Molecular dynamics simulation of cationic and anionic clays containing amino acids

被引:104
作者
Newman, SP
Di Cristina, T
Coveney, PV
Jones, W
机构
[1] Univ London, Ctr Computat Sci, London E1 4NS, England
[2] Univ Cambridge, Dept Chem, Cambridge CB2 1EW, England
关键词
D O I
10.1021/la0114528
中图分类号
O6 [化学];
学科分类号
0703 [化学];
摘要
The detailed arrangements of guest species in the interlayers of a cationic and an anionic clay have been determined using molecular dynamics computer simulations. The guest species studied were the amino acids (S)-phenylalanine and (S)-tyrosine, chosen for comparison because both anionic and cationic forms are possible. A modified version of the Dreiding force field was used for all models. Our simulations provide for the first time a clear picture of the different arrangements in the interlayer of the two clay systems. Previous work using powder X-ray diffraction had allowed only possible arrangements to be proposed based on purely geometric considerations. In the anionic clay case, the interlayer anions assume a bilayer-like arrangement with their longest molecular axis oriented in an approximately perpendicular direction with respect to the hydroxide layers. In the montmorillonite system, the interlayer cations prefer a monolayer arrangement with their longest molecular axis parallel to the layers. We believe the difference to be a direct consequence of the different layer charge densities of the clays. In all cases, the water molecules are generally excluded from the hydrophobic midplane formed by the phenyl rings of the counterions. Given the poorly crystalline nature of such intercalates, computer simulations of the type reported here are likely to provide the only means of knowing such details of the interlayer arrangements.
引用
收藏
页码:2933 / 2939
页数:7
相关论文
共 30 条
[1]
*ACCELRYS, 2001, CER VERS 4 2
[2]
ALLEN MP, 1994, COMPUTER SIMULATION
[3]
Allmann R., 1969, NEUES JB MINER MONAT, V12, P544
[4]
[Anonymous], 1997, INORG MATER+
[5]
Molecular modelling of the mechanism of action of organic clay-swelling inhibitors [J].
Bains, AS ;
Boek, ES ;
Coveney, PV ;
Williams, SJ ;
Akbar, MV .
MOLECULAR SIMULATION, 2001, 26 (02) :101-+
[6]
Molecular modeling of clay hydration: A study of hysteresis loops in the swelling curves of sodium montmorillonites [J].
Boek, ES ;
Coveney, PV ;
Skipper, NT .
LANGMUIR, 1995, 11 (12) :4629-4631
[7]
A robust water potential parameterisation [J].
Boek, ES ;
Coveney, PV ;
Williams, SJ ;
Bains, AS .
MOLECULAR SIMULATION, 1996, 18 (03) :145-154
[8]
Monte Carlo molecular modeling studies of hydrated Li-, Na-, and K-smectites: Understanding the role of potassium as a clay swelling inhibitor [J].
Boek, ES ;
Coveney, PV ;
Skipper, NT .
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 1995, 117 (50) :12608-12617
[9]
ROLE OF ION-EXCHANGE IN SOLID-STATE CHEMISTRY [J].
CLEARFIELD, A .
CHEMICAL REVIEWS, 1988, 88 (01) :125-148
[10]
Anion exchange of methyl orange into Zn-Al synthetic hydrotalcite and photophysical characterization of the intercalates obtained [J].
Costantino, U ;
Coletti, N ;
Nocchetti, M ;
Aloisi, GG ;
Elisei, F .
LANGMUIR, 1999, 15 (13) :4454-4460