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Positron Annihilation Lifetimes in Cucurbiturils: Evidence of Internal Inclusion of Gold in CB[7]
Author(s) -
MontesNavajas Pedro,
Damonte Laura C.,
García Hermenegildo
Publication year - 2009
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.200800565
Subject(s) - cucurbituril , colloidal gold , chemistry , crystallography , analytical chemistry (journal) , nanoparticle , nanotechnology , materials science , supramolecular chemistry , crystal structure , organic chemistry
Positron lifetime spectroscopy serves to determine the void volumes of cucurbituril (CB) capsules, which are not amenable to standard gas adsorption methods. In the case of the host–guest complex Au§CB[7], it also provides evidence of the inclusion of gold nanoparticles in the CB cavity (see space‐filling model; Au golden, C gray, H cyan, N blue, O red).Positron annihilation lifetime (PAL) measurements are carried out to determine the cavity dimensions of hydrated and dehydrated cucurbiturils (CB[ n ]; n =5,6,7,8). In the case of hydrated samples, the dimensions of the cavity are unrelated to the number of glycoluril units of the CB, whereas for dehydrated samples the cavity dimensions measured by PAL follow the expected order, although the experimental values obtained by PAL are significantly smaller than the dimensions of each CB determined by crystallography. For a host–guest complex in which colloidal gold nanoparticles are assumed to be included inside CB[7], a significant reduction of the cavity size is measured. This represents an experimental evidence of the inclusion of gold inside CB[7], which complements previous high‐resolution transmission electron microscopy (TEM) images.