Circularly Polarized Luminescent Triptycene-Based Polymers

Abstract

A series of chiral fluorescent polymers containing optically active triptycene units in the main chain were synthesized via Sonogashira–Hagihara coupling copolymerizations of (R,R)- or (S,S)-2,6-diethynyltriptycene with a range of diiodoaryls. Their optical and chiroptical properties were investigated under various solution conditions. We observe that these polymers emitted circularly polarized light owing to the chiral triptycene framework with a handed twisted rigid structure, and the fluorescence colors could be tuned in the whole visible range from blue to red by replacing the achiral comonomer units. They possessed luminescence dissymmetry factors of approximately 1.0 × 10–3, regardless of the incorporated comonomer units.

Chirality in polythiophenes: A review

“…For 36d , just six repeating units were needed to form stable helix with the help of the hydrogen bonds between the pendant amino groups. This group also reported polymerization of thiophene and triptycene with axial chirality to afford optically active copolymers 37 and 38 with blue and green CPL 62 . Hara et al reported linear ( 39 ) and hyperbranched ( 40 ) PThs‐bearing binaphthol (BINOL) as chirality‐inducing pendant groups 63 .…”

“…This group also reported polymerization of thiophene and triptycene with axial chirality to afford optically active copolymers 37 and 38 with blue and green CPL. 62 Hara et al reported linear (39) and hyperbranched (40) PThs-bearing binaphthol (BINOL) as chirality-inducing pendant groups. 63 The hyperbranched PTh (40) exhibited clear CD bands in the absorption region of the PThs main chain (350-550 nm), whereas linear PTh (39) only presented CD band before 400 nm.…”

Circularly polarized luminescence from organic micro-/nano-structures

“…Organic materials have emerged as promising candidates owing to their easy processing, tunable chiral centers, and excellent photophysical properties 25 – 27 . Over the past few years, a lot of organic materials have been reported to exhibit CPL activity by combining the chiral units and the luminescent molecules via covalent bonds, such as transition metal complex 28 , 29 , small organic molecules 30 , 31 , and conjugated polymers 32 , 33 . However, they usually suffer from the relatively low luminescence dissymmetry factor ( g lum ), which quantifies the asymmetry degree of emission in left- and right-circularly polarized light.…”

Triptycene derivatives as chiral probes for studying the molecular enantiorecognition on sub‐2‐μm particle cellulose tris(3,5‐dimethylphenylcarbamate) chiral stationary phase

“…A tentative assignment of the enantiomer elution order of Tripty-NO2 was carried by ECD empirical correlation, using the enantiomers of Tripty-I2 as references of known stereochemistry. 30 At shorter wavelengths, the ECD analysis showed a strict analogy between the more retained (S,S)-enantiomer of Tripty-I2 on the Chiralpak IG CSP and the less eluted enantiomer of Tripty-NO2 on the Chiralpak IB-U CSP (Figure 4). Nevertheless, in the 350-to 260-nm wavelength region, a substantial difference in ECD profiles was noted.…”