A Copper(II) tris-imidazolylphosphine complex as a functional model of flavonol 2,4-dioxygenase

摘要

Reaction of tetrakis(acetonitrile)copper(I) perchlorate ([Cu(NCCH3)(4)][ClO4]), tris-1-ethyl-4-methylimidazolylphosphine (T1Et4MeIP) (1) and 3-hydroxyflavone (flavH) under ambient conditions produces an in-situ generated flavonol bound copper(II) complex, which converts to a stable green complex that formulates to [Cu(T1Et4MeIP)(flav)][ClO4] (2). The crystal structure of 2 was determined by X-ray diffraction and crystallizes in a triclinic system (P (1) over bar) with unit cell dimensions of a = 14.537(15) angstrom, b = 15.794(14) angstrom, c = 17.044(17) angstrom, alpha = 65.58(3)degrees, beta = 86.80(5)degrees, gamma = 73.34(4)degrees, V = 3376(6) angstrom(3) and Z = 2. While the five-coordinate copper(II) complex is stable under ambient conditions in the solid state, it undergoes oxidative scission of the flavonol pyrone ring under photolytic (300 nm) and/or thermal (120 degrees C) conditions in the presence of molecular oxygen. The degradative process produces the corresponding methylated products: methylbenzoate, methyl salicylate and N,N-dimethylbenzamide. In addition, the previously undisclosed single crystal X-ray structure of tris-1-ethyl-4-methylimidazolylphosphine (1), T1Et4MeIP, is also reported. (C) 2019 Elsevier B.V. All rights reserved.