Circularly Polarized Light with Sense and Wavelengths To Regulate Azobenzene Supramolecular Chirality in Optofluidic Medium

Abstract

Circularly polarized light (CPL) as a massless physical force causes absolute asymmetric photosynthesis, photodestruction, and photoresolution. CPL handedness has long been believed to be the determining factor in the resulting product's chirality. However, product chirality as a function of the CPL handedness, irradiation wavelength, and irradiation time has not yet been studied systematically. Herein, we investigate this topic using achiral polymethacrylate carrying achiral azobenzene as micrometer-size aggregates in an optofluidic medium with a tuned refractive index. Azobenzene chirality with a high degree of dissymmetry ratio (±1.3 × 10 at 313 nm) was generated, inverted, and switched in multiple cycles by irradiation with monochromatic incoherent CPL (313, 365, 405, and 436 nm) for 20 s using a weak incoherent light source (≈ 30 μW·cm). Moreover, the optical activity was retained for over 1 week in the dark. Photoinduced chirality was swapped by the irradiating wavelength, regardless of whether the CPL sense was the same. This scenario is similar to the so-called Cotton effect, which was first described in 1895. The tandem choice of both CPL sense and its wavelength was crucial for azobenzene chirality. Our experimental proof and theoretical simulation should provide new insight into the chirality of CPL-controlled molecules, supramolecules, and polymers.

A One‐Pot Polymerization for Concurrently Inducing Predominant Helicity in Optically Inactive Helical Polymer and Constructing Graphene‐Based Chiral Hybrid Foams

“…Chiral helical polymers have attracted much interest due to their intriguing helical structures and chiral amplification effect . They demonstrate substantial potential applications in chiral‐related fields including asymmetric catalysis, chiral recognition/separation, enantio‐selective release, enantio‐selective crystallization, etc.…”

Circularly Polarized Luminescent Carbon Dot Nanomaterials of Helical Superstructures for Circularly Polarized Light Detection

“…Circularly polarized luminescence (CPL) has drawn increasing attention [1][2][3][4][5][6] for their promising potentials in wide-ranging applications including stereopsis, [7] optical storage devices, [8] biological sensors, [9][10][11] asymmetrical catalysis and synthesis [12][13][14][15] and security systems. [16] In order to realize circularly polarized luminescence, asymmetrical environment and phosphors are essential elements.…”

Dynamic Modulation of Supramolecular Chirality Driven by Factors from Internal to External Levels

“…Molecules with azobenzene units and spiropyran, which show sensitive photoisomerism behavior, could be employed as building blocks for dynamic chirality adjustment . A micrometer‐sized aggregate of achiral polymethacrylate that contained achiral azobenzene with restricted conformational freedom was found to have an enhanced bisignated Cotton effect under circularly polarized light . Liu et al.…”

“…[18] Am icrometer-sized aggregate of achiral polymethacrylate that contained achiral azobenzene with restricted conformational freedom was found to have an enhanced bisignated Cotton effect under circularly polarized light. [19] Liu et al prepared supramolecular gels based on achiral azobenzene derivatives and ac hiral chaperone gelator. [20] For as upramolecular gel based on ac holesterol azopyridine conjugate (PAzPCC)a fter UV irradiation at l = 365 nm for 2h, parts of the chiral nanotubes broke into ribbons owing to isomerization of the azo units (Scheme 2a).…”