Topochemical control of the photodimerization of aromatic compounds by γ-cyclodextrin thioethers in aqueous solution
نویسندگان
چکیده
The formation of soluble 1:2 complexes within hydrophilic γ-cyclodextrin (γ-CD) thioethers allows to perform photodimerizations of aromatic guests under controlled, homogenous reaction conditions. The quantum yields for unsubstituted anthracene, acenaphthylene, and coumarin complexed in these γ-CD thioethers were found to be up to 10 times higher than in the non-complexed state. The configuration of the photoproduct reflected the configuration of the dimeric inclusion complex of the guest. Anti-parallel orientation of acenaphthylene within the CD cavity led to the exclusive formation of the anti photo-dimer in quantitative yield. Parallel orientation of coumarin within the complex of a CD thioether led to the formation of the syn head-to-head dimer. The degree of complexation of coumarin could be increased by employing the salting out effect.
منابع مشابه
Synthesis of uniform cyclodextrin thioethers to transport hydrophobic drugs
Methyl and ethyl thioether groups were introduced at all primary positions of α-, β-, and γ-cyclodextrin by nucleophilic displacement reactions starting from the corresponding per-(6-deoxy-6-bromo)cyclodextrins. Further modification of all 2-OH positions by etherification with iodo terminated triethylene glycol monomethyl ether (and tetraethylene glycol monomethyl ether, respectively) furnished...
متن کاملCyclodextrin-enhanced extraction and energy transfer of carcinogens in complex oil environments.
Reported herein is the use of γ-cyclodextrin for two tandem functions: (a) the extraction of carcinogenic polycyclic aromatic hydrocarbons (PAHs) from oil samples into aqueous solution and (b) the promotion of highly efficient energy transfer from the newly extracted PAHs to a high-quantum-yield fluorophore. The extraction proceeded in moderate to good efficiencies, and the resulting cyclodextr...
متن کاملEfficient extraction and detection of aromatic toxicants from crude oil and tar balls using multiple cyclodextrin derivatives.
Herein we report the efficient extraction of aromatic analytes from crude oil and tar balls using multiple cyclodextrin derivatives. The known propensity of the cyclodextrins to bind hydrophobic guests in their hydrophobic interiors enhanced the extraction of aromatic analytes from the oil layer to the aqueous layer, with methyl-β-cyclodextrin and β-cyclodextrin providing the most significant e...
متن کاملSolubility of Cyproterone Derivatives in the Presence of Hydroxypropyl-β-Cyclodextrin: Experimental and Molecular Modeling Studies
This study presents the influence of hydroxypropyl-β-cyclodextrin (HPBCD) on the aqueous solubility of acyl esters of cyproterone. First, a number of esters of cyproterone were synthesized. Then the phase solubility analysis of the compounds in the presence of HPBCD was investigated in phosphate buffer solution at a pH of 7.4. To gain a better understanding of the complexation mechanism, ...
متن کاملγ-CD-Functionalized TiO2 Nanoparticles For the Photocatalytic Degradation of Organic Dyes
In this work, an efficient photocatalyst based on gamma-cyclodextrin-modified titanium dioxide nanoparticles (TiO2/γ-CD NPs) was synthesized and used for photocatalytic degradation of rhodamine B (RhB), methyl orange (MO) and methylene blue (MB). The results of FESEM, EDX, TEM, FT-IR, XRD and BET surface area measurement showed that the TiO2 NPs were effectively modifi...
متن کامل