•Two polyacetylenes are developed for detection of Glyp.•The probes are applicable for monitoring Cu2+.•The PBP/Cu2+ sensor can detect Glyp with a detection limit of 80 nM.Two novel disubstituted polyacetylenes (TZP and PBP) with triazole and 2-(pyridin-2-yl)-1H-benzo[d]imidazole as the side groups, respectively, were successfully synthesized through using a post-functionalization strategy, and their fluorescence responses to metal ions and pesticides were investigated in detail. Strong emission from TZP and PBP could be efficiently quenched by a trace of Cu2+, through an electron or energy transfer process. The addition of Glyphosate (Glyp) to the solution of TZP/Cu2+ and PBP/Cu2+ complexes could recover the emission of TZP and PBP, and exhibit good “turn on” sensing signals for monitoring Glyp. These complex sensors had the high selectivity to Glyp without the interference from other anions and pesticides. The PBP/Cu2+ complex showed much higher sensitivity and a lower detection limit (8.0 × 10−8 M) for Glyp than that of TZP/Cu2+ complex. With the aid of PBP/Cu2+ complex, Glyp could be differed from other pesticides visually by its strong blue emission under the hand-held UV lamp, at the concentration as low as 1.0 × 10−5 M. This work provides a new strategy for the development of Glyp sensors.A new sensing platform utilizing the PBP/Cu2+ complexes for detection of glyphosate (Glyp) has been achieved. The sensor exhibits “turn on” fluorescence response and high selectivity to Glyp with the detection limit of about 8.0 × 10−8 M.

Mitochondria and lysosomes are essential cellular organelles in most eukaryotic cells by playing the physiological roles to support the normal functions of cells, as well as the life of the whole body. To date, small-molecule fluorescent probes have been considered as one of the vital tools for monitoring and visualizing multiple biological analytes. This review summarized the recent advances in small-molecule two-photon fluorescent probes for metal ions, reactive oxygen species (ROS) and reactive sulfur species (RSS), and changes inside micro-environment (e.g., pH, viscosity and polarity) in mitochondria and lysosomes, or served as mitotracker and lysotracker with the assistance of two-photon microscopy.Download high-res image (140KB)Download full-size image

•Disubstituted polyacetylenes (P1–P4) are designed for monitoring Pd2+.•P3 exhibits high selectivity and sensitivity toward Pd2+.•P3–Pd2+ complex can be applied for the detection of thiophanate-methyl (TM).•The mechanism was supported by MALDI-TOF mass and DFT calculations results.A series of disubstituted polyacetylenes-based fluorescent chemosensors for Pd2+ has been designed and synthesized. The optimization of sensing performance for Pd2+ ions is realized through modulating the coordination mode, type and number of coordination atoms in pendant groups. The receptor groups containing both N and S atoms (Poly [1-phenyl-2-[3-(2-pyridylmercapto)propyl]acetylene] (P2) and Poly [1-phenyl-2-[3-(5-methyl-1,3,4-thiadiazole-2-mercapto)propyl]acetylene] (P4)) can respond simultaneously for Pd2+ and Pt4+/2+ ions, and the only introduction of sulfur as the ligand atoms (Poly [1-phenyl-2-[3-(p-methylphenylthio)propyl]acetylene] (P1) and Poly [1-phenyl-2-[3-(2-Thienylthio)propyl]acetylene] (P3)) can exhibit high selectivity for Pd2+. P3 containing double sulfur atoms in pendants exhibits more high selectivity and sensitivity toward Pd2+ than that of P1 containing single sulfur atom. Aforementioned results were illustrated by fluorescence titration, Ksv fitting and cyclic voltammetry (CV) analysis. The emission of P3–Pd2+ complex can be turned on by the addition of thiophanate-methyl (TM) without the interference from other anions and pesticides. Thus, P3–Pd2+ complex can work as the novel Pd2+−mediated conjugated polymer-based fluorescent (CPF) chemosensors platform for thiophanate-methyl detection. The “on-off-on” sensing mechanism was supported by MALDI-TOF mass analysis, density functional theory (DFT) calculations and the association constants Ka fitting.Modulating sulfur functions to obtain disubstituted polyacetylenes-based fluorescent chemosensors for Pd2+ and the application of thiophanate-methyl detection.Download high-res image (131KB)Download full-size image

•MPCB showed a colorimetric and fluorescence “turn-on” response for SO2 derivatives.•MPCB can be used to detect SO2 derivatives in living cells under two-photon excitation.•MPCB can be predominantly present in mitochondria with a co-localization coefficient of 0.89.Two colorimetric and two-photon fluorescent probes (PCB and MPCB) for SO2 derivatives were designed and synthesized with rapid response, high selectivity, low detection limits, and large Stokes shifts. The probes displayed “turn on” fluorescence response to SO2 derivatives probably due to the nucleophilic addition to the electron-poor CN bond, which was supported by the DFT/TDDFT calculations. Compared with PCB, MPCB was obtained by incorporating a methyl pyridinium group, which endowed MPCB with the red-shifted spectra properties, better water-solubility, larger two-photon excitation action cross-section (δ′) and the important ability of locating in mitochondria. Bio-imaging study established that MPCB can be used to detect SO2 derivatives in living cells under two-photon excitation with large δ′ value (1551 × 0.125 = 193.88 GM), little cytotoxicity and good biocompatibility. Meanwhile, standard co-staining experiments of MPCB and Mito Tracker Red FM (co-localization coefficient: 0.89) revealed that MPCB can be used for the real-time sensing and bioimaging of SO2 derivatives in mitochondria.A mitochondria-targeted colorimetric and two-photon fluorescent probe (MPCB) was developed for highly selective detection of SO2 derivatives and bio-imaging in mitochondria under two-photon excitation.

•CuCM showed a 66-fold fluorescence enhancement response to Cu2+ in aqueous solution.•The Cu2+-promoted C=N bond hydrolysis sensing mechanism was fully confirmed.•CuCM can be used to detect Cu2+ in living cells under two-photon excitation.A carbazole-based “turn-on” two-photon fluorescent probe (CuCM) was successfully designed and characterized, which can be used for Cu2+ detection with high selectivity, low detection limit (32.8 nM), good water solubility, large Stokes shift (117 nm) and two-photon absorption cross sections (1328 GM at 860 nm). The fluorescence enhancement was attributed to the Cu2+-promoted C=N bond hydrolysis sensing mechanism, which is fully confirmed by the UV–vis absorption, fluorescence, 1H NMR titration and MALDI-TOF mass analysis. Bio-imaging study revealed that the new probe CuCM could be used as an effective two-photon fluorescent probe for detecting Cu2+ in living cells.A carbazole-based “turn-on” two-photon fluorescent probe (CuCM) was developed for highly selective detection of Cu2+ and bio-imaging under two-photon excitation.

Heterobimetallic dinuclear lanthanide alkoxide complexes Ln2Na8(OCH2CH2NMe2)12(OH)2 [Ln: I (Nd), II (Sm), III (Yb) and IV (Y)] were used as efficient acid–base bifunctional catalysts for the synthesis of carbamates from dialkyl carbonates and amines as well as the N-Boc protection of amines. The cooperative catalysts showed high catalytic activity and a wide scope of substrates with good to excellent yields under solvent-free conditions. The systems have shown higher catalytic activities due to the noteworthy synergistic interactions of Lewis acid center–Brønsted basic center. The comparison of catalytic efficiency between mono- and dinuclear heterobimetallic lanthanide alkoxide analogues was also investigated.

We develop a novel coumarin-alkyne derivative (NC7-AL), which can specifically react with Au3+ and give a colorimetric and fluorescent “turn-on” response toward Au3+. Notably, other alkynophilic metal species such as Au+, Ag+, Pd2+, Ni2+, Cu2+, and Hg2+ do not produce an interfering signal. A good linear relationship between emission intensity at 420 nm and Au3+ concentration from 0 to 2 equivalent is observed, and the detection limit (3σ/k) is estimated to be ca. 3.58 nmol/L. Harnessing the Au3+-induced color change from light yellow to colorless, we find that NC7-AL-based modified TLC plate can be used for convenient naked-eye detection of Au3+.A coumarin-based colorimetric and fluorescent probe (NC7-AL) was developed for highly selective detection of Au3+ ions.

Two water-soluble carbazole-based two-photon fluorescent (TPF) probes (HCH and HCM) for ClO− detection were developed with rapid response, high selectivity and large two-photon absorption cross sections, which utilized the oxidative dehydrogenation of oxime to the nitrile oxide. It is found that the alkyl substituent groups in the cationic pyridinium moieties could affect the one-/two-photon luminescent properties of probes, and HCH was more suitable for ClO− detection than HCM thanks to the better stability of fluorescence, larger fluorescence enhancement folds and two-photon absorption cross sections for HCHCNO, the corresponding product of HCH toward ClO−. Bio-imaging study revealed that HCH could be used to detect ClO− in living cells under two-photon excitation, and co-staining experiments of HCH and MitoTracker Red FM (co-localization coefficient: 0.90) established that HCH was predominantly present in mitochondria.

•PyCM showed a remarkable fluorescence “turn-on” response to Au3+/Au+ in aqueous solution.•The Au3+-induced CN bond hydrolysis sensing mechanism was fully confirmed.•PyCM can be used to detect Au3+ in living cells under two-photon excitation.•PyCM can be predominantly present in mitochondria (co-localization coefficient: 0.85).A carbazole-based two-photon fluorescent probe (PyCM) showed a remarkable fluorescence “turn-on” response to Au3+/Au+ in aqueous solution with a large Stokes shift (119 nm). A good linear relationship of emission intensity at 539 nm against Au3+/Au+ from 0 to 20 equiv. was observed, and the detection limits (3σ/k) were as low as 47 nM for Au3+ and 73 nM for Au+, respectively. The fluorescence enhancement was attributed to the gold ions-induced CN bond hydrolysis sensing mechanism, which is fully confirmed by the UV–vis absorption, fluorescence, IR, 1H NMR titration and MALDI-TOF mass analysis. Bio-imaging study established that PyCM could be used to detect Au3+ in living cells under two-photon excitation with large two-photon absorption cross sections (1321 GM at 860 nm), little cytotoxicity and good biocompatibility. Meanwhile, standard co-staining experiments of PyCM and MitoTracker Red FM (co-localization coefficient: 0.85) revealed that PyCM was predominantly present in mitochondria.A mitochondria-targeted two-photon fluorescent probe (PyCM) was developed for highly selective detection of gold ions and bio-imaging in mitochondria under two-photon excitation.

A practical lanthanide(III)-catalyzed transesterification of carboxylic esters, weakly reactive carbonates, and much less-reactive ethyl silicate with primary and secondary alcohols was developed. Heterobimetallic dinuclear lanthanide alkoxide complexes [Ln2Na8{(OCH2CH2NMe2)}12(OH)2] (Ln = Nd (I), Sm (II), and Yb (III)) were used as highly active catalysts for this reaction. The mild reaction conditions enabled the transesterification of various substrates to proceed in good to high yield. Efficient activation of transesterification may be endowed by the above complexes as cooperative acid–base difunctional catalysts, which is proposed to be responsible for the higher reactivity in comparison with simple acid/base catalysts.

A water-soluble fluorescent probe for Hg2+ based on a rhodamine B derivative was designed and synthesized. The new probe showed reversible colorimetric and fluorescent response to Hg2+ in a fully aqueous solution. The probe exhibited real-time detection of Hg2+ with high selectivity in media containing less than 1% organic cosolvent. Furthermore, bioimaging studies indicated that the new probe was cell permeable and suitable for the real-time imaging of Hg2+ in living cells by confocal microscopy.

A water-soluble fluorescent probe for Hg2+ based on a rhodamine B derivative was designed and synthesized. The new probe showed reversible colorimetric and fluorescent response to Hg2+ in a fully aqueous solution. The probe exhibited real-time detection of Hg2+ with high selectivity in media containing less than 1% organic cosolvent. Furthermore, bioimaging studies indicated that the new probe was cell permeable and suitable for the real-time imaging of Hg2+ in living cells by confocal microscopy.