Site-selective formation of optically active inclusion complexes of alkoxo-subphthalocyanines with beta-cyclodextrin at the toluene/water interface.
Several subphthalocyanine derivatives that contain an alkoxo substituent as an axial ligand (RO-Subpc, R = 9-anthracenemethyl, benzyl, phenyl, 3,5-dimethylbenzyl, 3,5-dimethylphenyl, 4-methylbenzyl, and 4-methylphenyl) were synthesized. The formation of inclusion complexes of RO-Subpc with beta-CD in DMSO and at the toluene/water interface was investigated by UV/Vis absorption spectroscopy, induced circular dichroism (ICD), and nuclear magnetic resonance (NMR) measurements. Interfacial tension measurements suggested that beta-CD adsorbed as a monolayer at the toluene/water interface and probably orientated towards the toluene phase with its primary face. The 1:1 composition of beta-CD.RO-Subpc inclusion complexes was confirmed in DMSO and at the toluene/water interface for BzO-Subpc, PhO-Subpc, MeBzO-Subpc, and MePhO-Subpc. A 2:1 inclusion complex of AnO-Subpc formed in DMSO. The observed ICD spectra of beta-CDRO-Subpc inclusion complexes are discussed with respect to molecular modeling and the simulation based on Tinoco-Kirkwood theory. Interestingly, the ICD spectra of beta-CD.BzO-Subpc and beta-CD.MeBzO-Subpc inclusion complexes exhibited a negative sign in DMSO and a positive sign at the toluene/water interface. This reversal of the ICD sign strongly suggests a difference in the structure of the inclusion complexes: beta-CD at the interface formed the inclusion complex with its primary face, whereas the secondary face of beta-CD bound favorably to RO-Subpc in DMSO.
Adachi
Kenta
K
Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan.
Watarai
Hitoshi
H
D002232:Carbocyanines / Q000737:chemistry*; D002942:Circular Dichroism; D004121:Dimethyl Sulfoxide / Q000737:chemistry; D015394:Molecular Structure; D055095:Optics and Photonics; D013237:Stereoisomerism; D014050:Toluene / Q000737:chemistry*; D014867:Water / Q000737:chemistry*; D047392:beta-Cyclodextrins / Q000737:chemistry*
D002232:Carbocyanines; D047392:beta-Cyclodextrins; D014867:Water; D014050:Toluene; C031215:betadex; D004121:Dimethyl Sulfoxide