All-Thiophene-Based Double Helix: Synthesis, Crystal Structure, Chiroptical Property and Arylation

Abstract

The all-thiophene-based double helix DH-1 was designed and prepared originally from the selective deprotonation of cyclooctatetrathiophene (tetra[3,4]thienylene, COTh ) and following the Negishi coupling reaction with 3,3′-bithiophene. The X-ray crystallographic studies revealed that DH-1 has a double-helical scaffold. The arylations including tetraphenylation and tetrathienylation were efficiently employed to replace the four α-protons of the central COTh of DH-1 with phenyl and thiophenyl groups via cross-coupling reactions. The chiral resolution of rac - DH-1 was fulfilled via chiral high-performance liquid chromatography, and the chiroptical properties were characterized by circular dichroism spectra and optical rotation. Ultraviolet–visible absorption and fluorescence behaviors of DH-1 and its arylation products were also characterized to describe the extended conjugated scaffold.

Recent Advances in Heterocyclic Nanographenes and Other Polycyclic Heteroaromatic Compounds

“…Subsequently, Wang and Li et al reported an attempted synthesis of compound 254.6 featuring a cross-dimensional double-helical structure based on the β,β-COTh core ( Scheme 254 ). 475 The common starting material rac - 254.1 was prepared via the Negishi coupling reaction between the 3,3′-bithiophene derivative 253.6 or 254.7 with the appropriate β,β-COTh precursor in 2:1 ratio in a way similar to that shown in Scheme 253 . The treatment of rac - 254.1 with n -BuLi generated the tetralithiated species rac - 254.2 , which could be transmetalated with ZnCl 2 and coupled with 3-bromothiophene to yield the 4-fold arylated product rac - 254.4a in 26% overall yield.…”

“… a Reagents and conditions: (a) n -BuLi, THF, −78 °C, then 60 °C, 2 h; (b) ZnCl 2 , −78 °C, then rt; (c) 3-bromothiophene, Pd­(PPh 3 ) 4 , THF, 120 °C, 48 h; (d) C 2 Br 2 Cl 4 , −78 °C, then rt, overnight; (e) phenylboronic acid, Cs 2 CO 3 , THF/H 2 O (50:1), 100 °C; (f) 253.6 , Pd­(PPh 3 ) 4 , THF, 120 °C; (g) 254.7 , Pd­(PPh 3 ) 4 , THF, 120 °C. …”

Assessing the Performance of DFT Functionals for Excited-State Properties of Pyridine-Thiophene Oligomers

“…Helical polymers are important because of potential applications in materials used for chiral recognition, liquid crystals, and optical materials. − Noncovalent interactions such as π–π and hydrogen bonding interactions help in stabilizing these type of systems. In recent times, synthetic helical polymers based on furan, thiophene, and so forth have garnered a lot of attention. − In earlier studies, , our group reported interaction energies, absorption spectra, and circular dichroism (CD) spectra of oligomers based on furan, thiophene, pyrrole, phenyl, and pyridine. All those studies were carried out at DFT (and TD-DFT) level of theory.…”

Near‐Infrared Circularly Polarized Luminescence through Intramolecular Excimer Formation of Oligo(p‐phenyleneethynylene)‐Based Double Helicates

“…The dynamic molecular motions of supramolecularly engineered flexible double helicates could be applied to molecular machines, photonics, catalysis, and molecular recognition . Although there are numerous applications based on the dynamic behavior of new artificial double helicates, only a few covalently conjugated double helicates consisting of carbon‐based helical fragments and chiral hinges have been reported . Recently, the dynamic behavior of double helicates covalently conjugated with ester or amide hinges in the presence of guest molecules, such as ions, or under photoirradiation, have been reported .…”