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Stimuli-responsive luminescent materials, which are dependent on changes in physical molecular packing modes, have attracted more and more interest over the past ten years. In this study, 2,2-dihydroxy-1,1-naphthalazine was synthesized and shown to exhibit different fluorescence emission in solution and solid states with characteristic aggregation-induced emission (AIE) properties. A remarkable change in the fluorescence of 2,2-dihydroxy-1,1-naphthalazine occurred upon mechanical grinding, heating, or exposure to solvents. According to the characterization by solid-state fluorescence spectroscopy, X-ray crystallography, differential scanning calorimetry, and X-ray powder diffraction, the fluorescence change could be attributed to transitions between two structurally different polymorphs. These significant properties could also give 2,2-dihydroxy-1,1-naphthalazine more potential applications as a multifunctional material. [ABSTRACT FROM AUTHOR]

Highlights: [•] Reversible fluorescent detection for sulfide can be realized successfully. [•] The probe exhibits highly sensitivity and selectivity toward the sulfide. [•] Fluorescence imaging of cells for sulfide in vivo was carried out successfully. [Copyright &y& Elsevier]

Abstract: A Schiff base-type fluorescent chemosensor, 2,2′-bipyridyl-3,3′-bis-(N,N′-disalicylidene)-formyhydrazone has been synthesized and characterized. Among the various metal ions, only Al3+ induces the fluorescence enhancement of the formylhydrazone and results in “OFF–ON” type sensing with excellent selectivity and high sensitivity in aqueous system. The lowest detection limit for Al3+ is 0.17 μM, which is much lower than the permissible concentration of Al3+ for drinking water in China. Also, the chemosensor can be applied to the monitoring of Al3+ ion in aqueous solution with a pH span 6–8. Furthermore, fluorescence microscopic imaging also indicates that the formylhydrazone chemosensor has the potential for the detection of Al3+ in the biological environment. [Copyright &y& Elsevier]

Graphene quantum dots (GQDs) are synthesized by the method of high-temperature pyrolysis from marigold granules and subsequently nitrogen-doped graphene quantum dots (N-GQDs) are synthesized from ethylenediamine by hydrothermal treatment, which shows a strong blue emission with 7.84% quantum yield (QY). This will be used in detection of Fe3+ in water environments and the field of bioimaging. Unlabelled Image • In this method, N-GQDs were synthesized from marigold rich in lutein as carbon source. • The synthesized N-GQDs are only 3.2 nm in size. • The N-GQDs specifically identify Fe3+. • The N-GQDs can enter cells and have good biocompatibility and low toxicity. • This work can detect the concentration of Fe3+ in the Yellow River water. [ABSTRACT FROM AUTHOR]

A new chromene pyrazoline derivatives fluorescent probe L was designed and synthesized. The probe L appears in a 55-fold fluorescence enhancement after 5 equiv. Zn 2+ was added, and it also exhibits high sensitivity and selectivity for response to Zn 2+ in ethanol-water (V:V = 1:1) solution through “OFF-ON” type process and a possible photoinduced electron transfer (PET). Notably, the probe L distinguishes between Zn 2+ and Cd 2+ . The association constant was considered as 2.38 × 10 3  M −1 via fluorescence titration experiments. The probe L-Zn 2+ complex forms a 1:1 binding stoichiometry which was discussed by Job’s plot. The probe is very highly sensitive with fluorometric detection limit of 1.603 × 10 −10  M. It also shows good reversibility upon addition of EDTA. Furthermore, the viability of L to Zn 2+ has practical application in live cell imaging. [ABSTRACT FROM AUTHOR]

A novel biphenyl-derived salicylhydrazone Schiff base ( BSS ) fluorescent probes for highly sensitive and selective identification of Cu 2+ has been synthesized. In addition, the recognition has been proved experimentally. The results indicated that the complex forms a 1:1 complex with Cu 2+ shows fluorescent quenching. Furthermore, the detection limit of 1.54 × 10 −8 M. More interesting, the probe BSS not only have a good biocompatibility in living cells, but also the sense behavior of Cu 2+ in the cell nucleus. [ABSTRACT FROM AUTHOR]

Abstract: A new fluorescent chemosensor, sodium 2-(2-(1H-benzo[d]imidazol-2-yl)quinolin-8-yloxy)acetate (HL), based on 8-hydroxyquinoline derivative has been designed, synthesized and characterized. Once combined with Hg2+ in aqueous solution, HL displays a fluorescence quenching effect to form the compound mercury(II) 2-(2-(1H-benzo[d]imidazol-2-yl)quinolin-8-yloxy)acetate chloride (LHg), which could be fast dissociated by the addition of cyanide in this system so that “ON–OFF–ON” type fluorescence change can be achieved. Cyanide induces the revival of fluorescence of LHg and results in “OFF–ON” type sensing with high sensitivity and rapid response in 100% aqueous system. Furthermore, the fluorescence microscopic imaging also indicates that LHg is suitable for the detection of CN− in biological environment. [Copyright &y& Elsevier]

Abstract: Six lanthanide nitrato complexes [Ln=La (1), Nd (2), Eu (3), Gd (4), Tb (5), Er (6)] with a tridentate salicylamide-type ligand, 2-(2-(diisopropylamino)-2-oxoethoxy)-N-(pyridin-2-ylmethyl)benzamide (L), have been synthesized. All complexes were characterized by elemental analysis, IR, TGA and conductivity measurements. The structures of 2, 3 and 4 were determined by X-ray single-crystal diffraction and their general formulae were shown to be [LnL(NO3)3(H2O)]·CH3CN. These data indicate the tridentate salicylamide-type ligand could effectively chelate the lanthanide ions to conform to a 1:1 metal-to-ligand stoichiometry. The luminescence properties of the europium and terbium complexes were also investigated. [Copyright &y& Elsevier]

A new visual bis(salamo)-based fluorescent chemosensor for detection of B 4 O 7 2− in environmental and biological systems was synthesized for the first time by Schiff base reaction. The bright blue fluorescence of the sensor and B 4 O 7 2− was very obvious and the limit of detection for B 4 O 7 2− was as low as 6.97 × 10-10 M. Importantly, the first attempt of exogenous detection in zebrafish gained success. • H 6 L was explored for detecting B 4 O 7 2−. • It can be used for detection in zebrafish. A newly synthesized fluorescent chemosensor H 6 L was explored for detecting B 4 O 7 2−, characterized by 1H NMR spectrum, mass spectrum and fluorescence spectra. During the detection process of B 4 O 7 2−, the fluorescence is significantly enhanced and naked eye recognition can be performed under 365 nm UV light without any interference by other typical anions. The limit of detection is as low as 6.97 × 10-10 M. In addition, in order to broaden the application of salamo-based fluorescence sensors in the field of biology, except for the fluorescence imaging of HeLa cells, the first attempt of exogenous detection in zebrafish was conducted successfully. [ABSTRACT FROM AUTHOR]

The probe H 2 L molecule has a good recognition ability for Al3+ ions. This probe molecule can also realize naked eye recognition of Al3+ under 365 nm UV light. It has the advantages of fast response speed, low detection limit and intuitiveness. • Salamo-based fluorescent chemosensor H 2 L detecting Al3+ and LOD was 5.98 × 10−9 M. • Fluorescence intensity of the probe obviously enhanced under UV and normal light. • Exogenous detection in zebraflsh of salamo-based probe gained satisfactory results. A new salamo-based probe H 2 L was synthesized and characterized by nuclear magnetic resonance, mass spectrometry and fluorescence spectroscopy. Compared with previous work of some other probes, the probe H 2 L can selectively recognize Al3+ in the fluorescence spectra and the detection limit is as low as 5.98 × 10−9 M. Beyond that, the color of solution becomes bright green under 365 nm UV light. Notably, under low concentrations, the probe can be used as a tool for exogenous detection of Al3+ in organisms. This result expands the application of salamo-based fluorescent probes in the field of biology. [ABSTRACT FROM AUTHOR]

A new sensor H 5 L for continuous identification of Cu2+, Al3+ and lysine was synthesized by Schiff base reactions. The sensor could specifically recognized Cu2+ in the EtOH/H 2 O (1:1 v /v) solution by UV–vis spectra, and the binding constant with Cu2+ can reach 1011 M−1, meanwhile, it was found by the naked-eye that the color of the solution was changed from colorless to yellow. The copper complex L-Cu 2+ formed by the sensor H 5 L and Cu2+ could further recognize Al3+ and lysine in the fluorescence spectra. The LOD values of the three objects were 2.67 × 10−8, 1.96 × 10−8 and 5.59 × 10−9 M, respectively. In addition, fluorescence intracellular images of Al3+ and lysine were performed and obtained satisfactory results. A novel salamo-like chemical sensor H 5 L for continuous recognition of Cu2+ and Al3+ and lysine was synthesized. The sensor can identify Cu2+ by UV–vis spectra and naked eye recognition. The formed copper(II) complex L-Cu 2+ can recognize Al3+ and lysine by fluorescence spectra, and good results of intracellular images were obtained. Unlabelled Image • A new bis(salamo)-based chemical sensor H 5 L for continuous recognition of Cu2+, Al3+ and lysine was synthesized. • H 5 L could recognize Cu2+ by UV-visible spectrum and naked eye, and the RGB analysis was obtained good results. • The confocal fluorescence imaging of Al3+ and lysine gained favorable results. [ABSTRACT FROM AUTHOR]