Characterization and biomimetic study of a hydroxo-bridged dinuclear phenanthroline cupric complex encapsulated in mesoporous silica: Models for catechol oxidase

Chia Hung Lee, She Tin Wong, Tien Sung Lin, Chung Yuan Mou

Research output: Contribution to journalArticlepeer-review

66 Citations (Scopus)

Abstract

We report the synthesis and characterization of a hydroxo-bridged dinuclear phenanthroline cupric complex, [(phen) 2Cu-OH-Cu(phen) 2](ClO 4) 3 (HPC, phen = phenanthroline), dispersed in molecular sieves: MCM-41's and sodium zeolite Y. We employed spectroscopic techniques (FT-IR, UV-visible, EPR, and EXAFS) to characterize and study the catalytic activities of immobilized HPC in the oxidation of 3,5-di-tert-butylcatechol (DTBC) to the corresponding quinone (3,5-di-tert-butylquinone, DTBQ) to mimic the functionality of catechol oxidases. HPC complexes can adsorb only on the outside surface of the Y zeolite due to its smaller pore size. The EXAFS spectrum gives 3.51 Å for the Cu⋯Cu distance in HPC encapsulated in the nanochannels of Al-MCM-41 mesoporous solids, which is comparable to the O⋯O distance of the two hydroxyl groups of DTBC, and this made a simultaneous coordination of the diol group to the dicupric center possible. The resultant complex then allows the transfer of two electrons from DTBC to the dicupric center leading to the production of DTBQ. The nanochannels of calcined Al-MCM-41 mesoporous solids provide stability, due to confined space and surface charge, which could prevent excessive separation of the dinuclear cupric centers after removal of the hydroxo bridge in the catalytic process. A catalytic reaction scheme is proposed based on the spectroscopic data obtained in the characterization. The study demonstrates that HPC encapsulated in the nanochannels of Al-MCM-41 mesoporous materials could be a viable system for a broad range of catalytic oxidation to mimic natural occurring enzymes.

Original languageEnglish
Pages (from-to)775-784
Number of pages10
JournalJournal of Physical Chemistry B
Volume109
Issue number2
DOIs
Publication statusPublished - Jan 20 2005
Externally publishedYes

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry

Fingerprint

Dive into the research topics of 'Characterization and biomimetic study of a hydroxo-bridged dinuclear phenanthroline cupric complex encapsulated in mesoporous silica: Models for catechol oxidase'. Together they form a unique fingerprint.

Cite this