Capel Berdiell, I orcid.org/0000-0003-3828-7097, Kulak, AN orcid.org/0000-0002-2798-9301, Warriner, SL orcid.org/0000-0002-7589-6011 et al. (1 more author) (2018) Heterometallic Coordination Polymer Gels Supported by 2,4,6-Tris(pyrazol-1-yl)-1,3,5-triazine. ACS Omega, 3 (12). pp. 18466-18474. ISSN 2470-1343
Abstract
Complexes of type [M(tpt)2]X2 (M2+ = Fe2+, Co2+, Ni2+; tpt = 2,4,6-tri{pyrazol-1-yl}-1,3,5-triazine; X– = BF4– or ClO4–) crystallize in a cubic lattice, with the metal ion and ligand conformation showing unusual symmetry-imposed disorder. Addition of 1 equiv AgX to the corresponding preformed [M(tpt)2]X2 salt in concentrated MeNO2 solution affords thixotropic gels. Gelation was not observed in analogous reactions using [Mn(tpt)2][ClO4]2, or from reactions in other, more donating solvents. Scanning electron microscopy (SEM) images from dilute solutions of the reagents confirmed the fibrous microstructure of the gels and their homogeneous elemental composition. However, energy-dispersive X-ray data show a reduced Fe/Ag ratio compared to the Co/Ag and Ni/Ag gels, where a 1:1 ratio of metals is evident. More concentrated gels decomposed to silver nanoparticles during SEM sample preparation. Mass spectrometry and 1H NMR indicate that silver induces partial ligand displacement reactions in [Fe(tpt)2]2+ and [Co(tpt)2]2+, but not in [Ni(tpt)2]2+. Hence, the strength of the gels, which follows the order M = Mn (no gel) < Fe < Co < Ni, correlates with the stability of octahedral [M(tpt)2]2+ under gelation conditions. Iron(II) complexes of the related ligands 2,4,6-tri{pyrazol-1-yl}pyridine (tpp) and 2,4,6-tri{pyrazol-1-yl}pyrimidine (tpym) did not undergo gelation with silver salts under the above conditions. The unique properties of tpt as a gelator in this work may reflect the crystallographically observed ability of metal-coordinated tpt to chelate to exogenous silver ions, through its pendant pyrazolyl group and triazinyl N donors. In contrast, the pendant azolyl substituents in silver complexes of the nongelators tpp and tpym only bind exogenous silver in monodentate fashion.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2018 American Chemical Society. This is an open access article published under a Creative Commons Attribution (CC-BY) License, which permits unrestricted use, distribution and reproduction in any medium, provided the author and source are cited: (https://pubs.acs.org/page/policy/authorchoice_ccby_termsofuse.html) |
Keywords: | Coordination compounds; Coordination polymers; Molecular structure; Phase; Phase transition; Reaction mechanism; Surface structure; Thermal properties |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Chemistry (Leeds) > Inorganic Chemistry (Leeds) The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Chemistry (Leeds) > Organic Chemistry (Leeds) |
Funding Information: | Funder Grant number Leverhulme Trust RPG-2015-095 |
Depositing User: | Symplectic Publications |
Date Deposited: | 20 Dec 2018 17:31 |
Last Modified: | 17 Dec 2024 11:57 |
Status: | Published |
Publisher: | American Chemical Society |
Identification Number: | 10.1021/acsomega.8b02508 |
Related URLs: | |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:140022 |