A quick accelerating microwave-assisted sustainable technique: permutated spiro-casing for imaging experiment.

A quick access tool for the one-pot, chromatography-free synthesis of the diversified dihydrospiro[indeno[1,2-b]pyridine-4,3'-indoline or acenaphthylene-1,4'-indeno[1,2-b]pyridine spiro-analogous via sustainable microwave condition in minimal 1:1 (v/v) aqueous ethanol without any metal catalyst is demonstrated here. This permutated spiro-casing was designed as fluorescence probe at physiological pH for selective detection of Zn2+, even in the presence of other competitive ions and showed a fluorescent enhancement with 1:1 metal/ligand complex. Moreover, this spiro sensor was successfully applied as an effective intracellular Zn2+ imaging agent in the biomedical study of human hepatocellular liver carcinoma cells (HepG2) due to its cell permeability property. A quick access technique for the permutated dihydrospiro-pyridine via chromatography-free sustainable microwave condition and its applications as organic fluorescence probe at physiological pH for selective detection of Zn2+ and effective intracellular Zn2+ imaging in HepG2 cells.

Aggregation-Induced Emission-Based Sensing Platform for Selective Detection of Zn2+ : Experimental and Theoretical Investigations.

Fluorescent chemosensors with aggregation induced emission enhancement (AIEE) emerge as promising tools in the field of sensing materials. Herein, we report the design, synthesis and applicability of a Schiff base chemosensor 1-(benzo[1,3]dioxol-4-ylmethylene-hydrazonomethyl)-naphthalen-2-ol (Hbdhn) of AIE characteristics that exhibits highly effective and selective response towards Zn2+ . The sensing effect of Hbdhn was evaluated by means of absorption/emission spectra and corresponding underlying photophysical mechanisms were proposed based on extensive quantum-chemical (TD)DFT calculations. The aggregated states in different DMSO/H2 O ratios and in a presence of Zn2+ were examined by fluorescence lifetime measurements, dynamic light scattering and scanning electron microscopy studies. The bioimaging abilities of Hbdhn were evaluated for Zn2+ in HepG2 cancer cells. The results demonstrate instant, stable in time and reproducible, colorimetric turn-on response with superb selectivity and sensitivity of Hbdhn towards Zn2+ , based on chelation enhanced fluorescence mechanism. AIEE improves further Hbdhn properties, leading to strong, long-lived fluorescence, with appearance of rod-like particles, in 90 % of water in DMSO and only 10 % of water in DMSO in the presence of Zn2+ . All these features combined with successful biomaging studies make Hbdhn one of the most promising candidate for practical applications among recently proposed related systems.

A versatile chemosensor for the detection of Al3+ and picric acid (PA) in aqueous solution.

Developing chemosensors for efficient detection of Al3+ and picric acid in water is in high demand but challenging. In this paper, we have demonstrated the potential of a probe, 6,6'-(1E,1'E)-(2-hydroxypropane-1,3-diyl)bis(azan-1-yl-1-ylidene)bis(methan-1-yl-1-ylidene)bis(2-methoxyphenol) (H2Vm), as a "switch-on" Al3+ responsive fluorescence chemosensor in water. In addition to the ability of H2Vm to sense Al3+, the Al2-Vm2 complex offers selectivity towards picric acid (PA) in HEPES buffer (pH = 7.4) solution (detection limit (20.13 × 10-9 M) via "switch-off" mode. The reversible fluorescence response with low detection limit (11.34 × 10-9 M) in the pH range of 6.0-9.0 makes H2Vm suitable for tracking Al3+ in live HCT cells. The resulting Al2-Vm2 complex is also responsive towards PA in HCT cells. Thus, a versatile fluorescence spectroscopy-based chemosensor for Al3+ and picric acid has been developed with possible applications in human health and national security.

Dihydroindeno[1,2-b]pyrroles: new Al3+ selective off-on chemosensors for bio-imaging in living HepG2 cells.

In this study, a new molecular organic probe has been designed and synthesized by using recyclable, inexpensive and non-toxic polyethylene glycol (PEG-400) as a promoting reaction medium in water under environmentally benevolent conditions. The probe has been explored as a potential chemosensor to detect Al3+ ions using a HEPES buffer (pH = 7.4) solution. Investigations of the fluorescence behaviour of this sensor in DMSO/H2O (2 : 8, v/v) solution displayed a dramatic switch-on response only in the presence of Al3+, while other metal ions, like Li+, Na+, K+, Ag+, Ca2+, Mg2+, Mn2+, Ba2+, Cu2+, Ni2+, Co2+, Fe2+, Zn2+, Cd2+, Hg2+, Pb2+, Sr2+, Fe3+ or Cr3+, have almost no influence on the fluorescence behaviour. Various common anions, such as ClO4-, Cl-, or NO3- in the form of Al3+ salts [e.g. Al(ClO4)3, AlCl3 or Al(NO3)3], had no influence on the fluorescence behaviour of the sensors. The detection limit for Al3+ is in the order of 10-6 M in DMSO/H2O (2 : 8, v/v) HEPES buffer (pH = 7.4) solution. Notably, this is the first report of a dihydroindeno[1,2-b]pyrrole moiety acting as a sensor for the selective detection of Al3+ ions through an off-on fluorescence response. The potential of the probe was also confirmed by employing it for fluorescence bio-imaging with Al3+ on HepG2 cells.

I2 catalyzed access of spiro[indoline-3,4'-pyridine] appended amine dyad: new ON-OFF chemosensors for Cu2+ and imaging in living cells.

An easy access to an amine-appended spiro[indoline-3,4'-pyridine] ON-OFF chemosensor by a one-pot four-component reaction using commercially available and an environmentally benign catalytic amount of molecular I2 (10 mol%) in aqueous ethanol at ambient temperature is described. The generated system could be utilized for the selective detection of Cu2+ as it demonstrated a colorimetric naked eye change along with an ON-OFF fluorescence response towards Cu2+ at physiological pH. The sensors exhibited high selectivity for Cu2+ over other common cations with detection limit in the range of 10-7 (M). Notably, this is the first report of a spiro[indoline-3,4'-pyridine] moiety acting as a sensor for Cu2+via a on-off fluorescence response. In addition, the probe system was successfully applied for imaging Cu2+ in human hepatocellular liver carcinoma cells (HepG2), demonstrating a new avenue for molecular imaging and biomedical applications.

A Schiff base platform: structures, sensing of Zn(ii) and PPi in aqueous medium and anticancer activity.

A reaction of N1,N3-bis(3-methoxysalicylidene) diethylenetriamine (H2Vd) and Zn(NO3)2·6H2O, ZnBr2, ZnI2 and Cd(NO3)2·4H2O in a methanol solution led to zinc and cadmium complexes of different nuclearities, [Zn2(Vd·H)2(X)2]·CH3OH (X = NO3, Br, I) [1a, 1b and 1c] and Cd3(Vd)2(NO3)2 (2). In 1(a-c), two H2Vd ligands bridge the two metal centers whereas in 2, they provide sideways support to two terminal Cd2+ ions, providing an all-oxygen envelope to the central Cd2+ ion. All four compounds were characterized by elemental analysis, FT-IR spectroscopy and single crystal X-ray diffraction analysis. Complexes 1(a-c) exhibit dinuclear structures, whereas 2 exhibits a nearly linear trinuclear structure. The structural differences among these complexes are attributable to various coordination modes and flexible configurations of the H2Vd ligand. The ligand H2Vd is an excellent probe for sensing Zn2+ in solution, whereas complexes 1(a-c) are able to selectively detect pyrophosphate (PPi) in aqueous medium. The structure of the pyrophosphate (PPi) complex has been proposed using DFT calculations and the selectivity is due to the unique ability of this anion to simultaneously coordinate to both the Zn metal centers. The anticancer activity of complexes 1(a-c) was also explored.