Formation of chiral surface with enantiomeric tartaric acid on gemini-structured self-assembled monolayers.
Chiral surfaces were prepared by L, D, and Meso-tartaric acids (TAs) adsorbed on gemini-structured self-assembled monolayers (SAMs) composed of ethylenebis [(12-mercaptododecyl) dimethyl ammonium bromide] (HS-gQA-SH). The formation and structure of the chiral surfaces were characterized by surface plasmon resonance spectroscopy (SPR) and Fourier transform infrared-reflection adsorption spectroscopy (FTIR-RAS). The thickness of enantiomeric TA layers on the HS-gQA-SH SAM was estimated to be c.a. 5-6 angstroms regardless of their chirality, in good agreement with the height of TA molecules anchoring on the surface with two COOH groups. All the TAs on the HS-gQA-SH SAM exhibit the same ionization state independent of their chirality in their vibration bands of carboxylic groups. We attempted a second-layer adsorption of the enantiomeric TAs on L-TA monomolecular layer (L-TA SAM) precomposed on the HS-gQA-SH. A strong affinity between first and second TA layers resulted in the film growth when their chirality is identical (i.e., L-TA on L-TA SAM). We found the structure of second L-TA layer was completely different from that of the first layer, where a crystalline-like L-TA phase was found as a predominant component. Our results imply a preferential crystalline growth of chiral molecules on the same chiral surface, which may lead to a work for optical resolution into two enantiomers at a solid-liquid interface.
Yokokawa
Shinobu
S
Department of Electronic Chemistry, Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8502, Japan.
Tamada
Kaoru
K
Hara
Masahiko
M
D000327:Adsorption; D015394:Molecular Structure; D036103:Nanotechnology / Q000379:methods*; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013237:Stereoisomerism; D020349:Surface Plasmon Resonance; D013499:Surface Properties; D013644:Tartrates / Q000737:chemistry*
D000644:Quaternary Ammonium Compounds; D013644:Tartrates; C029768:tartaric acid