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Photochromic fluorescence switching with aggregation-induced emission (AIE) property has attracted great research interest due to their wide application potential in optical electronics and biomaterials. In this work, three novel pyrene-dithienylethene-tetra(tri)phenylethylene triads were synthesized by connecting triphenylethene (TrPE) or tetraphenylethylene (TPE) and pyrene unit via dithienlethene (DTE) bridge. Efficient photochromism and fluorescence switching were demonstrated in solution, aggregates, solid powder, and poly(methyl methacrylate) (PMMA) films under alternating irradiation with UV/visible light. The photocyclization yield of DTE-Py-3 was examined by 1H NMR spectra and calculated as 59%. Moreover, these three compounds exhibited typical AIE character in THF/water mixture, the photochromic and fluorescent switching behavior were explored in aggregated state with 90% water fraction. Furthermore, they could be utilized in application of optical information storage and ink with naked-eye color and fluorescence double channel, indicating the promising potential in anti-counterfeiting. Interestingly, DTE-Py-3 could be reversibly switched by visible light in both directions, which endowed it with the application in biological filed. Efficient photochromic fluorescence switching were demonstrated in solution, aggregated solution, solid powder, and PMMA films under alternating UV/visible light irradiation. [Display omitted] • After AIE group was grafted onto the pyrene unit, typical AIE phenomenon were achieved for the target triads. • Photochromism and fluorescence photoswitching were achieved in solution, aggregated state, PMMA films and solid powder with the alternative UV/Visible light irradiation. • The application of optical information storage and ink were demonstrated. [ABSTRACT FROM AUTHOR]

A novel donor-acceptor Stenhouse adducts (DASAs) derivative (DASA-IDN) was constructed by introducing phenanthroimidazole (PI), tetraphenylethylene (TPE), triphenylamine (TPA) moieties into the DASAs molecular system. The multi-stimuli response process, photochromic and fluorescence properties of DASA-IDN were investigated. When irradiated with visible light, the color of DASA-IDN solution fade quickly and the fluorescence lighted up rapidly. Heating under darkroom could restore it to the initial state. Moreover, solid film of DASA-IDN have been achieved and utilized for information storage. Remarkably, DASA-IDN exhibited versatile switching behavior in response to acid, base and light, turning it into an efficient multi-stimuli responsive molecule. [Display omitted] • A visible light triggered phenanthroimidazole-based donor-acceptor Stenhouse adduct was constructed. • The reversible multi-stimuli responsive photochromic fluorescent switching was achieved. • The information storage has been demonstrated by using DASA-IDN PMMA film. [ABSTRACT FROM AUTHOR]

A novel all-visible-light controlled photochromic dithienylethene (DTE) derivatives bearing phenanthroimidazole (PI) unit were synthesized (DTE-PI). Upon alternating irradiation with 420/540 nm light, effective photochromic and fluorescent switches were demonstrated in solution, PMMA film, single crystal and solid powder. Remarkably, multi-stimuli responsive chromism and fluorescence switches were demonstrated by modulation of protonation. The effect of adding trifluoroacetic acid (TFA) on the performance of DTE-PI were carefully investigated. Interestingly, multi-stimuli responsive chromism and fluorescent switches were achieved with good reversibility when treated with excessive TFA. Neutralization by triethylamine (TEA) could restore it to the initial state. Notably, the photoswitchable dual-mode patterning application was developed successfully. [Display omitted] • An all-visible-light triggered phenanthroimidazole-based dithienylethene was constructed. • The reversible multi-stimuli responsive photochromic fluorescent switching was achieved. • Single crystal structure was obtained and reversible photochromism and fluorescent switching behavior. • All-visible-light patterning application on a filter paper was demonstrated. [ABSTRACT FROM AUTHOR]

Abstract: A series of novel, substituted, pyrido[1,2-a]benzimidazole derivatives were synthesized using a novel tandem annulation reaction between 2-acylbenzimidazole derivatives and 4-bromobut-2-enoic esters under mild conditions. The compounds were characterized using IR, 1H NMR, 13C NMR and HRMS; the crystal structure of 2,7,8-trimethyl-3-ethoxycarbonyl-4-phenylpyrido[1,2-a]benzimidazole was determined as orthorhombic. The absorbance and fluorescence spectra of the pyrido[1,2-a]benzimidazoles were measured in dichloromethane; an intense absorption maxima was observed at 250 nm and emission maxima were noted at 460 nm. The absorption spectra and fluorescence characteristics of the pyrido[1,2-a]benzimidazole derivatives revealed that a phenyl and a methyl group attached to the pyrido[1,2-a]benzimidazole ring markedly influenced maximum emission. [ABSTRACT FROM AUTHOR]

Abstract: The interaction between bovine haemoglobin and C.I. Solvent Red 24 was investigated by UV/vis absorption, fluorescence, resonance light-scattering spectra, synchronous fluorescence as well as three-dimensional fluorescence spectra techniques at pH 7.4. The dye effectively quenched the intrinsic fluorescence of bovine haemoglobin via static quenching. The process of dye to bovine haemoglobin was spontaneous, the related changes in enthalpy and entropy being 1.78 kJ mol−1, 81.58 J mol−1 K−1 respectively, according to the van''t Hoff equation, indicating that hydrophobic interaction played a major role in stabilizing the complex. Synchronous fluorescence spectroscopy and three-dimensional fluorescence spectra showed that the structure of the tyrosine residue environments was altered by the dye which interacted at the α1β2 interface of the bovine haemoglobin molecule. [Copyright &y& Elsevier]

It is noteworthy that highly selective molecular recognition endows host-guest gels, especially hydrogel, with valuable properties. Therefore, in pure water, a supramolecular hydrogel (SH-α - CD) was constructed by using benzimidazolium-based positive charged guest molecule (J2) assembled with cyclodextrin (α-CD) through host-guest interaction, and accompanied an aggregation-induced emission (AIE). The self-assemble process of the hydrogel-based AIEgen was investigated using 1H NMR titration, 2D NOESY, XRD and SEM. In particular, the hydrogel-based AIEgen was investigated as a good candidate for fluorescent quenching and gel state destruction dual-channel recognizing negative charged dye molecule methyl orange (MO). The competitive inclusion interaction triggered the dissolution of aggregate, which induced the gel to transform into sol, with disappearance of the AIE of SH-α-CD. However, the addition of the competitive dye molecules methylene blue (MB) and xylenol orange (XO) only made the fluorescence quenching of hydrogel-based AIEgen. Meanwhile, the hydrogel-based AIEgen also exhibited an excellent thermal responsiveness under temperature transition. Such a performance is highly beneficial for potential applications in probe material for organic dye molecules. A supramolecular hydrogel (SH-α-CD) was constructed by using benzimidazolium-based guest molecule (J2) assembled with α-cyclodextrin (α-CD) through host-guest interaction, and accompanied an aggregation-induced emission (AIE). It was investigated as a good candidate for fluorescent quenching and gel state destruction dual-channel recognizing negatively charged dye molecule methyl orange (MO). Image 1 • A hydrogel-based AIEgen was constructed by using benzimidazolium-based guest (J2) assembled with α-cyclodextrin. • The hydrogel-based AIEgen exhibited thermo-reversible gel-sol transformation with fluorescent On-Off property. • Supramolecular hydrogel was investigated as a good candidate for dual channel recognition methyl orange. • The supramolecular hydrogel should possess potential applications in probe material for organic dye molecules. [ABSTRACT FROM AUTHOR]

In order to investigate the effect of positional isomerization on the photoelectric properties of thermally activated delayed fluorescence (TADF) emitters, thereby fully stimulating the potential of the molecular backbone, herein, two red TADF isomers, oTPA-PPP and mTPA-PPP, were developed and synthesized by linking triphenylamine (TPA) donor into different positions of the pyrido [2′,3′:5,6] pyrazino [2,3-f] [1,10] phenanthroline (PPP). Their photoluminescent quantum yields (PLQYs) and external quantum efficiencies (EQEs) were significantly different by manipulating the substitution position of the donor. Compared with mTPA-PPP, oTPA-PPP exhibited higher PLQY benefiting from intramolecular hydrogen bonding and larger fluorescence radiative decay rate, as confirmed by both theoretical and experimental analyses. As a result, oTPA-PPP-based organic light-emitting diode (OLED) realized high EQE max of 19.2 % with red emission at 603 nm, whereas mTPA-PPP achieves an EQE max of 7.9 % at 596 nm. This work provides a simple and feasible molecular design strategy to design and select red TADF emitters with excellent properties. [Display omitted] • Two emitters' photophysical properties can be finely regulated and their molecular skeleton potential is excited. • Multi-nitrogen atom receptors promote RISC and radiative transition processes. • High k r of 5.29 × 107 s−1 for oTPA-PPP suppressed the non-radiative decay and enhanced PLQY to 92.8 %. • OTPA-PPP-based OLED realized high EQE of 19.2 % with red emission peaked at 603 nm. [ABSTRACT FROM AUTHOR]

Light is not the only stimuli which can coverts donor-acceptor Stenhouse adducts (DASAs) from the triene to the cyclopentenone form. Here, we firstly demonstrate that Cu2+ can drive linear-to-cyclic isomerization of DASAs in acetonitrile, which increase the rate of color fading. Three different generations of DASAs (DASA-1 , DASA-2 , and DASA-3) have been synthesized by Knoevenagel condensation to verify the universal applicability of the mechanism by which copper ions discolor DASAs. The Job's plot of DASA-1 to Cu2+ indicated DASA-1 binds to Cu2+ with a ratio of 1:1, and the 1H NMR titration spectrum of Cu2+ on DASAs as well as the UV–Vis absorption spectra with adding Cu2+ showed that copper ions could induce the process of linear-to-cyclic isomerization of DASAs in acetonitrile. Based on this, we propose copper ions as the eraser of a DASA derived ink to achieve repeatable erasing. Furthermore, DASAs have been utilized as a Cu2+ sensor with high selectivity and sensitivity. [Display omitted] • Three long wavelength visible light responsive DASAs dyes have been synthesized by Knoevenagel Condensation Reaction. • Copper ions can drive linear-to-cyclic isomerization of DASAs in acetonitrile. • A high-sensitivity Cu2+ test paper loaded with DASAs dye was prepared. [ABSTRACT FROM AUTHOR]

A novel supramolecular chemosensor (PNG) was successfully constructed by 5-(3-nitrophenyl)-furfural-functionalized Pillar[5]arene(PN) and bipyridine salt(G) via exo-wall π...π interactions. Interestingly, the chemosensor PNG could detect OH− and CO 2 with high selectivity, sensitivity and excellent recyclable properties. The fluorescent detection limits of PNG for OH− and CO 2 are 2.03 × 10−8 M and 9.1 × 10−8 M (2.22 ppm), respectively. The colorimetric detection limits for OH− and CO 2 are 3.78 × 10−8 M and 1.13 × 10−7 M (2.76 ppm), respectively. This study is simple and effective for OH− and CO 2 detection, and provides supramolecular fields with potential practical application in anion and gas detection. Image 1 • Synthesis of a novel arylfurfural functionalized pillar [5]arene (PN). • The PN and G could self-assemble to supramolecular chemosensor PNG by exo-wall π...π interactions. • The PNG shows excellent recyclable dual-channel detections for OH− and CO 2. • PNG -based sequential detection for OH− and CO 2 with high sensitivity and selectivity. [ABSTRACT FROM AUTHOR]

The aim of this study is to construct N -containing heterocyclic probes with large conjugate structures. Two triazolopyrimidine analogs LK-1 and LK-2 were designed and synthesized. Between them, LK-2 has a higher fluorescence quantum yield and selected as a fluorescent probe for detecting 2,4,6-trinitrophenol (TNP). Whether DMF or H 2 O as solvent, probe LK-2 shown low detection limit apparently (0.025 and 0.44 μM), fast and highly selective fluorescence response to TNP compared to other nitro-aromatic compounds. The static quenching mechanism is demonstrated by fluorescence lifetime. Nuclear magnetic titration and theoretical calculations further explain the identification process. What's more, application of LK-2 in actual water samples and test strip experiments demonstrate the potential of probe in practical significance. Image 1 •Two large conjugated triazolopyrimidine analogs, LK-1 and LK-2 were designed and synthesized. • LK-2 can detect TNP sensitively and efficiently in DMF or H 2 O. •The structure of LK-2 was further confirmed by single crystal. •DFT calculations were used to understand the possible procedure of detection. •Successfully applied to actual water sample testing and test strip experiments. [ABSTRACT FROM AUTHOR]

Two novel aggregation-induced emission (AIE) active Schiff bases (P4C12 and P5C12) harnessing excited-state intramolecular proton transfer (ESIPT) process derived from tetraphenylethylene and 4-(dodecyloxy)-2-hydroxybenzaldehyde were reported. P4C12 exhibits photochromism in original powder and crystalline states. In contrast, P5C12 exhibits photochromism in original powder, but totally different photochromic and fluorescence properties in its two crystalline polymorphs. The reed leaf crystal (P5C12-A) exhibits very weak fluorescence and reversible photochromic behavior, while the small block crystal (P5C12–B) emits relatively stronger fluorescence without photochromism. Detailed investigations indicate that, different crystal packing styles result in different photoinactivation ways, accounting for different photochemical and photophysical properties. As photochromic molecules, P4C12 and P5C12 show reversible color and fluorescence changes upon UV light irradiation and visible light with good fatigue resistance, which makes them suitable for data storage and anti-counterfeiting materials. Moreover, P4C12 shows anisotropic crystal without liquid crystal texture, while P5C12 shows reversible liquid crystal with smectic phase. • Two tetraphenylethene Schiff base derivatives (P4C12 and P5C12) showing significant AIE property. • P4C12 exhibits photochromism in its original powder and crystalline states, while P5C12 exhibits different photochromic and fluorescence properties in its two crystalline polymorphs. •Moreover, P4C12 is anisotropic crystal without liquid crystal texture, while P5C12 is reversible liquid crystal of smectic phase. [ABSTRACT FROM AUTHOR]

The development of efficient long-wavelength TADF emitters has been full of challenges owing to the various strict molecular design limiting factors. Herein, two orange-red TADF emitters, namely 3DMAC-BP-Br and 3DMAC-BP-CN, based on donor 9,9-dimethyl-9,10-dihydroacridine (DMAC) and rigid acceptor dibenzo[ a,c ]phenazine (BP) modified by electron-withdrawing bromine atom or cyano group, were designed and synthesized. Both emitters have large twisted D-A-D structure. The strong electron-withdrawing capabilities of the bromine atom or cyano group can dramatically affect photoelectric properties of the emitters by enhancing the intramolecular charge transfer (ICT) effect and enlarge conjugation with the BP group. Hence, both emitters have high PLQY values (83% and 92%, respectively) in doped films and possess simultaneously small ΔE ST values (0.04 and 0.02 eV, respectively). As a result, both 3DMAC-BP-Br and 3DMAC-BP-CN show superior device performance. Especially, DMAC-BP-CN based OLED exhibits a maximum external quantum efficiency (EQE) of 22.43% and low turn-on voltage of 2.8 V. [Display omitted] • Two orange-red TADF materials were synthesized based on BP acceptors modified by bromine or cyano. • 3DMAC-BP-CN in toluene exhibited red emission peaking at 619 nm due to the stronger electron-withdrawing ability of cyano. • Compared to 3DMAC-BP-Br, 3DMAC-BP-CN achieved more high PLQY (92%) and smaller ΔE ST (0.02 eV). • The OLED based on 3DMAC-BP-CN showed outstanding photoelectric performance, and its EQE max was up to 22.43%. [ABSTRACT FROM AUTHOR]

In this study, a benzo[e]indole[2,1-b][1,3]benzooxazine derivative 2-nitro-5a-(2-(2-thiophene)-ethylene)-6,6-dimethyl-5a,6-dihydro-12H-benzo[e]indolo[2,1-b][1,3]benzooxazi-ne (TEO) was explored as a sensitive probe for CN−. Unlike conventional spiropyrans that possess a 3 H -benzo[e]indole cation and a 4-nitrophenolate anion in the same conjugated structure, TEO enhances the positive charge of the 3H-benzo[e]indole cation, which considerably improves its sensitivity and reaction speed. UV–visible spectrophotometry was used to detect CN− with a detection limit of 0.1 μM and a rate constant of 0.528s−1. In this study, TEO probe showed high selectivity and sensitivity to CN−. Therefore, this probe allows overcoming the limitations of prevailing techniques against the S2− interference. In addition to UV titration for the determination of CN−, we also added fluorescence titration experiments. CN− of 0.1 μM can also be detected by fluorescence titration. Moreover, the probe was successfully used to detect amygdalin content in almonds. Compared with high-performance liquid chromatography (HPLC), this method avoids the complexity of the extraction process and the interference of polar components. Furthermore, the results are consistent with those obtained by the HPLC method. TEO was proposed as a highly sensitive CN− probe by UV–visible spectrophotometry. TEO transforms from a closed-loop structure to an open-loop structure in methanol buffer solution, and the conjugate system becomes larger after the switching. After joining the CN−, the pro-nuclear addition reaction took place with TEO , and TEO 's conjugate system was destroyed. CN− was identified by UV spectral changes. As CN− is added the color of the solution changes quickly from orange to light yellow, easily visible to the naked eye. [Display omitted] • TEO was proposed as a highly sensitive CN− probe by UV–visible spectrophotometry. • The probe showed superior sensitivity and selectivity toward CN−. • The minimum detection concentration of the probe was 0.1 μM. • The probe only responds to CN− and is not disturbed by S2−. • TEO can be used to detect the content of amygdalin. [ABSTRACT FROM AUTHOR]

Two highly efficient thermally activated delayed fluorescent (TADF) materials with twisted donor-acceptor-donor (D-A-D) structure, DMACBB and PXZBB, have been designed and synthesized based on bis(phenylsulfonyl)benzene as the acceptor (A) and 9,9-dimethyl-9,10-dihydroacridine (DMAC) or phenoxazine (PXZ) as the donor (D). Attaching the donor to the 3, 3′-positions of bis(phenylsulfonyl)benzene obtains larger torsion angle between donor and acceptor as well as suitable ICT effects, which results in almost complete separation of their FMOs and limited overlap. Both emitters successfully achieve small ΔE ST (≤0.2 eV), simultaneously exhibit high photoluminescence quantum yields (≥80%). Both of them possess distinct TADF features. The DMACBB-based device exhibits sky blue emission with the peak at 472 nm, while the PXZBB-based device shows slightly red-shifted and emits green light with the peak at 507 nm because of the stronger electron-donating ability of PXZ than that of DMAC. The TADF-OLED based on DMACBB achieves higher the maximum external quantum efficiency (EQE max of 10.1%) than the TADF-OLED based on PXZBB (EQE max of 8.2%) with the turn-on voltage of 3.5 V. • Two novel TADF emitters connecting two donors to the 3, 3'-position of bis(phenylsulfonyl) benzene have been synthesized. • Both DMACBB and PXZBB have typical TADF nature. The OLED based on DMACBB achieves higher EQE max than that of PXZBB. • Both TADF emitters achieve small ΔEST and simultaneously exhibit high PLQYs (≥80%) as well as better device performence. [ABSTRACT FROM AUTHOR]

In this work, we have developed a new carbazole-based fluorescent probe (E)-1-methyl-4-(2-(5-(9-phenyl-9 H -carbazol-3-yl) thiophen-2-yl)vinyl)pyridin-1-ium (PCTP) for ratiometric and colormetric ClO− sensing. PCTP displayed red emission due to the intramolecular charge transfer (ICT) effect of phenylcarbazol moiety, while this effect can be rapidly weakened and led to the significant fluorescence change (from red to green) in the presence of ClO−. PCTP is more highly selective and sensitive towards ClO− detection than other various biological related species. The detection limit (LOD) was calculated to be 10.8 nM. More importantly, PCTP has been successfully applied in ClO− imaging in living cells and zebrafishes. • A novel colormetric and ratiometric fluorescent probe (PCTP) was designed and synthesized for detecting ClO−. • PCTP displays a low detection limit (10.8 nM) and large Stokes shift (124 nm). • PCTP successfully performed well in sensing ClO− in living cells and zebrafishes. [ABSTRACT FROM AUTHOR]

We designed and synthesized two new visible light triggered photochromic and aggregation-induced emission compound derived from the third generation donor−acceptor Stenhouse adducts (DASAs) with indoline-tri/tetra-phenylethylene moiety (abbreviation: SPE-IF/TPE-IF). The chemical structures of these compounds are identified by NMR, MS and so on. The key intermediate SPE-ID/TPE-ID as donor showed excellent AIE properties in water-THF (v/v) solutions. The absorption and emission of SPE-IF/TPE-IF were investigated by UV–Vis and fluorescence spectroscopy, respectively. The results shown they exhibited photochromic with fatigue resistance and fluorescent switching properties with visible light regulation. The open/colored triene and closed/colorless cyclopentenone isomers of SPE-IF/TPE-IF were equipped with high photo bleaching and fluorescence effect upon alternating visible light irradiation and heating both in solution and in PMMA doped solid state. And the solvent dependence effect of TPE-IF was studied. The photochromic mechanism of SPE-IF/TPE-IF was also basically investigated by computational method. These results indicate SPE-IF or TPE-IF is a promising candidate for visible light-responsive smart materials. Image 1 • The third generation DASAs with AIE including SPE-IF/TPE-IF were synthesized. • The fluorescence switching of SPE-IF/TPE-IF was investigated both in solvent and doped in PMMA film. • The equilibration kinetics and solvent effect of the TPE-IF were studied. [ABSTRACT FROM AUTHOR]

Thermally activated delayed fluorescence (TADF) chiral emitters attract widespread attention due to their high exciton utilization as well as potential applications. In this work, we developed a pair of chiral donors, (R) and (S)-9-methyl-2,9-diphenyl-9,10-dihydroacridine (PMAc), for general TADF molecular design. The enantiomers (R) and (S)-TTR-PMAc are accordingly constructed. Interestingly, they are not only TADF emitters, but also possess dual stable conformations, i.e. nearly planar and nearly orthogonal conformations. (R) and (S)-TTR-PMAc show similar physical properties under conventional non-polarized environment. While under chiroptical environments, they exhibit obvious mirror-like circular dichroism (CD) and circularly polarized luminescence (CPL) properties. Moreover, by further comparing the CPL properties originated from each conformer, we confirm that molecular conformations can significantly influence the chiroptical performance. Image 1 • Chiral donors (R/S)-PMAc with asymmetric carbons are for TADF molecular design. • Enantiomers (R/S)-TTR-PMAc with dual conformations are designed and synthesized. • (R/S)-TTR-PMAc show TADF and CPL properties. • Chiroptical properties can be significantly influenced by molecular conformations. [ABSTRACT FROM AUTHOR]

As one of the vital amino acids in human body, l -Arginine (L-Arg) plays important roles in many biological functions, and the development of convenient detection L-Arg is essential in the current research. Herein, a novel pillar[5]arene-based fluorometric and colorimetric dual-channel sensor (PNS) was designed and synthesized, which exhibited superior performance for detecting L-Arg. The colorimetric and fluorometric limits of detection (LODs) for L-Arg are 0.6 μM and 0.2 μM, respectively. In addition, the sensing process of PNS for L-Arg showed excellent selectivity and the sensing mechanism was based on multiple surpramolecular interactions. Meanwhile, PNS -based test paper has been prepared, which could act as a convenient and efficient test kit to detect L-Arg in water. Herein, a novel pillar[5]arene-based fluorometric and colorimetric dual-channel sensor (PNS) was designed and synthesized, which exhibited superior performance for detecting L-Arg. The colorimetric and fluorometric limit of detections of PNS (LODs) for L-Arg are 0.6 μM and 0.2 μM, respectively. In addition, the sensing process of PNS for L-Arg showed excellent selectivity and the sensing mechanism was based on multiple surpramolecular interactions. Meanwhile, PNS -based test paper has been prepared, which could act as a convenient and efficient test kit to detect L-Arg in water. Image 1 • Novel pillar[5]arene-based fluorometric and colorimetric L-Arg sensor. • Sensing L-Arg by multiple supramolecular interactions. • Selectively and sensitively detection L-Arg. • The LODs for dual-channel detecting L-Arg could reach to 0.2 μM. • The PNS -based test paper for detecting L-Arg in water was prepared. [ABSTRACT FROM AUTHOR]