Cyclodextrin inclusion compounds of vanadium complexes: Structural characterization and catalytic sulfoxidation

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• 作者：Ines Lippold ; Kristin Vlay ; Helmar Gö ; rls ; Winfried Plass
• 关键词：Cyclodextrins ; Host– ; guest chemistry ; Inclusion compounds ; Salicylidene hydrazide ligands ; Vanadium ; X-ray diffraction ; Sulfoxidation
• 刊名：Journal of Inorganic Biochemistry
• 出版年：2009
• 出版时间：April 2009
• 年：2009
• 卷：103
• 期：4
• 页码：480-486
• 全文大小：714 K

文摘

Reaction of potassium vanadate with the hydrazone ligand derived from Schiff-base condensation of salicylaldehyde and biphenyl-4-carboxylic acid hydrazide (H₂salhybiph) in the presence of two equivalents α-cyclodextrin (α-CD) in water yields the 1:2 inclusion compound K[VO₂(salhybiph)@(α-CD)₂]. Characterization in solution confirmed the integrity of the inclusion compound in the polar solvent water. The inclusion compound crystallizes together with additional water molecules as K[VO₂(salhybiph)@(α-CD)₂] · 18H₂O in the monoclinic space group P2(1). Two α-CD rings forming a hydrogen bonded head to head dimer are hosting the hydrophobic biphenyl side chain of the complex K[VO₂(salhybiph)]. The supramolecular aggregation of the inclusion compound in the solid state is established through hydrogen bonding interactions among adjacent α-CD hosts and with vanadate moieties of the guest complexes as well as ionic interactions with the potassium counterions. In contrast the supramolecular structure of the guest complex K[VO₂(salhybiph)] without the presence of CD host molecules is governed by π–π-stacking interactions and additional CH/π interactions. The new inclusion complex K[VO₂(salhybiph)@(α-CD)₂] and the analogous 1:1 inclusion compound with β-CD were tested as catalyst in the oxidation of methyl phenyl sulfide (thioanisol) using hydrogen peroxide as oxidant in a water/ethanol mixture, under neutral as well as acidic conditions.