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Tracking 'Apolar' NMe4+ Ions within Two Polyoxothiomolybdates that Have the Same Pores: Smaller Clathrate and Larger Highly Porous Clusters in Action.
- Source :
-
Chemistry - A European Journal . Mar2014, Vol. 20 Issue 11, p3097-3105. 9p. - Publication Year :
- 2014
-
Abstract
- Two nanosized polyoxothiometalates were synthesized based on linking oxomolybdate building blocks with {Mo2O2S2}2+ groups. Remarkably, both compounds are formed selectively primarily upon changing the related concentrations in a logical way; they exhibit common structural features based on the same {Mo9O6S3}-type pores, which result in connections between {Mo6O21} pentagons and {Mo2O2S2}2+ linkers. Whereas the much larger spherical Mo132-type Keplerate contains twenty pores, the smaller Mo63-type cluster remarkably contains only two. The two compounds and a similar Keplerate exhibit interesting supramolecular properties related to interactions with the unusual predominantly apolar NMe4+ cations. Structural characterization of the Mo63-type compound reveals in the solid state a clathrate-like species that contains four NMe4+ cations embedded in two types of structurally well-adapted pockets. Related NMR spectroscopic investigations in solution using NMe4+ as the NMR spectroscopic probe are in agreement with the solid-state description. 1H NMR spectroscopic experiments (1D variable-temperature, 2D total correlation spectroscopy (TOCSY), exchange spectroscopy (EXSY), and diffusion-ordered spectroscopy (DOSY)) feature firmly immobilized and mobile NMe4+ ions in relationship with the type of host-guest arrangements. The use of the 1H NMR DOSY spectroscopic methodology has been successfully applied to track the interactions of the NMe4+ cations with the {Mo9O6S3} pores of a sulfurated Keplerate, thereby allowing the first quantitative analysis of this type of plugging process. The stability constant K=(210±20) mol−1 L is discussed related to the character of the process. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 09476539
- Volume :
- 20
- Issue :
- 11
- Database :
- Academic Search Index
- Journal :
- Chemistry - A European Journal
- Publication Type :
- Academic Journal
- Accession number :
- 94728503
- Full Text :
- https://doi.org/10.1002/chem.201303719