Synthesis and Conformation of Substituted Chiral Binaphthyl-Azobenzene Cyclic Dyads with Chiroptical Switching Capabilities

Abstract

Abstract:Optically active binaphthyl-azobenezene cyclic dyads were synthesized to develop a photochromic switching molecule. Azobenezene moieties were cis-trans isomerized by photoirradiation. As a reflection of the structural change, the specific optical rotation and circular dichroism underwent significant shifts. Under certain conditions, the positive-negative and zero-positive (or zero-negative) signals were reversed. Optical rotation may potentially be applied in noise-cancelling nondestructive photoswiches. The conformations were studied by experimental and theoretical methods. The results revealed that the helical chirality, (P) or (M), of the cis-azobenzene moiety was induced by intramolecular axial chirality. The twist direction depended on the axial chirality as well as the azobenzene linkage position to the binaphthyls, but was independent of the identity of substituted groups. 2,2'-Linked-(R)-binaphthyl was found to induce cis-(P)-azobenzene, whereas symmetrically 7,7'-linked-(R)-binaphthyl was found to induce cis-(M)-azobenzene.

Covalent functionalization of graphene by azobenzene with molecular hydrogen bonds for long-term solar thermal storage

“…The long τ 1/2 indicates high Δ E a for per metastable Z-AZO on RGO 13 . As shown in Table 1 , Δ E a for Z- ortho -AZO on RGO up to 1.2 eV calculated by equation (2) substantially outperforms other AZO derivatives 5 7 8 9 10 29 and noticeably conquers the limitation of short reversion of Z-AZO. Where T is the storage temperature and τ 1/2 is the half-life.…”

“…Azobenzene derivatives (AZO) show the great potential for solar thermal storage due to good absorption at 350–450 nm, reversible isomerization and thermal reversion controlled by functional groups and steric structures. However, the utilization of AZO is restricted by low density of thermal storage (Δ H for per molecule) during cis (Z) → trans (E) reversion, short half-lives ( τ 1/2 , the time required for a quantity of Z-isomers to fall to half its value by Z → E reversion) of metastable states caused by low Δ E a , and low work temperatures 2 5 7 8 9 .…”

“…An important strategy to overcome these problems is to tune transition bands and the formation of molecular hydrogen bonds (H-bonds) in AZO by the incorporation of electron donating or withdrawing groups in the ortho position 7 8 9 10 11 12 13 14 . Metastable Z- ortho -AZO is thermally stabilized by changing orbital energy or the formation of intramolecular H-bonds.…”

Photoprogrammable Mesogenic Soft Helical Architectures: A Promising Avenue toward Future Chiro‐Optics

“…Moreover, the azobenzene-based macrocyclic molecule was designed to change the optical chirality dramatically and to avoid multi-conformation of a single trans-or cis-isomer during photoisomerization. [104][105][106][107] Such macrocyclic materials were synthesized through cyclization between the azobenzene derivatives and chiral sugars ( Figure 8E-a), which transferred the chirality to the mesogenic azobenzene moiety, enabling significant CD modulation of not only the absorption, but also the sign of the Cotton band (i.e., the chirality of the material) ( Figure 8E-b). In addition, such macrocyclic materials exhibited the gel state in cyclohexane and ethanol, with interconversion between gel and sol through diverse stimuli, including light, temperature, and mechanical force.…”

Synthesis and Properties of 2'-Deoxyuridine Analogues Bearing Various Azobenzene Derivatives at the C5 Position

“…Next, the thermo-stability of ONs with various para-substituted dU Az in the cis-form was investigated [25]. The ONs modified with dU Az analogues were cis-isomerized by the appropriate wavelength of light and subsequently heated to 60 °C.…”