Polyoxometalate based hybrid chiral material: Synthesis, characterizations and aerobic asymmetric oxidation reaction

Abstract

A new hybrid chiral material, comprising Keggin type mono ruthenium substituted phosphotungstate (PW₁₁Ru) and chiral (R-(-)-1-cyclohexylethylamine (Cy)), was synthesized in an aqueous medium by simple ligand substitution. The bonding was confirmed by FT-IR, multinuclear NMR (³¹P, ¹³C and ¹⁵N), while the chirality was confirmed by CD spectroscopy and a polarimeter. The study reveals the attachment of Cy and PW₁₁Ru through N → Ru bond. An attempt was made to use the synthesized material as a heterogeneous catalyst for carrying out aerobic asymmetric oxidation of styrene and found that only 0.001 mg (7.9 × 10⁻⁶mmol) of Cy was sufficient to achieve very high TON.

Keywords:

• Chiral
• Ruthenium
• Heterogeneous catalyst
• Phosphotungstate
• R-(-)-1-Cyclohexylethylamine

Acknowledgement

AP is thankful to Science and Engineering Research Board (SERB), Project No. EMR/2016/005718, New Delhi for the financial support.

Disclosure statement

No potential conflict of interest was reported by the authors.