been investigated. Single-crystal X-ray diffraction studies reveal the formation of [Zn₂(p-ClC₆H₄Sb)₂(O)₂(OCH₃)₂(t-BuPO₃)₃(py)₂] (1), [Zn₂(p-ClC₆H₄Sb^V)₄(Sb^III)₂(O)₈(t-BuPO₃H)₄(t-BuPO₃)₂(py)₂Cl₂] (2), and [Zn₂(RSb)₄(O)₄(OCH₃)₄(t-BuPO₃)₄(py)₂], where R = p-ClC₆H₄ (3) and R = p-iPrC₆H₄ (4), respectively. Interestingly, in the synthesis of 2, complete dearylation of organoantimony moieties followed by C-F bond formation, a reduction from Sb (V) to Sb (III), and Sb···Cl weak intermolecular interactions have been observed. ESI-MS studies suggested that clusters 1-4 maintained their structural integrity in the solution state also. Solution NMR studies (¹H, ³¹P, and ¹³C) support well the observed solid-state structures. 1-4 were tested for antibacterial activity using a microdilution assay. 1 and 4 showed the best activity with lower MIC values (0.78-6.25 μg/mL) against all the tested pathogens. The total antioxidant activity of 1-4 was evaluated through the phosphomolybdenum assay, which showed a total antioxidant activity ranging from 28.96 to 86.46 mg AAE/g compound with the ascorbic acid standard.

Stibonic acids and related stibonate-phosphonate clusters: Synthesis, characterization and bioactivity evaluation

The reaction of 4-(azobenzene)phenylstibonic acid with t-butylphosphonic acid led to the isolation of the tetranuclear oxo-hydroxo antimony cluster of formulae [(4-azobenzene-C₆H₄Sb)₄(OH)₄(^tBuPO₃)₆] (C1). The reaction of (p-t-butyl phenyl stibonic acid with phenyl phosphonic acid resulted in the isolation of complex with formulae [(p-t-BuC₆H₄Sb)₄(O)₂(PhPO₃)₄(PhPO₃H)₄] (C2). Based upon the initial results from docking studies, parent stibonic acids, t-butyl-phenylstibonic acid, p-isopropylphenylstibonic acid, 4-azobenzenephenylstibonic acid, and the derived tetranuclear organoantimonate-phosphonate clusters were screened against different cancer cell lines, various Gram-positive and Gram-Negative bacteria and mycobacteria for possible bioactivity profile.

Assembling Homometallic Sb6 and Heterometallic Ti4Sb2 Oxo Clusters

Isolation and structural characterization of novel organoantimony(V)-based oxo clusters are reported. (RSb)₄(OH)₄(t-BuPO₃)₆ and (RSb)₂(O)(t-BuPO₃H)₆ independently in the presence of pyridine under solvothermal conditions afford the hexanuclear organoantimonate clusters [(RSb)₆(μ₃-O)₂(μ₂-O)₆(t-BuPO₃)₄], where R = p-i-PrC₆H₄ (1), p-ClC₆H₄ (2). Further, reaction of organostibonate phosphonate with Ti(OⁱPr)₄ in the presence of pyridine under solvothermal conditions afforded the mixed-metal titanium stibonate hexanuclear clusters [(RSb)₂Ti₄(μ₃-O)₂(μ₂-O)₂(t-BuPO₃)₄(μ-OCH₃)₄(OCH₃)₄], where R = p-i-PrC₆H₄ (3), p-ClC₆H₄ (4). Band gap measurements were performed on 1-4. They reveal a remarkable reduction in the band gap on moving from the heavier main-group-based oxo cages (1 and 2) to the titanium-incorporated oxo cages (3 and 4).

Si10Cu6N4 Cage Hexacoppersilsesquioxanes Containing N Ligands: Synthesis, Structure, and High Catalytic Activity in Peroxide Oxidations

The synthesis, composition, and catalytic properties of a new family of hexanuclear Cu(II)-based phenylsilsesquioxanes are described here. Structural studies of 17 synthesized compounds revealed the general principle underlying their molecular topology: viz., a central metal oxide layer consisting of two Cu₃ trimers is coordinated by two cyclic [PhSiO_1.5]₅ siloxanolate ligands to form a skewed sandwich architecture with the composition [(PhSiO_1.5)₁₀(CuO)₆]²⁺. In addition to this O ligation by the siloxanolate rings, two opposite copper ions are additionally coordinated by the nitrogen atoms of corresponding N ligand(s), such as 2,2'-bipyridine (compounds 1-9), 1,10-phenanthroline (compounds 10-13), mixed 1,10-phenanthroline/2,2'-bipyridine (compound 14), or bathophenanthroline (compounds 15-17). Finally, the charge balance is maintained by two HO^- (compounds 1-7, 10-13, and 15-17), two H₃CO^- (compound 8), or two CH₃COO^- (compounds 9 and 14) anions. Complexes 1 and 10 exhibited a high activity in the oxidative amidation oxidation of alcohols. Compounds 1, 10, and 15 are very efficient homogeneous catalysts in the oxidation of alkanes and alcohols with peroxides.

Family of Polynuclear Nickel Cagelike Phenylsilsesquioxanes; Features of Periodic Networks and Magnetic Properties

A new family of bi-, tetra-, penta-, and hexanickel cagelike phenylsilsesquioxanes 1-6 was obtained by self-assembly and transmetalation procedures. Their crystal structures were established by single-crystal X-ray analysis, and features of crystal packing relevant to the network formation were studied by a topological analysis. Compounds 1, 2, and 4 are isolated architectures, while 3, 5, and 6 present extended 1D and 3D networks. The investigation of magnetic properties revealed the presence of ferro- (1 and 3-5) or antiferromagnetic (2 and 6) interactions between Ni(II) ions, giving rise in the most cases (1, 2, and 4-6) to the presence of a slow relaxation of the magnetization, which can originate from the spin frustration.

Cage-like Fe,Na-Germsesquioxanes: Structure, Magnetism, and Catalytic Activity

A series of four unprecedented heterometallic metallagermsesquioxanes were synthesized. Their cage-like architectures have a unique type of molecular topology consisting of the hexairon oxo {Fe₆ O₁₉ } core surrounded in a triangular manner by three cyclic germoxanolates [PhGe(O)O]₅ . This structural organization induces antiferromagnetic interactions between the Fe^III ions through the oxygen atoms. Evaluated for this first time in catalysis, these compounds showed a high catalytic activity in the oxidation of alkanes and the oxidative formation of benzamides from alcohols.

First cage-like pentanuclear Co(ii)-silsesquioxane

A new pentanuclear “cylinder”-like cobalt(ii) phenylsilsesquioxane [(PhSiO_1.5)₁₀(CoO)₅(NaOH)] exhibits a slow relaxation of the magnetization and a high catalytic activity and stereoselectivity in the oxidation of alkanes and alcohols.