covalent organic helical cages
Covalent Organic Helical Cages as Sandwich Compound Containers
A covalent organic helical cage (COHC) with D3 symmetry bearing two 1,3,5-trimethylphenyl cores and six di-tert-butyldiethynylallene moieties was synthesized and fully characterized. This molecular structure cage, unlike a previously reported one, favors inclusion-complex formation with organometallic sandwich compounds due to the presence of methyl groups on the aryl rings. The strong chiroptical responses of these COHCs, along with their ability to entrap guest molecules, enabled the detection of a ruthenium sandwich compound by means of electronic circular dichroism (ECD) spectroscopy.
A Covalent Organic Helical Cage with Remarkable Chiroptical Amplification
From collagen to DNA, helical morphologies are ubiquitous in nature. These fascinating chiral structures have led researchers to mimic them with helicates and helicenes. However, even when covalent organic helical cages are of great interest due to their potential as artificial chiral receptors, they have not been explored so far. We propose a general and broad methodology for the construction of covalent organic helical cages through axial chirality by connecting the opposite bases of a prism with loop-like lateral edges. We used this approach to design and synthesize a covalent organic helical cage with high efficiency. Crystal structure analysis, NMR, and electronic circular dichroism of this novel cage certified its helical morphology, inclusion complex formation, and outstanding chiroptical responses. We believe that these results pave the way for the construction of a broad variety of covalent organic helical cages in the near future.