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Rational design of a visible-light photochromic diarylethene: a simple strategy by extending conjugation with electron donating groups
摘要： Photochromic diarylethenes have been widely used in many fields. However, their cyclization process must be induced by UV light. In this article, a simple strategy is developed by extending π-conjugation with electron donating groups. The modified dirylethene derivative can photocyclolize under 405-nm light with a good photochromic efficiency. Meanwhile, its absorption and moderate fluorescence can be switched effectively in both directions by visible lights (405 and 520 nm, respectively) in different solutions and in living cells. We believe that this simple method will become a versatile strategy for developing various dirylethylenes with visible-light photochromism.
关键词： fluorescence photoswitching,diarylethylenes,photoreaction quantum yield,visible-light photochromism
更新于2025-11-19 16:56:35
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Solid materials with tunable reverse photochromism
摘要： Herein we report on a novel, straightforward and universal strategy to achieve solid materials with highly tunable reverse photochromism. This was accomplished by means of commercially available spiropyran dyes, which can produce different types of stable merocyanine states (i.e. non-protonated and protonated forms) displaying distinct reverse photochromic properties (i.e. colours and colouration rates). To finely control the concentration ratio of these species and, as such, tailor the optical performance of the photochromes, we exploited their differential interaction with surrounding media of distinctive nature (i.e. non-volatile protic and aprotic polar solvents). In this way, solutions displaying different photochromic responses were prepared for individual spiropyrans without requiring chemical derivatization, an approach that can be generalized to other spiro dyes with distinct acid-base properties. To transfer this behaviour to the solid state, core-shell capsules of these solutions were prepared, which were then used as ink materials for the fabrication of flexible polymeric films with unprecedented tunability of their photochromic properties that can be employed as rewritable multi-coloured devices.
关键词： rewritable devices,merocyanine forms,reverse/negative photochromism,spiropyrans,microcapsules
更新于2025-11-19 16:56:35
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Tuning Molecular Solar Thermal properties by modification of a promising norbornadiene photoswitch
摘要： Carefully targeted modifications to the norbornadiene-quadricyclane couple should give molecules with great potential for solar energy storage. Here we report the synthesis of derivatives of a well-studied compound, 2-cyano-3-anisyl norbornadiene (NBD5). The conjugation was extended by conversion of the nitrile into acrylonitrile and acrylate derivatives over two steps. Despite red-shifting the absorbance properties, the metastable quadricyclanes exhibited extremely short lifetimes. Meanwhile, treatment of NBD5 with acetyl halides in the presence of aluminum trihalides led to the formation of 7-acetyl norbornenes through a Meerwein-Wagner rearrangement. Subsequent transformations made it possible to synthesise norbornadienes with varying degrees of steric bulk at the 7-position of the molecular scaffold. It was found that the bulkier this group was, the more stable the quadricyclane form. This reaction sequence allows for the synthesis of norbornadiene derivatives which are more suited to molecular solar thermal applications in domestic heating despite providing a slightly lower energy density.
关键词： Meerwein-Wagner rearrangement,conjugation,strained molecules,photochromism,energy density
更新于2025-11-19 16:56:35
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Reversible luminescence modulation and temperature sensing properties of Pr <sup>3+</sup> /Yb <sup>3+</sup> codoped K <sub/>0.5</sub> Na <sub/>0.5</sub> NbO <sub/>3</sub> ceramics
摘要： In this work, we have prepared a novel (K0.5Na0.5)0.99-xPrxYb0.01NbO3 (abbreviated as KNN:xPr3+/0.01Yb3+, x=0.0006, 0.0008, 0.001, 0.002, 0.003 and 0.004) ceramic, which possess visible UC emissions, photochromic (PC) and optical thermometric properties. Under the excitation of a 980-nm diode laser, all the samples show the featured emissions of Pr3+ ions and the UC emission intensity is greatly dependent on the Pr3+ doping content. The optimal UC luminescence intensity is obtained at x=0.001. All the prepared samples show a strong PC reaction, and a large luminescence quenching degree (ΔRt) of 74.94% is found. The optical thermometric properties of both the irradiated and unirradiated KNN:0.001Pr3+/0.01Yb3+ ceramics in the temperature range of 123-573 K have been investigated via measuring the temperature-dependent UC emission spectra of green emissions, which originate from the two 3P1 and 3P0 thermally coupled levels. It has been found that the prepared samples have both excellent PC behaviors and temperature sensing performances. These results suggest that the KNN:xPr3+/0.01Yb3+ ceramics are promising candidates for the applications in PC reaction and thermometers.
关键词： Ferroelectrics,Thermometer,Upconversion,Rare-earth ions,Photochromism
更新于2025-11-14 15:28:36
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Hemithioindigos for cellular photopharmacology: desymmetrised molecular switch scaffolds enabling design control over the isomer-dependency of potent antimitotic bioactivity
摘要： Druglike small molecules with photoswitchable bioactivity – photopharmaceuticals – allow biologists to perform studies with exquisitely precise and reversible, spatial and temporal control over critical biological systems inaccessible to genetic manipulation. The photoresponsive pharmacophores disclosed have been almost exclusively azobenzenes, which has limited the structural and substituent scope of photopharmacology. More detrimentally, for azobenzene reagents, it is not researchers’ needs for adapted experimental tools, but rather protein binding site sterics, that typically force whether the trans (dark) or cis (lit) isomer is the more bioactive. We now present first hemithioindigo-based pharmacophores enabling photoswitchable control over endogenous biological activity in cellulo. HOTubs optically control microtubule depolymerisation and cell death in unmodified mammalian cells. Notably, we show how the asymmetry of hemithioindigos allows a priori design of either Z- or E- (dark- or lit)-toxic antimitotics, whereas the corresponding azobenzenes are exclusively lit-toxic. We thus demonstrate that hemithioindigos enable an important expansion of the substituent and design scope of photopharmacological interventions for biological systems.
关键词： Photopharmacology,Drug design,Photochromism,Cytoskeleton,Antiproliferation
更新于2025-09-23 15:23:52
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Photomechanical organic crystals as smart materials for advanced applications
摘要： Photomechanical molecular crystals are receiving great attention due to their efficient conversion of light into mechanical work and surpassing advantages including faster response time, higher Young’s modulus and ordered structure various measured photomechanical crystals with different motions (contraction, expansion, bending, fragmentation, hopping, curling and twisting) are springing up in the forefront of smart materials research. The photomechanical motions of these single crystals during irradiation is triggered by solid-state photochemical reactions and accompanied with phase transformation. This short review intends to summarize recent developments in the growing research on photoresponsive molecular crystals. The basic mechanisms of different kinds of photomechanical materials are described in detail, the recent advances of photomechanical crystals for promising applications as smart materials are also highlighted.
关键词： crystal engineering,photomechanical crystals,photochemistry,molecular machines,photochromism
更新于2025-09-23 15:23:52
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Metal-Organic Frameworks as Hosts for Fluorinated Azobenzenes: A Path Towards Quantitative Photoswitching with Visible Light
摘要： Fifteen new photochromic hybrid materials were synthesized by gas phase loading of fluorinated azobenzenes, namely ortho-tetrafluoroazobenzene (tF-AZB), 4H,4H'-octafluoroazobenzene (oF-AZB), and perfluoroazobenzene (pF-AZB), into the pores of the well-known metal-organic frameworks MOF-5, MIL-53(Al), MIL-53(Ga), MIL-68(Ga), and MIL-68(In). Their composition was analysed by elemental (CHNS) and DSC/TGA analysis. For pF-AZB0.34@MIL-53(Al) a structural model based on high-resolution synchrotron powder diffraction data was developed and the host-guest and guest-guest interactions were elucidated from this model. These interactions of O-H…F and π…π type were confirmed by significant shifts of the O-H frequencies in loaded and unloaded MOFs of the MIL-53 and MIL-68 series. Most remarkably, all of the synthesized F-AZB@MOF systems can be switched with visible light and some of them show almost quantitative (> 95 %) photo-isomerization between its E and Z forms with no significant fatigue after repeated switching cycles.
关键词： azobenzene,fluorinated derivatives,solid state switching,metal-organic frameworks,photochromism
更新于2025-09-23 15:23:52
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A Visible-Light-Driven Molecular Motor Based on Pyrene
摘要： The aromatic core of an overcrowded alkene-based molecular motor is extended with the goal of inducing isomerization with visible light instead of harmful UV light. In our design, the common naphthalene moiety in the upper half of the motor is changed to pyrene. The photochemical and thermal isomerization processes are studied in detail using DFT calculations as well as NMR and UV/vis spectroscopy. Our studies confirm that extension of the π-system of the upper half successfully leads to a shift of the excitation wavelength into the visible region, while retaining proper rotary function.
关键词： Molecular Switches,Photochromism,Overcrowded Alkenes,Molecular Motors,Pyrene
更新于2025-09-23 15:23:52
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A unimolecular platform based on diarylethene with multiple stimuli-gated photochromism
摘要： The gated photochromic systems have attracted great interest in scientific researches due to their merits in the opto-electronic fields, whereas the multi-stimuli gating function in a unimolecular platform has rarely been addressed. Herein, a new strategy to realize multi-stimuli gated photochromic function was devised relying on a simple Schiff-based diarylethene derivative. The compound shows no photoswitching properties in solution under irradiation with any wavelength of light. It is noteworthy that mecury(II) ions, water and protons can trigger its photo-reactivity independently with different absorption changes, respectively. Therefore, a molecular logic circuit with four inputs, including mecury(II) ions, water, protons and UV light, was fabricated on the basis of the unimolecular platform, suggesting promise for application in multi-controlled photoswitchings. These results could be valuable for the further development of photoswitchings with multiple stimuli responses.
关键词： Diarylethenes,photoswitching,molecular logic circuit,multiple stimuli responses,gated photochromism
更新于2025-09-23 15:23:52
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{μ-Bis(diphenylphosphino)methane}(1-alkyl-2-(arylazo)imidazole) copper(I) perchlorate : Synthesis, Structure and Photochromism
摘要： 1-Alkyl-2-(arylazo)imidazole (RaaiR/), a bidentate N(azo), N(imidazolyl) chelator, and bis(diphenylphosphino)methane (dppm), a P, P bridger, have been used to prepare phosphino bridged dinuclear-Cu(I) complexes, [Cu(μ-dppm)(RaaiR/)]2(ClO4)2. The structures of the complexes have been established by spectral (UV-Vis, IR, 1H-NMR) data and the confirmation has been done in case of [Cu(μ-dppm)(HaaiEt)]2(ClO4)2 by single crystal X-ray diffraction studies. Optical stimulation using UV light (365 nm) in methanol solution of the complexes shows that the coordinated RaaiR/ undergoes trans-to-cis isomerization about –N=N-Ar. The rate of trans-to-cis isomerization varies 1.11×10-8 - 1.89×10-8 s-1 and is largely dependent on mass of the photochrome and strain/steric crowding generated about –N=N- bond. Quantum yields (φt→c) of trans-to-cis isomerization, 0.0843 – 0.1421, are calculated and free ligand shows higher φ (0.17 – 0.26) than their complex phase. The cis-to-trans isomerisation is a thermally induced process. The activation energy (Ea) of cis-to-trans isomerisation is calculated by controlled temperature experiment and is found that Ea (ligands) > Ea (complexes).
关键词： photochromism.,Copper (I) complexes,bis-(diphenylphosphino)methane,Arylazoimidazole,spectral study
更新于2025-09-23 15:23:52