A bifunctional probe for Al3+ and Zn2+ based on diarylethene with an ethylimidazo[2,1-b]thiazole-6-hydrazide unit

A new diarylethene with ethylimidazo[2,1-b]thiazole-6-hydrazide unit was synthesized, and its photochromic and fluorescent behaviors have been systematically investigated by the stimulation of lights and metal ions in methanol. This new diarylethene exhibited high selectivity and sensitivity toward Al³⁺ and Zn²⁺. The addition of Al³⁺ and Zn²⁺ displayed excellent colorimetric response behaviour with the concomitant color change from colorless to yellow, which could be easily observed by the naked eye. Upon addition of Al³⁺, the fluorescence intensity was enhanced by 180–fold and the emission peak of 1O–Al³⁺ blue-shifted by 15?nm accompanied with a color change from colorless to bright blue. In contrast, when stimulated with Zn²⁺, its fluorescence intensity was enhanced by 35–fold and the emission peak of 1O–Zn²⁺ red-shifted by 16?nm with an evident color change from black to bright green. The LOD for Al³⁺ and Zn²⁺ were determined to be 2.97?×?10^?9?mol?L^?1 and 5.98?×?10^?9?mol?L^?1, respectively. Moreover, a logic circuit was constructed with the fluorescence intensity as the output signal responding to the light and chemical species as the inputs.     

A fluorescent sensor for Al3+ based on a photochromic diarylethene with a hydrazinobenzothiazole Schiff base unit

A new fluorescent turn-on chemosensor for Al³⁺ based on a diarylethene unit was designed and synthesized. Photochromism, fluorescence switch, and metal ion recognition behaviors of this diarylethene derivative were investigated by absorption and fluorescence emission spectra. It shows an outstanding fluorometric sensing ability toward Al³⁺ ion, and the detection limit was measured to be 9.3 × 10^?8 mol L^?1 via fluorescence methods. Based on these interesting properties, a combinational logic circuit was constructed successfully.     

A highly selective fluorescent sensor for Ca2+ and Sr2+ based on diarylethene with a furan-carbohydrazide unit

A fluorescent sensor based on diarylethene has been designed and synthesized. The sensor not only exhibited excellent photochromic properties, but also has distinguishing ability for Ca²⁺ and Sr²⁺ from other metal ions. Upon addition of Ca²⁺ and Sr²⁺, its emission intensity enhanced 27-fold and 24-fold respectively, accompanied by the emission peak shifted from 439 nm to 484 nm for Ca²⁺, and to 479 nm for Sr²⁺. The 1:1 stoichiometry between the sensor and the two ions was confirmed by Job's plot and HRMS. The LOD for Ca²⁺ and Sr²⁺ was determined to be 9.4 × 10^?8 mol L^?1 and 7.2 × 10^?8 mol L^?1, respectively. Furthermore, the sensor was applied in the detection of Ca²⁺ and Sr²⁺ in practical samples successfully.     

A new fluorescence probe based on diarylethene with a benzothiazine unit for selective detection of Cd2+

A novel photochromic diarylethene derivative containing a benzothiazine unit has been synthesized. Its photochromism and fluorescent selectivity to metal ions were studied in detail in methanol solution. Under the stimulation of Cd²⁺ ions, the derivative showed a significant fluorescence enhancement and obvious red shift, accompanied by the fluorescent color changed from dark purple to bright blue. The 1: 1 stoichiometry between the derivative and Cd²⁺ was verified by titration experiments and high resolution mass spectrometry. In addition, a molecular logic circuit was designed with the emission intensity at 476?nm as output and the stimuli of Cd²⁺/EDTA and UV/vis as inputs.     

A sensitive sensor for Cu(II) based on a novel diarylethene with a bipyridyl moiety

A novel diarylethene with a bipyridyl unit has been designed and synthesized for the first time. Its photochromic behaviors could be modulated by protonation and coordination with Cu(II). The absorption maximum of the closed-ring isomer shifted from 569 to 666 nm when trifluoroacetic acid was added. Furthermore, the closed-ring isomer behaved as a sensitive colorimetric sensor, exhibiting an open-ring reaction upon exposure to Cu(II). Its high selectivity toward Cu(II) over other competitive species makes the ‘naked-eye’ detection of Cu(II) possible.     

A highly selective fluorescent probe for Sn based on a new photochromic diarylethene with a phenol-containing Schiff base unit

A novel diarylethene with a phenol-containing Schiff base unit was successfully synthesized and its multi-responsive photoswitching property was investigated by the stimulation of base/acid and light. The diarylethene showed not only normal photochromism by photoirradiation, but also abnormal photochromism by base and light stimuli. By the stimulation of sodium hydroxide, the absorption maximum of its open-ring isomer showed extraordinarily large redshift of 60 nm, accompanied with a notable color change from colorless to yellow. Subsequent irradiation with 297 nm light further caused a dramatic change in its structure transformation from the deprotonated open-ring isomer to the original closed-ring isomer. Similarly, its deprotonated closed-ring isomer returned to its original open-ring isomer upon irradiation with appropriate visible light. Its deprotonated forms could be restored by the stimulation of hydrochloric acid. Moreover, the diarylethene could be served as a fluorescence probe for recognition of Sn²⁺ with high selectivity.     

Thermochromism of 1, 4-Bis[2-(4-pyridyl)ethenyl]-benzene Derivatives

Three kinds of thermochromic materials (DC8, DC12, DC16) were synthesized by linking the rigid 1, 4-bis[2-(4-pyridyl)ethenyl]-benzene (bpeb) with different lengths of alkyl chains. They exhibit remarkable fluorescent color changes under the irradiation of 365 nm light with elevating temperature, which is supposed to be caused by the transition between the crystal state and the amorphous state. Interestingly, the DC16 solid also has a photochromic character. It should be noticed that the phase transition temperatures of three materials measured by differential scanning calorimetry are higher than those of the fluorescence color changes during the heating process. Thus, the allochroic effect is attributed to the synergistic effect of both heating and photo-inducement (365 nm). Ethanol can turn the heated powder into the initial crystal again which indicates that their thermochromic behavior is reversible and makes the fluorescence recover.     

A highly selective fluorescence switch for Cu2+ and Fe3+ based on a new diarylethene with a triazole-linked rhodamine 6G unit

A new diarylethene compound with a triazole-linked rhodamine 6G unit attached to the imino group (1O) was designed and synthesized. According to the test results, the solution color and fluorescence color of diarylethene can be modulated by lights and metal ions. The solution color could change from colorless to light purple when irradiated with UV light. When Cu²⁺ was added to the diarylethene solution, the color of diarylethene solution became blue, the fluorescence color turned from dark to bright yellow. Although the solution color did not change by adding Fe³⁺, its fluorescence color varied from dark to yellow. Moreover, it was found that the complex ratio of the diarylethene to Cu²⁺ was 1:1 and the binding stoichiometry of the diarylethene to Fe³⁺ was also 1:1 based on the data of NMR, MS, and other experiments. Based on these findings, photochromic figure of the diarylethene with UV/Vis light, Cu²⁺ and Fe³⁺ was constructed. Furthermore, the logic circuit was designed by input signals (ultraviolet stimulus, visible light stimulus, Cu²⁺ (or Fe³⁺) and EDTA) and an output signal (fluorescent intensity at 566?nm (or 575?nm)).     

A multi-controllable selective fluorescent turn-on chemosensor for Al3+ and Zn2+ based on a new diarylethene with a 3-(4-methylphenyl)-1H-pyrazol-5-amine Schiff base group

A novel diarylethene containing a 3-(4-methylphenyl)-1H-pyrazol-5-amine was synthesized. Its multi-responsive properties induced by UV/Vis lights and metal ions were studied in detail by absorption and fluorescence emission spectroscopy. It showed excellent fluorescence sensing ability for Al³⁺ and Zn²⁺ with very low detection limit. In addition, based on the multi-responsive characteristics, a logic circuit was constructed by using both UV/Vis lights and chemical species stimuli as inputs and fluorescence intensity as outputs. Moreover, the diarylethene was successfully applied to effectively detect Al³⁺ and Zn²⁺ in actual water samples.     

Synthesis and photophysical studies of novel 2-[5-(4-diethylaminophenyl)thiophen-2-yl]quinazoline derivatives

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Syntheses, structures and photochromism of two novel copper(II) complexes with 1,2-bis(2′-methyl-5′-(2″-pyridyl)-3′-thienyl)perfluorocyclopentene

Two novel Cu(II) complexes with 1,2-bis(2′-methyl-5′-(2″-pyridyl)-3′-thienyl)perfluorocyclopentene (BM-2-PTP) or its closed-form (closed-BM-2-PTP) were synthesized and characterized by X-ray crystallographic analysis. Both complexes are tetra-coordinated to two N atoms from distinct ligands and two Cl atoms from anions, forming 1-D polymeric structures. [Cu(BM-2-PTP)Cl₂] (1) showed typical spectral changes as analogous Ag(I) complexes with the same ligand upon appropriate light stimulus. However, closed-BM-2-PTP displayed different photocyclization from its open-ring form upon irradiation with UV light, indicating the photogenerated closed form turned into two kinds of closed-ring isomers. Furthermore, [Cu(closed-BM-2-PTP)Cl₂] (2) was revealed to contain two conformers by X-ray crystallographic analysis and displayed similarities in photocyclization to its free ligand. The distinct absorptions of the UV spectrum were attributed to the coexistence of two conformers in complex 2, both of which showed effective photoreactivities in the crystalline phase. The photochromic mechanism of complex 2 is tentatively concluded as two conformers displaying independent photoreactions.     

Deprotonation of 1,1′-methylenebis[4-tert-butyl-2-(diphenylphosphino)-benzene] and its analogues: synthesis and crystal structure of {5-But-2-[4-But-2-(Ph2P)C6H3(Ph)CH]C6H3P(Ph)K(OEt2)}2

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Synthesis of new pharmacologically oriented heterocyclic ensembles, [2-(1H-pyrazol-1-yl)thiazol-4-yl]furoxans

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Design,synthesis and biological evaluation of 5-(2-(4-(substituted benzo[d]isoxazol-3-yl)piperazin-1-yl)acetyl)indolin-2-one and 5-(2-(4-substitutedpiperazin-1-yl)acetyl)indolin-2-one analogues as novel anti-tubercular agents

A series of thirty-six novel 5-(2-(4-(benzo[d]isoxazol-3-yl)piperazin-1-yl)acetyl)indolin-2-one and 5-(2-(4-substitutedpiperazin-1-yl)acetyl)indolin-2-one analogues were synthesized, characterized and screened for their in vitro anti-tubercular activity against Mycobacterium tuberculosis H37Rv strain. These compounds exhibited minimum inhibitory concentration between 1.56 and 50 μg/mL. Among these derivatives, compounds 10c, 10d, 10j, 10o and 10v (MIC 6.25 μg/mL) displayed moderate activity, while compounds 10e, 10l, 10q, 10w,10x, 12d, 12e and 12i (MIC 3.12 μg/mL) showed good anti-tubercular activity and compounds 10f, 10k, 10p, 10r, 12f, 12j and 12k (MIC 1.56 μg/mL) exhibited excellent anti-tubercular activity. In addition, MTT assay was accomplished on the active analogues of the series against mouse macrophage (RAW 264.7) cells to evaluate the cytotoxic effect of the newly synthesized compounds and selectivity index of the compounds was determined.     

Robust thermostable polymer composition based on poly[N,N′-(1,3-phenylene)isophthalamide] and 3,3-bis(4-acrylamidophenyl)phthalide for laser 3D printing

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Crystal Structure and Photochromic Properties of [1-(2-Methyl-5-(4-cyanophenyl)-3-thienyl)]-2-(2-methyl-5-phenyl-3-thienyl)perfluorocyclopentene

A new photochromic diarylethene, [1-(2-methyl-5-(4-cyanophenyl)-3-thienyl-2-(2-methyl-5-phenyl-3-thienyl)]perfluorocyclopentene(1o, C28H17F6NS2), was synthesized and its structure was determined by single-crystal X-ray diffraction analysis. Its crystal belongs to the monoclinic system, space group P21/c with a = 24.1381(5), b = 9.3834(6), c = 11.1073(8), β = 94.477(4)°, Z = 4, V = 2508.1(3) A3, D3 c = 1.445 mg/m, μ = 0.275, F(000) = 1112, the final R = 0.0482 and wR = 0.1429 for 5834 observed reflections(I 2σ(I)). Further study demonstrated the diarylethene underwent reversible photochromism, changing between colorless and blue in hexane solution, crystalline phase and PMMA films, respectively.     

An efficient ultrasonic-assisted synthesis of ethyl-5-(aryl)-2-(2-alkokxy-2-oxoethylidene)-7-methyl-3-oxo-3, 5-dihydro-2H-thiazolo [3, 2-a] pyrimidine-6-carboxylate derivatives

Dihydropyrimidinone derivatives were prepared by tri-component reaction of ethyl aceto acetate, aldehydes and thiourea in the presence of modified montmorillonite nanostructure as a catalyst and used as key intermediates for the synthesis of ethyl-5-(aryl)-2-(2-alkokxy-2-oxoethylidene)-7-methyl-3-oxo-3,5-dihydro-2H-thiazolo[3,2-a]pyri midine-6-carboxylate derivatives with use of diethyl and dimethyl acetylene dicarboxylate by two methods: (a) in methanol as a solvent under ultrasonic irradiation at ambient temperature (b) in methanol as a solvent at ambient temperature (conventional magnetic stirring). Ultrasound-assisted synthesis provides excellent yields in short reaction times (15–25 min) at room temperature.     

Synthesis of 1-aryl-3H-[1,2,5]triazepino[5,4-a]benzimidazol-4(5H)-ones and quantum chemical investigation of the rotamers of the Boc-protected hydrazide key intermediate

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Highly efficient blue emission from boron complexes of 1-(o-hydroxyphenyl)imidazo[1,5-a]pyridine

Two boron complexes of 1-(o-hydroxyphenyl)imidazo[1,5-a]pyridine, which were named as BOHPIP, have been synthesized. These complexes exhibited blue emission in solution with high quantum yields (ΦFL?=?up to 0.71). In addition, 1-(o-hydroxyphenyl)imidazo[1,5-a]pyridine-BPh2 complex showed the strong blue emission even in the solid state (ΦFL?=?0.58).