In this paper, a thioacetal chemosensor 1 incorporating simultaneously a carbazole moiety and an azobenzene moiety was synthesized. Among other metal ions, Hg2+ proved to be able to selectively induce both color and fluorescence changes of 1. The mechanism of Hg2+-promoted cleavage of thioacetal was confirmed by 1H NMR experiments. Upon the addition of Hg2+ into the yellow CH3CN/H2O solution of 1, the resultant azobenzene-containing thioglycolamide was precipitated from the solution as a mercuric salt, leading to a colorless solution. Therefore, a novel color change pattern was developed.

•A novel turn-on fluorescent sensor based on quinoline and naphthalimide was designed and synthesized.•The sensor is highly sensitive and selective to hydrogen sulfate with 8-fold fluorescence enhancement.•The sensing mechanism has been suggested to proceed via a hydrolysis process.A new fluorescence turn-on chemosensor 1 based on quinoline and naphthalimide was prepared and its anion sensing toward various anions behavior was explored in this paper. Sensor 1 exhibited a highly selective fluorescent response toward HSO4− with an 8-fold fluorescence intensity enhancement in the presence of 10 equiv. of HSO4− in DMSO-H2O (1/1, v/v) solution. The sensor also displayed high sensitivity to hydrogen sulfate and the detection limit was calculated to be 7.79 × 10− 7 M. The sensing mechanism has been suggested to proceed via a hydrolysis process of the Schiff base group. The hydrolysis product has been isolated and further identified by 1H NMR and MS.

•A new fluorescence chemosensor based on coumarin and naphthalimide was synthesized.•The chemosensor exhibits high selectivity for Fe3+ with fluorescence-enhancement.•The detection limit could reach 0.388 μM.A new Fe3+-selective “turn-on” chemosensor 1 based on coumarin and naphthalimide was designed and synthesized. The chemosensor exhibits high selectivity for Fe3+ over other ions (Mn2+, Co2+, Ni2+, Cu2+, Ag+, Cd2+, Pb2+, Ca2+, Al3+, Ba2+, Hg2+, Li+, Mg2+, Sr2+, Zn2+ and K+) with fluorescence-enhancement in THF-H2O solution. The binding ratio of 1-Fe3+ complex was determined to be 1:1 according to the Job plot. The association constant Ka of Fe3+ binding with sensor 1 was (2.589 ± 0.206) × 103 M−1. The detection limit was calculated to be 0.388 μM.

A colorimetric chemosensor TBS-NA, 4-(tert-butyldimethylsilyloxy)-N-butyl-naphthalimide was designed and synthesized. Addition of fluoride ion to a CH3CN solution of TBS-NA can result in an obvious color change (from colorless to yellow) and UV–Vis absorption spectral change in a short time. This indicated that TBS-NA had highly selectivity for fluoride detection over other anions, such as Cl−, Br−, I−, HSO4−, ClO4− and AcO− in CH3CN solutions, and the selectively detection was due to the selective cleavage of Si–O bond in TBS-NA by fluoride. The detection limit was calculated to be 0.59 μM.Highlights► The sensor TBS-NA can detect fluoride ion with high selectivity in CH3CN solution over other anions. ► Addition of fluoride ion to a CH3CN solution of TSB-NA can result in an obvious color change (from colorless to yellow) and UV–Vis absorption spectral change in a short time. ► The absorbance of TBS-NA at 474 nm increased linearly with the concentration of fluoride from 10 to 100 μM. ► The detection limit was calculated to be 0.59 μM.

•The new POSS that supported the prolinamide-type catalysts was synthesized and used to catalyze asymmetric Aldol reactions.•The higher ee value has been obtained after the C2-symmetric bisprolinamide chrial catalyst was immobilized onto the POSS.•The POSS supported catalyst could be recycled simply and reused in five consecutive cycles maintaining its effectiveness.POSS supported prolinamide-type catalysts were synthesized and used to catalyze asymmetric Aldol reactions between unmodified ketones and aldehydes. Immobilization of the prolinamide-type catalysts onto POSS resulted in good yields and improved diastereoselectivity as well as enantioselectivity. The POSS-supported catalysts were recycled simply by precipitation and filtration, and could be reused in five consecutive cycles without losing its effectiveness.