Thyveetil, M-A.; Coveney, P.V.; Greenwell, H.C.; Suter, J.L., “Computer Simulation Study of the Structural Stability and Materials Properties of DNA-Intercalated Layered Double Hydroxides”, J. Amer. Chem. Soc., DOI:10.1021/ja077679s (2008).
LDH-DNA
LDH-DNAN = number of water/Al
Shows distortion of helix as LDH dehydrates.
Compared % Watson-Crick bonds still intact at high T (upto 500K) & P (upto 100 atm), DNA significantly stabilised when intercalated.
cf green rusts at hydrothermal vents in Archean
LDH-DNA
LDH-Cl Materials PropertiesAnalysis of thermal undulations and stress strain to give hard to determine materials properties.
Thyveetil, M-A.; Coveney, P.V.; Suter, J.L.; Greenwell, H.C., “Emergence of undulations and determination of materials properties in large-scale molecular dynamics simulations of layered double hydroxides”, Chem. Mater., 19, 5510-5523 (2007).
LDH-Cl Materials PropertiesThe system exhibits emergent properties, which are suppressed in smaller-scale simulations.Undulatory modes are caused by the collective thermal motion of atoms in the LDH layers. At lengthscales larger than 20.7 Å, these thermal undulations cause the LDH sheets to interact and the oscillationsare damped. The thermal undulations provide information about the materials properties of the system.In this way, we obtain values for the bending modulus of 8.3 ± 0.4 x 10-19 J with in-plane Young’smoduli of 63.4 ± 0.5 GPa for a hydrated system and 139 ± 1 GPa for the LDH sheets alone.
Cinnamate LDHs
Dimer Pr ecursor
(a
)
(c
)
(b
)
(e
)
(d
)
(f
)
Precursor Dimer
Newman, S.P.; Greenwell, H.C.; Coveney, P.V.; Jones, W. “Computer simulation of interlayer arrangement in cinnamate intercalated layered double hydroxides” J. Mol. Structure., 647, 1-3, 75 (2003)
Cinnamate LDHs
DFT - LDH-t-BuO catalysis
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
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Step 2
HT+ -O-t-BuCatalyst
Transesterification
R-OHAlcoh
ol
HT+-OR
t-BuOH
O
R’-C-OR’’Ester
O--
R’-C-OR’’A
HT+-OR
Step 1
O-+HT
R’-C-OR’’
ORIntermediate
O
R’-C-OR + R’’-OH
Step 3
DFT - LDH-t-BuO catalysis
Catalyst Regeneration
Product Formation
Greenwell, H.C.; Stackhouse, S.; Coveney, P.V.; Jones, W. “A density functional theory study of catalytic trans-esterification by tert-butoxide MgAl anionic clays”. J. Phys. Chem. B. 107, 15, 3476-3485 (2003).
Postulate new reaction scheme:-
’’
Step 2
HT+ -OH..HO-t-Bu Catalyst Transesterification
R-OH Alcohol
HT+-OR + t-BuOH…OH2
O R’-C-OR’’ Ester O-- R’-C-OR’’ + t-BuOH…OH2
HT+-OR
Step 1
O-+HT R’-C-OR’’ OR + t-BuOH…OH2 Intermediate
O R’-C-OR + R’’-OH Transesterified Product Step 3
HT+ -NO3.xH2O Catalyst -O-t-Bu Catalyst
