A new strategy has been developed to synthesize difurylperhydrocyclopentene derivatives. The compound displays reversible photochromism in solution and thin-film. The results show that furan is superior to thiophene in terms of strong fluorescence, higher photocyclization conversion and cyclization quantum yield, as well as better fatigue resistance. Owing to the molecule being derived absolutely from C, H, and O atoms, the compound exhibits no cytotoxicity, which enables it to potentially serve as a biodegradable and biorenewable material for in vivo applications.

A great deal of effort has been devoted to developing gated photochromic systems due to their advantages in the smart materials and opto-electronic fields, whereas the gating function through certain ions has rarely been addressed. Since the photochromic materials gated by ions can be readily further processed into a multi-functional molecular switch and probe, we herein designed and conveniently synthesized a star-shaped Schiff-based diarylethene derivative showing typical photochromic properties in solution. This compound possesses two response channels (colorimetric and fluorogenic) to Cu2+ ions with photoswitching characteristics, making it a viable photochromic probe. It is noteworthy that its photochromic reactivity can be locked when Cu2+ ions are introduced into the solution. Moreover, the photoinactive and photoactive states can be interchanged reversibly by binding Cu2+ ions and unbinding Cu2+ ions using EDTA, which shows promise for application in multi-controlled molecular switches and smart materials. The mechanism of the photochromic properties locked by Cu2+ ions is reasonably proposed by theoretical simulations. These results could be valuable for the further development of molecular switching systems with multiple stimuli responses.

While numerous efforts have been devoted to developing easy-to-use probes based on block copolymers for detecting analytes due to their advantages in the fields of self-assembly and sensing, a progressive response on block copolymers in response to a continuing chemical event is not readily achievable. Herein, we report the self-assembly of a 4-piperazinyl-1,8-naphthalimide based functional block copolymer (PS-b-PN), whose self-assembly and photophysics can be controlled by the stoichiometry-dependent metal–ligand interaction upon the side chain. The work takes advantages of (1) stoichiometry-controlled coordination–structural transformation of the piperazinyl moiety on PS-b-PN toward Fe3+ ions, thereby resulting in a shrinkage–expansion conversion of the self-assembled nanostructures in solution as well as in thin film, and (2) stoichiometry–controlled competition between photoinduced electron transfer and spin–orbital coupling process upon naphthalimide fluorophore leading to a boost–decline emission change of the system. Except Fe3+ ions, such a stoichiometry-dependent returnable property cannot be observed in the presence of other transition ions. The strategy for realizing the dual-channel sequential response on the basis of the progressively alterable nanomorphologies and emissions might provide deeper insights for the further development of advanced polymeric sensors.

We present a density functional theory study on the thermal bistability of a number of photochromic diarylethenes, with emphasis on the free energy barrier of the ground-state ring-opening process. We found that the free energy barrier is correlated with the geometrical and vibrational character of the transition state, in particular the distance between the two reactive carbon atoms, the out-of-plane angles of the methyl groups at the reactive carbon atoms, and the imaginary vibrational frequency. Based on these relationships we propose a linear fitting expression for the free energy barrier in terms of the three aforementioned transition-state quantities and obtained a correlation coefficient of R2 = 0.971. In this way quantum chemical calculations may provide insight and structure–property relationships, which can be applied in the development of novel photochromic materials.

•A new spirooxazine derivative bearing a carbazole moiety was synthesized.•Its photochromic properties were extensively studied.•The mechanism and kinetics of the thermal fading process were additionally investigated by theoretical simulations.A novel photochromic spirooxazine derivative bearing a carbazole moiety (SOC) was synthesized and studied in solution under flash photolysis conditions. It is found to exhibit excellent characteristics like high photochromic response, large steady-state optical density, fast thermal bleaching rate and good fatigue-resistance. The effect of different solvents on the photochromic properties of the compound was evaluated, revealing that the photochromic properties can be modulated by different solvents based on the corresponding polarity. The mechanism and kinetics of the thermal fading process of compound SOC were additionally investigated by theoretical simulations, where the isomerization pathway from the trans-trans-cis conformation was found to be several times faster than that from the cis-trans-cis conformation. This type of fast-bleaching and fatigue-resistent photochromic compounds is expected to pave an exciting avenue in future development of high-performance photochromic materials.A new spirooxazine derivative featuring a carbazole moiety is successfully developed, which exhibits excellent characteristics like high photochromic response, large steady-state optical density, fast thermal bleaching rate and good fatigue-resistance, as well as tunable photochromic properties based on the polarity of solvents. The mechanism and kinetics of the thermal fading process are investigated in depth.

•A molecular switch with gated photochromic properties was developed.•Its photochromic properties triggered by Cu2+ ions and water were extensively studied.•The mechanism was additionally investigated by theoretical simulations.We describe a gated photochromic behavior of an unsymmetrical dithienylethene derivative, which is intrinsically inert to photoisomerization in organic solvents and which is activated by addition of Cu2+ ions or water. The mechanism behind the gated photochromic property is interpreted by theoretical simulations, suggesting that the energy levels of frontier molecular orbitals are altered by the interaction of the Schiff base moiety with Cu2+ ions or water molecules. Potential applications of such gated photochromic materials have been exemplified not only by the reversible interchange between the photoactive and photoinactive states triggered by Cu2+ ions and EDTA, but also by the construction of a keypad with sequence-dependent input signals at the molecular level.A molecular switch with gated photochromic properties is successfully developed, which is intrinsically inert to photoisomerization in organic solvents and which is activated by addition of Cu2+ ions or water. The mechanism behind the gated photochromic property is investigated by theoretical stimulations. This gated photochromic behavior brings up the construction of a molecular keypad with sequence-dependent input signals.

A great deal of effort has been devoted to developing gated photochromic systems due to their advantages in the smart materials and opto-electronic fields, whereas the gating function through certain ions has rarely been addressed. Since the photochromic materials gated by ions can be readily further processed into a multi-functional molecular switch and probe, we herein designed and conveniently synthesized a star-shaped Schiff-based diarylethene derivative showing typical photochromic properties in solution. This compound possesses two response channels (colorimetric and fluorogenic) to Cu2+ ions with photoswitching characteristics, making it a viable photochromic probe. It is noteworthy that its photochromic reactivity can be locked when Cu2+ ions are introduced into the solution. Moreover, the photoinactive and photoactive states can be interchanged reversibly by binding Cu2+ ions and unbinding Cu2+ ions using EDTA, which shows promise for application in multi-controlled molecular switches and smart materials. The mechanism of the photochromic properties locked by Cu2+ ions is reasonably proposed by theoretical simulations. These results could be valuable for the further development of molecular switching systems with multiple stimuli responses.