Chiroptical materials are gaining increasing interest due to their innovative character and their applications in optoelectronics and data encryption technologies. Fully harnessing the potential of building blocks from the "chiral pool", such as native cyclodextrins (CDs), as they often lack chromophores suitable for the construction of materials with significant chiroptical properties. Here, we present the synthesis and characterization of a two-level molecular stack consisting of a point-chiral element (CD) and an axially chiral element (biphenyl), capable of effectively translating the overall stereochemical information contained in CDs into stimuli-responsive chiroptical properties. alpha- and beta-permethylated CDs were efficiently capped with two different 2,2'-difunctionalized 1,1 '-biphenyl units. In CD derivatives containing the rigid 2,2 '-dihydroxy-1,1 '-biphenyl cap, two intramolecular hydrogen bonds act synergistically as stereoselective actuators, enabling effective communication between the two levels and the transfer of nonchromophoric stereochemical information from the cyclic-oligosaccharide to the atropoisomeric cap. The chiroptical properties can be finely tuned by external stimuli such as temperature and solvent. The way chirality is transferred from the CD platform to the biphenyl cap was revealed thanks to crystallographic and computational analyses, together with electronic circular dichroism (ECD) studies.The use of building blocks from the "chiral pool" is challenging for the construction of chiroptical materials, as they often lack chromophores suitable for significant chiroptical properties. A two-level molecular stack, which combines a point-chiral element (cyclodextrin) and an axially chiral element (biphenyl), is capable of effectively translating the overall stereochemical information contained in the cyclodextrin core into stimuli-responsive chiroptical properties.image
Enabling Stereochemical Communication and Stimuli-Responsive Chiroptical Properties in Biphenyl-Capped Cyclodextrins
Pescitelli, Gennaro;Cupellini, Lorenzo;
2023-01-01
Abstract
Chiroptical materials are gaining increasing interest due to their innovative character and their applications in optoelectronics and data encryption technologies. Fully harnessing the potential of building blocks from the "chiral pool", such as native cyclodextrins (CDs), as they often lack chromophores suitable for the construction of materials with significant chiroptical properties. Here, we present the synthesis and characterization of a two-level molecular stack consisting of a point-chiral element (CD) and an axially chiral element (biphenyl), capable of effectively translating the overall stereochemical information contained in CDs into stimuli-responsive chiroptical properties. alpha- and beta-permethylated CDs were efficiently capped with two different 2,2'-difunctionalized 1,1 '-biphenyl units. In CD derivatives containing the rigid 2,2 '-dihydroxy-1,1 '-biphenyl cap, two intramolecular hydrogen bonds act synergistically as stereoselective actuators, enabling effective communication between the two levels and the transfer of nonchromophoric stereochemical information from the cyclic-oligosaccharide to the atropoisomeric cap. The chiroptical properties can be finely tuned by external stimuli such as temperature and solvent. The way chirality is transferred from the CD platform to the biphenyl cap was revealed thanks to crystallographic and computational analyses, together with electronic circular dichroism (ECD) studies.The use of building blocks from the "chiral pool" is challenging for the construction of chiroptical materials, as they often lack chromophores suitable for significant chiroptical properties. A two-level molecular stack, which combines a point-chiral element (cyclodextrin) and an axially chiral element (biphenyl), is capable of effectively translating the overall stereochemical information contained in the cyclodextrin core into stimuli-responsive chiroptical properties.imageI documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
