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A new diarylethene with an antipyrine unit was synthesized and its multi-controllable photochromic and fluorescent behaviors induced by stimulation of light, acid/base, and metal ions were investigated in detail. The diarylethene showed favorable photochromism by photoirradiation, but its photochromism was entirely inhibited by the stimulation of tetrabutylammonium hydroxide. Its fluorescence showed sequence-dependent responses through efficient interaction of salicylaldehyde-linked antipyrine unit with light, base, and specific metal ions. Its fluorescence intensity was enhanced sharply with a notable color change from bright orange to bright yellow as a naked-eye fluorescent chemosensor for recognition of Al 3+ with high selectivity. Finally, two logic circuits were constructed on the basis of the multi-responsive photochromic and fluorescent behaviors of the unimolecular platform. [ABSTRACT FROM AUTHOR]

A novel photochromic diarylethene was synthesized and its structure was determined by single-crystal X-ray diffraction analysis. The diarylethene can serve as a ratiometric fluorescent chemosensor for highly selective recognition of Cu 2+ and HSO 4 – ions, respectively. The fluorometric titration for recognition Cu 2+ showed two distinct processes. First, the emission intensity at 427 nm decreased notably and a strong emission peak at 489 nm emerged when the concentration of Cu 2+ was less than 1.0 equiv. In the second one, the emission intensity at 489 nm dramatically decreased when the concentration of Cu 2+ increased from 1.0 to 10.0 equiv. Furthermore, the diarylethene can selectively recognize HSO 4 ˉ without any interference from other anions. Upon addition of HSO 4 ˉ in acetonitrile, its emission peak was red-shifted by 64 nm and the emission intensity was enhanced by 5-fold with notable fluorescence change from blue to bright cyan due to the formation of the anion/ligand (1:1) complex. [ABSTRACT FROM AUTHOR]

An asymmetrical photochromic diarylethene with one pyridine unit was synthesized, which could have two types of crystals controlled through the evaporation of either an ether solution or a hexane/chloroform (V = 1:1) solution at room temperature, respectively. The obtained open-ring isomer and closed-ring isomer of the diarylethene could be interconverted in solution, in a solid film, and even in the crystalline phase via alternating irradiation with UV and visible light. The diarylethene exhibited proton-controlling fluorescence switching behavior through alternating the stimulation of trifluoroacetic acid and triethylamine. Its fluorescence intensity could also be modulated reversibly through alternating irradiation with UV and visible light. Thus, the diarylethene could be used as a multi-addressable fluorescence switch when triggered with light and acid/base. Cyclic voltammograms with an oxidation wave of the closed-ring isomer was clearly observed at 0.82 V. [ABSTRACT FROM AUTHOR]

Abstract: A new class of isomeric diarylethenes with benzofuran and pyridine moieties was synthesized to investigate the effects of the position of the nitrogen atom in pyridine moiety on their photochromism, acidichromism, and fluorescence. The six-membered pyridine moiety was connected directly to the central cyclopentene ring as an aryl moiety and participated in the photoisomerization reaction in both solution and solid media. These isomeric diarylethenes exhibited multi-addressable switching behavior by the stimulation of acid/base and light. Addition of trifluoroacetic acid to the solutions of these compounds produced the corresponding protonated derivatives. The protonated derivatives exhibited excellent photochromism and notable acidichromism, and the different nitrogen atom position resulted in distinguishable absorption spectra and color changes. The results revealed that the effects of the nitrogen atom position in pyridine moiety played a very important role during the photoisomerization process of these isomeric diarylethenes. [Copyright &y& Elsevier]

Abstract: Five photochromic diarylethenes with a six-membered pyrimidine moiety were synthesized to investigate the effects of the substituents on their photochromic behaviors, and the structures of four of the diarylethenes were determined by single-crystal X-ray diffraction analysis. The pyrimidine moiety was connected directly to the central cyclopentene ring as an aryl moiety to participate the photoisomerization reaction in solution, solid amorphous films, and crystalline phase. All of the diarylethene derivatives showed favorable photochromism and functioned as notable fluorescent photo-switches in both solution and solid media. The electron-donating substituents enhanced their cyclization quantum yields, fatigue resistance, and fluorescence quantum yields, whereas the electron-withdrawing groups exerted inversed actions on the diarylethenes. The results revealed that the pyrimidine moiety and substituents played a very important role during the process of photoisomerization reactions. [Copyright &y& Elsevier]

Abstract: Four new photochromic diarylethenes with both benzofuran and benzene moieties were synthesized, and the structures of three diarylethenes were determined by single-crystal X-ray diffraction analysis. The six-membered benzene ring was connected directly to the central perfluorocyclopentene unit as an aryl moiety and available to participate in photoisomerization reaction. All the diarylethenes exhibit favorable photochromism and function as notable fluorescence switches in both hexane and poly(methyl methacrylate) films. The electron-donating substituents effectively enhanced the cyclization quantum yields, while the electron-withdrawing substituents notably shifted the fluorescent emission peaks to a longer wavelength in both solution and poly(methyl methacrylate) films. The result indicated that the different substituents linked at the reactive carbon atom of the benzene moiety had a significant effect on their optical and electrochemical properties. [Copyright &y& Elsevier]

Abstract: Four new photochromic diarylethenes, each bearing an indole moiety, were synthesized and three of their structures were determined by single-crystal X-ray diffraction analysis. Under alternating irradiation with UV and visible light, the compounds showed favorable photochromism in hexane, PMMA films and the crystalline phase. The cyclization quantum yields gradually increased and the molar absorption coefficients of the closed-ring isomers decreased going from the ortho- to meta- to the para-position of the substitution. The absorption maxima showed little change when the methoxy group was attached at any of the three positions on the terminal benzene ring. Each of the compounds displayed high fluorescence efficiency and remarkable fatigue resistance in both solution and PMMA films by photoirradiation. Of particular note, their fluorescent modulation efficiency could be achieved ca. 90% in solid media. Cyclic voltammograms testified that the methoxy group and its substituted position could effectively modulate the electrochemical behaviors of these diarylethenes. [Copyright &y& Elsevier]

Abstract: A new photochromic diarylethene with a formyl group, 1-(2-cyano-1,5-dimethyl-4-pyrryl)-2-(2-methyl-5-formyl-3-thienyl)perfluorocyclopentene,has been synthesized. The interaction between the formyl group of its ring-closed isomer with cysteine/homocysteine caused a notable change in its absorption spectrum, accompanied by an evident color change from blue to pale yellow upon addition of cysteine/homocysteine. Moreover, the competition tests revealed that no obvious interference was observed by performing the titrations with the mixtures of cysteine/homocysteine and other amino acids. The results indicated that the diarylethene could be used as a colorimetric sensor for the recognition of cysteine/homocysteine with high selectivity. [Copyright &y& Elsevier]

Abstract: A new fluorescence switch based on a photochromic diarylethene and a rhodamine B dye was designed and constructed successfully. With carefully selected components, the absorption band of the ring-closed photochromic diarylethene well overlapped with the emission band of the rhodamine B. The fluorescence emission intensity of rhodamine B is easily modulated with the photoisomerization of diarylethene by controlling the exposure time both in solution and in a solid medium. The photoswitchable system displayed high fluorescence quenching efficiency (>90%) and remarkable fatigue resistance in both solution and a solid medium. In a poly(methyl methacrylate) film, it can be repeated at least 20 cycles without observable change in emission intensity. A 99% fluorescence quenching efficiency can be achieved with an effective fluorescence change from bright wine red to the dark grey. [Copyright &y& Elsevier]

Abstract: A new photoinduced fluorescent switch based on a photochromic diarylethene with a rhodamine fluorophore has been successfully explored. The target compound exhibits excellent photochromism with good fatigue-resistance upon photo-irradiation. Upon addition of Cr(III), the color of the diarylethene turns from colorless to pink accompanied with a 300-fold increase in fluorescence emission intensity in methanol. In the presence of Cr(III), an efficient FRET process from the rhodamine moiety (FRET donor) to the closed-ring diarylethene moiety (FRET acceptor) occurs upon UV light stimuli, and its emission intensity can be recovered upon irradiation with visible light. Also, the ability of the compound to detect metal ions has been evaluated by monitoring the changes of emission intensity in methanol. Amongst the tested metal ions, only Cr(III), Al(III) and Fe(III) are efficiently detected. The result indicates that the diarylethene can selectively recognize Cr(III) with significant color and fluorescence changes. [Copyright &y& Elsevier]

Abstract: A new class of unsymmetrical photochromic diarylethenes bearing both benzofuran and thiophene moieties was synthesized and the effects of substitution on their properties were discussed systematically. Two compounds among them show distinctly different conformation in the single crystalline phase: one crystallizes with an anti-parallel conformation which exhibit good photochromism, whereas the other crystallizes with a parallel conformation which exhibits no photochromism in the crystalline phase. Each of the compounds exhibited remarkable photochromism and functioned as a fluorescent switch in both solution and PMMA films. The electron-donating groups significantly increased the cyclization quantum yield, depressed the cycloreversion quantum yield, shifted the emission peak to a longer wavelength, and decreased the emission intensity; while the electron-withdrawing groups functioned as an inverse action for these diarylethene derivatives. The cyclic voltammograms results revealed that these diarylethenes exhibited evident electrochromism during electrolysis and the oxidative cyclization is thermodynamically. [Copyright &y& Elsevier]

Abstract: A multiple responsive photochromic diarylethene, 1-[2,5-dimethyl-3-thienyl]-2-[2-methyl-5-(2-pyridyl)-3-thienyl]perfluorocyclopentene (1) with excellent fatigue resistance has been successfully synthesized. Easy and reversible conversion is observed between the two open- and closed-ring isomers of 1 upon irradiation with UV and visible light. Addition of trifluoroacetic acid to these two isomers gives two new protonated products featuring distinctively different color changes. Photochromic diarylethene 1b is found to have selective interaction with copper(II) ion. With increasing amount of copper(II) ion, the absorption maximum of the photostationary state at 563 nm decreases and disappears eventually, and the color of the solution changes from purple to colorless. Upon UV light irradiation, the solution color remains colorless and can no longer be restored. UV–vis absorption spectroscopy, fluorescence, and NMR spectroscopy were used to investigate the selective interaction between diarylethene 1b and copper(II) ion with results indicating that diarylethene 1b exhibits selective binding affinity for copper(II) ion. [Copyright &y& Elsevier]

Abstract: Four photochromic diarylethenes bearing a pyrrole moiety were synthesized, and the structures of two of the new isomeric compounds were determined by single-crystal X-ray diffraction analysis. Each of the diarylethene derivatives exhibited good photochromism both in solution and in poly(methyl methacrylate) films, which their photoconversion ratios from open-ring to closed-ring isomers were larger than 89% in hexane at photostationary state. They also functioned as effective fluorescent photoswitches both in hexane and in poly(methyl methacrylate) films. The absorption maxima, cyclization/cycloreversion quantum yields, and fluorescence quantum yields increased whereas the molar absorption coefficients and the emission peaks decreased notably when the cyano group was attached at any of the three positions on the terminal benzene ring. Cyclic voltammograms indicated that the introduction of cyano group decreased the band-gap of the open-ring isomer and increased that of the closed-ring isomer. The cyano group and its -substituted position can availably modulate the optical and electrochemical behaviours of these diarylethene derivatives. [Copyright &y& Elsevier]

Abstract: Five diarylethenes bearing a pyrrole moiety were synthesized in order to investigate the effects of the substituents on the properties of these compounds. The structures of three of the diarylethenes were determined by single-crystal X-ray diffraction analysis. All of the diarylethene derivatives exhibited notable photochromism and functioned as effective fluorescent photo-switches in solution and in poly(methyl methacrylate) films. The absorption maxima and the quantum yields of cyclization and cycloreversion increased whereas the emission peaks and the emission intensities decreased evidently when the electron-withdrawing/donating substituent was attached at the para-position on the terminal benzene ring. Cyclic voltammograms indicated that the electron-withdrawing/donating substituents decreased the bang gaps of the open-ring isomers but enhanced those of the closed-ring isomers, compared with the unsubstituted parent diarylethene. The properties of these diarylethene derivatives were significantly different from each other, which might be attributed to the different substituent effects. [Copyright &y& Elsevier]

Abstract: A new class of diarylethene bearing a biphenyl moiety was synthesized and the effects of substitution on photochromism, fluorescence and electrochemical character, were investigated. Under alternating irradiation with UV and visible light, the compounds exhibited good photochromism and functioned as fluorescent photoswitches both in solution and in PMMA film. Electron-donating substituents shifted the λ max of the diarylethenes to longer wavelengths and decreased their cyclization quantum yield, while electron-withdrawing substituents greatly increased both cyclization and cycloreversion quantum yield. In addition, cyclic voltammetry revealed that the substituents had a significant effect on the electrochemical behaviour of the diarylethene derivatives. [Copyright &y& Elsevier]

Abstract: Three unsymmetrical isomeric diarylethenes bearing an electron-withdrawing cyano group were synthesized and their structures determined using single-crystal X-ray diffraction analysis. Each of the compounds displayed excellent photochromism in solution, in PMMA film, as well as in the crystalline phase. The isomeric compounds also functioned as a fluorescence switch in PMMA films. The cyclization quantum yield and the absorption maxima of both the ring-opened and ring-closed isomers increased in the order: ortho-< meta-< para-substitution of the cyano group. Compared with the unsubstituted parent compound, the cycloreversion quantum yield decreased whereas the molar absorption coefficient of the ring-opened and the ring-closed isomers increased significantly when the cyano group was attached at any of the three positions on the terminal benzene ring. Cyclic voltammetry studies indicated that the position of cyano substitution had a marked effect on the electrochemical behaviours of these isomeric diarylethenes. [Copyright &y& Elsevier]

Abstract: Three unsymmetrical isomeric photochromic diarylethenes bearing a methoxy group at either the para-, meta- or ortho-positions on one terminal benzene ring were synthesized and their optical and electrochemical properties investigated. Each of the compounds exhibited high photo-reactive sensitivity and functioned as a fluorescent photo-switch both in solution and in PMMA film. The molar absorption coefficients of both of the open-ring and closed-ring isomers decreased when the methoxy group was attached at any of the three positions on the terminal benzene ring whereas the cycloreversion quantum yield gradually increased in going from the para- to meta- to the ortho-position of substitution. Oxidation waves were clearly observed at 0.55, 0.74 and 0.58 V from cyclic voltammograms for some compounds but not for others at these voltages. [Copyright &y& Elsevier]

Three novel gold(I) complexes based on triphenylamine, carbazole or tetraphenylethylene moiety have been successfully designed and synthesized. Meanwhile, their structures were characterized by nuclear magnetic resonance spectroscopy and elemental analysis. Their solid-state luminescence characteristics were surveyed by photoluminescence spectroscopy, and their distinct mechanical stimulus-responsive behaviors in the solid state were also investigated by photoluminescence spectroscopy. Interestingly, the solid-state phosphorescence and emission lifetimes of these mononuclear gold(I) complexes 1 – 3 could be tuned by introducing different fluorophores involving triphenylamine, carbazole or tetraphenylethylene. Furthermore, luminogen 1 exhibited switchable mechanochromic luminescence behavior with color change from yellow to colorless, and the solid-state luminescence on-off mechanochromism between yellow-green and colorless of luminogen 2 could also be observed. However, no mechanochromism phenomenon was observed for tetraphenylethene-containing luminogen 3 . The powder X-ray diffraction results suggested that the unusual high-contrast mechanochromism characteristics of luminogens 1 and 2 could be attributed to a crystalline-to- amorphous morphology transition. [ABSTRACT FROM AUTHOR]

Mechanochromic luminescent materials have received a great deal of attention due to their potential applications in sensors and optoelectronic devices. Meanwhile, the aggregation-induced emission active materials commonly exhibit bright luminescence upon aggregate formation, which is extremely important for preparation of high-contrast mechanochromism materials. On the other hand, it is well-known that pyridine-type ligands are one of the most versatile ligands. Unfortunately, the number of pyridine gold complexes is quite limited, not to mention pyridine-containing gold(I) complexes with aggregation-induced emission or mechanochromic phenomenon. In this work, a new bipyridine-based aggregation-induced phosphorescent emission active gold(I) complex is reported. The novel luminogen exhibits reversible mechanochromism phenomenon with phosphorescent changes between weak green and strong yellow emissions. Moreover, the luminogen shows a significative self-assembly behavior. This work will be beneficial for the exploitation of force-responsive phosphorescent sensor materials with remarkable self-assembly behavior. [ABSTRACT FROM AUTHOR]

A new photochromic diarylethene with a 2-(1 H -dithienobenzoimidazole)phenol unit has been synthesized. The gated photochromism and fluorescence switching behaviors of the compound induced by acid/base were investigated. Addition of acid enhanced its fluorescence intensity and the remotely photochromic reactivity was activated. Moreover, the fluorescence intensity of the diarylethene was notably enhanced by 6-fold with a concomitant emission peak blue-shifted from 500 nm to 469 nm triggered by Al 3+ . And the compound exhibited a “turn-off” fluorescence switching property for the detection of CN − with a fluorescence color change from blue to dark. Therefore, it could be served as a sensitive fluorescence probe for the detection of Al 3+ /CN − . Finally, a logic circuit was fabricated on the basis of the unimolecular platform by using the fluorescence emission intensity at 469 nm as output and the combinational stimuli of UV/vis and Al 3+ /EDTA as inputs. [ABSTRACT FROM AUTHOR]

A carbazole-based gold(I) complex 1 has been successfully synthesized. Its structure was characterized by nuclear magnetic resonance spectroscopy, elemental analysis and single crystal X-ray diffractometry. Its aggregation-induced emission behavior was studied by ultraviolet/visible, photoluminescence spectroscopy and scanning electron microscope. Its solid-state mechanochromic and thin-film vapochromic luminescence behaviors were also investigated by photoluminescence spectroscopy. The results demonstrated that luminogen 1 showed obvious aggregation-induced emission property. Furthermore, 1 also exhibited reversible high-contrast mechanochromic and vapochromic luminescence behaviors. More interestingly, 1 can emit persistent room-temperature phosphorescence with a solid-state emission lifetime up to 86.84 ms, which is the highest lifetime value among all the reported gold(I) complexes so far. To the best of our knowledge, the gold(I) complex is the first example of an AIE-active luminogen with persistent room-temperature phosphorescence, reversible mechanochromism and vapochromism characteristics. [ABSTRACT FROM AUTHOR]

Abstract: A novel asymmetrical diarylethene with a stilbene-linked terpyridine chromophore has been synthesized by Heck reaction. It exhibited effectively switchable fluorescence when triggered by UV/Vis and Hg2+/EDTA. Induced by Hg2+, its emission peak was red-shifted by 60 nm and emission intensity was enhanced by 4-fold with a concomitant color change from light blue to bright green due to the formation of a 1:2 metal/ligand complex. As a result, the diarylethene can serve as a fluorescence chemosensor for highly selective recognition of Hg2+ in dichloromethane. Moreover, a complicated logic circuit was constructed with the unimolecular platform by using the fluorescence intensity at 514 nm as outputs and the combinational stimuli of light and chemical species as inputs. [Copyright &y& Elsevier]

Abstract: A new photochromic diarylethene with a triazole-bridged methylquinoline group has been synthesized by click chemistry reaction. The diarylethene exhibited typical photochromism and fluorescent switching properties by photoirradiation. Especially, its fluorescence and recognition of different metal ions could be effectively modulated by controlling the volume ratio of acetonitrile and water in acetonitrile/water binary solvent system. In acetonitrile, the diarylethene was found to be highly selective towards Zn2+ and Cd2+. However, it could recognize selectively Cr3+, Al3+, and Fe3+ with significant fluorescence change from dark to bright blue in the mixture solvent of acetonitrile and water (v/v = 7/3). Moreover, a logic circuit was constructed with the unimolecular platform by using the fluorescence intensity at 432 nm as output and the combinational stimuli of light and chemical as inputs. [Copyright &y& Elsevier]

Abstract: A new unsymmetrical photochromic diarylethene with a di-2-picolylamine unit was synthesized, and its structure was determined by single-crystal X-ray diffraction analysis. The diarylethene exhibited favorable photochromism with remarkable fatigue resistance in both solution and the crystalline phase. The interaction between the di-2-picolylamine with Zn2+ caused a notable change in its fluorescence intensity, accompanied by an evident color change from the black to bright blue upon addition of Zn2+. No obvious interference was observed by performing the titrations with other metal ions. The results revealed that the photochromic diarylethene could be used as a fluorescence probe for the recognition of Zn2+ with high selectivity. [Copyright &y& Elsevier]

Abstract: Three new isomeric pyridine-containing diarylethenes with a benzofuran moiety were synthesized, and the structures of two diarylethenes were determined by single X-ray diffraction analysis. Their properties such as photochromism, acidchromism, fluorescence, as well as electrochemical properties, were investigated in detailed. The diarylethenes exhibited multi-addressable switching behavior by light and acid/base stimuli in solution and functioned as a remarkable fluorescent switch in both solution and poly(methyl methacrylate) films. Among these isomeric derivatives, the example with the nitrogen atom at the ortho-position of pyridine showed the largest absorption maxima, molar absorption coefficients, and cyclization quantum yield. The nitrogen atom position in the terminal pyridine unit could efficiently modulate the optical and electrochemical properties of the diarylethenes with a benzofuran moiety. The results suggested that the benzofuran moiety and the nitrogen atom position in the terminal pyridine unit played a vital role during the process of photoisomerization reaction for these isomeric diarylethenes. [Copyright &y& Elsevier]

Nitroreductase (NTR) is overexpressed in hypoxic tumor cells, which is closely related to inflammation, tumorigenesis, tumor invasion and metastasis. Therefore, developing fluorescence probes for detecting intracellular NTR sensitivity has great significance for diagnosis and treatment of tumors. Therefore, we designed a novel fluorescent probe (Pro-CN) based on julolidine skeleton for the detection of NTR. The probe could discriminate rapidly NTR from other biological species like sulfhydryl compounds and some ions. Meanwhile, a fine linear relationship between fluorescence intensity of the probe and NTR consistence has been observed with a very low detection limit of 4.4 ng/mL. In addition, Pro-CN was successfully applied in imaging endogenous NTR in Hela cells and living zebrafish. The excellent performance of the probe makes it have great potential for monitoring NTR in complex biological systems, and it also provides the possibility of its application in human health, disease diagnosis and treatment. [Display omitted] • Probe Pro-CN exhibits a turn-on fluorescence for sensing NTR. • Pro-CN is highly sensitive to sense NTR with a very low detection limit of 4.4 ng/mL. • Pro-CN was successfully applied for imaging endogenous NTR in living Hela cells and zebrafish. [ABSTRACT FROM AUTHOR]

Abstract: Three isomeric pyridine-containing diarylethenes were synthesized to study the effects of nitrogen atom position (ortho, para, meta) on their photochromic properties. Among these diarylethenes, the example with the nitrogen atom at the ortho-position of pyridine displayed the largest absorption maximum and molar absorption coefficients. The cyclization quantum yields increased in order of para < meta < ortho, whereas their cycloreversion quantum yields decreased in order of para > meta > ortho. Compared to the diarylethene with terminal phenyl ring, those with a terminal pyridine showed enhanced cyclization quantum yields and emission intensities. Moreover, these pyridine-containing diarylethenes exhibited multi-addressable switching behavior under the stimulation of both proton and light. Addition of trifluoroacetic acid to the solutions of the diarylethenes resulted in notable color change, and their N-protonated forms also possessed excellent photochromism. These results indicated that the nitrogen atom position played a pivotal role in the process of photoisomerization of the diarylethenes. [Copyright &y& Elsevier]

A series of four novel BF 2 complexes of N -acetyl 2-aminobenzothiazoles featuring rigid rotorless polyheteroaromatic structures have been designed and synthesized. All of these compounds exhibited AIE properties with excellent solid-state fluorescence quantum yields up to 81.7%. Theoretical calculations revealed the characteristics of their ground-state structures and excitation processes. Their seemingly abnormal nonradiative decay in solutions was investigated from both direct vibrational relaxation and S 0 /S 1 surface crossing perspectives by the two-channel model. The minimum energy conical intersection (MECI) located by SF-TDDFT method indicated that the CI is mainly induced by the deformation of the BF 2 complex ring, leads to elevated energy level, and thus is not responsible for the fluorescence quenching. The potential energy curve (PEC) constructed along the distortion angle θ of BF 2 complex ring showed that when θ reaches 50° (the dark-state region approaching MECI), the energy barrier is only 0.11 eV, suggesting that the deformed dark state could serve as an effective deactivation channel via ultrafast internal conversion (IC). Crystallographic analysis illustrated that the F atoms perpendicular to the polyheterocycle could effectively prohibit detrimental π-π stacking and enhance intermolecular interactions, thereby resulting in efficient solid-state emission. [Display omitted] • Four BF 2 complexes of N -acetyl 2-aminobenzothiazoles were identified as AIEgens. • Deformation-induced MECI is not responsible for their nonradiative decay. • Accessible dark-state region upon deformation causes fluorescence quenching. [ABSTRACT FROM AUTHOR]

Three carbazole-containing isocyano-bridged mononuclear gold(I) complexes with different substituents are reported. The complexes display an aggregate luminescence change effect involving a color change from blue to yellow-green. In the solid state, luminogens 1 – 3 exhibit varying room-temperature phosphorescence involving blue, light yellow, and yellow emissions. In contrast, at 77 K, the gold(I) phosphors 1 – 3 display stronger (blue-green or yellow-green depending on the phosphor) phosphorescence with longer luminescence lifetimes. In addition, the solid-state phosphorescence of 1 – 3 is adjusted by moderate mechanical stimulus. More specifically, phosphor 1 shows reversible high-contrast mechanoluminochromic behavior involving interconversion between blue and yellow-green luminescence and phosphor 2 shows reversible mechanoluminochromism phenomenon involving luminescent interconversion between light yellow and light green. In contrast, solid-state phosphor 3 displays an irreversible mechanoluminochromism phenomenon—a strong yellow-green luminescence is observed after grinding. Subsequent treatment with dichloromethane vapor results in a blue-emitting sample. Image 1 • Three carbazole-containing mononuclear gold(I) complexes were synthesized. • All these complexes exhibited aggregate luminescence change effect. • Complexes 1–3 exhibited various solid-state phosphorescence at room temperature and at 77 K. • Phosphors 1 and 2 showed reversible mechanoluminochromism characteristics. • Phosphor 3 showed irreversible mechanoluminochromic behavior. [ABSTRACT FROM AUTHOR]

Abstract Three perylenediimide derivatives were reduced to their persistent radical anions in N-methyl-2-pyrrolidone (NMP) under ambient conditions by a visible light photoinduced electron transfer (PET). UV–vis and electron paramagnetic resonance (EPR) measurements were carried out to confirm the formation of radicals. The relationships between molecular structure, electrochemical property, phototransformation kinetics, and air stability of radical anions were investigated by the introduction of pyrimidine rings at the core position and fluoroalkylation substituents at the imide position. This study reveals that the electron-deficient pyrimidine rings and electron-withdrawing fluoroalkylation substituents can effectively enhance the phototransformation rate and the radical stability at ambient conditions. The effects of solvents and illuminance levels on the photoinduced reduction of perylenediimides were also studied. A photocatalytic reduction of Ag+ was successfully carried out using the perylenediimide with pyrimidine and fluoroalkylation substituents as catalyst upon irradiation with visible light. Graphical abstract A series of perylenediimide derivatives (PDIs) were successfully synthesized for the generation of visible-light-triggered persistent organic radical anions in NMP and under ambient conditions that is highly dependent on the substituents. An application of the visible light photocatalytic reduction of Ag+ using PDI 2•− was successfully explored to recovery of elemental silver in NMP. Image 1 Highlights • Three PDIs were reduced to their persistent radical anions by visible light irradiation under ambient conditions. • The pyrimidine rings and fluoroalkylation substituents can effectively enhance the radical stability. • The visible light photocatalytic reduction of Ag+ using PDIs was first successfully explored to recovery of elemental Ag. [ABSTRACT FROM AUTHOR]

Abstract Thiols such as amino acids Cys/Hcy and peptides GSH play vital roles in biological systems. Due to their similar structures and reaction activities, it is still desirable to develop new probes to simultaneously detect and discriminate Cys/Hcy and GSH. Taking advantage of the reductive activity of SH in these thiols, we combined two fluorophores coumarin and 7-nitrobenzofurazan with an ether bond to form the CA-NBD sensor to detect and discriminate Cys/Hcy and GSH simultaneously. CA-NBD showed high selectivity towards Cys/Hcy and GSH over other analytes with apparent colorimetric and fluorescent signals. At the excitation wavelength of 460 nm, CA-NBD could be used to discriminate Cys/Hcy from GSH with different fluorescence response. Furthermore, CA-NBD was successfully used to detect thiols in living Hela cells with low cytotoxicity. Graphical abstract A structurally simple and versatile fluorescent probe CA-NBD was synthesized, which could be used as a dual emission fluorescent probe for the detection and discrimination of Cys/Hcy and GSH in aqueous solution under mild conditions. Furthermore, the probe was successfully used to simultaneously detect Cys and GSH in living cells with low cytotoxicity. Image 1 Highlights • Coumarin and 7-nitrobenzofurazan were combined by an ether bond to form CA-NBD. • CA-NBD can be used as a naked-eye detector for biothiols over other amino acids. • CA-NBD can detect and discriminate Cys/Hcy and GSH simultaneously. • CA-NBD can be used to detect Cys in living cells with low cytotoxicity. [ABSTRACT FROM AUTHOR]

Abstract A selective fluorescent and colorimetric chemosensor for the detection of Al3+ and CN− was constructed from diarylethene with a salicylidene Schiff base. When triggered by Al3+, the diarylethene exhibited a remarkable fluorescence color change from dark to bright green. The interaction between its open-ring and closed-ring isomer with CN− caused a notable change in its absorption spectrum with significant color change from colorless to yellow and pink to darkcyan, respectively. Additionally, its light and metal-responsive fluorescence behaviors could be applied to logic gate with the fluorescence intensity as output and combinational stimuli of light and chemical species as inputs. Graphical abstract A novel photochromic diarylethene with a salicylidene Schiff base substituent could serve as a selective fluorescent and colorimetric chemosensor for Al3+ and CN− based on completely different mechanisms. Image 1 Highlights • A new diarylethene-based chemosensor by using 2-aminophenol and perfluorodiarylethene via a salicylidene Schiff base linkage was synthesized. • The chemosensor can serve as a selective fluorescent and colorimetric chemosensor for Al3+ and CN− based on completely different mechanisms. • An integrated logic circuit were successfully designed and constructed with the fluorescence intensity as the output signals and the inputs of UV/Vis, Al3+ and EDTA stimuli. [ABSTRACT FROM AUTHOR]

Abstract Three new carbazole-based fluorescent molecules 1 – 3 functionalized with tetraphenylethene have been successfully synthesized, and these compounds have high thermal stability, and they exhibited different fluorescence in solid states with the superior luminescence quantum yields of 99.04% (1), 98.90% (2) and 39.83% (3). Their aggregation-induced behaviors were explored by the study of photoluminescence spectroscopy. The results showed that luminogens 1 – 3 exhibited remarkable aggregation-induced emission effect. Furthermore, their distinct mechanical stimulus-responsive fluorescence characteristics were also surveyed by solid-state photoluminescence spectroscopy. Interestingly, the various emitting colors of these luminogens could be changed into the same green, and the repeatabilities of their mechanochromic luminescence behaviors were outstanding, and the powder X-ray diffraction results indicated that the reversible conversion from a crystalline to an amorphous state was responsible for the obvious mechanofluorochromism phenomena of compounds 1 – 3. This work will be valuable for the exploitation of mechanical-force sensors with typical aggregation-induced emission feature. Graphical abstract Three carbazole-based fluorescent molecules were successfully synthesized. These luminogens showed color-tunable solid-state fluorescence, high thermal stability, typical aggregation-induced emission, and reversible mechanofluorochromism characteristics. Image 1 Highlights • Three novel carbazole-based tetraphenylethene-containing compounds were synthesized. • All these compounds showed high thermal stability and strong solid-state fluorescence. • These luminogens exhibited typical aggregation-induced emission characteristics. • These luminogens with different substituents exhibited color-tunable solid-state fluorescence. • These luminogens exhibited highly reversible mechanofluorochromic behaviors. [ABSTRACT FROM AUTHOR]

Abstract In consideration of the nucleophilic capacity of thiophenols, which could cleave sulfonamide bond under neutral conditions, a cyclometalated iridium(III) complex (probe 1) comprised 2,4-dinitrobenzenesulfonamide (DNBS) as the recognition unit was designed and synthesized to high selectivity and sensitivity detect thiophenols successfully based on internal charge transfer (ICT) mechanism. Upon addition with thiophenols to 20% DMSO/PBS solution of nearly non-fluorescent probe 1 (10 μM, pH = 7.4), fluorescent product (complex 2) was formed after cleavage of DNBS group and a significant emission enhancement at 470 nm was observed. In addition, it could be successfully applied to detect thiophenol in water samples with a high recovery, confirming its practical value in environment science. Graphical abstract A cyclometalated iridium (III) complex comprised 2,4-dinitrobenzenesulfonamide (DNBS) as the recognition unit (probe 1) was synthesized and its fluorescent behaviors toward thiophenols in 20% DMSO/PBS solution and water samples were investigated systematically. The results demonstrated that probe 1 could serve as a sensitive and selective fluorescent probe to detect thiophenols and could not be disturbed by aliphatic thiols. Image 1 Highlights • A iridium (Ⅲ) complex probe comprised 2,4-dinitrobenzenesulfonamide as recognition unit was designed and synthesized. • Its detection behaviors toward thiophenols in 20% DMSO/PBS and water samples were investigated systematically. • The mechanisms of recognition of thiophenols had been discussed through 1H NMR spectrum. [ABSTRACT FROM AUTHOR]

Abstract A diarylethene based multi-functional sensor has been designed and synthesized. It not only exhibited excellent photochromism, but also has recognition performance for Cd2+ and Cu2+. Upon addition of 7.0 equiv. Cd2+, its emission intensity enhanced 106-fold, and the fluorescent color changed from dark to blue. Meanwhile, it also displayed colorimetric sensing ability to Cu2+ with the solution color changed from colorless to yellow, that could be observed by the naked eyes. The 1: 1 stoichiometry between the sensor and the two ions was verified by Job's plot and MS. The LOD for Cd2+ and Cu2+ was determined to be 1.89 × 10−7 mol L−1 and 4.12 × 10−8 mol L−1, respectively. Furthermore, the sensor was successfully applied in the detection of Cd2+ and Cu2+ in practical samples. Graphical abstract A diarylethene based multi-functional sensor for fluorescent detection of Cd2+ and colorimetric detection of Cu2+ has been synthesized. The sensor could be applied to detect Cd2+ and Cu2+ in practical samples with high accuracy. Image 1 Highlights • This article reports a multi-functional sensor based on diarylethene and phthalimide unit for the first time. • The sensor could act as a fluorescent sensor for detecting Cd2+ and a colorimetric sensor for detecting Cu2+. • The sensor could be applied to detect Cd2+ and Cu2+ in practical samples with high accuracy. [ABSTRACT FROM AUTHOR]

The fluorescent probe with both aggregation-induced emission (AIE) and excited-state intramolecular proton transfer (ESIPT) shows significant advantages, such as no self-quenching at high concentration, large Stokes shift, high selectivity towards analyte etc. Based on tetraphenylethene and ESIPT structural modules, three AIE-ESIPT molecules containing one different atom (S, O, N) have been constructed in this paper. The effects of three atoms on the optical properties of fluorescent molecules have been investigated by fluorescence spectroscopy and X-ray crystallographic analyses. Interestingly, the cyclic detection of HCl and NH 3 gases can be achieved with the BTY-TPE -based portable test paper. In addition, BOY-TPE and HBIY-TPE can detect ClO− by naked eye with low detection limit, good biocompatibility. Three AIE-ESIPT fluorescent probes respectively containing S, O, N atoms have been synthesized. The effects of S, O, and N atoms on the optical properties of fluorescent molecules have been investigated by fluorescence spectroscopy and X-ray crystallographic analyses and DFT calculation. The results indicate that all three exhibit AIE and ESIPT properties, X-ray crystallographic analysis indicate a significant difference in molecular packing, which should be the dominant factor in the polymorph dependence of ESIPT luminescence. It is interesting to note that BTY-TPE -based test paper can be used for cyclic detection of HCl and NH 3 gases. In addition, BOY-TPE and HBIY-TPE can be used as intracellular probes for detecting ClO−.[ [Display omitted] ] • Three AIE-ESIPT double-mechanism fluorescent crystals have been synthesized. • Effects of S, O, and N on the properties of three fluorescent crystals were discussed. • BTY-TPE -based test strip could repeatable detect HCl and NH 3 gases. • Both BOY-TPE and HBIY-TPE with extremely low detection limit for detecting ClO−. • Both BOY-TPE and HBIY-TPE could detect ClO− in living cells. [ABSTRACT FROM AUTHOR]

In this work, a new diarylethene chemosensor with excellent photochromic properties upon UV-vis irradiation was designed and synthesized. Moreover, the fabricated probe could detect the CN − via colorimetric assay with the color change from colorless to yellow that can be observed by the naked eye. The sensor also exhibited an outstanding fluorescent relay-response toward Al 3+ /Cr 3+ with high selectivity and sensitivity. Upon binding with Al 3+ , the generated diarylethene aluminum complex, confirmed by Job's plot titrations and mass spectrometry analysis, could exhibit a remarkable fluorescence enhancement (Φ = 0.583) with a limit of detection (LOD) of 5.47 × 10 −7  M. The diarylethene-based chelate can be further used as a new platform for sensitive detection of Cr 3+ through fluorescence quenching caused by Al 3+ replacement. [ABSTRACT FROM AUTHOR]

In this work, we successfully introduced a novel strategy for the rational design of a fluorescence turn-on probe based on diarylethene for copper ion and cyanide ion recognition. The probe was designed by conjugating diarylethene bromide with 2-(methylquinoline-8-yloxy) acetohydrazide and exhibited a 45-fold and 15-fold fluorescent enhancement in the presence of 5 equiv. of Cu 2+ and 34 equiv. of CN − respectively. This probe is more stable than chemosensors with Schiff base structure and has multicolor changes with the stimuli of lights, CN − , and Cu 2+ . This probe can be used to distinguish Cu 2+ from CN − in vitro . Furthermore, a logic circuit was designed based on the fluorescent properties of this probe. [ABSTRACT FROM AUTHOR]

A novel photo-controlled solid-state fluorescence switching based on carbon dots (CDs) and diarylethene was designed and constructed. It was characterized by TEM, XRD, XPS, and FT-IR. The polymethyl methacrylate (PMMA) was used to disperse the CDs and prevent its fluorescence quenching due to aggregation. The fluorescence switching not only had excellent modulation efficiency, but also exhibited good photochromic properties. Upon irradiation with UV light, the fluorescence modulation efficiency was determined to be 96.3%. The mechanism of the reversible fluorescence modulation was attributed to the FRET between the CDs (energy donor) and the closed-ring diarylethene (energy acceptor). This work suggests the strategy of constructing solid-state fluorescence switching is feasible, and will provide new ways for the potential application of CDs and diarylethene. A solid-state fluorescence switching was designed and constructed with carbon dots (CDs) and diarylethene, and the fluorescence switch is dispersed into PMMA films to achieve the solid-state fluorescence switching of CDs. [Display omitted] • A solid-state fluorescence switching based on carbon dots (CDs) and diarylethene was designed and constructed. • The reversible fluorescent switching behavior of the DT-CDs system was UV/vis lights controlled process based on the FRET. • The PMMA was used to disperse the CDs and inhibit its fluorescence quenching caused by its aggregation. [ABSTRACT FROM AUTHOR]

A new water-soluble colorimetric and ratiometric fluorescent probe for detecting hypochlorite ion (ClO−) based on a phenothiazzine group was designed and synthesized. As ratiometric fluorescent probe, LD - Lyso showed rapid, accuracy, and selective fluorescence sensing effect for ClO− in PBS buffer solution with a large Stokes shift (195 nm), it displayed a significant blue-shift phenomenon and a 25-fold enhancement of the fluorescence intensity ratio (I 550 /I 635) toward ClO−, fluorescence notably changing from red to green, the detection limit as low as 8.74 μM; As colorimetric probe, LD - Lyso also showed a significant shift in absorption band (from 450 to 395 nm) upon treatment with ClO− along with the visible color changed from faint yellow to colorless, the detection limit as low as 0.01 μM. In addition, the detecting mechanism of LD - Lyso towards ClO− via the intramolecular charge transfer (ICT) mechanism was proved by ESI-MS and DFT calculation, and the application as testing strips for detecting ClO− was realized. [Display omitted] • A novel phenothiazine-based ratiometric fluorescent probe LD - Lyso for detecting ClO− was synthesized. • LD - Lyso towards ClO− represented excellent sensitivity, low detection limit, and remarkable Stokes shift. • LD - Lyso was applied for sensing ClO− in real water samples and testing strips. [ABSTRACT FROM AUTHOR]

Hydrogen sulfide (H 2 S), as an important participant in physiological processes, affects the function of many cells and plays a significant role in freshness indicator of protein foods. In order to improve the detection of H 2 S in vitro and in vivo, fluorescent 'off-on' chemodosimeter for sequential detecting H 2 S and Zn2+ with low detection limit was designed and synthesized in this study. Results showed that, in the detection of H 2 S, Probe 2 released Probe 1 with "AIE + ESIPT" and reversible mechanofluorochromic properties with the addition of Zn2+. Furthermore, the Probe 2 -based test kit was successfully prepared to detect the freshness of pork. As Probe 2 could be used to detect H 2 S and Probe 1 could be used to detect Zn2+ with strong fluorescence change in both water and living cells, Probe 1 and Probe 2 could be great candidates in the detection of H 2 S and Zn2+ both in vitro and in vivo. Probe 2 was synthesized by linking NBD with amine of benzimidazole, which behaved as a fast fluorescent 'off-on' chemodosimeter for H 2 S with limit of detection in micromolar range. Interestingly, Probe 2 release Probe 1 by thiolysis of NBD amine, the system could regenerate Probe 2 after adding Zn2+. Probe 1 has "AIE + ESIPT" and reversible mechanofluorochromic properties, and could specifically recognize Zn2+. Furthermore, Probe 2 -based test strips could be used to sensitively detect various levels of H 2 S gas and monitor the released H 2 S level in the pork samples, giving powerful evidence for the practical application of Probe 2. Preliminary actual water samples testing and biological experiments have demonstrated the value of Probe 1 and Probe 2 could be used for both endogenous and exogenous detection. [Display omitted] • Novel Probe 2 based on NBD substituted imidazole amino group for detecting H 2 S. • "AIE + ESIPT"-based fast fluorescent 'off-on' Probe 2 for sequential detecting H 2 S and Zn2+. • Probe 2 releases Probe 1 by thiolysis of NBD amine, and returns to Probe 2 after adding Zn2+. • Probe 2 -based test strip could detect H 2 S generated during food spoilage. • Both Probe 1 and Probe 2 could detect in actual water sample and living cells. [ABSTRACT FROM AUTHOR]

A new diarylethene derivative 1O with hydrazinobenzothiazole unit had been synthesized and its multi-controllable switching behaviors induced by UV/vis lights and chemical stimuli (Cd 2+ , Zn 2+ and acid/base) were investigated systemically. 1O could be served as naked-eyes probe to discriminate Cd 2+ and Zn 2+ with obviously different behaviors in fluorescence and absorption spectra. When stimulated by Cd 2+ , its solution color turned light yellow and fluorescence color changed from dark to bright yellow. Similarly, its solution color turned deep yellow accompanied with fluorescence color change from dark to orange when triggered by Zn 2+ . Because coordinating ability of 1O with Cd 2+ was much stronger than that with Zn 2+ , an obvious blue-shift (ca. 51 nm) was observed accompany by a visual fluorescence color change from orange to bright yellow after Cd 2+ was added into 1O-Zn 2+ , implying 1O could also stepwise detect Zn 2+ and Cd 2+ . Moreover, 1O exhibited an obviously solvent-dependent acidichromism. Upon addition with base, the ring-closed absorption peak of 1C showed a prominent bathochromic shift to near-infrared region accompany with an obvious color change from blue to green. Furthermore, a logic circuit was constructed with stimuli of UV/vis lights, Cd 2+ and EDTA as inputs and fluorescence intensity at 559 nm as an output. [ABSTRACT FROM AUTHOR]

A new asymmetrical photochromic diarylethene has been synthesized by using 1,8-naphthyridine as a functional group and perfluorodiarylethene as photoswitching unit via a peptide bond linkage, and its molecular structure was characterized by single crystal X-ray diffraction analysis. The compound exhibited favorable photochromism upon irradiation with UV/vis light, and its fluorescent behaviour could be efficiently modulated by light, base/acid, and metal ion in THF. The deprotonated derivative of the diarylethene also showed good photochromism, and displayed remarkable “turn-on” fluorescence response during photocyclization process. Furthermore, the diarylethene was highly selective toward Cd 2+ with an obvious fluorescent color change from dark to bright green in THF. Finally, a logic circuit was fabricated with four inputs of the combinational stimuli of UV/vis and Cd 2+ /EDTA, and one output of fluorescence intensity. [ABSTRACT FROM AUTHOR]

Photochromic diarylethene dimers (R-DTE-C C C C-DTE-R, R = benzene, 1oo ; R = triphenylamine, 2oo ; DTE = dithienylethene) with remarkable stepwise photochromic process were synthesized successfully. Dimer 2oo , whose two terminal redox-active triphenylamine centers were separated by two photochromic DTE-acetylide moieties, could accomplish photoswitchable charge delocalization between the N⋯N electro-active centers. Upon UV-light irradiation, due to the progressive increase of π-conjugated systems as the order of 2oo → 2co → 2cc , the electronic interaction of two N-centers in 2oo was increasingly facilitated following the stepwise photocyclization. Furthermore, for monocationic species [2oo] + / [2co] + / [2cc] + , their absorption strength was gradually increased during the conversion of [2oo] + →[2co] + →[2cc] + , which demonstrated that the extent of charge delocalization along the molecular backbones was progressively enhanced during the stepwise photocyclization. The lower electronic density of reactive carbon atoms during the oxidation of N 0 to N + could result more difficult photocyclization reaction to produce oxidized species [2oo] 2 + / [2co] 2 + . Additionally, compound 2 exhibited eight switchable states through stepwise photochromic and reversible redox processes. [ABSTRACT FROM AUTHOR]

Herein, a valid fluorescence sensor using covalent organic framework (COF) coupled with Eu3+ is built for the detection of TC. Based on the Schiff base reaction, a new covalent organic framework (Bpydah-Tt-COF) rich in N atoms is synthesized by using [2,2′-bipyridine]-5,5′-dicarbaldehyde (Bpydah) and 1,3,5-triazine-2,4,6-triamine (Tt). Since the abundance of N atoms (up to 33.46%) on the skeleton of Bpydah-Tt-COF, more Eu3+ can facilely anchor on Bpydah-Tt-COF by means of post-modification. Therefore, a Eu3+-functioned covalent organic framework (Bpydah-Tt-COF@Eu) is synthesized and used for sensitive detection of TC via "antenna effect". And the detection sensitivity (3.1 nM) and detection range (from 0.08 to 35 μM) for TC by Bpydah-Tt-COF@Eu fluorescence sensor will be significantly improved due to more target analytes can be identified by Eu3+ on the Bpydah-Tt-COF@Eu. Besides, the Bpydah-Tt-COF@Eu fluorescence sensor has been successfully utilized for TC monitoring in actual samples with good precision (RSD<1.98%) and recoveries (99.89–105.1%). Based on the Schiff base reaction, a new covalent organic framework (Bpydah-Tt-COF) rich in N atoms was synthesized by using [2,2′-bipyridine]-5,5′-dicarbaldehyde (Bpydah) and 1,3,5-triazine-2,4,6-triamine (Tt). Thanks to the abundant binding sites (bipyridine N, imine bind, triazine N) in the skeleton of Bpydah-Tt-COF, the Eu3+ can be easily grafted onto the Bpydah-Tt-COF skeleton by means of post-modification. Under the excitation wavelength at 375 nm, tetracycline (TC) can coordinate with the coordination unsaturated Eu3+ on Bpydah-Tt-COF and TC can efficiently sensitize the Eu3+ based on antenna effect (AE). [Display omitted] • A novel and sensitive fluorescence sensor based on N-rich COF@Eu was constructed. • The proposed sensor realized a rapid, highly sensitive and selective for detection of TC. • The proposed sensor showed a satisfactory result on detection of TC in real samples. [ABSTRACT FROM AUTHOR]

A new photochromic diarylethene with a benzoisothiazole unit has been designed and synthesized. The diarylethene could act as a colorimetric and fluorescence dual-channel chemosensor for CO 3 2− with short response time, high selectivity, and excellent sensitivity. Moreover, the response mechanism of the chemosensor to CO 3 2− was studied systematically in methanol. The chemosensor could be used to the detection of CO 3 2− in practical water samples, and also be made into test papers for CO 3 2− recognition with high efficiency. A dual-channel chemosensor has been designed and synthesized for detecting CO 3 2− with excellent selectivity and sensitivity. The chemosensor could be used to detect CO 3 2− in practical water samples, and be made into test strips for CO 3 2− recognition with high efficiency. [Display omitted] • A new diarylethene derivative with a benzoisothiazole unit has been designed and synthesized. • The derivative could act as a dual-channel chemosensor for CO 3 2− detection with excellent selectivity and sensitivity. • The chemosensor could be made into test strips for CO 3 2− recognition with high efficiency. [ABSTRACT FROM AUTHOR]

Six fluorescent dyes containing the same central benzothiadiazole skeleton were synthesized. Fluorogenic compounds 1 and 2 demonstrated typical aggregation-induced emission enhancement and aggregation-induced emission phenomena. These benzothiadiazole-modified dyes emitted different crystal-state fluorescence including green, yellow-green, yellowish brown, orange red and red colors, and these compounds displayed contrasting force-responsive fluorescence characteristics. More specifically, compound 1 exhibited red-shifted mechanofluorochromism behavior, and compounds 4 – 6 exhibited blue-shifted mechanofluorochromism phenomena, while compounds 2 and 3 showed no fluorescence change under mechanical stimulation. Among these benzothiadiazole derivatives, luminogens 1 and 6 presented mechanically triggered high-contrast bathochromic and hypsochromic fluorescence responses, respectively. Based on their various crystal fluorescence and force-sensitive emissive properties of fluorogenic molecules 1 – 6 , an interesting multilevel information encryption system was successfully constructed. Indeed, this study not only provided a valuable reference for the preparation of luminophores possessing rich mechanoluminochromic natures, but also extended ideas for the development of advanced information encryption systems. • Six benzothiadiazole derivatives were synthesized. • Compound 1 showed aggregation-induced emission enhancement feature. • Compound 2 showed aggregation-induced emission feature. • Solids 1 , 4 , 5 , and 6 displayed hypso- or bathochromic mechanofluorochromic behaviors. • A multilevel information encryption system was successfully constructed. [ABSTRACT FROM AUTHOR]

Cysteine is an organic small molecule that plays an important role in human physiological processes. It is meaningful to detect it easily with high selectivity and sensitivity. In this work, a fluorescent probe Lyso-CDC based on chalcone fluorescent dyes for the effective detection of Cys in lysosomes was designed and synthesized. After adding Cys, the fluorescence of the probe Lyso-CDC at 568 nm was significantly enhanced, displaying a large Stokes shift (168 nm) and a color change from light yellow to bright yellow that was visible to naked eyes. The selectivity and sensitivity of the probe Lyso-CDC for Cys were much higher than other amino acids, and the detection limit for Cys was calculated to be 1.44 × 10−8 M. Furthermore, the probe Lyso-CDC possessed low cytotoxicity, excellent biocompatibility and outstanding lysosome targeting ability. The probe was successfully applied to detect Cys in lysosomes of living cells. [Display omitted] • Lyso-CDC was easy to synthesize. • Lyso-CDC specifically recognized Cys with a large Stokes shift of 168 nm. • Lyso-CDC had a low detection limit of 1.44 × 10−8 M for Cys. • Lyso-CDC has been successfully used to detect and image Cys in living cells. • Lyso-CDC was lysosome-targeting. [ABSTRACT FROM AUTHOR]

As an important reactive oxygen species (ROS), hypochlorous acid (HClO) plays pivotal role in the human immune system and ensures the normal function of the organisms. HClO is derived from mitochondria and can regulate intracellular redox balance. Nevertheless, abnormal HClO levels is related to immune system disorders, neurodegenerative injury and cancer. Therefore, fast and sensitive monitoring HClO in mitochondria is extremely significant for some diseases indication. Herein, we designed a mitochondrial-targeted probe HDCl to detect HClO in living cells, which was a hybrid of coumarin, quaternized pyridine (mitochondrial target site) and N, N-dimethylthiocarbamate (DMTC, hypochlorous acid recognition site). The probe HDCl present high sensitivity, high selectivity and ultrafast (<5 s) responding properties for HClO in phosphate buffer solution (PBS) with the very low detection limit of 2.8 nM and trigger a significant enhanced fluorescent signal at 641 nm. Additionally, with a massive Stokes shift (176 nm), HDCl has been successfully applied to imaging HClO in mitochondria of living cells and in zebrafish. [Display omitted] • Probe HDCl exhibited a turn-on fluorescence in the presence of HClO and its response mechanism was studied in PBS. • HDCl exhibited huge Stokes shift, high specificity, ultra-low detection limit and ultrafast (<5 s) response towards HClO. • HDCl can target mitochondria of cells. • HDCl was applied to detect exogenous and endogenous HClO in living cells and zebrafish. [ABSTRACT FROM AUTHOR]

A deep-red emissive fluorescence probe PT-HBI with phenothiazine and 4-(4-hydroxybenzylidene)-1,2-dimethyl-1 H -imidazole-5(4 H)-one (HBI) motif was designed and synthesized for rapid detection of HClO in a fine ratiometric manner. PT-HBI exhibited remarkable ratiometric fluorescence response to HClO within 50 s, achieving a large Stokes shift (120 nm), high sensitivity (LOD = 0.31 μM) and excellent selectivity. Among the tested analytes, only addition HClO to PT-HBI enables result from a significant fluorescence change from red emission (λ max = 660 nm) to yellow emission (λ max = 540 nm) with the ratio of F 540 /F 660 displaying a 175-fold enhancement. In particular, PT-HBI was capable of monitoring exogenous HClO in Hela cells by ratiometric fluorescence imaging. Moreover, the probe PT-HBI has provided an extensive application for detection of HClO in real water samples and on paper-based sensor to detect HClO in different concentration. • Probe PT-HBI displayed a large emission shift (120 nm) and a 175-fold enhancement in the ratio of F 540 /F 660 for the detection of HClO. • Probe PT-HBI exhibited rapid response time (<50 s), high sensitivity and excellent selectivity in response to HClO. • Probe PT-HBI was successfully applied to exogenous cellular HClO imaging and lysosome co-location. • Probe PT-HBI has been successfully used to constructed paper-based sensing material to detect HClO in different concentration. [ABSTRACT FROM AUTHOR]