Photoresponsive and fluorescence behaviors of azobenzene‐containing amphiphilic block copolymers

Lee, Ting Lei; Lo, Chieh Tsung

doi:10.1002/polb.24323

Cited by 12 publications

(18 citation statements)

References 39 publications

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“…Such behavior indicated that the confined domains generated by the self-assembly of Azo and PEG facilitated the organization of azobenzene molecules. Studies have suggested that when azobenzene molecules are confined, such as in azobenzene-containing homopolymers, in microphase-separated domains of block copolymers, or in the core of micelles, mesogens tend to assemble into H-aggregation [23,25,26,46]. Although the self-assembly of azobenzene molecules and PEG through hydrogen bonds was unable to form compact microdomains to heavily turn nonassociated mesogens into aggregated mesogens, as micelles and block copolymers do, the formation of Azo/PEG complexes could nonetheless facilitate the aggregation of mesogens.…”

Section: Resultsmentioning

confidence: 99%

“…Synthetic methods for preparing azobenzene-containing polymers with well-defined photochemical and photochemical properties have been reported extensively [16,18,19,20,21,22,23,24,25,26]. Although these approaches provide precise control of theses polymers′ molecular structures, the multistep synthetic routes are costly in terms of both time and money.…”

Section: Introductionmentioning

confidence: 99%

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Hydrogen Bonding-Induced Assembled Structures and Photoresponsive Behavior of Azobenzene Molecule/Polyethylene Glycol Complexes

et al. 2019

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We investigated the self-assembled structures and photoresponsive and crystallization behaviors of supramolecules composed of 4-methoxy-4′-hydroxyazobenzene (Azo) molecules and polyethylene glycol (PEG) that were formed through hydrogen-bonding interactions. The Azo/PEG complexes exhibited the characteristics of photoresponse and crystallization, which originated from Azo and PEG, respectively. When Azo/PEG complexes were dissolved in solvents, hydrogen-bonding interaction hindered the rotation and inversion of mesogens, causing a reduction in the photoisomerization rate compared with the photoisomerization rate of the neat Azo. The confinement of Azo/PEG complexes in thin films further resulted in a substantial decrease in the photoisomerization rate but an increase in the amounts of H-aggregated and J-aggregated mesogens. Regarding PEG crystallization, ultraviolet irradiation of Azo/PEG complexes increased the quantity of high-polarity cis isomers, which improved the compatibility between mesogens and PEG, subsequently increasing the crystallization temperature of PEG. Moreover, the complexation of Azo and PEG induced microphase separation, forming a lamellar morphology. Within the Azo-rich microphases, mesogens aggregated to form tilted monosmectic layers. By contrast, PEG crystallization within the PEG-rich microphases was hard confined, indicating that the domain size of the lamellar morphology was unchanged during PEG crystallization.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Hydrogen Bonding-Induced Assembled Structures and Photoresponsive Behavior of Azobenzene Molecule/Polyethylene Glycol Complexes

et al. 2019

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“…We hypothesize that the mechanism that underlies the effect concerns photochemical cis ‐ trans isomerization of the dye molecules. A similar effect has been observed to date with various compounds that belong to the same group of azobenzene derivatives as the EB dye that we used . These results substantiate our hypothesis and provide a focus for the further investigation of the effect background.…”

Section: Resultsmentioning

confidence: 99%

“…We estimated the lifetime of the “tagged” molecules to be approximately 1 second, which corresponds to the data published in the literature . Although the effect of the light‐driven fluorescent enhancement was discussed in the literature, no data were published with respect to the EB complexes.…”

Section: Introductionmentioning

confidence: 99%

Intravital molecular tagging velocimetry of cerebral blood flow using Evans Blue

Nаmykin

Shushunova

Ulanova

et al. 2018

Journal of Biophotonics

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The effects of light-driven enhancement of Evans Blue dye complexes with blood plasma proteins were observed for the first time, both in vitro and in vivo. The possible background of the effect concerns the photochemical cis-trans isomerization of the azo dye molecules. The effect was induced in the solution with a red laser with a wavelength of 638 nm, which corresponds to the peak of the dye absorption. The lifetime of the enhanced fluorescence is approximately 1 second and enables its use as an optically tagged molecular flow tracer for blood flow velocity measurements. Utilizing the effect, we performed for the first time the intravital molecular tagging velocimetry of the blood velocity in blood vessels in a living animal. The results of the measurements of the blood flow velocities in the cerebral veins of a group of healthy mice are presented.

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“…The fluorescence enhancement of azobenzene derivatives can be induced by trans to cis photoisomerization of azobenzene under UV light irradiation, aggregation-induced emission (AIE), and the fluorescence resonance energy transfer (FRET) process, according to the literature. [56][57][58][59][60] Herein, fluorene-azo oligomers in chloroform were exposed to 365 nm light to investigate their fluorescence changes. 4F in chloroform was also irradiated under the same conditions for comparison.…”

Section: Changes In Fluorescent Emission Induced By Photoisomerizationmentioning

confidence: 99%

Synthesis of Discrete Conjugated Fluorene‐Azo Oligomers for the Investigation of Azobenzene Position‐Dependent Physical Properties and Photoresponsive Behavior

Liu

Shi

et al. 2021

Macro Chemistry & Physics

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It is well known that macromolecular structure, including composition, topology and sequence, significantly determines the properties of conjugated polymers/oligomers. To accurately understand the structure-induced properties, discrete oligomers/polymers with molecularly defined structures are the ideal model because they provide distinct nonstatistical results. Herein, a series of discrete conjugated fluorene-azo oligomers with different positions of the azobenzene units along the main chain (i.e., sequence) are efficiently prepared based on CuAAC "click" chemistry via a stepwise chain-growth strategy. Position-dependent behavior has an evident impact on the properties of oligomers, such as thermal properties, optical properties and photoresponsive behavior in both solution and thin film states. In addition, the fluorene-azo oligomers show less photodegradation of 9,9-dioctyl-fluorene in the solid-state than oligofluorene during UV light irradiation; however, position-dependent photodegradation is found in solution. Optimized configurations and UV-vis absorption spectra of fluorene-azo oligomers are calculated by density functional theory. Experimental results and theoretical analysis indicate that the location of azobenzene can play a dominant role in determining the properties of fluorene-azo oligomers resulting from sequence-mandated conformational changes. Undoubtedly, this work can provide deeper insight into the structure-property relationships based on precisely sequence-defined polymer structures.

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Photoresponsive and fluorescence behaviors of azobenzene‐containing amphiphilic block copolymers

Cited by 12 publications

References 39 publications

Hydrogen Bonding-Induced Assembled Structures and Photoresponsive Behavior of Azobenzene Molecule/Polyethylene Glycol Complexes

Hydrogen Bonding-Induced Assembled Structures and Photoresponsive Behavior of Azobenzene Molecule/Polyethylene Glycol Complexes

Intravital molecular tagging velocimetry of cerebral blood flow using Evans Blue

Synthesis of Discrete Conjugated Fluorene‐Azo Oligomers for the Investigation of Azobenzene Position‐Dependent Physical Properties and Photoresponsive Behavior

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