Aggregation-induced emission luminogens(AIEgens)exhibit viscosity-responsive behavior resembling those of molecular rotors;however,their response mechanisms are more complex and cannot be adequately described using si...Aggregation-induced emission luminogens(AIEgens)exhibit viscosity-responsive behavior resembling those of molecular rotors;however,their response mechanisms are more complex and cannot be adequately described using simple rotational models.AIEgens demonstrate intricate dynamics that are highly dependent on their molecular structures.In this study,we synthesized water-soluble derivatives of representative AIEgens,including tetraphenylethene(TPE),bis(N,N-dialkylamino)anthracene(BDAA),and bridged stilbene,and systematically investigated the dependence of their photophysical properties in water/glycerol mixed solvents on temperature and viscosity.To elucidate the origin of their viscosity responsiveness,quantum chemical calculations were conducted to analyze their potential energy surfaces(PESs).The results revealed that compared to typical molecular rotors,these AIEgens exhibit significantly higher sensitivity to viscosity in low-viscosity regions.Notably,for TPE and BDAA derivatives,the viscosity responsiveness was found to be governed not by the activation energy barrier(ΔE_(a))based on the PES,but rather by the viscosity-dependent constraints on molecular structural changes.Furthermore,molecules possessing multiple aromatic rings or large,flexible,rotatable moieties were found to exhibit enhanced sensitivity to viscosity due to increased frictional interactions in solutions.This study provides critical insights into the mechanistic origins of the viscosity responsiveness of AIEgens,thereby advancing the fundamental understanding of their behavior and expanding their potential application as viscositysensitive probes.展开更多
Supramolecular liquid crystals(SLCs)are attractive materials for fabricating devices with new optoelectronic functions.Conventional SLCs are made from hydrogen-bonded mesogens.However,these mesogens suffer from high m...Supramolecular liquid crystals(SLCs)are attractive materials for fabricating devices with new optoelectronic functions.Conventional SLCs are made from hydrogen-bonded mesogens.However,these mesogens suffer from high melting points,and the types of formable aggregates are limited owing to the directionality of the hydro-gen bonding.Therefore,to fabricate non-hydrogen-bonded SLCs,we hypothesized that the introduction of tertiary amide groups into calamitic molecules would be advantageous because they have an L-shaped structure with N-or C-alkyl side chains not aligned along the long axis and theflexibility to undergo cis–trans isomeriza-tion.In this study,we developed a novel non-hydrogen-bonded SLC by assembling an L-shaped dimer composed of calamitic molecules(phenyltolanes)with tertiary amides at their ends.These molecules exhibited a smectic B phase.The phase tran-sition temperature of the SLCs from crystal to liquid crystal phase was low despite the longπ-conjugated core.Wide-angle X-ray diffraction and variable-temperature Fourier-transform infrared measurements revealed dimer formation by weak inter-molecular interactions,that is,the molecular recognition of L-shaped molecules,and mobility of the alkyl groups attached to amide driven by cis–trans isomerization in the liquid crystal phase.Thus,cis–trans isomerization of tertiary amides contributed enormously to the formation and lower clearing points of this SLC.The developed method can be used not only to develop non-hydrogen-bonded SLCs but also to develop novel soft matter with controlled properties by incorporating the SLCs,as the aggregates can be controlled to impart desired functionalities.展开更多
基金JSPS Research Fellowships for Young Scientistssupported in part by JST SPRING,Japan(Nos.JPMJSP2106 and JPMJSP2180,Takuya Tanaka.and Yuki Sawatari.)+1 种基金MEXT/JSPS KAKENHI grants(No.23H02036,Gen-ichi Konishi)Murata Science and Education Foundation(Gen-ichi Konishi)。
文摘Aggregation-induced emission luminogens(AIEgens)exhibit viscosity-responsive behavior resembling those of molecular rotors;however,their response mechanisms are more complex and cannot be adequately described using simple rotational models.AIEgens demonstrate intricate dynamics that are highly dependent on their molecular structures.In this study,we synthesized water-soluble derivatives of representative AIEgens,including tetraphenylethene(TPE),bis(N,N-dialkylamino)anthracene(BDAA),and bridged stilbene,and systematically investigated the dependence of their photophysical properties in water/glycerol mixed solvents on temperature and viscosity.To elucidate the origin of their viscosity responsiveness,quantum chemical calculations were conducted to analyze their potential energy surfaces(PESs).The results revealed that compared to typical molecular rotors,these AIEgens exhibit significantly higher sensitivity to viscosity in low-viscosity regions.Notably,for TPE and BDAA derivatives,the viscosity responsiveness was found to be governed not by the activation energy barrier(ΔE_(a))based on the PES,but rather by the viscosity-dependent constraints on molecular structural changes.Furthermore,molecules possessing multiple aromatic rings or large,flexible,rotatable moieties were found to exhibit enhanced sensitivity to viscosity due to increased frictional interactions in solutions.This study provides critical insights into the mechanistic origins of the viscosity responsiveness of AIEgens,thereby advancing the fundamental understanding of their behavior and expanding their potential application as viscositysensitive probes.
基金Japan Science and Technology Agency,Grant/Award Number:JPMJPR1096Japan Society for the Promotion of Science,Grant/Award Numbers:17H05145,23H02036Izumi Science and Technology Foundation。
文摘Supramolecular liquid crystals(SLCs)are attractive materials for fabricating devices with new optoelectronic functions.Conventional SLCs are made from hydrogen-bonded mesogens.However,these mesogens suffer from high melting points,and the types of formable aggregates are limited owing to the directionality of the hydro-gen bonding.Therefore,to fabricate non-hydrogen-bonded SLCs,we hypothesized that the introduction of tertiary amide groups into calamitic molecules would be advantageous because they have an L-shaped structure with N-or C-alkyl side chains not aligned along the long axis and theflexibility to undergo cis–trans isomeriza-tion.In this study,we developed a novel non-hydrogen-bonded SLC by assembling an L-shaped dimer composed of calamitic molecules(phenyltolanes)with tertiary amides at their ends.These molecules exhibited a smectic B phase.The phase tran-sition temperature of the SLCs from crystal to liquid crystal phase was low despite the longπ-conjugated core.Wide-angle X-ray diffraction and variable-temperature Fourier-transform infrared measurements revealed dimer formation by weak inter-molecular interactions,that is,the molecular recognition of L-shaped molecules,and mobility of the alkyl groups attached to amide driven by cis–trans isomerization in the liquid crystal phase.Thus,cis–trans isomerization of tertiary amides contributed enormously to the formation and lower clearing points of this SLC.The developed method can be used not only to develop non-hydrogen-bonded SLCs but also to develop novel soft matter with controlled properties by incorporating the SLCs,as the aggregates can be controlled to impart desired functionalities.
