ABSTRACT
This paper reports an efficient preparation of bridged bis-ß-CD AZO-CDim 1 bearing azobenzene as a linker and exhibiting high solubility in water. The photoisomerization properties were studied by UV-vis and HPLC and supported by ab initio calculations. The cis/trans ratio of AZO-CDim 1 is 7:93 without irradiation and 37:63 after 120 min of irradiation at 365 nm; the reaction is reversible after irradiation at 254 nm. The photoinduced, switchable binding behavior of AZO-CDim 1 was evaluated by ITC, NMR and molecular modeling in the presence of a ditopic adamantyl guest. The results indicate that AZO-CDim 1 can form two different inclusion complexes with an adamantyl dimer depending on its photoinduced isomers. Both cavities of cis-AZO-CDim 1 are complexed simultaneously by two adamantyl units of the guest forming a 1:1 complex while trans-AZO-CDim 1 seems to lead to the formation of supramolecular polymers with an n:n stoichiometry.
ABSTRACT
A reaction platform based on a cyclodextrin dimer, which is able to simultaneously include a substrate in one cavity and an organometallic catalyst into the other, proved to be highly efficient for aqueous hydroformylation reaction of higher olefins.
Subject(s)
Aldehydes/chemical synthesis , Alkenes/chemistry , Cyclodextrins/chemistry , Organometallic Compounds/chemistry , Aldehydes/chemistry , Catalysis , Dimerization , Macromolecular Substances/chemistry , Molecular Dynamics Simulation , Molecular Structure , Water/chemistryABSTRACT
A wide range of chiral mono- and ditopic cyclodextrin-based receptors have been synthesized by CuI-catalyzed azide-alkyne cycloaddition starting from mono-6-azido-ß-cyclodextrin and chiral amino acids. Of interest, microwaves proved very efficient to access a wide range of ditopic ß-cyclodextrin receptors with quantitative yields.
