An ultrathin amino-acid based copper(II) coordination polymer nanosheet for efficient epoxidation of β-caryophyllene

Abstract

• CuIle-e nanosheet and CuIle-m nanoshuttle were fabricated from natural amino acid. • Stable catalytic systems, CuIle-e /acetone/TBHP and CuIle-e /THF/O 2 /TBHP, were built. • Good yields (86.1% or 87.2%) for β-caryophyllene epoxide were achieved. • Superior recyclability of CuIle-e nanosheet was realized. Natural amino acids are important building blocks for the construction of intriguing coordination polymers (CPs) because of their abundance, inexpensiveness and environmental benignness. Herein, two copper(II) CPs, namely, 2D CuIle-e nanosheet ( e : ethanol) and 1D CuIle-m nanoshuttle ( m : methanol), were fabricated from L -isoleucine ( Ile ) and well characterized with single-crystal x-ray diffraction, XPS spectra, TEM and AFM, etc. More importantly, two novel and stable catalytic nanosystems, i.e. CuIle-e /acetone/TBHP ( tert-butyl hydroperoxide) and CuIle-e /THF/O 2 /TBHP, were thus conveniently built by using ultrathin 2D CuIle-e nanosheet (~ 2.3 nm) in suitable aprotic solvents. Under mild conditions, complete conversion of β-caryophyllene and good yields (86.1% or 87.2%) for β-caryophyllene epoxide were gained via CuIle-e /acetone/TBHP or CuIle-e /THF/O 2 (1 atm)/TBHP (10.0 mol%), respectively. Notably, ultrathin CuIle-e nanosheet showed fairly satisfactory stability, which may open a unique window for the facile fabrication of new amino-acid based CP nanosystems with outstanding catalytic performances in actual applications. Two amino acid-based ultrathin CP nanosystems, CuIle-e /acetone/TBHP and CuIle-e /THF/1 atm O 2 /TBHP, were employed for the highly efficient epoxidation of β-caryophyllene under mild conditions.