Thiophene and naphthalene-based double helix: Synthesis,structures and chirality

Both racemate and enantiomer of a novel double helix, binaphthylcyclooctaterthiophene (BN—COTh), which is a DNA-like molecule constructed by two single helices intertwined with each other via covalent bonds, have been synthesized with two building blocks, cycloocta-tetrathiophene (COTh) and cyclooctadinaphthyldithiophene (CONT) fused together via Negishi coupling reaction. Another homologue, dinaphthylcyclooctaterthiophene (DN-COTh) has been employed together as a model compound. Besides the synthetic work, BN—COTh and DN-COTh have been investigated by studying their crystal structures, spectroscopic behaviors, chiral resolution and chiral characteristics, including circular dichroism (CD) spectra and optical rotations. In addition, the novel crystal of enantiomer of (R,R,R)-BN—COTh has been explored. The enantiomer molecules packing along b-axis to form a larger and extended assembly packing due to intermolecular interactions between the enantiomer molecules and chloroform molecules in crystal.