abstract
The Zr-IV-based metal-organic framework (MOF) UiO-67 has been examined as a promoter of the hydrolysis of phosphoester bonds by using sodium para-nitrophenylphosphate (pNPP) as a model substrate. The reactions were followed by H-1 NMR spectroscopy and performed under mild conditions using 2-100 mol% of the MOF relative to pNPP. All of the systems studied promoted the hydrolysis of pNPP to give para-nitrophenol (pNPh) and inorganic phosphate. A reaction half-life of ca. 30 min was achieved using 17 mol% of UiO-67 at 55 degrees C and 30 mol% at ambient temperature; >= 98% removal of pNPP was reached within 1 h for both reaction temperatures. H-1 NMR spectra of the reaction solutions, together with powder X-ray diffraction, FT-IR spectroscopy and solid-state NMR data for the recovered MOF, revealed that (i) pNPP was encapsulated and then converted to pNPh within the cavities of UiO-67, (ii) both pNPh and inorganic phosphate were retained in the solid promoter, and (iii) the MOF suffered partial structural breakdown into the components Zr6O4(OH)(4) and 4,4'-biphenyldicarboxylate, with partial release of the latter into solution. These structural changes eventually compromized the recyclability of the promoter, although the material could be recovered and reused in a second cycle without loss of activity. (C) 2015 Elsevier Inc. All rights reserved.
keywords
CHEMICAL WARFARE AGENTS; BIMETALLIC TETRABENZIMIDAZOLE COMPLEXES; ORGANOPHOSPHATE NERVE AGENTS; MODEL PHOSPHODIESTER; ESTER HYDROLYSIS; SULFUR MUSTARD; DEGRADATION; PHOSPHATE; STABILITY; PHOSPHOTRIESTERASE
subject category
Chemistry; Science & Technology - Other Topics; Materials Science
authors
Nunes, P; Gomes, AC; Pillinger, M; Goncalves, IS; Abrantes, M
our authors
Ana Catarina Costa Gomes Alves
Assistant Researcher
Isabel Maria de Sousa Gonçalves
Associate Professor
Martyn Pillinger
Principal ResearcherProjects
Use of molecular containers to modify metallocene-based catalysts (PTDC/QEQ-SUP/1906/2012)
PTNMR - Portuguese Nuclear Magnetic Resonance Network (REDE/1517/RMN/2005)
acknowledgements
This work was partly financed by FEDER (Fundo Europeu de Desenvolvimento Regional) through COMPETE (Programa Operacional Factores de Competitividade) and by national funds through the FCT (Fundacao para a Ciencia e a Tecnologia) with the projects CICECO (Centre for Research in Ceramics and Composite Materials) - FCOMP-01-0124-FEDER-037271 (FCT ref. PEst-C/CTM/LA0011/2013), FCOMP-01-0124-FEDER-029779 (FCT ref. PTDC/QEQ-SUP/1906/2012, including the research grant with ref. BPD/UI89/4864/2013 to A. C. G.) and the Centro de Quimica Estrutural (PEst-OE/QUI/UI0100/2013). The NMR spectrometers are part of The National NMR Network (REDE/1517/RMN/2005), supported by POCI 2010 (Programa Operacional Ciencia e Inovacao 2010) and the FCT. The authors also thank the Portuguese NMR Network (Instituto Superior Tecnico Center) (RECI/QEQ-QIN/0189/2012) for providing access to the NMR facilities.