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A novel fluorescent material that can change its emission properties in response to different external stimuli holds significant importance for the development of sensors, information storage, and encryption materials. In this work, we designed and synthesized two zinc(II) coordination compounds, [Zn(HL)I2]·CH3OH (1) and [Zn(HL)Br2]·CH3OH (2), which exhibit remarkable changes in their emission properties under three different external stimuli. The two compounds were prepared using a simple one-pot method by reacting zinc(II) salts with 4-(N,N-diphenylamino)benzaldehyde and 3-amino-2-pyridinone. Under the stimulation of NH3 vapor, both compounds underwent decomposition, leading to a transformation of their fluorescence from yellow to blue, exhibiting a significant blue-shift of more than 170 nm. After exposure to HCl vapor, the fluorescence color of the two original compounds changed from yellow to red, and the color change could be easily distinguished by the naked eye under UV light irradiation. Then after fumigation with NH3 vapor, the color of both samples changed from red to blue. Based on the high-contrast NH3-responsive properties and HCl-responsive properties, we designed and developed test papers capable of detecting HCl vapor and NH3 vapor. Furthermore, due to the transformation from the crystalline state to the amorphous state during grinding, the two compounds also demonstrated high-contrast mechanochromic luminescence properties. After grinding, the color of the two compounds changes significantly from yellow to orange. [ABSTRACT FROM AUTHOR]

Four new Zn(II) metal–organic frameworks (MOFs): {[Zn(L1)(BTEC)0.5]·3.1H2O}n (1), {[Zn(L2)0.5(BTEC)0.5]·1.5H2O}n (2), {[Zn2(L3)(BTEC)(H2O)]·H2O}n (3), and {[Zn2(L4)(BTEC)]·H2O}n (4) were constructed by selecting N-containing linkers with the Zn(II)/H4BTEC system (H4BTEC = 1,2,4,5-benzenetetracarboxylic acid, L1 = 1,4-bis(1-(pyridin-4-ylmethyl)-1H-benzo[d]imidazol-2-yl)cyclohexane, L2 = 1,4-bis(1-(pyridin-4-ylmethyl)-1H-benzo[d]imidazol-2-yl)butane, L3 = 1,5-bis(1-(pyridin-4-ylmethyl)-1H-benzo[d]imidazol-2-yl)pentane, L4 = 1,4-bis(1-(pyridin-4-ylmethyl)-1H-benzo[d]imidazol-2-yl)methyl)benzene). Structural analyses indicate that 1 exhibits a (3,4)-connected 2D 3,4L13 sheet. 2 manifests a rare (4,4,4)-connected 2D 4,4,4L10 layer. 3 displays an unprecedented (3,3,4,4,4)-connected 3D network based on the point symbol {4·82}2{42·6·83}2{42·6}2{42·82·102}{84·122} and 4 presents an unusual 4,4,4,6,6T3 3D network with a 5-node (4,4,4,6,6)-connected network. The structural variety of these Zn(II) MOFs demonstrates that different N-containing ligands can induce the BTEC4− linkers exhibiting various coordination modes, exerting a great influence on the final MOF frameworks. Further, MOFs 1–4 are favorable dual-functional fluorescent sensors for the detection of Fe3+/acetylacetone with high sensitivity and selectivity. To our knowledge, this is the first report of fluorescent MOFs based on L1–L4 ligands for the detection of Fe3+ and acac in the naked eye range. [ABSTRACT FROM AUTHOR]

Three water-stable 2D cadmium(II)-coordination polymers (CPs), namely {[Cd(MIP)](L)·1.35H2O}n (1), [Cd(NTP)(L)]n (2) and [Cd(1,4-NDC)(L)]n (3) (L = 1,3-bis(5,6-dimethylbenzimidazol-1-yl)propane, H2MIP = 5-methylisophthalic acid, H2NTP = 2-nitroterephthalic acid and 1,4-H2NDC = 1,4-naphthalenedicarboxylic acid), were synthesized and characterized. 1 exhibits a 3,4L83 framework, 2 is a 3,5L2 network and 3 exhibits a rare 3,4-connected 3,4L27 network. 1 and 3 are dual-function luminescence sensors for sensing Cr2O72− (pH = 3.0)/CrO42− (pH = 13.0) in aqueous solution with high sensitivity, selectivity and excellent recyclable behaviors. [ABSTRACT FROM AUTHOR]

Five new CdII-based ternary metal–organic frameworks (MOFs) constructed from structurally related ligands, namely, [Cd(L1)(DCTP)]n (1), [Cd2(L2)2(DCTP)2]n (2), {[Cd2(L3)(DCTP)2]·3.75H2O}n (3), {[Cd(L4)(DCTP)]·0.85H2O}n (4) and [Cd0.5(L5)0.5(DCTP)0.5]n (5) (H2DCTP = 2,5-dichloroterephthalic acid, L1 = 1,4-di(1H-benzo[d]imidazol-2-yl)butane, L2 = 1,5-di(1H-benzo[d]imidazol-2-yl)pentane, L3 = 1,3-bis(1-(pyridin-4-ylmethyl)-1H-benzo[d]imidazol-2-yl)propane, L4 = 1,4-bis(1-(pyridin-4-ylmethyl)-1H-benzo[d]imidazol-2-yl)butane and L5 = 1,6-bis(1-(pyridin-4-ylmethyl)-1H-benzo[d]imidazol-2-yl)hexane), have been hydrothermally synthesized and characterized. While 1 and 5 show the common 2D hcb and 3D sqc6 topologies, respectively, 2 exhibits a rare (4,4)-connected 2-node 2D 4,4L62 network, 3 reveals an unprecedented 3D (3,3,4,5)-connected framework with the point symbol {4·92}2{42·82·92}{42·84·93·10}2{93}2 and 4 presents an unusual (3,5)-connected 3D gra topological framework. The results show that the coordination mode of dicarboxylate ligands and the auxiliary N-containing linkers have a crucial impact on the structural diversities of ternary Cd-MOFs. Further, 2 and 3 are favorable dual-functional fluorescent sensors for the detection of Fe3+/acetylacetone and Cr2O72− (pH = 4)/acetylacetone, respectively, with high sensitivity and selectivity. [ABSTRACT FROM AUTHOR]

Two ternary Ni(II) coordination polymers (CPs) named as: {[Ni2(L1)2(1,8-NDC)2(H2O)2]·2H2O}n (1), {[Ni2(L2)1.5(FA)(H2O)3]·3.75H2O}n (2), (L1 = 1,6-bis(5,6-dimethylbenzimidazol-1-yl)hexane, L2 = bis(5,6-dimethylbenzimidazol-1-yl)methane, 1,8-H2NDC = 1,8-naphthalenedicarboxylic acid, H4FA = 4,4′-(hexafluoroisopropylidene)diphthalic acid) were hydrothermally synthesized and characterized through physicochemical and spectroscopic methods. CP 1 features a 1D double straight-line chain and further extends into a 2D layers via π–π stacking interactions, while CP 2 shows a unique 2D (5,4,4)-connected network. The thermal stabilities, luminescence properties and photocatalytic activities of CPs 1–2 for methylene blue decomposition were also presented in detail. Two luminescent Ni(II) coordination polymers (CPs) were synthesized under hydrothermal condition. The crystal structure of CP 1 features a 1D double straight-line chain and further extends into a 2D layers via π–π stacking interactions, while CP 2 shows a unique 2D (5,4,4)-connected network. The photocatalytic experiments in the presence of catalysts CP 1 indicated higher degradation efficiency for MB solution than CP 2, and ·OH radical plays a key effect in the efficient degradation of MB. [ABSTRACT FROM AUTHOR]

Two new Cd2+ coordination polymers (CPs), namely {[Cd(L)(1,4-PDA)]·0.7(C2H5OH)}n (1) and {[Cd(L)0.5(1,8-NDC)·H2O]}n (2) [L = 1,4-bis(5,6-dimethybenzimidazol-1-yl)-2-butene, 1,4-H2PDA = 1.4-phenylenediacetic acid, 1,8-H2NDC = 1,8-naphthalenedicarboxylic acid], were hydrothermally synthesized and characterized. 1 is a (4,4)-layered structure and further extended into a 3D supramolecular network via π–π stacking interactions. 2 features a 2D (3,4)-connected 3,4L83 framework. 1 and 2 can act as luminescence sensors for detecting acetylacetone (acac) and Fe3+ with high sensitivity, selectivity and recyclability. This is the first dual fluorosensors employing CPs for the detection of Fe3+ and acac. The mechanism for the luminescent sensing of acac and Fe3+ was suggested. [ABSTRACT FROM AUTHOR]

An NDI-based compound (2-NDI) with 2-butyric acid attached at imide N atoms was intelligently constructed. 2-NDI exhibits 2-NDI − monomer (low concentration) and 2-NDI − excimer (high concentration) emission state in different solvents after 365 nm illumination, forming multi-color radical fluorescence. It shows dynamic free radical emission in DMF solvent with rare white light emission. Theoretical calculations show that the fluorescence is derived from the D n -D 0 vertical emission of 2-NDI − monomer and 2-NDI − excimer. Finally, 2-NDI is made into PMMA film, which is successfully applied to information anti-counterfeiting and dynamic information encryption systems. [Display omitted] • 2-NDI was synthesized and showed different free radical emission colors in different solvents. • The dynamic fluorescence of 2-NDI in DMF solution changed with the irradiation time. • 2-NDI shows different free radical fluorescence emission types at different concentrations. • DFT shows that the free radical fluorescence is the vertical emission of D n -D 0. • 2-NDI PMMA film can be used for dynamic information encryption and anti-counterfeiting. Developing innovative materials with environmentally stable 1,4,5,8-Naphthalene diimide radicals (NDI −) emissions is significant. In this work, we have successfully constructed an NDI-based material 2-NDI (N, N′-bis(2-butyric acid)-1,4,5,8-naphthalene diimide) that emits strong fluorescence in solvents and polymethyl methacrylate (PMMA) upon irradiation. The radical 2-NDI − exhibits multi-color emission in different solvent systems, and the fluorescence emission is concentration-dependent. It is worth noting that it exhibits a rare dynamic fluorescence in DMF solvent, with the fluorescence color changing from yellow-green to orange and finally to white. Theoretical calculations show that the fluorescence is derived from the D n -D 0 vertical emission of 2-NDI − monomer and excimer. Owing to the outstanding free radical fluorescence emission properties, various films (PMMA systems) based on 2-NDI in different solvents have been successfully made to be applied in multiple dynamic information anti-counterfeiting and encryption. This work achieved simple and stable fluorescence emission based on NDI −, making it a potential candidate for practical applications and providing a new platform for the future design of NDI-based photochromic materials. [ABSTRACT FROM AUTHOR]

A Naphthalenediimide-based photochromic 2D MOF was successfully synthesized. After irradiation and immersion in acetonitrile solution, the single-crystal-to-single-crystal transition occurred, and 1-P and 1@MeCN were obtained, respectively. 1-P is a rare example of structural visualization during the formation of free radicals after NDI-based photochromism. 1@MeCN improves the photochromic performance of the system by introducing solvent molecules. Finally, for the first time, 1@MeCN was combined with organic glass for practical applications in ink-free printing, purple light detection/filtering, and information anti-counterfeiting. [Display omitted] • A photochromic MOF (1) based on the NDI ligand was synthesized and characterized. • Captured a rare process of structural visualization of free radical formation in 1-P. • The effect of solvent on the photochromic properties (1@MeCN) was revealed. • 1 and 1@MeCN were first used to selectively detect and filter 395 nm purple light. • The 1@MeCN glass was prepared for the first time. It is still a great challenge to understand the structural variation during the photochromic process, to rationally regulate the photochromic performance, and to expand the practical application of NDI-based photochromic materials. Herein, we found a 2D NDI-type photochromic MOF (1). When illuminated by 395 nm purple light, 1 underwent a single-crystal-to-single-crystal (SCSC) transition, resulting in 1-P , which is a rare structural visualization phenomenon during the formation of free radicals. In addition, it was demonstrated for the first time that the introduction of solvent molecules into the system (1@MeCN) can modulate the photochromic ability caused by electron transfer. It was found that 1 and 1@MeCN have the most sensitive response to 395 nm purple light, and are ideal candidates for detecting and filtering purple light. Finally, a photochromic glass based on 1@MeCN was reported, which is first applied in ink-free printing, purple light detection/filtering, and information anti-counterfeiting. [ABSTRACT FROM AUTHOR]

Nowadays, photoactive viologen units have been widely encapsulated in metal-organic frameworks and assembled into multifunctional materials with photochromism and other light regulating properties. A novel host-guest MOF material, {[Zn(bcbpy) 0.5 (IPA)]·CH 3 CN} n (1), has been constructed by a viologen ligand 1,1′-bis((3-carboxylatobenzyl)-4,4′-bipyridinium)-dichloride (H 2 bcbpy·2Cl), isophthalic acid (IPA) and zinc(II) chloride. Complex 1 exhibits UV and X-ray dual photochromism and photo-controlled luminescence properties. Complex 1 also exhibits a temperature-dependent phosphorescence from cyan to yellow when the temperature increases from 77 to 297 K. 1T will be obtained when 1 is heated in air at 230 °C for 30 min, 1T shows less sensitive photochromic property than 1 due to its longer C–H⋯O hydrogen bond distance for electron transfer pathway. In addition, complex 1 has the potential application as an inkless and erasable printing material due to the excellent photochromic property. [Display omitted] • A UV and X-ray dual photochromic complex 1 was synthesized and characterized. • Complex 1 exhibits photo-controlled luminescence properties. • Complex 1 exhibits temperature-dependent phosphorescence properties. • Complex 1 has the potential to be used as an inkless and erasable printing material. [ABSTRACT FROM AUTHOR]

The development of stimulus-responsive luminescent materials, especially those based on a single compound exhibiting multicolor and high-contrast (Δλem ≥ 100 nm) chromic properties, is a critical challenge. In this work, we synthesized and characterized a zinc(II) complex (1). As expected, 1 displays aggregation-induced emission enhancement (AIEE) in THF/H2O mixtures, and remarkable multicolor switching under external stimuli in the solid state. Complex 1 shows reversible mechanochromic luminescence behavior with a large wavelength shift (Δλem = 100 nm) during the grinding–fuming cycles, due to the phase transformation between the crystalline and amorphous states. More impressively, 1 exhibits obvious acidochromic properties (Δλem = 130 nm) which originate from the adsorption of vapor and a gas–solid reaction on the crystal surface. Furthermore, 1 exhibits electrochemical oxidation behavior accompanied by quenching of yellow-green emission due to the overlap of an emission band and an absorption band. The above-mentioned color changes under ambient light can also be observed by the naked eye during the mechanical, acid–base vapor and electrical stimulation. Based on the high-contrast and multicolor switching, complex 1 was successfully developed into test papers and films in the field of rapid detection of mechanical stimuli and HCl/NH3 vapors. [ABSTRACT FROM AUTHOR]

We developed a new MWNTs paste by mixing with oxide-conductive powders for screen-printing. Optimum density and length of CNTs were got after purifying process. Rapid sintering processing (RSP) was adopted for fixing CNT to substrate and removing organic binding material. CNTs were exposed to erect on the surface by developing multi-step post-treatment. Large area cathode (>5 inch) of carbon nanotubes was fabricated using screen-printing. The good cathode of emission uniformity property was obtained. The current density is 35 mA/mm2 at the electric field 2.5 V/μm. The turn-on field of CNTs is approximately 2.0 V/μm. Therefore, the cathode is suitable for FED. [Copyright &y& Elsevier]

Two new complexes with composition {[Ni(L1)(mip)(H 2 O)]·3.6H 2 O} n (1) and {[Co(L2) 2 (npht)]·H 2 O} n (2) [H 2 mip = 5-methylphthalic acid, H 2 npht = 5-nitrophthalic acid, L1 = 1,3-bis(thiabendazol-1-ylmethyl)benzene, L2 = 1,4-bis(thiabendazol-1-ylmethyl)benzene)] were hydrothermally synthesized and characterized by physicochemical and spectroscopic methods. 1 displays a binuclear [Ni 2 L1 2 (mip) 2 structure and further extends into a 2D layer via O–H⋯O hydrogen bond interactions, 2 holds a 1D zigzag linear chain which is further packed via C–H⋯O hydrogen bond interactions into a 3D supramolecular network. Sensing experiments indicate that both complexes can be as high selectivity and sensitivity fluorescent chemosensors for ethylene glycol and Fe3+/Cu2+. Two new complexes were synthesized under hydrothermal condition. The complex 1 displays a binuclear [Ni 2 L1 2 (mip) 2 structure and further extends into a 2D layer via O–H⋯O hydrogen bond. 2 holds a 1D zigzag linear chain which is further linked through C–H⋯O hydrogen bond into a 3D supramolecular network. Sensing experiments indicate that both compounds can be used as highly selective and sensitive fluorescent chemosensors for ethylene glycol and Fe3+/Cu2+. Image 1 • Two bis(thiabendazole) complexes were synthesized and characterized. • 1 and 2 are packed into 2D/3D supramolecular networks by hydrogen bonding. • 1 and 2 exhibit highly sensitive and selective for detection of ethylene glycol. • 1 and 2 could as good fluorescent chemosensors for Fe3+/Cu2+. [ABSTRACT FROM AUTHOR]

[Display omitted] • Complexes 1 , 2 and 3 exhibit reversible photochromic behavior. • Complexes 1 , 2 and 3 exhibit long-lived persistent phosphorescence. • Complex 2 exhibits excitation wavelength dependent fluorescence. • Three complexes show great potential in data encryption and anticounterfeiting. • 2 was fabricated in inkless printing performance and information transmission. Long persistent luminescence materials have wide application prospects in the fields of optical communication, sensors, and anticounterfeiting. Recently, some researchers have proved the feasibility of charge transfer effect in the construction of visible light excited room temperature phosphorescence (RTP) materials. However, materials with electronic effects require elaborate design to exhibit long-lived phosphorescence. Herein, a series of coordination compounds based on viologen ligand HL⋅Cl (4-carboxybenzyl)-4,4′-bipyridinium chloride) and Zn2+ with benzoic acid derivatives (o- , m- , p- phthalic acid) were reported. They exhibit not only reversible photochromic properties, but also long-lived persistent phosphorescence. Three complexes possess different structures through different auxiliary ligands with different optical physical properties. Complex 1 exhibits dynamic phosphorescence emission at low temperatures. Interestingly, we synthesized the first viologen complex (complex 2) with excitation wavelength dependent fluorescence, and the emission color gradually changed from blue to red with the increase of excitation wavelength. In addition, the applications of three complexes in data encryption and anticounterfeiting are further demonstrated. This work not only presents coordination compounds with dynamic afterglow materials, excitation wavelength- and time-dependent emission properties, but also provides a new strategy for the charge transfer effect in visible light-excited RTP materials. [ABSTRACT FROM AUTHOR]

Two complexes based on phosphorescent viologen ligands have been synthesized. Complexes 1 and 2 not only possess reversible photochromic and electrochromic properties, but also exhibit fluorescence and persistent luminescence. They have potential applications in inkless print, color-changing films, data encryption, and anti-counterfeiting. [Display omitted] • Complexes 1 and 2 exhibit reversible photochromic and electrochromic behaviors. • Complexes 1 and 2 exhibit long-lived persistent phosphorescence. • Complexes show great potential in data encryption and anticounterfeiting. • Complexes have potential applications in inkless printing, color-changing films. Viologen-based complexes have garnered significant attention due to their multifunctional stimuli-responsive properties and tunable persistent luminescence. However, achieving ultralong afterglow emission and color change in these complexes remains a challenge, limiting their application in the field of persistent luminescence. Herein, two novel viologen-based complexes were successfully designed and synthesized using N,N′-bis(2-carboxyethyl)-4,4′-bipyridinium dichloride (H 2 bybpy) ligands and trimesic acid (H 3 BTC) with the transition metals Zn(II)/Cd(II). Complexes 1 and 2 display reversible photochromic and electrochromic properties. Interestingly, complexes 1 and 2 in their crystal state exhibit dual fluorescence and persistent luminescence, emitting a green and cyan afterglow when the UV lamp is turned off at 77 K. Incorporating phosphorescent molecules and changing the metal significantly extended the duration of persistent luminescence and altered the hue. The complexes were also demonstrated to have potential applications in inkless printing, color-changing films, data encryption, and anti-counterfeiting. This work enhances the application of viologen-based complexes in light-controlled persistent fluorescence and provides ideas for achieving ultra-long afterglow emission. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel "turn-on" fluorescent chemosensor for the detection of Al3+ was developed. • The probe exhibited anti-interference recognition and low detection limit of 22.0 nM. • The detection mechanism of the probe for Al3+ is the formation of Al-complex. • HL can be utilized as a film to detect Al3+ ions. Many Al3+ sensors have been reported in the literature, the lack of spectral features and poor coordination of Al3+ pose a significant challenge to detection. Herein, the design and synthesis of a Schiff's base (HL) sensor is reported, which exhibits a turn-on response to Al3+ in an aqueous solution, and the fluorescence color of HL from light green to cyan upon the addition of Al3+. The limit of detection (LOD) for Al3+ was determined to be 2.20 x 10−8 M. The mechanism for fluorescence sensing was revealed through the analysis of single-crystal X-ray diffraction, DFT, and UV–vis absorption spectra. HL gradually coordinated with Al3+ during the titration process, leading to the formation of HL-Al crystals. The outcome of this study resulted in the successful preparation and application of flexible and foldable films for visual detection of Al3+. [ABSTRACT FROM AUTHOR]

Selective detection of antibiotics and MnO4− is crucial for human health improvement and protecting the environment. Two stable Zn(II)-based metal–organic frameworks (MOFs) {[Zn6(L1)2(NDC)5(μ2-OH)2]·0.5H2O}n (1), and {[Zn(L2)(NDC)]·2H2O}n (2) (H2NDC = 1,4-naphthalenedicarboxylic acid, L1 = 1,5-bis(1-(pyridine-4-ylmethyl)-1H-benzo[d]imidazol-2-yl)pentane, L2 = 1,6-bis(1-(pyridine-4-ylmethyl)-1H-benzo[d]imidazol-2-yl)hexane) were successfully synthesized by adopting the mixed ligands approach. 1 is a rare 3D 3,5,6T23 framework based polynuclear complex group. 2 possesses a 2D sql layer. The two MOFs exhibit excellent chemical and thermal stability. The title compounds are promising dual-functional fluorescent sensors for detecting enrofloxacin/MnO4− anions with high selectivity and sensitivity (Ksv values toward enrofloxacin: 4.29 × 106 L mol−1 for 1 and 4.59 × 106 L mol−1 for 2 and toward MnO4−: 1.05 × 104 for 1, 5.48 × 103 L mol−1 for 2, respectively), which are the first observations of fluorescent MOFs for the sensing of enrofloxacin and MnO4− anions. [ABSTRACT FROM AUTHOR]

Background: Endoscopic resection for large, laterally spreading tumors (LSTs) in the cecum is challenging. Here we report on the clinical outcomes of hybrid endoscopic submucosal dissection (ESD) in large cecal LSTs.Methods: We retrospectively reviewed data from patients with cecal LSTs ≥ 2 cm who underwent ESD or hybrid ESD procedures between January of 2008 and June of 2019. We compared the baseline characteristics and clinical outcomes, including procedure time, the en bloc and complete resection rates, and adverse events.Results: A total of 62 patients were enrolled in the study. There were 27 patients in the ESD group and 35 patients in the hybrid ESD group, respectively. Hybrid ESD was more used for lesions with submucosal fibrosis. No other significant differences were found in patient characteristics between the two groups. The hybrid ESD group had a significantly shorter procedure time compared with the ESD group (27.60 ± 17.21 vs. 52.63 ± 44.202 min, P = 0.001). The en bloc resection rate (77.1% vs. 81.5%, P = 0.677) and complete resection rate (71.4% vs. 81.5%, P = 0.359) of hybrid ESD were relatively lower than that of the ESD group in despite of no significant difference was found. The perforation and post-procedure bleeding rate (2.9% vs. 3.7%, P = 0.684) were similar between the two groups. One patient perforated during the ESD procedure, which was surgically treated. One patient in the hybrid ESD group experienced post-procedure bleeding, which was successfully treated with endoscopic hemostasis. Post-procedural fever and abdominal pain occurred in six patients in the ESD group and five patients in the hybrid ESD group. One patient in the ESD group experienced recurrence, which was endoscopically resected.Conclusion: The results of this study indicate that hybrid ESD may be an alternative resection strategy for large cecal LSTs with submucosal fibrosis. [ABSTRACT FROM AUTHOR]

In this work, we successfully synthesized two Schiff base (HL) complexes, ZnLCl 2 (1) and [Cd 2 L 2 Cl 4 ]·CH 3 CN (2), via the one-pot reaction of metal salts with 4-[bis(4-bromophenyl)amino]benzaldehyde and 3-hydroxy-2-naphthoic acid hydrazide. Complex 2 exhibits not only acidochromic properties but also NH 3 -induced discoloration behavior, which is rarely reported among triphenylamine derivatives or complexes. However, complex 1 shows no color change upon fuming with HCl or NH 3 vapor. The experimental results show that acidochromism may be due to the decomposition of the structure by HCl vapor, while NH 3 -induced discoloration is mainly attributed to the phase change of 2 from crystalline to amorphous state. In addition, complexes 1 and 2 showed high-contrast mechanochromic luminescence (MCL) change from yellow to orange and green to yellow, respectively. Complexes 1 and 2 also exhibit electrochromic behavior with color change from yellow to brown. Moreover, complex 2 was successfully made into test paper for mechanical stimuli and the rapid detection of HCl and NH 3 vapor. The complex 2 can be fixed on a mask coat to fabricate a 2 -based wearable hazardous gas sensor, suggesting that 2 is expected to develop into the next generation wearable sensors for detection of HCl and NH 3 vapor. [Display omitted] • Complexes 1 and 2 showed reversible mechanochromic luminescence behavior. • 2 exhibits acidochromic properties and NH 3 -induced discoloration behavior. • Complexes 1 and 2 also exhibit electrochromic behavior. • 2 can be made into test paper for repeated writing and HCl/NH 3 vapor detecting. • 2 can be made wearable sensor for detection of HCl and NH 3 vapor. [ABSTRACT FROM AUTHOR]

A novel Schiff base ligand HL ·CH 3 COOH with excited-state intramolecular proton transfer (ESIPT) and its zinc (Ⅱ) complex 1 were successfully synthesized, and both of them show high-contrast mechano- and acidochromic luminescence. [Display omitted] A new Schiff base compound (HL ·CH 3 COOH) with D-A structure and its zinc(II) complex (1) were successfully obtained. Due to the introduction of diethylamino and rotatable aromatic rings, both HL ·CH 3 COOH and the complex adopt loosely packing patterns. HL ·CH 3 COOH exhibits keto-form emission due to the excited-state intramolecular proton transfer (ESIPT) process, while complex 1 shows enol-form emission. They all show reversible mechanochromic luminescence (MCL) behavior, which is caused by the phase transformation from crystalline state to amorphous state revealed by Powder X-ray diffraction (PXRD) studies, and is accompanied by the departure of CH 3 COOH molecules for HL ·CH 3 COOH. HL ·CH 3 COOH and complex 1 can be protonated under the fumigation of HCl, resulting in the acidochromic properties, accompanied with the phase transformation. HCl also destroyed the interactions between CH 3 COOH and Schiff base molecules, leading to the departure of acetic acid molecules. More interestingly, HL ·CH 3 COOH also exhibited NH 3 -stimuli response properties due to the prohibition of the ESIPT process. [ABSTRACT FROM AUTHOR]

Multistimuli responsive materials based on the viologen coordination polymers have attracted much interest in the past few years due to the increasing demand for smart materials. In this paper, based on a viologen ligand 1-(3-carboxybenzyl)- 4,4′-bipyridinium chloride (Hcbbpy) and zinc(II) ion, a new crystalline complex, namely, {[Zn(cbbpy)Cl 2 ]·H 2 O} n (1) has been designed and synthesized. In complex 1 , every cbbpy ligand as a bridge links two Zn2+ ions via carboxylate O atom and pyridine N atom to extend to a 1D zigzag chain. The 1D chains are extended to 3D supramolecular structure through π···π stacking and hydrogen bonding. More importantly, 1 exhibits fast photochromic behaviors in response to UV and X-ray due to the formation of viologen radicals. Complex 1 also shows photo-modulated luminescence property in the solid state. In addition, complex 1 can be deposited on filter paper and displays the potential application as inkless print material. [Display omitted] • A new viologen complex was successfully synthesized and characterized. • Complex 1 shows fast response to UV light and X-ray irradiation. • Complex 1 can be deposited on filter paper and displays as inkless print material. [ABSTRACT FROM AUTHOR]