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Mechanically Induced Switching of Molecular Layers
摘要： Within the field of switchable surfaces, azobenzenes are an extensively studied group of molecules, known for reversibly changing conformation upon illumination with light of different wavelengths. Relying on the ability of the molecules to change properties and structure as a response to external stimuli, they have been incorporated in various devices, such as molecular switches and motors. In contrast to the well-documented switching by light irradiation, we report the discovery of mechanically triggered switching of self-assembled azobenzene monolayers, resulting in changes of surface wettability, adhesion, and friction. This mechanically induced cis?trans isomerization is triggered either locally and selectively by AFM or macroscopically by particle impact. The process is optically reversible, enabling consecutive switching cycles. Collective switching behavior was also observed, propagating from the original point of impact in a domino-like manner. Finally, local force application facilitated nondestructive and erasable nanopatterning, the cis?trans nanolithography.
关键词： Molecular switch,self-assembled monolayers,mechanical switching,nanolithography,azobenzene
更新于2025-09-19 17:15:36
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Light-wavelength-based Quantitative Control of Dihydrofolate Reductase Activity Using Photochromic Isostere of Inhibitor
摘要： Photopharmacology has attracted research attention as a new tool to achieve the optical control of biomolecules following the methods of caged compounds and optogenetics. We have developed an efficient photopharmacological inhibitor, azoMTX, for Escherichia coli dihydrofolate reductase (eDHFR) by replacing some atoms of the original ligand, methotrexate, to obtain the photoisomerization property. This fine molecular design enabled the quick structural conversion between the active 'bent' Z-isomer and the inactive 'extended' E-isomer of azoMTX, and this property afforded quantitative control of the enzyme activity, depending on the wavelength of irradiated light. The real-time photoreversible control of enzyme activity was also achieved.
关键词： methotrexate,photochromism,enzymes,azobenzene,photopharmacology
更新于2025-09-19 17:15:36
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Photo-responsive Azobenzene-MXene hybrid and its optical modulated electrochemical effects
摘要： The 2D transition metal carbide (MXene) is a new type of promising material for energy storage due to its metallic conductivity and highly active surface. This paper describes a new photo-responsive Azo-MXene hybrid that is fabricated through electrostatic interactions between the negatively charged MXene and the cationic Azo-surfactants. After performing systematical characterizations, we found a strong electrostatic interaction force between the MXene and Azo-surfactants in this hybrid and a uniform distribution of Azo groups in the MXene structure. Notably, this Azo-MXene hybrid can self-assemble to an aggregated structure due to the hydrophobization of Azo on the surface of MXene. Furthermore, the self-assembly of this hybrid can be modulated by ultraviolet light irradiation. This process of transition is also responsible for the hybrid's electrochemical performance upon ultraviolet light irradiation, which may be applied as a photo-responsive conductive material for photo-energy conversion and storage devices.
关键词： Assembly,Azobenzene,MXene,Irradiation,Isomerization
更新于2025-09-19 17:15:36
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Electrical detection of plasmon-induced isomerization in molecule–nanoparticle network devices
摘要： We use a network of molecularly linked gold nanoparticles (NPSAN: nanoparticle self-assembled network) to demonstrate the electrical detection (conductance variation) of plasmon-induced isomerization (PII) of azobenzene derivatives (azobenzene bithiophene: AzBT). We show that PII is more efficient in a 3D-like NPSAN (cluster-NPSAN) than in a purely two-dimensional NPSAN (i.e., a monolayer of AzBT functionalized Au NPs). By comparison with the usual optical (UV-visible light) isomerization of AzBT, PII shows faster (a factor > ～10) isomerization kinetics. Possible PII mechanisms are discussed: electric field-induced isomerization, two-phonon process, and plasmon-induced resonance energy transfer (PIRET), the latter being the most likely.
关键词： azobenzene derivatives,nanoparticle networks,electrical detection,plasmonics,plasmon-induced isomerization
更新于2025-09-19 17:15:36
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Azobenzene-based small molecular photoswitches for protein modulation
摘要： Molecular photoswitches are a class of chemical structures that can readily isomerize between distinct geometries upon irradiation with light. Molecular photoswitches are utilized to control protein structure and function with temporal and spatial precision. In this review, we summarize the recent progress in the development of azobenzene-based molecular photoswitches and their applications in the photocontrol of protein structure and function. For clarity of discussion, we divide the known photoswitchable proteins into different categories: protein motifs, ion channels, receptors, and enzymes. Basic approaches and considerations for the structure-guided design of photoswitchable ligands are discussed. The applications and limitations of current photoswitches are also discussed.
关键词： protein modulation,molecular design,azobenzene,photocontrol,photoswitches
更新于2025-09-19 17:15:36
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Optically Tunable Field Effect Transistors with Conjugated Polymer Entailing Azobenzene Groups in the Side Chains
摘要： Semiconducting conjugated polymers with photoswitching behavior are highly demanded for field-effect transistors (FETs) with tunable electronic properties. Herein a new design strategy is established for photoresponsive conjugated polymers by incorporating photochromic units (azobenzene) into the flexible side alkyl chains. It is shown that azobenzene groups in the side chains of the DPP (diketopyrrolopyrrole)-quaterthiophene polymer (PDAZO) can undergo trans/cis photoisomerization in fully reversible and fast manner. Optically tunable FETs with bistable states are successfully fabricated with thin films of PDAZO. The drain-source currents are reduced by 80.1% after UV light irradiation for ≈28 s, which are easily restored after further visible light irradiation for ≈33 s. Such fast optically tunable FETs are not reported before. Moreover, such current photomodulation can be implemented for multiple light irradiation cycles with good photofatigue resistance. Additionally, thin film charge mobility of PDAZO can be reversibly modulated by alternating UV and visible light irradiations. On the basis of theoretical calculations and GIWAXS data, it is hypothesized that the dipole moment and configuration changes associated with the trans-/cis-photoisomerization of azobenzene groups in PDAZO can affect the respective intra-chain and inter-chain charge transporting, which is responsible for the optically tunable behavior for FETs with thin films of PDAZO.
关键词： side alkyl chains,semiconducting polymers,thin-film field-effect transistors,azobenzene,photoresponsiveness
更新于2025-09-19 17:15:36
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Aggregation-induced chiroptical generation and photoinduced switching of achiral azobenzene- <i>alt</i> -fluorene copolymer endowed with left- and right-handed helical polysilanes
摘要： The left and right helicities of azobenzene (Azo)-containing main-chain polymer (PF8Azo) were successfully controlled with an enantiomeric pair of rigid rod-like helical polysilanes carrying (S)- and (R)-2-methylbutyl groups (PSi-S and PSi-R, respectively) as their hetero-aggregates in a mixture of chloroform and methanol solvents and in the solid state. Optimizing the good and poor cosolvents and their volume fractions showed that the molar ratio of PF8Azo to PSi-S/-R and the molecular weight of PF8Azo were crucial to boost the CD amplitudes of PF8Azo/PSi-S and PF8Azo/PSi-R hetero-aggregates. The photoresponsive trans–cis transformation caused noticeable changes in the sign and magnitude of the chiroptical behavior due to the hetero-aggregates. Moreover, the optically active PF8Azo homo-aggregates were produced by complete photoscissoring reactions at 313 nm, which could be assigned to the Sis–Sis* transitions of PSi-S and PSi-R.
关键词： achiral azobenzene-alt-fluorene copolymer,helical polysilanes,photoinduced switching,Aggregation-induced chiroptical generation
更新于2025-09-19 17:15:36
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Photoinduced reversible solid-to-liquid transitions using photoswitchable materials
摘要： Heating and cooling can induce reversible solid-to-liquid transitions of matter. In contrast, athermal photochemical processes can induce reversible solid-to-liquid transitions of some newly developed azobenzene compounds. Azobenzene is photoswitchable. UV light induces trans-to-cis isomerization; visible light or heat induces cis-to-trans isomerization. Trans and cis isomers usually have different melting points (Tms) or glass transition temperatures (Tgs). If Tms or Tgs of an azobenzene compound in trans and cis forms are above and below room temperature, respectively, light may induce reversible solid-to-liquid transitions. In this review, we introduce azobenzene compounds that exhibit photoinduced reversible solid-to-liquid transitions, discuss the mechanisms and design principles, and show their potential applications in healable coatings, adhesives, transfer printing, lithography, actuators, fuels, and gas separation. Finally, we discuss remaining challenges in this field.
关键词： photoswitch,isomerization,azobenzene,solid-to-liquid transition,photochemistry
更新于2025-09-19 17:15:36
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Study of the Molecular Bending in Azobenzene Self-Assembled Monolayers Observed by Tip-Enhanced Raman Spectroscopy in Scanning Tunneling Mode
摘要： Tip-enhanced Raman Spectroscopy (TERS) is capable of amplifying the extremely weak Raman response of azobenzene self-assembled monolayers (SAMs), thus allowing for the chemical characterization of the sample surface at the nanoscale. Recently, we introduced a physical model describing the TERS intensity of azobenzene SAMs probed in a scanning tunneling mode configuration (STM-TERS), that takes into account the molecular bending induced by the high electric field inside the tunneling junction. The model predicts quite well the experimental variation in the TERS intensity of a hexil azobenzene SAM (AzoC6) on gold polycrystalline film (111) with changing the electric field in the gap between the tip and the substrate. Nevertheless, a disagreement between the model and the experiment has been observed while studying, in the same conditions, the TERS intensity of undecyl azobenzene (AzoC11) SAM formed by molecules featuring an alkyl chain nearly two times longer with respect to the previous case. In this work we extend the molecular bending model through considering an additional bending mechanism due to the mechanical interaction between the tip and the SAM, occurring when the tip-to-sample distance is shorter than the molecular length. The extended model is able to describe well the TERS intensity behavior with changing either the bias voltage or the tip-to-sample distance for both AzoC6 and AzoC11. Eventually, we determine quantitatively the difference in elastic properties of the two molecules physically accounting for the difference in the TERS intensity behavior of the two SAMs.
关键词： STM-TERS,self-assembled monolayers,SAMs,Tip-enhanced Raman Spectroscopy,TERS,molecular bending,azobenzene
更新于2025-09-19 17:13:59
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Effect of surface amphiphilic property of azobenzene self-assembled electrode materials on properties of supercapacitors
摘要： In this report, novel azobenzene self-assembled complexes (azo-Cn, n = 8, 12, 16) were used as an electrode material for pseudo-capacitors. The as-prepared azo-Cn exhibited a good reversible redox process and possessed a specific capacitance as high as 221.0 F g?1 at 10 mV s?1. However, with the value n increased from 8 to 16, the specific capacitances of azo-Cn electrode materials decreased. In order to study the reasons, the effect of surface amphiphilic property of azobenzene self-assembled electrode materials on the properties of supercapacitors was studied and the results showed that the capacitive behaviors of azo-Cn could be greatly improved by better surface hydrophilic properties and azo-C8 with good supercapacitive characteristics could be the potential ideal electrode materials for low-cost and high-efficiency electrochemical supercapacitors.
关键词： Supercapacitors,Azobenzene,Amphiphilicity,Self-assembly
更新于2025-09-19 17:13:59