Crystallization of Amino Acids on Self-Assembled Monolayers of Rigid Thiols on Gold
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- 作者：Alfred Y. Lee ; Abraham Ulman ; and Allan S. Myerson
- 刊名：Langmuir
- 出版年：2002
- 出版时间：July 23, 2002
- 年：2002
- 卷：18
- 期：15
- 页码：5886 - 5898
- 全文大小：2394K
- 年卷期：v.18,no.15(July 23, 2002)
- ISSN：1520-5827
文摘
Self-assembled monolayers (SAMs) of rigid biphenyl thiols are employed as heterogeneous nucleantsfor the crystallization of L-alanine and DL-valine. Powder X-ray diffraction and interfacial anglemeasurements reveal that the L-alanine crystallographic planes corresponding to nucleation are {200},{020}, and {011} on SAMs of 4'-hydroxy-(4-mercaptobiphenyl), 4'-methyl-(4-mercaptobiphenyl), and 4-(4-mercaptophenyl)pyridine on gold (111) surfaces, respectively. In the case of DL-valine, monolayer surfacesthat act as hydrogen bond acceptors (e.g., 4'-hydroxy-(4-mercaptobiphenyl) and 4-(4-mercaptophenyl)pyridine) induce the racemic crystal to nucleate from the {020} plane whereas the nucleating plane forthe 4'-methyl-(4-mercaptobiphenyl) surface is the fast-growing {100} face. The observation of crystalnucleation and orientation can be attributed to the strong interfacial interactions, in particular, hydrogenbonding, between the surface functionalities of the monolayer film and the individual molecules of thecrystallizing phase. Molecular modeling studies are also undertaken to examine the molecular recognitionprocess across the interface between the surfactant monolayer and the crystallographic planes. Similarto binding studies of solvents and impurities on crystal habit surfaces, binding energies between SAMsand particular amino acid crystal faces are calculated and the results are in good agreement with theobserved nucleation planes of the amino acids. In addition to L-alanine and DL-valine, the interaction ofSAMs and mixed SAMs of rigid thiols on the morphology of 
-glycine is examined (Kang, J. F.; Zaccaro,J.; Ulman, A.; Myerson, A. Langmuir 2000, 16, 3791), and similarly the calculations are in good agreement.These results suggest that binding energy calculations can be a valid method to screen self-assembledmonolayers as potential templates for nucleation and growth of organic and inorganic crystals.
-glycine is examined (Kang, J. F.; Zaccaro,J.; Ulman, A.; Myerson, A. Langmuir 2000, 16, 3791), and similarly the calculations are in good agreement.These results suggest that binding energy calculations can be a valid method to screen self-assembledmonolayers as potential templates for nucleation and growth of organic and inorganic crystals.