Reversible Near-Infrared Fluorescent Probe for Rapid Sensing Sulfur Dioxide and Formaldehyde: Recognition and Photoactivation Mechanism and Applications in Bioimaging and Encryption Ink.

A novel near-infrared (NIR) fluorescent Probe 1 was successfully developed for the reversible detection of sulfur dioxide derivatives and formaldehyde. The purple solution of Probe 1 faded to colorless in 1.8 s with the addition of HSO3-. Meanwhile, its fluorescence signal disappeared instantaneously with a 39 nM detection limit. The probe exhibited excellent selectivity toward HSO3- over other potential interfering agents. Then, its absorption and fluorescence bands were able to effectively recover in response to formaldehyde. Remarkably, this reverse process was able to accelerate 84 times under UV light in 122 s and achieved a recovery rate of 98% by UV light, the photoactivation mechanism was fully determined by HRMS and theoretical calculation. Furthermore, we demonstrated that Probe 1 was successfully applied for the detection of sulfur dioxide derivatives and formaldehyde in living cells and data encryption.

Gold-catalyzed cycloadditions of allenes via metal carbenes.

In recent years, gold-catalyzed cycloadditions of allenes, especially those involving a gold carbene intermediate, have received significant interest, as they avoid the utilization of potentially hazardous and inaccessible diazo compounds as starting materials for carbene generation. Cycloaddition reactions consisting of the uncomplicated addition of two or more unsaturated functional groups are one of the most efficient synthetic methodologies for the rapid assembly of carbo- and heterocyclic structures from simple acyclic precursors. In this review, we introduce an overview of the advances in the gold-catalyzed cycloaddition of allenes via a metal carbene intermediate and categorize these reactions according to the reaction types of the cycloadditions.

Recent progress towards the transition-metal-catalyzed Nazarov cyclization of alkynes via metal carbenes.

In recent years, transition-metal-catalyzed tandem cyclization reactions of alkynes, especially those involving a metal carbene intermediate, have received worthwhile interest, as this type of reaction does not require the use of risky and potentially explosive diazo compounds as starting materials for carbene generation. A significant and general strategy for the stereospecific synthesis of 5-membered cycles is Nazarov cyclization based on the 4π-conrotatory electrocyclization of a conjugated pentadienyl cation to afford a cyclopentenyl cation. In this review, we introduce an overview of recent advances in the transition-metal-catalyzed Nazarov cyclization of alkynes via a metal carbene intermediate, and categorize these reactions according to the structure of the metal carbene. Our aim is to accelerate advancements in this enchanting area of research.

A near-Infrared Fluorescent Chemodosimeter for Ratiometric Detecting Fluoride Based on Desilylation Reaction.

A new chemodosimeter based on dicyanomethylene-4H-chromene chromophore (probe 1) was developed as a ratiometric fluorescent probe in near-infrared range for F(-) with good selectivity in acetonitrile. Probe 1 could be used to directly visualize F(-) by the naked eye and showed more than 621-fold fluorescence enhancement at 715 nm upon reaction with F(-) upon excitation at 625 nm. The recognition of probe 1 to fluoride was featured by F(-)-induced red-shifts of both absorption (185 nm) and fluorescence peaks (132 nm) based on internal charge transfer (ICT) in acetonitrile. The desilylation reaction of 1 by F(-) was proposed for its dual absorption and emission ratiometric detection of fluoride.

Two new reversible naphthalimide-based fluorescent chemosensors for Hg(2.).

Naphthalimide-based fluorescent probes 1 and 2 were synthesized, and were designed to form probe-Hg complexes through Hg(2+) ions coordinated to the amide group and imidazole group. They showed high sensitivity and were selective 'naked-eye' chemosensors for Hg(2+) in phosphate buffer. The fluorescence of compounds 1 and 2 could be quenched up to 90% by the addition of Hg(2+) . Reversible probes can detect Hg(2+) ions over a wide pH range (7.0-10.0). Copyright © 2015 John Wiley & Sons, Ltd.

A New Turn on Fluorescent Probe for Selective Detection of Cysteine/Homocysteine.

A new fluorescent probe (probe 1) was developed for recognition of cysteine (Cys) and homocysteine (Hcy). Probe 1 exhibited a large absorption peak blue-shift (107 nm) as well as enhanced fluorescence responses to Cys/Hcy based on cyclization of thiol containing amino acids with aldehydes, inhibiting the C = N isomerization-induced quenching process by an intramolecular hydrogen bond. The detection mechanism was proved by (1)H NMR and mass spectrometry analysis.

Incidence rate of angel wing and its effect on wing bone development and serum biochemical parameters in geese.

The first purpose of this study was to reveal the distribution of the angel wing (AW) of geese. Our data showed that the total incidence of AW was 6.67% in 150-day-old White Zhedong (ZD) geese, the occurrence of AW in left wing is higher than that in right wing and bilateral wing than unilateral wing (both P < 0.01). In 70-day-old Hybrid-Wanxi (HW) geese, the total incidence of AW was 8.86%, with similar incidence rate between unilateral and bilateral. The sex has not apparently affected the incidence of AW in both ZD and HW geese. To explore the potential relationship between wing type with body weight, organ index, bone characteristic, or blood biochemical parameters in 70-day-old HW geese. We found that the body weight and organ index were similar between normal wing (NW) and AW geese. The length for the humerus, metacarpal and phalanx, and the phalanx weights, as well as the angle between the humerus and the radial ulna (HRU) in NW geese were pronounced greater than that in AW geese (P < 0.05). Furthermore, the angel wing was strongly associated with lower platelet size indicators. Collectively, AW affected the wing bone length, phalanx weight, and HRU, and the occurrence of AW may be related with dysfunctional platelet activation in geese.

A simple and effective dansyl acid based "turn-on" fluorescent probe for detecting labile ferrous iron in physiological saline and live cells.

Labile ferrous iron (Fe2+) plays important biochemical functions in many physiologically essential processes. It is very important to find an effective method to detect Fe2+. Herein, a simple and effective Fe2+ fluorescent probe (FeP1) has been constructed via a unique strategy of Fe2+-induced reducing reaction. As expected, FeP1 exhibited a 'turn-on' fluorescence response toward Fe2+ over various small analytes, with high selectivity and excellent sensitivity (DL = 18 nM) for the detection of Fe2+ in Tris-DMSO (4:1, pH = 7.4, v/v) solution. Moreover, the probe can act in different real samples, such as physiological saline and living cells.

A novel probe based on rhodamine 101 spirolactam and 2-(2'-hydroxy-5'-methylphenyl)benzothiazole moieties for three-in-one detection of paramagnetic Cu2+, Co2+ and Ni2.

A novel probe based on rhodamine 101 spirolactam and 2-(2'-hydroxy-5'-methylphenyl)benzothiazole moieties (probe 1) was developed as a three-in-one platform for detection of paramagnetic Cu2+, Co2+ and Ni2+ through different processes. Ratiometric changes in emission intensities at 565 nm and 460 nm for 1 (λex = 350 nm) were observed in presence of Co2+, Cu2+ and Ni2+ respectively. This probe displayed ratiometric colorimetric responses and 'turn-on' fluorescence responses (λex = 540 nm) toward Cu2+ and Co2+. Whereas probe 1 exhibited very weak absorption around 480 nm, no 'turn-on' emission (λex = 540 nm) in presence of Ni2+. The detection limits were 0.11 µM and 0.17 µM for Cu2+ and Co2+ ions respectively from ratiometric colorimetric measurements and 26 nM, 54 nM and 101 nM for Cu2+, Co2+ and Ni2+ respectively from ratiometric fluorometric measurements. The excited-state intramolecular proton transfer (ESIPT)-prohibited coupled ring-open process for 1-Cu2+ (1-Co2+) and ESIPT-prohibited irreversible process for 1-Ni2+ were proposed according to the spectral results. Furthermore, probe 1 was utilized to determine Cu2+ and Co2+ in real-life samples with good recoveries.

Synthesis and swelling behaviors of carboxymethyl cellulose-based superabsorbent resin hybridized with graphene oxide.

Well-dispersed graphene oxide sheets were successfully incorporated into a superabsorbent resin through in situ graft polymerization of acrylic acid on carboxymethyl cellulose backbone in the presence of graphene oxide as filler. The structure and properties of the resultant superabsorbent resin were studied in detail by means of a variety of characterization methods. The influence of the feed ratio of starting materials (such as GO, initiator, cross-linker, the ratio of CMC to AA and the neutralized degree of AA) and pH values on water absorbency and retention ability was extensively determined and discussed. The obtained results showed that the introduction of graphene oxide had no obvious influence on the inherent structure of the superabsorbent resin but changed the surface morphology significantly. Importantly, the hybrid superabsorbent resin showed an enhanced thermal stability and remarkably improved swelling ratio as well as water-retention ability comparing with that of the pure superabsorbent resin.