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Synthesis of graphene supported bis(diphenylphosphinomethyl)amino ligands and their Pd(II) and Pt(II) complexes: Highly efficient and recoverable nano-catalysts on vitamin K-3 production

2016    Urus, Serhan; Caylar, Mahmut; Karteri, Ibrahim

Novel graphene oxide (GO) supported bis(diphenylphosphinomethyl)amino [GO@CHONHRN(CH2PPh2)(2)] type ligands and their Pd(II) and Pt(II) complexes have been synthesized and characterized using FT-MIR/FAR, SEM, EDX, TEM, XRD, TGA and UV-Visible techniques. Additionally, GO@CHONHRN(CH2PPh2)(2)MX2 (M: Pd(II) and Pt(II)) type complexes were used as heterogeneous nano-catalysts in vitamin K-3 (2-methyl-1,4-naphthoquinone, menadione) synthesis. Graphene-supported aminomethylphosphine-Pd (II) complexes showed the best catalytic activities with high selectivities compared to the graphene-supported aminomethylphosphine-Pt(II) complexes and the literature. Selectivities and the conversions were around 60-65% with of 95-99% and respectively for the GO@aminomethylphosphine-Pd(II) complexes. The area ratio of D and G peaks of GO sheets was calculated as I-D/I-G = 1.19 using Raman spectra. The average grain size of GO and GO@aminomethylphosphine-Pd(II) complexes are determined as 18.02 nm and 46.06 nm from Scherrer's equation, respectively. The band gap (E-g) values of the GO based aminomethylphosphine-metal complexes are analyzed and enhanced from 3.31 eV to 4.21 eV. (C) 2016 Elsevier B.V. All rights reserved.