A Promiscuous Dicopper(II) System Promoting the Hydrolysis of Bis(2,4-dinitrophenyl)phosphate: Gaining Mechanistic Insight by Means of Structural and Spectroscopic DFT Studies

作者：Rey Nicolas A; Neves Ademir; De Almeida Wagner B; Dos Santos Helio F; Costa Luiz Antonio S^*

来源：International Journal of Quantum Chemistry, 2010, 110(7): 1432-1442.

DOI：10.1002/qua.22334

• density functional theory
• dicopper hydroxo-bridged complex
• BDNPP substrate
• hydrolysis mechanism
• spectroscopic study

Catechol oxidases (COs) are plant enzymes that belong to the oxidoreductases class. They contain a dinuclear copper center in their active site. In this article, we have investigated the dicopper(II) model complex [Cu(2)(mu-OH)(C(21)H(33)ON(6))](2 ) (Complex-A) under a computational perspective, using the DFT method, since this approach has been very useful in the treatment of bimetallic copper systems. The structural and spectroscopic study of Complex-A as well as the structural analysis of the BDNPP/Complex-A (Complex-B) adduct have been carried out. The calculated parameters for Complex-A are in good accordance with the experimental X-ay data. Some remarkable points can be observed from the calculated UV vis relative excitations. The Complex-B computed structure verifies its identity as a key intermediate species in the BDNPP hydrolysis mechanism. The Cu(II)center dot center dot center dot Cu(II) calculated distance in Complex-B (3.026 angstrom) is shorter than the calculated for Complex-A (3.080 angstrom); one copper atom is bonded to the oxygen of phosphate [Cu (2)center dot center dot center dot O64-P] at 2.511 angstrom. These arguments clearly suggest a monodentate interaction and lead to a new mechanism involving terminal substrate coordination and subsequent intramolecular nucleophilic attack by a bridging hydroxide. Such a hypothesis is completely new in terms of homobimetallic copper systems, and may have important implications regarding the chemistry of several biological dinuclear catalytic sites.

• 出版日期2010-6