%0 Journal Article
%A Xu, Jun
%A E. G. Lucier, Bryan
%A Lin, Zhi
%A Sutrisno, Andre
%A Terskikh, Victor
V.
%A Huang, Yining
%D 2014
%T New Insights
into the Short-Range Structures of Microporous
Titanosilicates As Revealed by 47/49Ti, 23Na, 39K, and 29Si Solid-State NMR Spectroscopy
%U https://acs.figshare.com/articles/journal_contribution/New_Insights_into_the_Short_Range_Structures_of_Microporous_Titanosilicates_As_Revealed_by_sup_47_49_sup_Ti_sup_23_sup_Na_sup_39_sup_K_and_sup_29_sup_Si_Solid_State_NMR_Spectroscopy/2231530
%R 10.1021/jp5077966.s001
%2 https://acs.figshare.com/ndownloader/files/3867460
%K 23 Na NMR
%K Several titanosilicates feature
%K 29 Si NMR resonances
%K 39 K SSNMR
%K EFG
%K ETS
%K 23 Na experiments
%K DFT
%K 23 Na
%K GTS
%K 29 Si NMR experiments
%K CQ
%K Ti
%K TiO
%K AM
%K 4O
%X Seven
prototypical microporous titanosilicates have been studied
by multinuclear solid-state NMR (SSNMR) spectroscopy, representing
four typical Ti environments: square-pyramidal TiO5 units
(natisite, AM-1, ETS-4), edge-shared brookite-type TiO6 chains (AM-4), cubane-type Ti4O16 clusters
(sitinakite, GTS-1), and corner-shared TiO6 chains (ETS-10,
ETS-4). 47/49Ti SSNMR spectra at 21.1 T are related to
the coordination, crystal symmetry, and local environment of Ti. Distortions
in Ti–O bond lengths and O–Ti–O coordination
angles are reflected via CQ(47/49Ti) values that range from 8 to 16 MHz. Several titanosilicates feature
axially symmetric 47/49Ti electric field gradient (EFG)
tensors that permit facile spectral assignment and detection of deviations
in local symmetry. This study uses 29Si NMR experiments
to assess phase purity and crystallinity. 23Na NMR is used
to probe the location and mobility of the sodium ions in the framework.
The potential of 39K SSNMR for investigation of extra-framework
counter cations is demonstrated by ETS-10, with increased spectral
resolution and enhanced sensitivity to changes in local environment
versus 23Na experiments. Plane-wave DFT calculations predicted 47/49Ti NMR parameters assisting in spectral assignments and
help correlate 23Na and 29Si NMR resonances
to crystallographic sites. The approach described in this work should
promote further SSNMR investigations of microporous solids, such as
titanosilicates, with unknown or poorly defined structures.
%I ACS Publications