•Two bromine substituted indole chalcone derivatives were synthesized.•The compounds exhibit fluorescence turn-on response to cyanide anions.•Bonding mechanism of indole compound hydrogen bonding reaction between CN− and NH.•Bonding mechanism of the corresponding N-ethylindole compound is Michael reaction.Two bromine substituted indole chalcone derivatives were synthesized via typical condensation reaction between 2-(hydroxyl)-4-bromine acetophenone and 3-indolealdehyde (1) or N-ethyl-3-indolealdehyde (2) in good yields. Their recognition properties for cyanide anions were investigated. The results indicate that the compounds exhibit quick and obvious color and fluorescence turn-on changes to cyanide anions with color changes from yellow to red (1) or from light yellow to deep yellow (2). Mechanism studies suggest that hydrogen bonding reaction between cyanide anions and NH moiety of compound 1 occurs, which leads to the red shift of absorption spectra and the deepening of color. To compound 2, bonding mechanism is typical Michael reaction mechanism.

A benzothiazolium salt containing carbazole group has been synthesized in a good yield via simple condensation reaction. Its photophysical properties and affinity for cyanide anion (tetrabutylammonium cyanide) have been investigated. The compound exhibited quick and well visible UV/Vis absorption and fluorescence responses to cyanide anion in MeCN, as the yellow color faded and the orange fluorescence disappeared. The in situ analysis by 1H NMR indicated that the cyanide anion was added to the C=N bond in the benzothiazolyl group.

•A novel silicon-oxygen aurone derivative TBDPSA was synthesized.•TBDPSA in aqueous solution exhibits obvious absorption and fluorescence response for F−.•The compound was successfully assembled on GO surface by π-π stacking.•GO improves recognition sensitivity and shortens response time of TBDPSA for F−.A novel silicon-oxygen aurone derivative TBDPSA was synthesized and used for the detection of fluoride anions in aqueous solution based on a specifically F−-triggered silicon-oxygen cleavage. Even though the compound has shown high selectivity, obvious absorption and fluorescence response for fluoride anions in aqueous solution, but it also is suffered from many limits, such as low detection sensitivity and long response time. Here the compound was successfully assembled on the graphene oxide (GO) surface by π-π stacking. GO improves recognition sensitivity and shortens response time of TBDPSA for fluoride anions by taking advantage of the nanocarrier GO. Compared with TBDPSA, the response time of GO/TBDPSA is shortened greatly from 1 h to < 5 s and the detection limit is lowered about four times with fluorescence as detected signal. Generally speaking, GO is an excellent promoter for accelerate recognition.Download high-res image (164KB)Download full-size image

•A novel Iridium (III) complex [Ir(ppy)2(Hppip)]PF6 (1) has been synthesized.•The complex exhibits aggregation-induced phosphorescence in hexane solution.•The complex aggregates and forms sphere structure with size at 100–200 nm in hexane.•Compound 1 may also be a pH sensor to monitor pH changes in PBS buffer solution.A novel Iridium (III) complex [Ir(ppy)2(Hppip)]PF6 (1) has been synthesized and characterized. The complex exhibits strong phosphorescence emission in high viscosity solvent glycerol and aggregation-induced phosphorescence emission in hexane solution. The high viscosity of glycerol and aggregation may restrict intramolecular rotation so that the compound exhibits stronger phosphorescence emission in glycerol and aggregated state. Compound 1 can also be a pH chemosensor to monitor pH changes in PBS buffer solution because of two successive protonation processes of pyridyl and imidazole moieties in acidic condition.Download high-res image (213KB)Download full-size image

•Two coumarin formhydrazide compounds were synthesized.•The compounds can recognize copper with absorption, color and fluorescence change.•Carbonyl and amine group in the compounds may complex with copper to form 1:1 complex.Two coumarin formhydrazide compounds as chemosensors for copper ions have been synthesized. The compounds can recognize copper ion with obvious absorption spectral change and fluorescence decrease in aqueous solution. The detection limit of the compound with terminal diethylamino group to Cu2 + in aq.-HEPES buffer acetonitrile (3:7, v/v, pH = 7.4) with fluorescence spectra as detected signal is 0.00041 μM. One carbonyl and amine group in one sensor molecule may complex with one copper ion to form 1:1 complex.Two coumarin formhydrazide compounds as chemosensors for copper ions have been synthesized, which can recognize copper ion with obvious absorption spectral change and fluorescence decrease in aqueous solution.

•A coumarin derivative with benzothiazole Schiff's base structure was synthesized.•The compound can recognize CN− and Cu2 + with obvious fluorescence and absorption change.•The detection selectivity can be visualized by naked eye.•The compound can recognize CN− based on nucleophilic addition mechanism.•The compound can recognize Cu2 + based on coordination reaction.A new diethylamine coumarin Schiff's base chemosensor for cyanide and copper ions with benzothiazole as terminal group has been synthesized with very simple method. Its photophysical properties and recognition properties for cyanide and copper ions have also been examined. The compound is found to be able to recognize cyanide anions based on nucleophilic addition and recognize copper ions based on coordination reaction, all these processes can be completed shortly. The detection limits of the compound for CN− and Cu2 + in acetonitrile are 0.0071 μM (CN−) and 0.014 μM (Cu2 +), respectively. Its detection selectivity for cyanide and copper ions can be visualized with naked eye in solution and test paper. The color changes from reddish brown to white after the addition of cyanide or copper ions in test paper.A new diethylamine coumarin Schiff's base chemosensor for cyanide anions and copper ions with benzothiazole as terminal group has been synthesized with very simple method, which can recognize cyanide anions based on nucleophilic addition and recognize copper ions based on coordination reaction.

•A pyrene based ESIPT chromophore was synthesized.•Planar molecular structure was determined by X-ray crystallography.•The chromophore possesses high efficient solid-state emission.A pyrene-based 2-aryl-benzothiazole derivative, 2-(1′-hydroxypyrenyl)benzothiazole (1H2PBT), was synthesized. Its crystal structure and photophysical properties were investigated. In comparison with the generally studied parent compound, 2-(2′-hydroxyphenyl)benzothiazole (HBT), 1H2PBT exhibited red-shifted absorption and emission in solution, as well as impressive solid state emission with high efficiency (0.35).

•Four coumarin amide derivatives with 4-methyl coumarin or pyrene as terminal group were synthesized.•The compounds can recognize cyanide anions with obvious absorption and fluorescence spectra change.•Michael additions between the chemosensors and cyanide anions take place at the 4-position of coumarin.Four coumarin amide derivatives with 4-methyl coumarin or pyrene as terminal group have been synthesized. Their photophysical properties and recognition properties for cyanide anions have been examined. The results indicate that the compounds can recognize cyanide anions with obvious absorption and fluorescence spectra change, at the same time, obvious color and fluorescence change can be observed by naked eye. The in situ hydrogen nuclear magnetic resonance spectra and photophysical properties change confirm that Michael additions between the chemosensors and cyanide anions take place at the 4-position of coumarin.

•Two coumarin hydrazide compounds as chemosensors for copper and cyanide ions were synthesized.•The compounds can recognize copper and cyanide ions with obvious absorption and fluorescence change.•Complexation between compounds and copper form and cyanide is bonded to 4-position of coumarin.Two coumarin hydrazide compounds were synthesized by 7-N,N-diethylaminecoumarin-3-formyl chloride and 2-pyridinecarboxylic acid hydrazide or benzoylhydrazine. The compounds are found to be able to recognize copper ions and cyanide anions accompanied by obvious UV–vis absorption change and fluorescence turn-off response. Mechanism studies suggested that complexation between compounds and copper forms and cyanide may be bonded to 4-position of coumarin.Two coumarin hydrazide compounds as chemosensors for copper and cyanide were synthesized and can recognize copper ions and cyanide anions with obvious absorption change and fluorescence turn-off response.

•Four coumarinic chalcone derivatives were synthesized.•The compounds exhibit obvious color and fluorescence response to CN− and Cu2+.•CN− is possibly bonded to 4-position of coumarin or α carbon atom of CC bridge.Four coumarinic chalcone derivatives were synthesized via typical condensation reaction between 4-(hydroxyl)coumarinketone and 4-(diethylamino)-benzaldehyde or 7-(diethylamino)coumarinaldehyde in good yields. Their crystal structures and recognition properties for cyanide and copper ions were investigated. The results indicate that the compounds exhibit quick and obvious color and fluorescence response to the ions with high sensitivity and selectivity in acetonitrile. Mechanism studies suggest that cyanide group is possibly bonded to 4-position of coumarin group or the α carbon atom of CC bridge. Coordinate between the compounds and copper ions forms.

Two new branched pyridinium inner salt dyes, 2,6-di[2-(N-ethyl-carbazole-3-yl)vinyl]-N-(3-sulfonatepropyl)pyridinium, inner salt (2) and 2,4,6-tri[2-(N-ethyl-carbazole-3-yl)vinyl]-N-(3-sulfonatepropyl)pyridinium, inner salt (3), with N-ethyl-carbazolyl as electron donor group and pyridine cation as electron acceptor group have been synthesized. Their single- and two-photon related fluorescence properties in various solvents have also been examined. These dyes exhibit stronger fluorescence emission relative to the corresponding linear counterpart and common pyridinium dyes with discrete cation and anion components. Three-branched organic dye 3 has a high fluorescence quantum yield as 0.12 and exhibits strong orange two-photon excited fluorescence at 608 nm in THF with large two-photon absorption cross-section being 606 GM.Two new branched pyridinium inner salt dyes with N-ethyl-carbazolyl as electron donor group have been synthesized. Three-branched organic dye has a high fluorescence quantum yield as 0.12 and exhibits strong orange two-photon excited fluorescence at 608 nm in THF with two-photon absorption cross-section being 606 GM. Highlights► Two new branched pyridinium inner salt dyes were synthesized. ► The dyes exhibit strong yellow or orange fluorescence emission. ► Three-branched organic dye exhibits strong orange two-photon excited fluorescence in THF.

•Two chemosensors for cyanide anions were synthesized.•The compounds can recognize cyanide with obvious color and fluorescence change.•The compounds allow naked eye detection of cyanide anions.Two chemosensors for cyanide anions based on N-methylpyridinium cation and the boronic acid moiety structures have been synthesized. Spectral shifts and intensity changes in acetonitrile allow for both absorption and fluorescence emission wavelength ratiometric and colorimetric sensing. The compounds are found to be able to recognize cyanide anion with obvious color change and fluorescence turn-on response due to the sensors' ability to bind the cyanide anion through boronic acid functional group.Two fluorescence turn-on chemosensors for cyanide anions based on pyridine cation and the boronic acid moiety were prepared and can recognize cyanide anion with obvious color change and fluorescence turn-on response.

Three aurone derivatives, Z-2-[(4-N,N-dimethylaminophenyl)methylene] benzofuran-3-one (1), Z-2-[(N-ethylcarbazol-3-yl)methylene]benzofuran-3-one (2) and Z-2-[(pyren-1-yl)methylene]benzofuran-3-one (3) have been synthesized by the cyclization of 2′-hydroxychalcones. Their crystal structure, single- and two-photon related absorption and fluorescence properties have been examined. Pumped by 860 nm laser pulses in femtosecond regime, the compounds exhibit strong yellow–green two-photon excited fluorescence at 539 nm (1), 505 nm (2) and 524 nm (3) in THF with two-photon absorption (TPA) cross-section being 1536GM (1), 608GM (2) and 236GM (3).Graphical abstractHighlights► Three aurone derivatives were synthesized. ► The compounds exhibit strong yellow–green two-photon excited fluorescence. ► The compounds exhibit large two-photon absorption cross-section.

•Three 4-hydroxy aurone compounds were synthesized.•The compounds can recognize cyanide anions with obvious color and fluorescence change.•The compounds allow naked eye detection of cyanide anions.Three new 4-hydroxy aurone compounds 1–3 with dimethylamino (1), bromine (2) and cyano (3) as terminal group have been synthesized. Their photophysical properties as well as recognition properties for cyanide anions in acetonitrile and aqueous solution have also been examined. These compounds exhibit remarkable response to cyanide anions with obvious color and fluorescence change owing to hydrogen bonding reaction between cyanide anions and the O–H moiety of the sensors, which allows naked eye detection of cyanide anions.Graphical abstract

Three o-hydroxy chalcone derivatives 1–3 with carbazolyl (1), pyrene (2) and 4-nitrobenzene (3) as terminal group have been synthesized. Their crystal structures, photophysical properties in CH3CN and recognition properties for cyanide anions have also been examined. The research indicates that the stronger electroaffinity of the chalcone derivative's β-unit is beneficial to Michael reaction and can improve the response rate of the compound to cyanide anions. These compounds are found to be able to recognize cyanide anions with fluorescence turn-on response. Especially, compound 3 with strong electron accepting group exhibits remarkable response to cyanide anions in CH3CNH2O (1:1, v/v) solution with a ca. 40-fold intensity enhancement.Graphical abstractThree o-hydroxy chalcone derivatives with carbazolyl (1), pyrene (2) and 4-nitrobenzene (3) as terminal group have been synthesized, which exhibit remarkable response to cyanide anions. Compound 3 can recognize cyanide anions with fluorescence turn-on response in CH3CNH2O (1:1, v/v) solution.Highlights► Three o-hydroxy chalcone derivatives were synthesized. ► The compounds can recognize cyanide anions with fluorescence turn-on response. ► The compound containing nitro group can recognize cyanides in aqueous solution.

A new acceptor-π-acceptor quadrupolar compound with a dimesitylboryl as acceptor and 2,7-dithienylfluorene as the conjugated bridge has been synthesized using the Suzuki–Miyaura coupling reaction. Its single and two-photon related photo-physical properties were experimentally examined. The combination of a large two-photon cross-section (δ = 1150 GM at 730 nm in hexane), high emission quantum yield (Ф = 0.81 in hexane) and a strong binding constant with fluoride anions (K1 = 3.0 × 105 mol−1 L) make this compound attractive for application as a two-photon excited fluorescent chemosensor for fluoride anions.

A new cationic triarylborane has been synthesized by methylation of a dimethylamino electron donor group in a neutral donor-π-acceptor type system, which also includes a dimesitylboryl group as electron acceptor. Its single- and two-photon excited fluorescence emission properties have been examined, and it has been found to be a highly fluorescent chemosensor for fluoride anions in THF solutions. This cation exhibits a higher sensitivity for fluoride anions compared to its neutral precursor, which is attributed to the increased Lewis acidity of the boron center, as well as its enhanced Coulombic attraction for anions. It has also been demonstrated to be water-tolerant.

A novel two-branched organoboron compound, N,N-bis(7-dimesitylboryl-9,9-diethyl-9H-fluorene-2-yl)aniline, containing a phenylamino group as a π-electron donor, fluorene groups as π-bridges and dimesitylboryl groups as electron acceptors, was synthesized and its photophysical properties in various solvents as well as its fluoride anion recognition properties were investigated. The synthesised compound exhibited strong fluorescence in all solvents with the fluorescence changing from blue to orange on going from solvents of low polarity to those of high polarity. The compound was able to recognize fluoride anions in high sensitivity owing to strong interactions between boron atoms and fluoride anions.

Two novel, V-shaped fluorene derivatives branched from triphenylamine and their linear analogue were synthesized via Cu-mediated Ullmann condensation and subsequent Pd-catalyzed Heck coupling reaction. Their two-photon excited fluorescence properties as well as their linear absorption and single-photon excited fluorescence properties were examined. When excited at 730 nm by a Ti:sapphire femtosecond laser, the compounds exhibited strong two-photon excited blue fluorescence. The two-photon excited fluorescence cross-sections of V-shaped derivatives in toluene at 730 nm were ∼506 GM in the case of N, N-bis{7-[4′-(N, N-diphenylamino)styryl]-9,9-diethyl-9H-fluorene-2-yl}-aniline) and 397 GM for N, N-Bis{7-[4′-(N, N-diphenylamino)styryl]-9,9-diethyl-9H-fluorene-2-yl}-4-acetyl-aniline), respectively.

Three new hemicyanine dyes that feature a fixed pyridine cation as electron acceptor, trans,trans-4-{4-[4-(N,N-diphenylamino)styryl]styryl}-N-methylpyridinium iodide (1), trans,trans-4-{4-[4-(N-carbazolyl)styryl]styryl}-N-methylpyridinium iodide (2) and trans,trans-4-{4-[2-(benzothiazole-2-yl)ethenyl]styryl}-N-methylpyridinium iodide (3), have been synthesized. The crystal structure of dye 1 was determined. X-ray diffraction analyses reveal that 1 crystal belongs to monoclinic, P21/c space group. Composite materials with these organic dyes doped into polymer-impregnated composite glass were prepared. Photophysical properties of these dyes in various solvents and composite glass were investigated in detail. Generally, photophysical properties of the dyes greatly increase in glass matrices compared with that in solution and there is no obvious fluorescence quenching in high doped concentration. The relationships between molecular structure and photophysical properties of this series of dyes were discussed.

A new A-π-D-π-A type organoboron compound, 3,6-bis(dimesitylboryl)-N-butyl-carbazole (abbreviated as BBC), with trivalent boron as electron acceptor and carbazole as electron donor and π-conjugated core, has been synthesized and its single and two-photon related photophysical properties experimentally investigated. Pumped by 720 nm laser pulses in femtosecond regime, it showed strong two-photon excited blue-violet fluorescence at 393 nm in toluene and 403 nm in THF. The measured two-photon absorption cross-section by two-photon fluorescence method in toluene and THF is 34 GM and 38 GM, respectively.

•A novel siloxane-aurone compound as fluorescence chemodosimeter for F− was synthesized.•The compound can recognize F− in aqueous solution.•The compound can recognize F− with high sensitivity and fast response rate.•The recognition mechanism is the F−-promoted dissociation of silicon-oxygen bond.A novel siloxane-aurone compound, 4′-cyano-4-tert-butyldiphenylsiloxane-aurone (named as TBDCN), was synthesized. The compound exhibits high sensitivity, fast response rate and high selectivity for fluoride anions recognition with obvious absorption and fluorescence response in aqueous solution, which is more sensitive than the traditionally type of chemodosimeters based on F−-triggered cleavage. The detection limits of TBDCN for F− are determined to be 1.9 μM and 0.0017 μM with absorption and fluorescence as detected signal, respectively, which satisfy the requirement from U.S. Environmental Protection Agency. The recognition mechanism is the F−-promoted dissociation of silicon-oxygen bond based on in situ mass spectra and 1H NMR spectra analysis.