Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - Molecular modeling, multinuclear NMR, and diffraction studies in the templated synthesis and characterization of the aluminophosphate molecular sieve STA-2
AU - Castro, Maria
AU - Seymour, Valerie R.
AU - Carnevale, Diego
AU - Griffin, John M.
AU - Ashbrook, Sharon E.
AU - Wright, Paul A.
AU - Apperley, David C.
AU - Parker, Julia E.
AU - Thompson, Stephen P.
AU - Fecant, Antoine
AU - Bats, Nicolas
PY - 2010/7/29
Y1 - 2010/7/29
N2 - Molecular modeling has been used to assist in the design of a new structure directing agent (SDA) for the synthesis of the AlPO(4) form of STA-2, bis-cliazabicyclooctane-butane (BDAB). This is incorporated as a divalent cation within the large cages of STA-2, as determined via a combination of solid-state (13)C and (15)N MAS NMR, supported by (14)N and (1)H-(15)N HMQC solution NMR and density functional calculations. As prepared AlPO4 STA-2 containing cationic SDA molecules achieves neutrality by the inclusion of hydroxide ions bridging between 5-fold coordinated framework Al atoms. Synchrotron X-ray powder diffraction data of the dehydrated as-prepared form indicates triclinic symmetry (Al(12)P(12)O(48)(OH)(2)center dot BDAB, P1, a = 12.3821(2) angstrom, b = 12.3795(2) angstrom, c = 12.3797(3) angstrom, alpha = 63.3585(8)degrees, 63.4830(7)degrees, gamma = 63.4218(7)) with the distortion from rhombohedral R (3) over bar symmetry resulting from the partial order of hydroxide ions in bridging Al-OH-Al sites within cancrinite cages. Upon calcination in oxygen, the organic SDA is removed, leaving AlPO(4) STA-2 with a pore volume of 0.22 cm(3) g(-1) (R (3) over bar, Al(36)P(36)O(144), a = 12.9270(2) angstrom, c = 30.7976(4) angstrom). Dehydrated calcined AlPO(4) STA-2 has two crystallographically distinct P and Al sites: (31)P MAS NMR resolves the two distinct P sites, and although 27AI MAS NMR only partially resolves the two Al sites, they are separated by MQMAS. Furthermore, 2D (27)Al -> (31)P MQ-J-HETCOR correlation spectroscopy confirms that each framework Al is linked to the two different P sites via AI-O-P connections in a 3:1 ratio (and vice versa for P linked to different Al). The (27)Al and (31)P resonances are assigned to the crystallographic Al and P sites by calculation of the NMR parameters using the CASTEP DFT program for an energy-minimized AlPO(4)(SAT) framework.
AB - Molecular modeling has been used to assist in the design of a new structure directing agent (SDA) for the synthesis of the AlPO(4) form of STA-2, bis-cliazabicyclooctane-butane (BDAB). This is incorporated as a divalent cation within the large cages of STA-2, as determined via a combination of solid-state (13)C and (15)N MAS NMR, supported by (14)N and (1)H-(15)N HMQC solution NMR and density functional calculations. As prepared AlPO4 STA-2 containing cationic SDA molecules achieves neutrality by the inclusion of hydroxide ions bridging between 5-fold coordinated framework Al atoms. Synchrotron X-ray powder diffraction data of the dehydrated as-prepared form indicates triclinic symmetry (Al(12)P(12)O(48)(OH)(2)center dot BDAB, P1, a = 12.3821(2) angstrom, b = 12.3795(2) angstrom, c = 12.3797(3) angstrom, alpha = 63.3585(8)degrees, 63.4830(7)degrees, gamma = 63.4218(7)) with the distortion from rhombohedral R (3) over bar symmetry resulting from the partial order of hydroxide ions in bridging Al-OH-Al sites within cancrinite cages. Upon calcination in oxygen, the organic SDA is removed, leaving AlPO(4) STA-2 with a pore volume of 0.22 cm(3) g(-1) (R (3) over bar, Al(36)P(36)O(144), a = 12.9270(2) angstrom, c = 30.7976(4) angstrom). Dehydrated calcined AlPO(4) STA-2 has two crystallographically distinct P and Al sites: (31)P MAS NMR resolves the two distinct P sites, and although 27AI MAS NMR only partially resolves the two Al sites, they are separated by MQMAS. Furthermore, 2D (27)Al -> (31)P MQ-J-HETCOR correlation spectroscopy confirms that each framework Al is linked to the two different P sites via AI-O-P connections in a 3:1 ratio (and vice versa for P linked to different Al). The (27)Al and (31)P resonances are assigned to the crystallographic Al and P sites by calculation of the NMR parameters using the CASTEP DFT program for an energy-minimized AlPO(4)(SAT) framework.
KW - UNIVERSAL FORCE-FIELD
KW - CRYSTALLINE INORGANIC SOLIDS
KW - QUANTUM MAS NMR
KW - 1ST-PRINCIPLES CALCULATIONS
KW - MICROCRYSTAL DIFFRACTION
KW - QUADRUPOLAR NUCLEI
KW - RESOLUTION
KW - CATALYSTS
KW - ASSIGNMENT
KW - PARAMETERS
U2 - 10.1021/jp104120y
DO - 10.1021/jp104120y
M3 - Journal article
VL - 114
SP - 12698
EP - 12710
JO - The Journal of Physical Chemistry C
JF - The Journal of Physical Chemistry C
SN - 1932-7447
IS - 29
ER -