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Fluorophore substituted boron diketonate 3 shows solvatochromism with a large Stokes shift ranging from 121 nm to 166 nm and emitting strongly in its solid states 3a (463 nm) and 3b (563 nm). Boron diketonate provides a choice of fast turn-off or ratiometric detection of a diamine with respect to the fluorophore substitution on the boron-chelating ring. Naphthyl substituted 3a emission was quenched rapidly and selectively on interaction with ethylenediamine. The detection limit was found to be 0.8 μM. Pyrene substituted 3b exhibited selective calorimetric and ratiometric detection of ethylenediamine with a detection limit of 1.2 μM. Diamine involves a substitution reaction with the elimination of methylsulfanyl group in 3 and it was supported by NMR and mass techniques. The rates of reaction of 3a and 3b with ethylenediamine, Kobs, were determined and found to be 2.18–9.96 × 10−4 s−1 in chloroform. Detection of vaporized diamine over other monoamines under UV-light (365 nm) was achieved with a demonstration of boron diketonate 3 coated silica gel TLC plate test strip array.

The stereo/regio/chemoselective syntheses of a library of novel spiro[acenaphthylene-1,3′-pyrrolizin]-2-one and spiro[acenaphthylene-1,5′-pyrrolo[1,2-c]thiazol]-2-one have been achieved through 1,3-dipolar cycloaddition. Intermediate azomethine ylides generated in situ from α-amino acids and acenaphthylene-1,2-dione react with α-aroylidine ketenedithioacetal (AKDTA) derivatives to give the target product in excellent yield under ultrasound irradiation. Further, spiro-S,S-acetals are converted to spiro-2H-pyranones by a one-pot cyclization strategy.

A highly efficient domino protocol has been developed for the synthesis of 6-aryl-4-(methylthio/amine-1-yl)-2-oxo-2H-pyran-3-carbonitriles and 4-aryl-2-(amine-1-yl)-5,6,7,8-tetrahydronaphthalene-1-carbonitriles from simple and readily available α-aroylketene dithioacetals, malononitrile, secondary amines, and cyclohexanone. This elegant domino process involved consecutive addition–elimination, intramolecular cyclization, and ring opening and closing sequences. Notably, in situ generated 2-imino-4-(methylthio/amine-1-yl)-6-aryl-2H-pyran-3-carbonitrile plays multiple roles in the construction of various novel polyaromatic hydrocarbons.

Regioselective synthesis of 1,1-bis(methylthio)-6-nitro-5-arylhex-1-en-3-one has been achieved from α-alkenoylketene dithioacetals with nitromethane using l-proline catalyst via Michael addition. The synthesized compounds 3a–j were well characterised by NMR and mass spectral techniques. One of the structures was confirmed by single crystal XRD. The enantioselectivity and its specific rotation of synthesized compounds were analyzed. All the compounds were screened for their anti-oxidant property, most of the compounds having the ability to scavenge free radicals.

Boron diketonate complexes were synthesized via a one-pot method. The method focused on the selective synthesis of unsymmetric boron diketonate by involving BF3–OEt2 and β-ketothiolester intermediates generated in situ from α-aroylketene dithioacetals using p-toluenesulfonic acid as a catalyst. The unsymmetrical boron diketonate complexes are emissive both in solution and in the solid state with high quantum yield and large Stokes shift. The boron diketonate 6e selectively senses picric acid over other nitroaromatic compounds with a detection limit of 21.5 μM.

A regioselective synthesis of 3-pyrazolyl-4-aryl substituted pyrrole derivatives from α-aroylidineketene dithioacetals using a convenient and efficient protocol. The pyrrolylpyrazole molecules were expected to have good application in biological system consequently most of the compounds shows excellent antibacterial activity when compared with streptomycin drug. All the synthesized compounds were studied for their anticancer activity in which 5 b, 5 e, 5 g, 5 i have cytotoxic potential on cervical cancer cells at lower concentration.

An efficient route for the synthesis of novel thioether containing dihydropyrano[2,3-c]pyrazoles has been accomplished via a solvent-free, catalyst-free, one-pot, five component domino strategy. This synthetic approach offers several advantages such as an easy work-up, no need for purification techniques and a short reaction time with good atom economy and high yields of the products (81–86%).

An efficient chemo/regio/stereoselective synthesis of novel and functionalized spiro-oxindole/pyrrolizine/pyrrolidine scaffolds has been achieved. The in situ generated azomethine ylide from isatin & L-proline/phenyl alanine underwent 1,3-dipolar cycloaddition with α-aroylidineketene dithioacetals under simple reaction conditions affording spiro-oxindole derivatives. This protocol exhibits an interesting double bond selectivity of α-aroylidineketene dithioacetals. Furthermore, utilizing this spiro-oxindoles scaffold, biologically important benzimidazole and pyrimidine based poly heterocycles were also synthesized.

A new class of highly substituted pyrroles have been synthesized via a simple, fast, and efficient method using environmentally friendly iodine catalyzed [3 + 2] annulation. N-Methyl-N-[(E)-1-(methylsulfanyl)-2-nitro-1-ethenyl]amine (NMSM) 1 and β-nitrostyrenes 3 underwent cycloaddition to afford the desired products 4 in excellent yields under solvent and metal free conditions. All the pyrrole derivatives were evaluated for their in vitro anti-bacterial activity. Among the synthesized pyrrole derivatives, 4b, 4c, 4e, 4g, 4i, 4j, 4l, 4m and 4n displayed good inhibitory properties against a panel of Gram positive and negative infectious pathogens.

An efficient, four-component reaction for the synthesis of hydrazono-sulfonamide adducts via in situ generated ketenimine was discovered. Highly porous copper benzenetricarboxylate [Cu(BTC)], a metal–organic framework (MOF), was used as a heterogeneous catalyst for the four-component coupling reaction involving aldehyde, alkyne, tosyl azide, and phenylhydrazine in a one pot process. For the first time, a copper(II) catalyst was utilized to generate a ketenimine intermediate. The Cu(BTC) catalyst was recycled and reused six times without any substantial loss in the yield. In addition, pyrene adduct (5r) shows remarkable aggregation induced emission enhancement (AIEE) properties, and was studied in detail using THF : water solvent mixtures. Adduct 5r is almost non-emissive in pure THF solution, however, it emits a greenish-yellow colour in the aggregated state. Formation of nano-aggregates was confirmed by TEM analysis. A theoretical DFT study supports the observed photophysical changes.

A novel hydrazono-sulfonamide adduct (AVM) was designed and synthesized. Due to the inhibition of CN isomerization with a higher water content, the adduct shows remarkable aggregation induced emission enhancement (AIEE) properties in a THF:water solvent system. The formation of nanoaggregates was confirmed by transmission electron microscopy (TEM) analysis. Theoretical DFT calculations supported the observed photophysical changes. These aggregates of AVM act as selective and sensitive sensors for picric acid via a fluorescence quenching mechanism. The efficiency of the quenching process was calculated using the Stern–Volmer equation. The detection limit was found to be 80 nM. In addition, contact mode detection using fluorescent test strips was developed to demonstrate the solid phase sensing of picric acid.

We have reported the synthesis of novel di & trisubstituted pyrroles and their biological activity. Most of the compounds show antibacterial activity towards gram positive and gram negative bacteria. The agar-diffusion method was used for prelude screening studies, which showed a hopeful broad range of antibacterial activity. The minimum inhibitory concentration (MIC) for bacteria was determined by the micro dilution method of selected active compounds. For the same compounds cytotoxicity assay was also performed. The photophysical properties were studied for the selected compounds and their results were suitably supported by DFT computation.

We have developed an easy method to construct diheteroaryls from α-aroylidineketene dithioacetals in a multicomponent manner. The reaction proceeded with high chemo/regioselectivity to yield 4-alkoxy-6-(4-aryl-1H-pyrrol-3-yl)pyrimidin-2-amines under milder conditions. It is found that α-aroylidineketene dithioacetals (2) undergo cycloaddition with (p-tolylsulfonyl)methyl isocyanide (3) [TosMIC], guanidine nitrate (5) and alcohol in the presence of NaH/THF to furnish the target 6-pyrrolylpyrimidines (8) in excellent yields.

An efficient green synthetic approach has been developed towards the synthesis of 2-aryl substituted benzimidazoles from α-aroylketene dithioacetals (AKDTAs) 1 and o-phenylenediamine (OPD) 2. The reaction has been achieved in water with a catalytic amount of acetic acid. 2-Arylbenzimidazoles have been synthesized in remarkable yields under both thermal and microwave conditions. The metal catalyst free condition makes this transformation very green, practical and attractive.