Metastable Chiral Azobenzenes Stabilized in a Double Racemate

Mohan, Amalu; Sasikumar, Devika; Bhat, Vinayak; Hariharan, Mahesh

doi:10.1002/ange.201910687

“…Another approach to studying photo-responsive surfaces which has developed rapidly in recent years has been to employ photoactive polymers. The photo-response of polymers results from chromophore photoisomerization or the photothermal effect [107,[124][125][126][127][128][129][130]. Azobenzene is a typical example of photochromic molecule [131,132].…”

Section: Photo-responsive Surfaces 351 Atmospheric Environmentmentioning

confidence: 99%

Stimuli-responsive surfaces for switchable wettability and adhesion

Li

¹

,

Li

²

,

Ni

³

et al. 2021

J. R. Soc. Interface.

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Diverse unique surfaces exist in nature, e.g. lotus leaf, rose petal and rice leaf. They show similar contact angles but different adhesion properties. According to the different wettability and adhesion characteristics, this review reclassifies different contact states of droplets on surfaces. Inspired by the biological surfaces, smart artificial surfaces have been developed which respond to external stimuli and consequently switch between different states. Responsive surfaces driven by various stimuli, e.g. stretching, magnetic, photo, electric, temperature, humidity and pH, are discussed. Studies reporting on either atmospheric or underwater environments are discussed. The application of tailoring surface wettability and adhesion includes microfluidics/droplet manipulation, liquid transport and harvesting, water energy harvesting and flexible smart devices. Particular attention is placed on the horizontal comparison of smart surfaces with the same stimuli. Finally, the current challenges and future prospects in this field are also identified.

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“…Drawing inspiration from the photosynthetic RCs, and our continuous efforts to achieve a long‐lived charge‐separated state in molecular assembly motivated us to venture into the MIR of the SB‐CS state [22, 43, 47–52] . In the current work, we have adapted two design strategies to achieve a long‐lived CS state as proof of concept.…”

Section: Introductionmentioning

confidence: 99%

A Symmetry‐Broken Charge‐Separated State in the Marcus Inverted Region

Sebastian

¹

,

Hariharan

²

2023

Self Cite

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We report a long‐lived charge‐separated state in a chromophoric pair (DC‐PDI2) that uniquely integrates the advantages of fundamental processes of photosynthetic reaction centers: i) Symmetry‐breaking charge‐separation (SB‐CS) and ii) Marcus‐inverted‐region dependence. The near‐orthogonal bichromophoric DC‐PDI2 manifests an ultrafast evolution of the SB‐CS state with a time constant of τSB-CS ${{\tau }_{{\rm S}{\rm B}-{\rm C}{\rm S}}}$ =0.35±0.02 ps and a slow charge recombination (CR) kinetics with τCR ${{\tau }_{{\rm C}{\rm R}}}$ =4.09±0.01 ns in ACN. The rate constant of CR of DC‐PDI2 is 11 686 times slower than SB‐CS in ACN, as the CR of the PDI radical ion‐pair occurs in the deep inverted region of the Marcus parabola ( -ΔGCR ${{-{\rm \Delta }G}_{{\rm C}{\rm R}}}$ >λ). In contrast, an analogous benzyloxy (BnO)‐substituted DC‐BPDI2 showcases a ≈10‐fold accelerated CR kinetics with τnormalCnormalR/τnormalSnormalB-normalCnormalS ${{\tau }_{{\rm C}{\rm R}}/{\tau }_{{\rm S}{\rm B}-{\rm C}{\rm S}}}$ lowering to ≈1536 in ACN, by virtue of a decreased CR driving force. The present investigation demonstrates a control of molecular engineering to tune the energetics and kinetics of the SB‐CS material, which is essential for next‐generation optoelectronic devices.

show abstract

A Symmetry‐Broken Charge‐Separated State in the Marcus Inverted Region

Sebastian

¹

,

Hariharan

²

2023

Self Cite

View full text Add to dashboard Cite

We report a long‐lived charge‐separated state in a chromophoric pair (DC‐PDI2) that uniquely integrates the advantages of fundamental processes of photosynthetic reaction centers: i) Symmetry‐breaking charge‐separation (SB‐CS) and ii) Marcus‐inverted‐region dependence. The near‐orthogonal bichromophoric DC‐PDI2 manifests an ultrafast evolution of the SB‐CS state with a time constant of τSB-CS ${{\tau }_{{\rm S}{\rm B}-{\rm C}{\rm S}}}$ =0.35±0.02 ps and a slow charge recombination (CR) kinetics with τCR ${{\tau }_{{\rm C}{\rm R}}}$ =4.09±0.01 ns in ACN. The rate constant of CR of DC‐PDI2 is 11 686 times slower than SB‐CS in ACN, as the CR of the PDI radical ion‐pair occurs in the deep inverted region of the Marcus parabola ( -ΔGCR ${{-{\rm \Delta }G}_{{\rm C}{\rm R}}}$ >λ). In contrast, an analogous benzyloxy (BnO)‐substituted DC‐BPDI2 showcases a ≈10‐fold accelerated CR kinetics with τnormalCnormalR/τnormalSnormalB-normalCnormalS ${{\tau }_{{\rm C}{\rm R}}/{\tau }_{{\rm S}{\rm B}-{\rm C}{\rm S}}}$ lowering to ≈1536 in ACN, by virtue of a decreased CR driving force. The present investigation demonstrates a control of molecular engineering to tune the energetics and kinetics of the SB‐CS material, which is essential for next‐generation optoelectronic devices.

show abstract

Metastable Chiral Azobenzenes Stabilized in a Double Racemate

Cited by 5 publications

References 65 publications

Stimuli-responsive surfaces for switchable wettability and adhesion

Stimuli-responsive surfaces for switchable wettability and adhesion

A Symmetry‐Broken Charge‐Separated State in the Marcus Inverted Region

A Symmetry‐Broken Charge‐Separated State in the Marcus Inverted Region

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