Spiropyran Groups Research Articles

Illuminating Biomimetic Nanochannels: Unveiling Macroscopic Anticounterfeiting and Photoswitchable Ion Conductivity via Polymer Tailoring.

Artificial photomodulated channels represent a significant advancement toward practical photogated systems because of their remote noncontact stimulation. Ion transport behaviors in artificial photomodulated channels, however, still require further investigation, especially in multiple nanochannels that closely resemble biological structures. Herein, we present the design and development of photoswitchable ion nanochannels inspired by natural channelrhodopsins (ChRs), utilizing photoresponsive polymers grafted anodic aluminum oxide (AAO) membranes. Our approach integrates spiropyran (SP) as photoresponsive molecules into nanochannels through surface-initiated atom transfer radical polymerization (SI-ATRP), creating a responsive system that modulates ionic conductivity and hydrophilicity in response to light stimuli. A key design feature is the reversible ring-opening photoisomerization of spiropyran groups under UV irradiation. This transformation, observable at the molecular level and macroscopically, allows the surface inside the nanochannels to switch between hydrophobic and hydrophilic states, thus efficiently modulating ion transport via changing water wetting behaviors. The patternable and erasable polySP-grafted AAO, based on a controllable and reversible photochromic effect, also shows potential applications in anticounterfeiting. This study pioneers achieving macroscopic anticounterfeiting and photoinduced photoswitching through reversible surface chemistry and expands the application of polymer-grafted structures in multiple nanochannels.

Photosensitive polyimide enabled simple, reversible and environmentally friendly selective metallization on diverse substrates

For breaking through the limitation of metal patterning in constructing conductive pathways of electronic devices, which is proposed to be an upgrade of traditional etching technique, a photo-reversible, transparent and soluble polyimide carrying spiropyran side chains is synthesized. The merocyanine isomers produced from the spiropyran moieties under digitalized ultraviolet irradiation bind the silver−histidine complexes in water, while the absorbed silver ions are in-situ reduced into metal silver seeds by the photo-generated radicals from histidine molecules, catalyzing copper deposition and yielding the desired copper patterns. Accordingly, the conventional time-consuming steps (like surface modification, immobilization of catalytic ions and (photo)chemical reduction) are simplified to a single one, and the environmentally unfriendly solvent and costly/toxic palladium reagent are excluded. The Cu patterns deposited on the polyimide show high resolution, electrical conductivity (1.785 × 10−6 Ω‧cm), adhesion strength (18.14 MPa) and fatigue resistance (> 2.6 million cycles of bending). Due to the absence of invasive surface treatments (e.g., surface hydrolysis and laser direct structuring), extremely low surface roughness of 7.83 nm is achieved. Besides, the developed strategy can be easily expanded to stretchable elastomer and other organic/inorganic substrates with irregular surfaces, showing promising application prospects. The solubility of the polyimide and ultraviolet/visible light triggered reversibility of the included spiropyran groups further enable repeated recycling, erasing and re-patterning.

Phototunable and Photopatternable Polymer Semiconductors.

ConspectusIn recent decades, there has been rapid development in the field of polymer semiconductors, particularly those based on conjugated donor-acceptor (D-A) polymers exhibiting high charge mobilities. Furthermore, the application of polymer semiconductors has been successfully extended to a wide range of functional devices, including sensors, photodetectors, radio frequency identification (RFID) tags, electronic paper, skin electronics, and artificial synapses. Over the past few years, there has been a growing focus on stimuli-responsive polymer semiconductors, which have the potential to impart additional functionalities to conventional field-effect transistors, garnering increased attention within the research community. In this context, phototunable polymer semiconductors have received significant attention due to their ability to utilize light as an external stimulus, enabling remote control of device performance with high spatiotemporal resolution. Meanwhile, integration of field-effect transistors with polymer semiconductors can enable the realization of complex functions. To achieve this, precise and controllable patterning of polymer semiconductors becomes essential. In this Account, we discuss our research findings in the context of phototunable and photopatternable polymer semiconductors. These developments encompass the following key aspects: (i) polymer semiconductors, such as poly(diketopyrrolopyrrole-quaterthiophene) (PDPP4T), exhibit phototunability when blended with the photochromic compound hexaarylbiimidazole (HABI). The photo/thermal-responsive field-effect transistors (FETs) can be fabricated using blending thin films. Remarkably, these photo/thermal-responsive transistors can function as photonically programmable and thermally erasable nonvolatile memory devices. (ii) By incorporating photoswitchable groups like azo and spiropyran into the side chains of conjugated D-A polymers, we can create phototunable polymer semiconductors. The reversible isomerization of azo and spiropyran groups significantly influences the charge transport properties of these polymer semiconductors. Consequently, the performance of the resulting FETs can be reversibly tuned through UV/visible or near-infrared light (NIR) irradiation. Notably, the incorporation of two distinct azo groups into the side chains leads to polymer semiconductors with tristable semiconducting states, offering the ability to logically control device performance using light irradiation at three different wavelengths. (iii) Photopatterning of p-type, n-type, and ambipolar semiconductors featuring alkyl side chains can be achieved using a diazirine-based, four-armed photo-cross-linker (4CNN) with a loading concentration of no more than 3% (w/w). Furthermore, the semiconducting performances of FETs with patterned thin films were found to be satisfactorily uniform. Importantly, the cross-linked thin films are robust and show good resistance to organic solvents, which is useful for fabricating all-solution processable multilayer electronic devices. (iv) The introduction of azide groups into the side chains of conjugated polymers results in a single-component semiconducting photoresist. The presence of azide groups renders the side chains with photo-cross-linking ability, enabling the successful formation of uniform patterns, even as small as 5 μm, under UV light irradiation. Benefiting from the single component feature, field-effect transistors with individual patterned thin films display satisfactorily uniform performances. Moreover, this semiconducting photoresist has proven effective for efficiently photopatterning other polymer semiconductors, demonstrating its versatility.

Photoresponsive Spiropyran and DEGMA-Based Copolymers with Photo-Switchable Glass Transition Temperatures.

Herein, novel photoresponsive spiropyran (SP)-based P(DEGMA-co-SpMA) copolymers with variable percentages of SP fractions are synthesized. The SP group present in these polymers exhibited the abilities of reversible photoisomerism. Their photoresponsive, structural, and thermal properties have been investigated and compared using various characterization techniques. These light-responsive copolymers are found to exhibit photoswitchable glass transition temperature (Tg ), high thermal stability (Td > 250°C), instant photochromism as well as fluorescence upon exposure to UV light. It is demonstrated that the Tg of these synthesized polymers increased when irradiated with UV light (λ = 365nm), as a consequence of the photoisomerization of incorporated SP groups into their merocyanine form. This increase in Tg is attributed to an increase in polarity and a decrease in the overall entropy of the polymeric system when it switches from the ring-closed SP form (less-ordered state) to the ring-opened merocyanine form (more-ordered state). Therefore, such polymers with a unique feature of phototunable glass transition temperatures provide the possibility to be integrated into functional materials for various photoresponsive applications.

The guest CH3CN molecule triggers solid-state photochromism in a Cu2I2-based MOF for advanced time-dependent encryption and inkless erasable printing

It remains a big challenge to develop solid-state stimuli-responsive materials for time-dependent information encryption and inkless erasable printing with long retention times. Herein, a 2D Cu2I2-based MOF with photoresponsive spiropyran (SP) groups orderly installed on its skeleton is developed. The structural isomerization from SP to colored merocyanine (MC) form can be triggered by removing the CH3CN guests. Besides, the degree of structural isomerization and the retention time can be adjusted by controlling the amount of CH3CN guests, exhibiting dynamic photochromic behavior with multicolor states and tunable retention time. Based on these advantages, time-dependent information encryption is successfully achieved. Furthermore, the long retention time (>72 h) of the MC form under daylight conditions in the CH3CN-removed Cu2I2-based MOF and good repeatability make it promising in various applications, such as temporary calendars, price-cards, billboards, and reusable identity cards. This work provides a novel design strategy to fabricate multi-functional MOF-based smart materials for challenging applications of time-dependent information encryption and inkless erasable printing.

Photochromic and Luminescent Properties of a Salt of a Hybrid Molecule Based on C60 Fullerene and Spiropyran-A Promising Approach to the Creation of Anticancer Drugs.

For the first time a pyrrolidinofullerene salt containing a spiropyran group and an ammonium group, capable of reversibly reacting to UV radiation, has been synthesized. Photoinduced reactions of the synthesized compounds were studied using absorption and luminescence spectroscopies, spectral and kinetic characteristics were measured. The hybrid molecule was found to exhibit intrinsic fluorescence even in the spirocyclic form. The C60 derivative showed a higher stability and better spectral and luminescent properties than the precursor.

Photoresponsive reversible self-assembly of rod-coil amphiphiles containing spiropyran groups.

Stimuli-responsive assembly deformation is a key feature in constructing smart soft materials, which makes them versatile and autonomous. In this study, rod-coil amphiphilic compounds containing spiropyran (SP) groups were developed and synthesized to investigate their stimuli-responsive assembly in a solution system with 99% water content. In addition to photochromic phenomena, reversible light-mediated morphological alterations occurred in these molecular aggregates. Based on the different flexible chain segments of rod-coil amphiphiles, the initial assemblies underwent a dissociation-reassembly process under ultraviolet (UV) irradiation, whereupon they deformed or disassembled to assemblies. Furthermore, as the UV source was removed, the original nanostructures were gradually recovered again via the ring-closing reaction process. These compounds, interestingly, can selectively combine with copper ions to produce cross-linked co-assembled nanostructures. The copper ion complex solution of rod-coil amphiphilic compounds emitted unique bright blue fluorescence, which allowed for the specific visual identification of copper ions in aqueous solutions.

Photo-controlled fluorescence “Double-Check” for human serum albumin and its applications

Photo-controlled method may improve the accuracy of fluorescent probes. Here, two new fluorescent probes HSP and MSP were designed based on naphthalimide and spiropyran. HSP exhibits a fluorescent emission at 540 nm after Human Serum Albumin (HSA) was added. Then with UV light irradiation, the spiropyran group of HSP is isomerized into the merocyanine, and the HSP/HSA hybrid displays red fluorescence emission at 610 nm, which demonstrats the probe have a unique fluorescence "double-check" mechanism to accurately detect HSA. As a comparison, a new probe MSP which structure similar to HSP was designed. Compared with HSP, the recognition effect of probe MSP on HSA is not obvious, which showed that the hydrophilic group hydroxyl displays an important influence on the response of the probe HSP to HSA. In addition, the HSP/HSA hybrid can also be used to detect SO2 effectively. Most importantly, we have successfully applied HSP/HSA hybrid to image SO2 in living cells.

Spiropyran-based photoswitchable acrylic nanofibers: A stimuli-responsive substrate for light controlled C6 glioma cells attachment/detachment

Reversible and remote cell manipulation with high spatiotemporal precision is now a highly attractive subject in various biological applications such as tissue engineering and cell-matrix interaction. Herein, photoresponsive poly(methyl methacrylate-co-hydroxy ethyl methacrylate-co-spiropyran ethyl acrylate) terpolymer (MHSP) was prepared using emulsion polymerization and the corresponding nanofibers (MHSP@NF) and film (MHSP@F) were prepared using electrospinning and drop-casting techniques, respectively. Structure of MHSP@NF with cylindrical cross-section and uniform diameter size of 169 nm were characterized by 1H-NMR and SEM analyses. Time-dependent UV–vis spectra of the prepared acrylic nanofibers and films demonstrated maximum forward photoisomerization after 3- and 8-min UV irradiation at 365 nm together with a 96° and 5° decrement in their surface water contact angles, respectively. High photoresponsivity of the nanofibers was attributed to their extensive surface area which exposes more spiropyran groups to UV light. MHSP@F and MHSP@NF with chemically-attached spiropyran groups demonstrated significant biocompatibility with negligible toxicity toward C6 glioma cancer cells up to 5 days. However, MH/SP@NF with doped SPOH exhibited a sudden decrease in cell viability relating to the migration and leakage of SPOH molecules. Photoreversible cell adhesion results showed a dramatic and switchable C6 cells attachment/detachment upon alternating UV and visible lights irradiations for MHSP@NF sample, while this was not observed for the similar film. These indicate potentiality of MHSP@NF as a promising substrate for dynamic switching of biomolecules and cell sheet engineering.

Magneto-responsive photochromic acrylic copolymer nanoparticles: An investigation into the mutual interactions and photoisomerization kinetics

Photoresponsive and magneto-responsive smart materials have received specific attention. Here, novel bifunctional polyacrylic nanoparticles were prepared via miniemulsion polymerization in which, magnetite nanoparticles (10–15 nm) were resided in the core and poly (methyl methacrylate-co-spiropyran ethyl acrylate) (poly (MMA-co-SPEA)) was located in the shell. Chemical bonding of spiropyran onto the surface of magnetite provided their close vicinity, leading to effective interactions which have not been studied before. The interactions between the excited state of merocyanine (MC) zwitterion from spiropyran (SP) group and magnetic field of the superparamagnetic Fe3O4 NPs were investigated. The results revealed the existence of mutual interactions and successful increment in the absorption intensity (up to 176%) and optical stability, 9% changes in the rate of photoisomerization and increment in the half life time of MC isomers. These were achieved in the presence of magnetite as well as enhancement in the magnetic properties by 10% under UV irradiation at 365 nm. Such synergistic and two-way interactions between magnetic field of the superparamagnetic Fe3O4 NPs and the produced instant dipole moments in MC may offer a new route toward preparation of dual responsive nanocomposite particles for light-triggered magnetic switches, magnetic-triggered photo switches and simultaneous sensing and separation probes.

Facile access to photo-switchable, dynamic-optical, multi-colored and solid-state materials from carbon dots and cellulose for photo-rewritable paper and advanced anti-counterfeiting

Dynamic optical materials can respond to external stimuli to give intriguing and chameleon-like visual effect and carry more information, they hence have attracted considerable attention. In this work, we propose a simple and efficient strategy to construct multi-color solid-state carbon dots (CDs) materials with photo-switchable and reversible dynamic-optical properties. A photochromic and positively-charged cellulose derivative C-Im+-SP with an imidazole salt (Im+) group and a spiropyran (SP) group is designed and synthesized. Subsequently, C-Im+-SP is spontaneously coated on the surface of negatively-charged CDs (NCDs) via electrostatic attraction to form a physical protective shell, which not only inhibits aggregation-caused quenching (ACQ) in NCDs but also promotes effective fluorescence resonance energy transfer (FRET). The resultant NCDs@C-Im+-SP exhibits a photo-triggering reversible dynamic-optical property. The NCDs to C-Im+-SP ratio can be used to effectively regulate fluorescence emission and fluorescence kinetics. The polymeric C-Im+-SP shell layer endows NCDs with excellent processability and formability, whereby NCDs@C-Im+-SP materials can be utilized as functional coatings and inks to fabricate photo-rewritable paper and dynamic anti-counterfeit patterns that have considerable potential applications for special coatings, complex anti-counterfeiting, and information encryption.

Multi-Stimuli-Responsive Field-Effect Transistor with Conjugated Polymer Entailing Spiropyran in the Side Chains

Multi-stimuli-responsive field-effect transistors (FETs) with organic/polymeric semiconductors have received increasing attention. Herein, we report a novel strategy for fabricating multi-stimuli-r...

Heat Stroke in Cell Tissues Related to Sulfur Dioxide Level Is Precisely Monitored by Light-Controlled Fluorescent Probes.

Heat stroke (HS) can cause serious organism damage or even death. Early understanding of the mechanism of heat cytotoxicity can prevent or treat heat stroke related diseases. In this work, probe Ly-NT-SP was synthesized, characterized, and used for sulfur dioxide (SO2) detection in lysosomes. PBS solutions of probe Ly-NT-SP at pH 5.0 present a marked broad emission band in the green zone (535 nm). After UV irradiation, the spiropyran group in Ly-NT-SP isomerizes to the merocyanine form (Ly-NT-MR), which presented a weak red-shifted emission at 630 nm. In addition, photocontrolled isomerization of Ly-NT-SP to Ly-NT-MR generated a C═C-C═N+ fragment able to react, through a Michael addition, with SO2 to yield a highly emissive adduct with a marked fluorescence in the green channel (535 nm). In vitro studies showed a remarkable selectivity of photoactivated Ly-NT-MR to SO2 with a limit of detection as low as 4.7 μM. MTT viability assays demonstrated that the Ly-NT-SP is nontoxic to HeLa cells and can be used to detect SO2 in lysosomes. Taking advantage of this, the sensor is successfully applied to image increasing SO2 values in lysosomes during heat shock for the first time. Moreover, we also confirmed that the increased SO2 can protect the small intestine against damage induced by heat shock through regulating oxidative stress in cells and mice.

Preparation and analysis of photochromic behavior of carboxymethyl chitin derivatives containing spiropyran moieties

ABSTRACT 1ʹ-(2-Acryloxyethyl)-3,3ʹ-dimethyl-6-nitrospiro[2 H-1-benzopyran-2,2ʹ-indoline] (SPA) was synthesized and grafted onto a water-soluble carboxymethyl chitin (CMCH) macromolecule to prepare a photochromic copolymer (CMCH-g-SPA). The structure of CMCH-g-SPA was characterized by Fourier-transform infrared (FT-IR) spectroscopy, thermogravimetric (TG) analysis, X-ray diffraction (XRD) analysis, water-solubility evaluation, and UV-vis spectroscopy. XRD patterns of CMCH-g-SPA revealed that grafting copolymerization disrupts the CMCH semicrystalline structure, thus improving water solubility. UV-vis spectroscopy results supported the negative photochromic behavior of the merocyanine (MC) form of CMCH-g-SPA (CMCH-g-MCA) present in a water solution of the target copolymer. In addition to high solvent polarity, the intermolecular and intramolecular electrostatic attraction between the indolenine cation and the COO− anion were found to be influencing factors, which stabilize these MC form of spiropyran groups grafted onto CMCH. In a water solution, visible light bleaching was completed over a short period (8 minutes) under artificial visible light irradiation and the thermal coloration reaction, whose rate constant at 25 °C was 4.64 × 10−4 s−1, which fit the first-order reaction equation. After ten photochromic cycles in water solution, the relative absorption intensity of CMCH-g-MCA decreased by 7.92%.

Poly(2‐isopropyl‐2‐oxazoline) Bearing a Spiropyran Side‐Chain: Synthesis and Evaluation of Photo and Temperature‐Responsive Properties

AbstractPoly(2‐isopropyl‐2‐oxazoline)s with varied loading of the spiropyran side‐chain are synthesized, and their photochemical and thermosensitive properties are characterized in aqueous solution. The absorption spectrum of the sample aqueous solution (0.1 wt%) indicates that 7.8 mol% of the pendant groups are in the zwitterionic merocyanine form. The introduction of spiropyran groups causes a marked decrease in the cloud point of the aqueous solution even when the pendant groups contain the zwitterionic merocyanine form. The cloud point of the aqueous solution of the samples in the spiropyran form is slightly (less than 1 °C) lower than that bearing the merocyanine group. Moreover, the photoinduced phase transition is demonstrated at an optimum temperature for the spiropyran‐bearing poly(2‐isopropyl‐2‐oxazoline). This material can be made applicable to a light‐driven drug releasing system by introducing a hydrophobic group to form micelles and increasing the photoinduced change of the cloud point.

Reversible Surface Wettability Control of Fluorinated Polyimides Having Spiropyran Groups by Photo-irradiation

Reversible Surface Wettability Control of Fluorinated Polyimides Having Spiropyran Groups by Photo-irradiation

Reversible Surface Wettability Change of Polyimide Having Spiropyran Groups by Photo-irradiation

Reversible Surface Wettability Change of Polyimide Having Spiropyran Groups by Photo-irradiation

Enhanced Photogeneration of Reactive Oxygen Species and Targeted Photothermal Therapy of C6 Glioma Brain Cancer Cells by Folate-Conjugated Gold-Photoactive Polymer Nanoparticles.

Tumor-selective photodynamic therapy is a successful method for ablation of malignant and cancerous cells. Herein, we introduce the design and preparation of functionalized acrylic copolymer nanoparticles with spiropyran (SP) and imidazole groups through a facile semicontinuous emulsion polymerization. Then, Au3+ ions were immobilized and reduced on their surface to obtain photoresponsive gold-decorated polymer nanoparticles (PGPNPs). The prepared PGPNPs were surface-modified with folic acid as a site-specific tumor cell targeting agent and improve intracellular uptake via endocytosis. Fourier transform infrared spectroscopy and energy dispersive X-ray spectroscopy analyses, UV-vis spectroscopy, scanning electron microscopy, and high-resolution transmission electron microscopy images were employed to characterize their spectral and morphological properties. Fluorescence microscopy images and inductively coupled plasma analysis demonstrated the cell line labeling capability and improved targeting efficiency of folate-conjugated PGPNPs (FA-PGPNPs) toward rat brain cancer cells (C6 glioma) with 71.8% cell uptake in comparison with 28.8% for the nonconjugated ones. Nonpolar SP groups are converted to zwitterionic merocyanine isomers under UV irradiation at 365 nm and their conjugation with Au nanoparticles exhibited enhanced photogeneration of reactive oxygen species (ROS). These were confirmed by intracellular ROS analysis and cytotoxicity evaluation on malignant C6 glioma cells. Owing to the strong surface plasmon resonance absorption of gold nanoparticles, FA-PGPNPs provided elevated local photothermal efficiency under near-IR irradiation at 808 nm. The prepared multifunctional FA-PGPNPs with a comprehensive integration of prospective materials introduced promising nanoprobes with targeting ability, enhanced tumor photodynamic therapy, cell tracking, and photothermal therapy.

Photoregulating Antifouling and Bioadhesion Functional Coating Surface Based on Spiropyran.

Dynamic regulation of the interactions between specific molecules on functional surfaces and biomolecules, for example, proteins or cells, is critical for biosensor and biomedical devices. Herein, we present a spiropyran (SP)-based light-responsive surface coating, hPG (hyperbranched polyglycerol)-SP, to control the adsorption of proteins and adhesion of cells. In the normal state, the SP groups on the coating surface were in hydrophobic ring-closed form, which promotes the nonspecific protein adsorption and cell adhesion. Under UV irradiation, the grafted SP groups were dynamically isomerized into hydrophilic/zwitterionic merocyanine. Both hydrophilicity and zwitterions support the formation of a hydrated layer and hence the resulting hPG-MC coatings highly resist protein adsorption and cell adhesion. Moreover, the presented hPG also provided a robust bioinert background to suppress the nonspecific protein adsorption and cells adhesion. Therefore, this functionalized coating exhibited a good photoregulated antifouling behavior. Moreover, the detachment of adsorbed proteins and adhered cells from the coating surface was also realized.

Anderson-Type Polyoxometalates Functionalized by Tetrathiafulvalene Groups: Synthesis, Electrochemical Studies, and NLO Properties.

Three polyoxometalates (POMs) functionalized by tetrathiafulvalene (TTF) molecules have been synthesized by a coupling reaction between the Anderson-type POMs [MnMo6O18{(OCH2)3CNH2}2]3- or [AlMo6O18(OH)3{(OCH2)3CNH2}]3- and the TTF carboxylic acid derivative (MeS)3TTF(S-CH2-CO2H). The monofunctionalized TTF-AlMo6 POM contains one TTF group covalently grafted on an Al Anderson platform. The symmetrical TTF-MnMo6-TTF POM possesses two TTF groups grafted on each side of a Mn Anderson derivative while the asymmetrical TTF-MnMo6-SP POM contains a TTF and a spiropyran groups. These three trianionic species have been characterized by elemental analysis, 1H and 13C NMR, FT-IR spectroscopy, ESI-MS spectrometry, and single-crystal X-ray diffraction (for TTF-MnMo6-TTF). In the solid state, the grafted TTF molecules of TTF-MnMo6-TTF POMs interact via S···S and π···π interactions and form chains. The electrochemical properties of the complexes reflect the contributions of both the inorganic POM and the TTF moieties. Despite adsorption of the oxidized hybrid species on the Pt grid working electrode, UV-vis-NIR spectroelectrochemical investigations evidence peaks characteristic of the oxidation of the TTF units. Finally, hyper-Rayleigh scattering (HRS) measurements show that the three novel TTF derivatives exhibit β values between 20 and 37 × 10-30 esu. Moreover it is observed that the oxidation of the TTF moieties by Fe3+ ions increases the NLO response. These values are in the order of magnitude of that found for the well-known 4-dimethylamino- N-methyl-4-stilbazolium (DAS+) cation (β = 60 × 10-30 esu).