No abstract

The synthesis of novel pyrazolo[3,4-h]quinoline-3-carbonitriles has been achieved through a onepot, four-component domino strategy under solvent-free microwave conditions. One of these compounds exhibited fluorescence under UV lamp and was found to be highly sensitive toward Fe 3+ ions in DMSO against various metal ions with a detection limit of 8.6 × 10 −7 M.

The reaction of 2,4-bis((Z)-arylidene)dihydrothiophen-3(2H)-ones and 2-(1-arylethylidene)malononitriles proceeded through a tandem sequence of reactions in a single step affording 2-thiaspiro[4.5]deca-6,8-dienes in quantitative yields.

A new fluorescent chemosensor, viz. 2‐amino‐4‐(4‐methoxyphenyl)‐6‐(10H‐phenothiazin‐2‐yl)‐pyridine‐3‐carbonitrile has been synthesized through a facile one‐pot, four‐component domino strategy under solvent‐free microwave heating. This phenothiazine tethered 2‐aminopyridine‐3‐carbonitrile hybrid exhibited strong orange fluorescence under UV lamp and was highly selective and sensitive towards Fe3+ ions and picric acid. The probe displayed a lower limit of detection of 4.9 μM and 98 nM for Fe3+ ions and picric acid in DMSO, respectively.

The one‐pot three‐component domino reaction of 2‐acetylphenothiazine, 4‐Cl/4‐Me benzaldehyde and malononitrile afforded 3‐amino‐4′‐chloro/4′‐methyl‐5‐(10H‐phenothiazin‐2‐yl)‐[1,1′‐biphenyl]‐2,4‐dicarbonitriles in good yields. These phenothiazine‐tethered biaryls exhibited strong red fluorescence under UV lamp in solid state and green fluorescence in DMSO. These probes were sensitive towards multi‐analytes like Fe3+, Cu2+, picric acid and 4‐nitrophenol with good lower limit of detection.