Modeling using statistical methods as ANOVA and design expert help in predicting, improving, and perfecting a system’s behavior by integration between all experimental data and different parameters, in addition to it doesn’t consume time or materials as the other techniques statistically independence. It investigates the adsorption effectiveness of mullite nanoparticles (MNPs) in removing methyl red dye (acid red 2) as azo benzene derivative dye. Many parameters as pH, dose, contact duration, and dye concentration were studied. The crystal structure, morphology, nanoscale and surface area of the adsorbent MNPs material were investigated using X-ray diffraction, Brunauer-Emmett-Teller, and transmission electron microscopy methods. The adsorbent had high crystallinity with particles size of 5 to 25 nm and an average equal 12.3 nm. In addition, it had mesoporous characteristics with high surface area (an average pore size of 7.224 nm, 93.71 m2/g of surface area, and 0.426 cm3/g of pore volume). Its contact angle is 115.3, which explains its hydrophobic character. By using a dosage of 0.05 g at pH 4, for 10 min and 800 rpm, more than 99% removal was achieved. Application of the adsorption isotherm and Kinetics, it follows pseudo-2nd order and the DKR isotherm of the removal procedure.Supplementary InformationThe online version contains supplementary material available at 10.1038/s41598-025-27886-x.

Azobenzene (AB) and its derivatives are known for their reversible trans ↔ cis isomerization in solution and the solid phase in response to UV/Vis radiation. While the forward trans → cis isomerization is triggered by UV radiation, the backward cis → trans isomerization can be triggered either by visible light or by temperature. The function of these molecules is highly dependent on the activation barrier for the forward and backward isomerization and is the key for governing the properties of photo-switchable molecules. Typically when the molecules are deposited on a surface, they are stabilized in their equilibrium state, trans. So it is feasible to understand the dynamics and energy barriers of trans → cis isomerization experimentally. However, the energy barrier for the reverse process (cis → trans isomerization) on surfaces is generally elusive and not accessible due to the fact that AB derivatives do not condense into the phase of non-equilibrium state, cis. Though the energy barriers may be computed theoretically, the experimental determination is not straightforward. Here, we demonstrate a novel approach where the cis isomers of two AB derivatives are condensed onto the highly oriented pyrolytic graphite (HOPG) surface from a cis dominant solution of the molecules. Further, by analysing the percentage of on-surface thermal-induced cis → trans isomerization, we have determined the corresponding energy barrier. Temperature dependent atomic force micrographs of monolayer and submonolayer films of the molecules are used for the experiment.

Manipulating the energy barrier and extending the half-life of nonequilibrium states in photochromic switches presents viable solutions for applying them in molecular electronics. Typically, the half-life of the Z isomer of azobenzene (AB) is a few days. Arylazopyrazole-based molecular switches are one of the profoundly explored systems in recent times due to their superior bidirectional photoswitching and long half-life (over a thousand days at room temperature) of Z isomers. Herein, we utilize an efficient solid-state photoswitchable fluorinated tripodal N-functionalized arylazo-3,5-dimethylpyrazole derivative (FNAAP) to envisage and access multiple metastable states on the surface. The tripodal molecule forms well-ordered, large crystalline domains on graphite through non-bonding interactions between the molecules. By injecting electron/hole pairs into the self-assembled molecules on a surface using a scanning tunneling microscope (STM) tip, they are switched between 8 states (EEE, EEZ, EZE, ZEE, EZZ, ZEZ, ZZE and ZZZ) in a tunneling junction at ambient conditions. Contrary to the degeneracy-controlled four states in solution phase, all the eight states are remarkably stable on the surface and are well distinguishable by the tunneling current passing through the molecule at the tunneling junction. The change in current upon switching between these states is approximately an order of magnitude. This is particularly notable at positive sample voltage compared to negative sample voltage. The exceptional stability of the states at ambient conditions provides an opportunity to use a single FNAAP molecule as an 8-bit operation unit, with a potential storage capacity of ≈200 Tbits per 1 cm2 area using an atomically precise write and read tool like an STM tip.

A molecular solar thermal (MOST) storage systems is based on capturing solar energy via photoisomerization, which can be released later as thermal energy. Herein, the low viscosity, green light active, 2,6-difluoroazobenzene is introduced, which can be efficiently irradiated, pumped, and handled in its neat state. Synthesis as well as isomerization can be done conveniently in a continuous flow setup. Storage densities of 218kJkg-1 for 100% (Z)-isomer (137 kJkg-1 after green light irradiation) are the highest compared to other liquid azobenzenes (ABs). Additionally, the irradiation with green light and the processibility in the neat state make this compound a promising candidate for energy storage applications. Furthermore, the liquid AB can be employed as a MOST-active solvent. For example, the solvation of an electrolyte is demonstrated to induce a measurable conductivity, which then allows for complete electron-catalyzed back-isomerization. Alternatively, it can act as a solvent for a higher energy MOST material. As a proof-of-concept a norbornadiene (NBD) is dissolved in the AB solvent allowing to utilize the energy of the NBD as well as the AB solvent. Further optimization of the solute-solvents systems is required to fully harvest the potential of this new concept for efficient energy storage.

ABSTRACT In order to further expand the functional diversity and application of cholesteric liquid crystal (CLC) materials, the dye-doped CLCs are constructed by combining CLCs with the photoreversible cis-trans isomeric dye azobenzene (AZO), and the effect of different doping concentrations of AZO on the thermal and optical properties of CLCs were investigated. The experimental results show that: (1) Compared to undoped CLC, AZO-doped CLCs have a lower clearing point. The higher the doping concentration, the more the corresponding clearing point decreases (~6°C), and after ultraviolet (UV) irradiation, clearing point of AZO-doped CLCs decreases further (~9°C); (2) Under the applied electric field, higher AZO doping reduces the voltage corresponding to the transition from planar state to focal conic state and field-induced nematic state by 4 V ~10 V; (3) The electro-optical properties changed greatly, and the optimal doping concentration is 1.7 wt%. Compared with undoped CLC, the response time of AZO-doped CLCs with red central reflection wavelength reduced by 61.6 % and 35.6 % (after UV irradiation), and for infrared central reflection, it is reduced by 50.1 % and 61.2 %, respectively. In addition, 1.7 wt% AZO-doped CLC has a higher contrast ratio compared to undoped CLC.

Abstract In the era of precision medicine, photopharmacology that employs molecular photoswitches offers unique opportunities to control the action of bioactive molecules with high spatiotemporal resolution, while reducing drug side effects, systemic toxicity and the emergence of resistance. Over the past two decades, the field of photopharmacology has witnessed great achievements in treating with blindness, cancer, diabetes, antibiotic resistance, and to name but a few. Several challenges remain, however, in particular the fact that most photopharmacological agents trigger their activity by Ultraviolet light, which is damaging to normal cells and has poor tissue permeability. Visible light‐activated photopharmacological agents are hence highly desirable and have captured keen recent research interest. This review highlights strategies for the synthesis of visible light‐responsive azobenzenes (ABs) and their applications in the emerging photopharmacology. Such visible light‐activated photoswitchable drugs tremendously extend the scope of photopharmacology for future in vivo applications. Furthermore, we identify the current challenges and discuss future opportunities for rational design in photopharmacology that switches at a higher wavelength. We hope to inspire further research into the photochemistry of novel photopharmacological agents based on ABs or other photoswitches, which are triggered by the excitation light in “phototherapeutic window” of 650–900 nm, ultimately enabling full realization of these “smart” drugs in the clinical practice.

Abstract Advanced materials with physical properties such as electric conductivity that can be dynamically controlled by remote signals will enable new cutting‐edge applications. To date, while many materials with either photoswitchable conduction properties or high conductivities have been presented, the combination of both properties remains a challenge. Here, a series of conductive metal–organic framework (MOF) thin films is presented where the conductivity is reversibly remote controlled by light. The structures of the MOFs are Cu3(2,3,6,7,10,11‐hexahydroxytriphenylene)2 (Cu3(HHTP)2) with different photochromic molecules of type azobenzene (AB), diarylethene (DAE), spiropyran (SP) and hexaarylbiimidazole (HABI) derivatives embedded in the MOF pores. By photoisomerizations of the guest molecules, induced by UV light and reversed by visible light irradiation or thermal relaxation, the conduction properties of the photoswitch@Cu3(HHTP)2 films are reversibly modulated by up to 15%. These changes of the electrical conductivity can be understood by calculating the density of states (DOS) near the Fermi level, showing that the DOS decreases upon embedment of the guest molecules and as a result of their isomerization. Moreover, the application of such photoswitch@Cu3(HHTP)2 films as photoprogrammable gas sensors is demonstrated. With the introduction of photoswitchable conductive hybrid material, this study contributes to the extension of smart materials for innovative applications.

To enhance the therapeutic efficacy and safety of triple-negative breast cancer (TNBC) treatment, we developed a hypoxia-responsive drug delivery system utilizing digoxin (DIG) to inhibit HIF-1α and sensitize TNBC to doxorubicin (DOX). DIG, a cardiac steroid with a well-characterized pharmacological mechanism, was encapsulated in micelles composed of methoxy-polyethylene glycol (mPEG) and poly(lactic acid) (PLA) copolymers, incorporating an azobenzene (AZO) trigger for hypoxia-sensitive drug release. The loading ratio of DOX to DIG was optimized based on DIG's minimum effective dose. In vitro and in vivo studies demonstrated that the micelles efficiently delivered their payload to hypoxic tumor regions, enabling rapid drug release. DIG-mediated HIF-1α inhibition enhanced TNBC sensitivity to DOX, leading to significant suppression of both primary tumor growth and pulmonary metastasis. This study presents a promising and clinically feasible strategy for TNBC and other hypoxia-driven malignancies.

Aqueous nickel-organic batteries have the potential for grid-scale energy storage due to their high safety and sustainability merits. However, organic anodes generally store charge by coordinating with alkaline metal cations, which could cause electrolyte consumption. Here, azobenzene (AZO) is screened out from carbonyl, imine, and azo compounds to serve as anodes, combining it with Ni(OH)2 cathodes to construct a "rocking-chair" type battery system. Qualitative and quantitative analyses demonstrate the N═N group acts as the active center, while protons serve as charge carriers during the electrochemical reaction. Benefiting from the small ionic radius and fast ions transport of protons, this battery not only delivers an excellent rate performance, with a capacity of 281.5 mAh g-¹ at a current density of 1C (0.3 A g-¹) and maintains 274.4 mAh g-¹ at 100C, but also exhibits remarkable long-term cycling stability, retaining 92.5% of its initial capacity after 10000 cycles. Additionally, a pouch cell with a discharge capacity of 1.36 Ah is also assembled, yielding an energy density of 64.3Wh kg-¹ (based on the total mass). This work expands the range of organic anode materials, and inspires the development of aqueous nickel-organic batteries with a proton "rocking-chair" mechanism.

Aryl diazenes, particularly azobenzenes (AB), represent a versatile class of compounds with significant historical and practical relevance, ranging from dyes to molecular machines, solar thermal and electrochemical storage. Their oxygen‐substituted counterparts, azoxybenzenes (AOB), share structural similarities but have been less explored, especially in energy storage applications. This study investigates the redox properties of AOB, comparing them to AB, and evaluates their potential as redox‐active materials for energy storage systems. Through cyclic voltammetry (CV) and spectro‐electrochemical analyses, we demonstrate that AOBs exhibit a distinct redox behaviour, influenced by the solvent and electrolyte environment, with a reversible oxidation process. Despite their promising redox characteristics, AOBs suffer from capacity decay during galvanostatic cycling, likely due to the instability of the radical cation intermediate. These findings suggest that while AOBs offer intriguing redox properties, further investigation into stabilization strategies are needed for their application in energy storage.

The reversible photoisomerization of azobenzene (AZB) and its derivatives has been applied across various fields. Developing discrete AZB-functionalized organometallic cages is essential for manufacturing functional materials. In this work, we designed and fabricated a series of three-dimensional, hexaazobenzene-terminated poly-NHC-based (NHC=N-heterocyclic carbene) complexes [M3(A)2](BF4)3 and [M3(B)2](BF4)3 (M = Ag, Au). In the newly prepared MI-CNHC assemblies, these peripheral AZB units linked to the central backbones can undergo efficient and recyclable isomerization upon external stimulation, effectively creating a switchable organometallic assembly system. Compared to the NHC precursor, the metalized framework demonstrates higher isomerization efficiency, thereby establishing a foundation for the subsequent application of AZB-functionalized MI-CNHC assemblies.

Azobenzene (AZO) and its derivatives are of great importance in the dyestuff and pharmaceutical industries; however, their sustainable synthesis is much slower than expected due to the lack of high-performance catalysts. In this work, we report a robust yet highly efficient catalyst of PdS mesoporous nanospheres (MNSs) with confined mesostructures and binary elemental composition that achieved sustainable electrosynthesis of value-added AZO by selective hydrogenative coupling of nitrobenzene (NB) feedstocks in H2O under ambient conditions. Using a renewable electricity source and H2O, binary PdS MNSs exhibited a remarkable NB conversion of 95.4%, impressive AZO selectivity of 93.4%, and good cycling stability in selective NB hydrogenation reaction (NBHR) electrocatalysis. Detailed mechanism studies revealed that the confined mesoporous microenvironment of PdS MNSs facilitated the hydrogenative coupling of key intermediates (nitrosobenzene and phenylhydroxylamine) into AZO and/or azoxybenzene (AOB), while their electron-deficient S sites stabilized the Pd-spillovered active H* and inhibited the over-hydrogenation of AZO/AOB into AN. By coupling with the anodic methanol oxidation reaction (MOR), the (-)NBHR‖MOR(+) two-electrode system exhibits much better NB-to-AZO performance in a sustainable and energy-efficient manner. This work thus paves the way for designing functional mesoporous metal alloy electrocatalysts applied in the sustainable electrosynthesis of industrial value-added chemicals.

Photoswitches are the most fundamental components of photonic integrated chips. The double-bond trans-cis photoswitching molecules are the most widely studied photochromic materials, but there are still numerous challenges in exploring their ultrafast photoisomerization dynamics. Here, three azobenzene-like derivatives (azo-derivatives: azo-dipyridine (AP), azobenzene (AB) and phenylazopyridine (PAP)) were selected to investigate the factors to modify the trans-cis isomerization dynamics systemically. In the solution, the photoisomerization rate of azo-derivatives from trans to cis is positively correlated with their dipole moments and their rate order AP < AB < PAP is consistent with the energy barrier obtained by potential energy surface scanning of excited states. When these azo-derivatives are assembled into nanocrystal in the suspension solutions, their isomerization rates will all accelerate, but the rate order is completely opposite to that of the solution phase. The crystal structure and energy decomposition analysis based on force field show that the weaker the intermolecular hydrogen bonding and the stronger the π-π stacking, the more favorable it is for trans-cis isomerization of azo-derivatives. This work reveals key factors that affect the trans-cis isomerization of azo-like derivatives, the dipole moment in solution, hydrogen bonding, and π-π stacking in the crystal, providing a theoretical basis for designing novel photoswitching molecular materials.

Caged compounds whose chemical bonds are cleavable by specific stimuli are useful tools for life science research because they facilitate control of various biological activities spatiotemporally. Although caged compounds activatable by hard X-rays can be employed for control in deep tissue owing to the high bio-permeability of X-rays, chemical bond cleavage by ionizing radiation has not been investigated adequately. Previously, we demonstrated that an azo bond tethered to a rhodamine scaffold can be efficiently cleaved by hydrated electrons, which is one of the radiolysis products of water, to release rhodamine. In this study, we synthesized novel azo benzene derivatives, AZO1-4, which can release 3-aminobenzamide (3-ABA), a poly (ADP-ribose) polymerase (PARP) inhibitor, and hydroxy groups or amino groups were introduced into them in order to assess the substituent effect on azo bond cleavage. While the amount of 3-ABA was nearly the same for all the azo compounds, decomposition of azo compounds increased according to the number of hydroxy groups. Furthermore, a methoxyl-radical-adding product was detected from AZO2. These results suggested that the hydroxy group accelerates not azo bond cleavage but the other decomposition pathway.

Exploring the interaction between black phosphorus (BP)-based hybrid systems and target proteins is of great significance for understanding the biological effects of 2D nanomaterials at the molecular level. Density functional theory (DFT) calculations revealed that different terminal groups of the azobenzene (AB) motif in BP@AB hybrids can affect the extent of interfacial charge transfer between the BP sheet and AB-derivatives, which determines the electrostatic interaction with proteins and hence biofunctions of BP@AB hybrids. With the advantage of AB modification, BP@AB hybrids displayed antitumor effects and induced production of cellular reactive oxygen species and apoptosis in cancer cells. Through the proteomics profiling, cellular ribosome and lipid metabolic processes were screened out as the target pathways of the BP@AB-NH2 in HeLa cells, while the BP@AB-S-S-AB system mainly targets the ERBB and PPAR signaling pathways. Molecular docking simulations revealed that due to the positive charge, ribosomal pathway proteins enriched in negatively charged amino acids such as lysine and arginine are preferentially adsorbed and bound by BP@AB-NH2 hybrids. Whereas for BP@AB-S-S-AB, receptors containing narrow and long pocket domains are more likely to bind with BP@AB-S-S-AB by van der Waals forces for the rod-like hybrids. Different biomolecule targeting and action modes of BP@AB hybrids have been rationalized by different electrostatic environments and matching of geometric configurations, shedding insight for designing efficient and targeted modification of a 2D nanomaterial-based strategy for cancer therapy.

G-quadruplex (G4) DNA structures are increasingly acknowledged as promising targets in cancer research, and the development of G4-specific stabilizing compounds may lay a fundamental foundation in precision medicine for cancer treatment. Here, we propose a light-responsive G4-binder for precise modulation of drug activation, providing dynamic and spatiotemporal control over G4-associated biological processes contributing to cancer cell death. We developed a specialized fluorinated azobenzene (AB) switch equipped with a quinoline unit and a positively charged carboxamide side chain, Q-Azo4F-C, designed for targeted binding to G4 structures within cells. Biophysical studies, combined with molecular dynamics simulations, provide insights into the unique coordination modes of the photoswitchable ligand in its trans and cis configurations when interacting with G4s. The observed variations in complexation processes between the two isomeric states in different cancer cell lines manifest in more than 25-fold reversible cytotoxic activity. Immunostaining conducted with the structure-specific G4 antibody (BG4), establishes a direct correlation between cytotoxicity and the varying extent of G4 induction regulated by the two isoforms. Finally, we demonstrate the photo-driven reversible regulation of G4 structures in lung cancer cells by Q-Azo4F-C. Our findings highlight the potential of light-responsive G4-binders in advancing precision cancer therapy through dynamic control of G4-mediated pathways.

Abstract G‐quadruplex (G4) DNA structures are increasingly acknowledged as promising targets in cancer research, and the development of G4‐specific stabilizing compounds may lay a fundamental foundation in precision medicine for cancer treatment. Here, we propose a light‐responsive G4‐binder for precise modulation of drug activation, providing dynamic and spatiotemporal control over G4‐associated biological processes contributing to cancer cell death. We developed a specialized fluorinated azobenzene (AB) switch equipped with a quinoline unit and a positively charged carboxamide side chain, Q‐Azo4F‐C, designed for targeted binding to G4 structures within cells. Biophysical studies, combined with molecular dynamics simulations, provide insights into the unique coordination modes of the photoswitchable ligand in its trans and cis configurations when interacting with G4s. The observed variations in complexation processes between the two isomeric states in different cancer cell lines manifest in more than 25‐fold reversible cytotoxic activity. Immunostaining conducted with the structure‐specific G4 antibody (BG4), establishes a direct correlation between cytotoxicity and the varying extent of G4 induction regulated by the two isoforms. Finally, we demonstrate the photo‐driven reversible regulation of G4 structures in lung cancer cells by Q‐Azo4F‐C. Our findings highlight the potential of light‐responsive G4‐binders in advancing precision cancer therapy through dynamic control of G4‐mediated pathways.

Light-responsive zwitterionic membrane surface modification for antifouling and antibacterial application

Dual responsive polymersomes as versatile, intelligent labeling system in biosensing

A novel supramolecular photoactuator in the form of a thin film of centimetric size has been developed as an alternative to traditional liquid crystal elastomers (LCE) involving azobenzene (AZO) units or photochromic microcrystals. This thin film is produced through spin coating without the need for alignment or crosslinking. The photoactuator combines a photochromic dithienylethene (DTE) functionalized with ureidopyrimidinone (UPy) units, and a telechelic thermoplastic elastomer, also functionalized with UPy, allowing quadruple hydrogen bonding between the two components. Upon alternating ultraviolet (UV) and visible light exposure, the film exhibits reversible bending and color changes, studied using displacement and absorption tracking setups. For the first time, the photomechanical effect (PME) is quantitatively correlated with photochromism, showing that DTE units drive the movement under both UV (photocyclization) and visible (photoreversion) light. In situ illumination techniques reveal that the PME arises from photoinduced strain within 160 nm UPy-bonded DTE domains, which expand and contract by approximately 50% under UV and visible light, respectively. The semicrystalline nature of the elastomer and a robust supramolecular network connecting both components are critical in converting microscopic photostrain into macroscopic actuation.