A bio-inspired zinc finger analogue anchored in 2D hexagonal mesoporous silica for room temperature CO2 activation via a hydrogenocarbonate route. (21st June 2017)

• Record Type: Journal Article
• Authors: Doghri, Hanène; Baranova, Elena A.; Albela, Belén; Saïd-Zina, Mongia; Bonneviot, Laurent
• Is Part Of: New journal of chemistry. Volume 41:Number 14(2017)
• Page Start: 6795
• Page End: 6809
• Publication Date: 2017-06-21
• Subjects: Chemistry -- Periodicals; Chimie -- Périodiques; 540
• DOI: 10.1039/c6nj03329f
• Languages: English
• ISSNs: 1144-0546

Abstract

Abstract : A room temperature hydrogenocarbonate intermediate in CO2 activation by a carbonic anhydrase active site analog inserted in the nanopores of mesostructured porous silicas. Abstract : Bio-inspired diethylenetriamine–zinc(ii ) complexes were anchored into the nanopores of hexagonal mesoporous MCM41-like silicas targeting a carbamate free and low temperature CO2 recycling process. A step-by-step approach was adopted to perform an in situ synthesis in order to mimic the zinc finger of carbonic anhydrases, the fastest family of enzymes. In the presence of a surface-masking pattern of TMA + ions, some silanol groups were capped using grafted trimethylsilyl functions, TMS gr, ( gr for grafted). After removing the masking ions, a tridentate diethylenetriamine ligand was anchored using diethylenetriamine propyltrimethoxysilane. The so-called DETA an ligands ( an for anchored) were partially monoprotonated using either cyclohexane or isopropanol as a solvent. Nonetheless, up to two thirds of them were metallated by Zn(ii ) ions, leading to the targeted anchored zinc finger mimic [Zn(DETA an )L] + (L = Cl − or OH − ). CO2 is then adsorbed at room temperature and in humid ambient air by the formation of an intermediate hydrogenocarbonate–zinc complex. Specific IR signatures at 1330 and 1400 cm −1 together with characteristic C 1s and Zn 2p3/2 XPS binding energies at 286.4 and 1024.6 eV advocate for a rather symmetrical bidentate [η 2 -CO3 ] structural unit in the anchored complex [Zn(DETA an )(η 2 -HCO3 *)] +, where the Zn(ii ) ion is most likely pentacoordinated. The internal pH value varied by less than 0.5 depending on the metal reacting with the DETA an ligand and its ability to generate HCO3 −, due to the buffering effect of surface silanol and amino groups according to the level of protonation of the DETA moieties measured from the N 1s XPS spectra. In contrast to nitrate ions, chloride ions were found to inhibit the formation of hydrogenocarbonate.