Heterophenes revisited

Abstract

By employing the furan annulation protocol, a new series of furan-containing teraryl [n.2]cyclophenes (n = 2-6 and 12) are prepared. These cyclophenes exhibit chargetransfer character in the absorption spectra and unusually large Stokes shifts in the emission spectra. They have neither particularly strong electron-donating moieties nor electron-withdrawing groups, but exhibit unusual second-order nonlinear optical (NLO) properties. The π-systems in teraryl system and in the bridging double bond are highly twisted. Interaction between these twisted π-systems may account for the significant enhancement in hyperpolarizability. Thiophene analog behaved similarly. The five-membered heteroaromatic rings may not only serve as electron donors, but also may accommodate the appropriate geometry to enable the interactions between the oligoaryl systems and the double bond leading to unusual photophysical and NLO properties.

Design and Synthesis of Cyclic Mismatch‐Binding Ligands (CMBLs) with Variable Linkers by Ring‐Closing Metathesis and their Photophysical and DNA Repeat Binding Properties

“…Electronic interactions between two π‐stacked aromatic units, like cyclophanes, are mainly possible through two ways, that is, through‐space interactions (π‐stack array) and through bonds (linear π‐conjugated array). On the other hand, heterophanes, which are a class of cyclophanes containing heteroaromatic units are especially interesting for their immense biological activities. These increasing interests in the chemistry and applications of cyclophanes promoted studies on incorporating heteroaromatic ring(s) into cyclophanes, which apparently enhances the structural diversity of this class of molecules.…”