Variable anchoring of boron in zeolite beta

Facile Monolayer Formation on SiO2 Surfaces via Organoboron Functionalities

“…These values are highly similar to those reported for boroxyl ring BO 3 species (17.5 ppm, 2.65 MHz) in borosilicates [12] and for extraframework B(OH) 3 groups in boron-doped zeolite b [13] or in boron-modified MCM-41. [14] At the highest annealing temperature in this study, 850 8C, a further shift was observed in the spectra, and although the line shapes suggested that at least two boron species were present, the clear trigonal site at 13 ppm confirms the anchoring of 11 B atoms to the framework on the basis of its similarity to that observed upon boroxylring opening [12] or the conversion of B(OH) 3 species into B(OH) n (OSi) 3Àn species.…”

“…[14] At the highest annealing temperature in this study, 850 8C, a further shift was observed in the spectra, and although the line shapes suggested that at least two boron species were present, the clear trigonal site at 13 ppm confirms the anchoring of 11 B atoms to the framework on the basis of its similarity to that observed upon boroxylring opening [12] or the conversion of B(OH) 3 species into B(OH) n (OSi) 3Àn species. [13][14][15] The shoulder at a higher shift indicates residual extraframework boron species. Above 400 8C, tetracoordinated boron species were observed at around 0 ppm.…”

“…13 C NMR cross-polarization signals were observed for both types of monolayers. These signals verified the presence of phenyl and cyclohexyl groups on the B1-SiO 2 and B2-SiO 2 NPs, respectively (see the Supporting Information for more details).…”

“…The boron species present at the various annealing temperatures were characterized further by 13 C and 11 B magic-angle spinning (MAS) solid-state NMR spectroscopy. 13 C NMR cross-polarization signals were observed for both types of monolayers.…”

Template burning effects on stability and boron coordination in boron levyne studied by in situ time resolved synchrotron powder diffraction

“…The experimental work as reviewed by Millini et al [1] and further performed by means of 11 B solid-state NMR [10,11] and IR spectroscopy [12], along with theoretical studies [13][14][15] have shown that the boron change in coordination upon heating is strongly related to the nature of the counterions (protons, large counterions, cationic organic structure directing agent (SDA)) and to the hydration/dehydration level. In particular, in fully hydrated proton forms, boron is tetrahedrally coordinated, whereas upon dehydration boron assumes a trigonal coordination [10,11,16]. Such transformation is also observed after calcination in the as-synthesized forms containing organic cations, e.g.…”