Two-dimensional supramolecular arrangements of enantiomers and racemic modification of 1,1'-binaphthyl-2,2'-dicarboxylic acid.
Formation of adlayers of the optically active compound 1,1'-binaphthyl-2, 2'-dicarboxylic acid (BINAC) on iodine-modified Au (111) surfaces in perchloric acid was investigated by in situ scanning tunneling microscopy (STM). Highly ordered arrays formed on the surfaces via simple spontaneous adsorption from a solution of enantiomers or the racemic BINAC, in spite of the fact that BINAC has a three-dimensionally complex stereochemical structure. Adlayers of both enantiomers essentially shared the same enantiomorphous structure. Observed parameters of the rectangular unit cell lattice for arrays of both enantiomers of BINAC were a = 2.3 +/- 0.2 nm and b = 0.7 +/- 0.2 nm. On the other hand, racemic modification formed an entirely different adlayer, which consisted of an alternate alignment of the two enantiomers, with an oblique unit cell lattice with parameters of a = 1.2 +/- 0.2 nm, b = 0.8 +/- 0.1 nm, and 74 +/- 3 degrees . No domain composed of a single enantiomer was observed. The stronger hetero-intermolecular interactions of enantiomer couples led to the formation of an alternate arrangement in the array prepared by racemic modification.
Kunitake
Masashi
M
Department of Applied Chemistry and Biochemistry, Faculty of Engineering, Kumamoto University, Kurokami, Kumamoto 860-8555, Japan. kunitake@chem.kumamoto-u.ac.jp
Hattori
Tetsutaro
T
Miyano
Sotaro
S
Itaya
Kingo
K
D000327:Adsorption; D001713:Biphenyl Compounds / Q000737:chemistry*; D006046:Gold / Q000737:chemistry; D007455:Iodine / Q000737:chemistry; D008567:Membranes, Artificial; D016252:Microscopy, Scanning Tunneling; D010472:Perchlorates / Q000737:chemistry; D012996:Solutions / Q000737:chemistry; D013237:Stereoisomerism; D013499:Surface Properties
D001713:Biphenyl Compounds; D008567:Membranes, Artificial; D010472:Perchlorates; D012996:Solutions; D006046:Gold; D007455:Iodine; C039204:diphenic acid