Photochromic Diarylethene Research Articles

Morphological control for hollow rod crystals of a photochromic diarylethene on spherulites by surface properties of substrates.

Sublimation methods utilizing the surface properties of substrates can address the challenge of controlling hollow morphologies in rod crystals. Spherulites were formed on the hydrophilic surface of the (0001) planes of α-quartz and sapphire substrates by sublimation of 1,2-bis(3,5-dimethyl-2-thienyl)perfluorocyclopentene (1a). Various types of hollow morphologies, distinguished by the size and shape of their cross sections and by the presence or absence of branching structures, were formed separately on α-quartz and sapphire substrates. Such precise control of the hollow morphologies was attributed to the wettability of each substrate, leading to the formation of spherulites of 1a. In addition, it was indicated that the formation process of the surface morphologies of spherulites was associated with the hollow morphologies of rod crystals of 1a.

Investigation on luminescence photoswitching stability in diarylethene-perovskite quantum dot hybrids.

Perovskite quantum dots (pQDs) have gathered a lot of attention because of their outstanding optoelectronic properties. Photoswitchable pQDs have the potential for application in single particle optical memories and bio-imaging. Hybrids of photochromic diarylethenes (DAE) and pQDs show a luminescence photoswitching property, however, the cycle stability in such systems is low because of photoinduced electron transfer (PET) from pQDs to DAE. In this study, various hybrids of DAEs and pQDs with different spacer lengths between the pQD donors and DAE acceptors were synthesized and their stability towards multiple cycles of luminescence photoswitching was evaluated. It was found that the electron transfer pathway can be blocked and very stable switchable hybrids can be produced when the distance between the donors and acceptors was long enough. Furthermore, the effect of softness of the basic ligands and the synthesis method of the pQDs on the cycle stability of the hybrids were investigated. The findings of this study suggest that the photoswitching stability can be improved in hybrid systems by proper molecular design of the photochromic molecule.

A Visible-Light-Responsive Fluorescent Diarylethene Having a Betaine Structure.

As a new molecular scaffold of photoswitchable fluorophore, we developed a photochromic diarylethene containing a betaine structure based on pyridinium N-enolate. A facile reaction of a pyridyl-substituted dithienylperfluorocyclopentene derivative with octafluorocyclopentene constructed the betaine structure. The introduction of the betaine moiety provided the diarylethene molecule with bathochromically shifted optical absorption and fluorescing ability, thus enabling the molecule to function as a visible-light-sensitive turn-off mode photoswitchable fluorophore. The molecule in the open-ring form emitted bright blueish green fluorescence. Upon irradiation with 405 nm light, the molecule underwent cyclization isomerization to form the closed-ring isomer and the fluorescence intensity significantly decreased. The turn-off mode fluorescence photoswitching was observed not only in solution but also in polymer films.

Photo-Modulation of Atomically Thin Molybdenum Diselenides Functionalized with Photochromic Molecules

Two-dimensional (2D) transition metal dichalcogenide semiconductors have garnered significant attention due to their extraordinary electrical and optical properties. It has been increasingly important to develop strategies for modulating their properties. A number of methods have been introduced, including doping, electric and magnetic fields, mechanical strain, etc. Herein, we report a novel approach of using photochromic molecules to modulate optoelectronic properties of monolayer MoSe2 with light. We have synthesized photochromic diarylethene (DAE) molecules that can switch between two isomeric forms, referred to as open and closed, under UV and visible light, respectively. The DAE molecules formed a uniform layer with a thickness of approximately 2 nm on monolayer MoSe2. Our density functional theory (DFT) calculations suggest that the TMD and DAE will align their band energy levels such that UV irradiation moves the lowest unoccupied molecular orbital (LUMO) energy of DAE in between the conduction band minimum (CBM) and valence band minimum (VBM) of MoSe2. This will facilitate photoexcited electron transfer from MoSe2 to DAE LUMO. Experimentally, we have confirmed our predictions by observing a strong quenching of photoluminescence (PL) and an increase of electrical conductivity in MoSe2. In contrast, visible light induced isomerization to the open form of DAE and expanded its energy levels, moving the LUMO level above the MoSe2 CBM. Therefore, the PL was retained and there was no significant change in electrical conductivity. We showed that this photoswitching can dynamically modulate the optoelectronic properties by demonstrating multiple cycles of PL emission and quenching, by alternating UV and visible light repeatedly. Lastly, our Kelvin probe force microscopy (KPFM) revealed that the potential of MoSe2 monolayers can also be modulated with photochromic molecules and external light irradiation. Our work elucidates photo-processes and exciton mechanisms at the hybrid interfaces and lays the foundation for novel applications including new phototransistors and other 2D optoelectronic devices.

Unconventional Photoswitching Behavior of a Diarylethene‐Perylenediimide Dyad in Nanoparticles Emerging from Multiple Intermolecular Energy Transfer Processes

AbstractPhotoswitchable fluorescent systems based on photochromic derivatives have various applications, including high‐resolution imaging and information processing. In this context, a key objective is to control, manipulate, and improve the fluorescence photoswitching of molecular systems. Herein, the intriguing zero‐order photokinetics properties of a photochromic‐fluorescent dyad made of one perylenediimide fluorophore (PDI) and two diarylethene photochromes (DAE) are reported, in the nanoparticles state, resulting from efficient intra‐ and intermolecular energy transfer processes from the PDI to the DAE, well‐rationalized by modified photokinetics equations for photochromism. It allowed the fine‐tuning of the photokinetics, leading to either classical or unconventional behavior, depending on the irradiation wavelength. Fluorescence photoswitching is investigated under a microscope, demonstrating a sigmoidal profile for fluorescence recovery which can be satisfyingly reproduced by a suitable mathematical model that is developed. These findings represent a significant advance in the development of enhanced photoswitchable fluorescent systems, showing high contrast, driven by few photons with tunable switching rates.

Mechanically Induced Transient Fluorescence of Photochromic Diarylethene Crystals for Sensing and Security Material

AbstractLuminescent materials responding to mechanical stimulation can visualize the strain and mechanical damage applied to objects. Mechanofluorochromism is a well‐known phenomenon induced by the mechanical force on fluorescent crystalline materials. However, simple application of the mechanofluorochromism is unsuitable for temporally and spatially detecting stress in detail because the fluorescent state is kept for rather long period. Here, the dynamic stress‐sensing luminescent solid material of a photochromic diarylethene with a fluorescent moiety is reported. Under the stress applied to the crystalline state, this material emitted cyan‐colored transient fluorescence that is rapidly diminished within a few second. This dynamic fluorescence phenomenon is well controlled by the combination of light irradiation and other external stimuli (organic solvent vapor and/or heat). In addition, the luminescence period is regulated by the excitation wavelength and magnitude of applied force. By utilizing these responses, the rewritable dynamic information encryption is successfully demonstrated. This material with transient fluorescence overcomes the persistence of fluorescence color of mechanochromism and present results provide a new principle for multifunctional light‐emitting materials responding to mechanical stimulation.

ДИОКСАЗОЛИЛЭТЕНЫ – СИНТЕЗ, ФОТОПЕРЕКЛЮЧЕНИЕ И РЕАКЦИИ С СИНГЛЕТНЫМ КИСЛОРОДОМ

Our work proposes a new group of photochromic diarylethenes based on oxazole. The method of their synthesis is based on the dimerization reaction of acetyloxazoles according to McMurry in the presence of low-valent titanium

Photoswitchable optoelectronic properties of 2D MoSe2/diarylethene hybrid structures

The ability to modulate optical and electrical properties of two-dimensional (2D) semiconductors has sparked considerable interest in transition metal dichalcogenides (TMDs). Herein, we introduce a facile strategy for modulating optoelectronic properties of monolayer MoSe2 with external light. Photochromic diarylethene (DAE) molecules formed a 2-nm-thick uniform layer on MoSe2, switching between its closed- and open-form isomers under UV and visible irradiation, respectively. We have discovered that the closed DAE conformation under UV has its lowest unoccupied molecular orbital energy level lower than the conduction band minimum of MoSe2, which facilitates photoinduced charge separation at the hybrid interface and quenches photoluminescence (PL) from monolayer flakes. In contrast, open isomers under visible light prevent photoexcited electron transfer from MoSe2 to DAE, thus retaining PL emission properties. Alternating UV and visible light repeatedly show a dynamic modulation of optoelectronic signatures of MoSe2. Conductive atomic force microscopy and Kelvin probe force microscopy also reveal an increase in conductivity and work function of MoSe2/DAE with photoswitched closed-form DAE. These results may open new opportunities for designing new phototransistors and other 2D optoelectronic devices.

Design and Synthesis of a Black Photochromic Diarylethene for Bioinspired Display Applications

Design and Synthesis of a Black Photochromic Diarylethene for Bioinspired Display Applications

Polaron interfacial entropy as a route to high thermoelectric performance in DAE-doped PEDOT:PSS films.

Enhancing the thermoelectric transport properties of conductive polymer materials has been a long-term challenge, in spite of the success seen with molecular doping strategies. However, the strong coupling between the thermopower and the electrical conductivity limits thermoelectric performance. Here, we use polaron interfacial occupied entropy engineering to break through this intercoupling for a PEDOT:PSS (poly(3,4-ethylenedioxythiophene)-poly(4-styrenesulfonate)) thin film by using photochromic diarylethene (DAE) dopants coupled with UV-light modulation. With a 10-fold enhancement of the thermopower from 13.5 μV K-1 to 135.4 μV K-1 and almost unchanged electrical conductivity, the DAE-doped PEDOT:PSS thin film achieved an extremely high power factor of 521.28 μW m-1 K-2 from an original value of 6.78 μW m-1 K-2. The thermopower was positively correlated with the UV-light intensity but decreased with increasing temperature, indicating resonant coupling between the planar closed DAE molecule and PEDOT. Both the experiments and theoretical calculations consistently confirmed the formation of an interface state due to this resonant coupling. Interfacial entropy engineering of polarons could play a critical role in enhancing the thermoelectric performance of the organic film.

Reversible change of luster color from pale yellow to wine red in microcrystalline film by photochromic diarylethene having a naphthyl group

Microcrystalline film prepared by photochromic diarylethene having a naphthyl group can reversibly change its luster color from pale yellow to wine red upon irradiation with light of different wavelengths.

Photoluminescence switching in quantum dots connected with fluorinated and hydrogenated photochromic molecules.

We investigate switching of photoluminescence (PL) from PbS quantum dots (QDs) crosslinked with two different types of photochromic diarylethene molecules, 4,4'-(1-cyclopentene-1,2-diyl)bis[5-methyl-2-thiophenecarboxylic acid] (1H) and 4,4'-(1-perfluorocyclopentene-1,2-diyl)bis[5-methyl-2-thiophenecarboxylic acid] (2F). Our results show that the QDs crosslinked with the hydrogenated molecule (1H) exhibit a greater amount of switching in photoluminescence intensity compared to QDs crosslinked with the fluorinated molecule (2F). With a combination of differential pulse voltammetry and density functional theory, we attribute the different amount of PL switching to the different energy levels between 1H and 2F molecules which result in different potential barrier heights across adjacent QDs. Our findings provide a deeper understanding of how the energy levels of bridge molecules influence charge tunneling and PL switching performance in QD systems and offer deeper insights for the future design and development of QD based photo-switches.

High-contrast multicolour photoswitching based on dithienylethene Schiff base with a hydrazinylquinoline moiety

A new asymmetrical photochromic diarylethene DTE-HQo composed of a 2-hydrazinoquinoline moiety as the binding unit for ions and dithenylethene as a photoswitching trigger was reported. DTE-HQo displayed favourable photochromism upon irradiation with UV/vis light. Its fluorescent behaviour could be efficiently modulated by light, Zn2+, Cd2+ and HSO4−. The binding of Zn2+ induced a strong fluorescence peak at 510 nm in DTE-HQo due to the formation of a 1:2 complex [Zn2+ + 2DTE-HQo], resulting in a notable colour change from dark to intense white emission. Triggered by Cd2+, DTE-HQo formed a 1:1 complex [Cd2+ + DTE-HQo], leading to an enhanced emission intensity by 21-fold with an emission peak red-shifted from 461 nm to 514 nm. Unexpectedly, [Zn2+ + 2DTE-HQo] underwent hydrolysis when stimulated with water, generating a yellow-emitting complex [Zn2+ + DTE-HQo]. This color change easily distinguishes it from Cd2+ complex. Additionally, DTE-HQo showed high selectivity towards HSO4− and exhibited distinct “turn-on” fluorescence with a colour change from dark to bright blue upon stimulation. Moreover, the strong emission complexes of DTE-HQo with Zn2+, Cd2+ and HSO4− could be effectively quenched during the photocyclization process. Therefore, DTE-HQo can serve as an unimolecular multicolour photoswitching chemosensor, offering potential applications as a multifunctional probe for detecting Zn2+, Cd2+ and HSO4−.

Surface Glass Transition Temperature Region of Diarylethene Films Determined by Nano-Marangoni Effect.

For the last two decades, research has addressed whether the glass transition temperature and the molecular motions on the surface of organic films are significantly different from those inside the bulk glasses. It is reported that the surface of the photochromic diarylethene film prepared by vacuum deposition has fluidity and the vacuum deposition of small amount of rubrene molecules induces surface tension fluctuations, generating dents due to the Marangoni flow in nanoscale. The depth of the dents increases in proportion to these radii for the colorless diarylethene film with a bulk glass transition temperature (Tg) close to room temperature. On the other hand, in the colored diarylethene obtained by UV irradiation to the colorless film, the depth becomes constant at a certain level. The Tg distribution in the depth direction is clarified based on an analysis of the dent depth. By approximating the obtained Tg depth distribution with an exponential function, the outermost surface Tg is about 100 K lower than the bulk Tg in the case of photoisomerized diarylethene.

Cover Feature: Fabrication of Hyperbranched Photomechanical Crystals Composed of a Photochromic Diarylethene (ChemPlusChem 12/2023)

Cover Feature: Fabrication of Hyperbranched Photomechanical Crystals Composed of a Photochromic Diarylethene (ChemPlusChem 12/2023)

Fabrication of Hyperbranched Photomechanical Crystals Composed of a Photochromic Diarylethene.

We report the fabrication of hyperbranched hollow crystals of 1,2-bis(2,5-dimethyl-3-thienyl)perfluorocyclopentene on a concave surface of the spherical glass substrate by sublimation and their practical photomechanical behaviors. The number of units of the branched structure of the hollow crystals composed of this compound is proportional to the substrate curvature of the substrate. Compared with the sublimation process of the same compound on the flat glass substrate, two kinds of the thin film domains are generated separately in the center and around the edge of the spherical glass substrate. Especially under the high relative humidity condition, the boundaries between these thin film domains move gradually around the edge through the center during as long as 6 h of sublimation time so that the hyperbranched hollow crystals are densely produced on the entire surface of the substrate. These hyperbranched hollow crystals can be prepared with the highly ordered molecular packing due to the very slow formation process of the crystalline walls of the hollow structures. Furthermore, the photo-induced bending behaviors in the few- and highly-branched hollow crystals have the practical roles in moving and bending the minute objects according to their characteristics of these branched shapes.

A photo-controlled fluorescent switching based on carbon dots and photochromic diarylethene for bioimaging.

Carbon dots (CDs) as luminescent zero-dimensional carbon nanomaterials have good aqueous dissolution, photostability, high quantum yield, and tunability of emission color. It has great application potential in many fields, including bioimaging, labeling of biological species, drug delivery, and sensing in biomedical. However, controlling the fluorescence emission of carbon dots remains a formidable challenge. Herein, we designed and exploited a photo-controlled fluorescent switching based on photochromic diarylethene (DT) and CDs for bioimaging. It could be modulated reversibly between "ON" and "OFF" under UV/vis light exposure. The fluorescent modulation efficiency was as high as 95.3%. The fluorescent switching could be used to the bioimaging in HeLa cells with low cell toxicity. Therefore, this fluorescent switching could be a promising candidate in many potential application areas, especially in bioimaging.

Construction of a Reversible Solid-state Fluorescence Switching Via Photochromic Diarylethene and Si-ZnO Quantum Dots.

Developing fluorescence switching as functional system is highly desirable for potential applications in the fields of light-responsive materials or devices. Attempt to construct fluorescence switching system tend to focus on the high fluorescence modulation efficiency, especially in solid state. Herein, a photo-controlled fluorescence switching system was constructed with photochromic diarylethene and trimethoxysilane modified zinc oxide quantum dots (Si-ZnO QDs) successfully. It was verified by the measurement of modulation efficiency, fatigue resistance as well as theoretical calculation. Upon irradiation with UV/Vis lights, the system exhibited excellent photochromic property and photo-controlled fluorescence switching performance. Furthermore, the excellent fluorescence switching characters could also be realized in solid state and the fluorescence modulation efficiency was determined to be 87.4%. The results will provide new strategies to the construction of reversible solid-state photo-controlled fluorescence switching for the application in the fields of optical data storage and security labels.

Preparation of a photochromic diarylethene microcapsule with high fatigue resistant and printed on cotton fabric

Photochromic compounds have been widely used in many fields due to their excellent properties. However, their properties would degrade significantly, due to the influence of environmental factors, such as oxygen, pH, and so on. Using microencapsulation technology to protect them was one of the ways to maintain their original good performance. Herein, photochromic microcapsule with poly (methyl methacrylate) (PMMA) as shell material and photochromic diarylethene as core material was prepared by the solvent evaporation method. The results showed that the prepared microcapsule had uniform particle size, smooth surface, tight coating, excellent photochromic sensitivity, and outstanding fatigue resistance. In addition, the photochromic microcapsule was printed on cotton fabric by adhesive, which also showed excellent reversible photochromic properties, soap washing resistance, and acid and alkali resistance.

Photochromic Single-Component Organic Fulgide Ferroelectric with Photo-Triggered Polarization Response.

Organic photochromic compounds have been widely investigated for optical memory storage and switches. Very recently, we pioneeringly discovered optical control of ferroelectric polarization switching in organic photochromic salicylaldehyde Schiff base and diarylethene derivatives, differently from the traditional ferroelectrics. However, the study of such intriguing photo-triggered ferroelectrics is still in its infancy and relatively scarce. In this manuscript, we synthesized a pair of new organic single-component fulgide isomers, (E and Z)-3-(1-(4-(tert-butyl)phenyl)ethylidene)-4-(propan-2-ylidene)dihydrofuran-2,5-dione (1E and 1Z). They undergo prominent photochromism from yellow to red. Interestingly, only polar 1E has been proven to be ferroelectric, while the centrosymmetric 1Z does not meet the basic requirement for ferroelectricity. Besides, experimental evidence shows that the Z-form can be converted to the E-form by light irradiation. More importantly, the ferroelectric domains of 1E can be manipulated by light in the absence of an electric field, benefiting from the remarkable photoisomerization. 1E also adopts good fatigue resistance to the photocyclization reaction. As far as we know, this is the first example of organic fulgide ferroelectric reported with photo-triggered ferroelectric polarization response. This work has developed a new system for studying photo-triggered ferroelectrics and would also provide an expected perspective on developing ferroelectrics for optical applications in trap future.