Subhamay Pramanik

Hexaphenylbenzene-based fluorescent aggregates for ratiometric detection of cyanide ions at nanomolar level: set-reset memorized sequential logic device.

A hexaphenylbenzene-based receptor 3 has been synthesized that forms a fluorescent spherical aggregate in mixed aqueous media due to its aggregation-induced emission enhancement attributes. These fluorescent spherical aggregates show ratiometric response toward cyanide ions via nucleophilic addition and undergo deaggregation to form smaller nanoaggregates. In addition, the solution-coated paper strips of 3 can detect cyanide ions in the range of ∼2.6 ng/cm(2), thus, providing a simple, portable, and low-cost method for detection of cyanide ions in aqueous media. Receptor 3 also behaves as a set-reset memorized sequential logic circuit with chemical inputs of CN(-) ions and trifluoroacetic acid or H(+) (pH ≤ 3).

Mercury assisted fluorescent supramolecular assembly of hexaphenylbenzene derivative for femtogram detection of picric acid.

Aggregates of hexaphenylbenzene derivatives 3, having pyrene groups form network of fluorescent nanofibres in presence of mercury ions. Further, fluorescent nanofibres of 3-Hg(2+) supramolecular ensemble exhibit sensitive and pronounced response towards the picric acid. In addition, the solution coated paper strips of 3-Hg(2+) supramolecular ensemble can detect picric acid in the range of 2.29 fg/cm(2), thus, providing a simple, portable and low cost method for detection of picric acid in solution and in contact mode.

Ferromagnetic α-Fe2O3 NPs: a potential catalyst in Sonogashira–Hagihara cross coupling and hetero-Diels–Alder reactions

Applications of ferromagnetic in situ generated α-Fe2O3 NPs as an efficient and recyclable catalyst for carbon–carbon bond formation via Sonogashira–Hagihara coupling reactions and the synthesis of pyran derivatives by hetero-Diels–Alder reactions have been demonstrated. This catalytic system is easily recoverable due to the ferromagnetic nature of α-Fe2O3 NPs and can be reused with sustained selectivity and activity.

Hexaphenylbenzene-based fluorescent aggregates for detection of zinc and pyrophosphate ions in aqueous media: tunable self-assembly behaviour and construction of a logic device

Hexaphenylbenzene based derivative 7 has been synthesized which formed spherical aggregates in mixed aqueous media. These aggregates exhibited an “on–on” response towards Zn2+ ions in aqueous media. Further, this sensing event was accompanied by the modulation of the self-assembly of aggregates from spherical structures to microrods in aqueous media. This in situ prepared 7-Zn2+ ensemble was utilized as a “not quenched” probe for the selective and sensitive detection of PPi ions in aqueous media. In addition, based upon the fluorescent signals of derivative 7 as outputs (λem = 450 and 370 nm) in the presence of chemical inputs (Zn2+ and PPi), we developed a combinatorial logic circuit with INHIBIT and AND gates.

AIEE Active Donor–Acceptor–Donor-Based Hexaphenylbenzene Probe for Recognition of Aliphatic and Aromatic Amines

In the present investigation, an intramolecular charge transfer (ICT) and aggregation induced emission enhancement (AIEE) active donor-acceptor-donor (D-A-D) system 5 having fumaronitrile as the acceptor and hexaphenylbenzene (HPB) as the donor moieties joined through rotatable phenyl rings has been designed and synthesized that is highly emissive in the solid state and exhibits stimuli-responsive reversible piezochromic behavior upon grinding and heating. Because of its AIEE characteristics, HPB derivative 5 undergoes aggregation to form fluorescent aggregates in mixed aqueous media that exhibit ratiometric fluorescence response toward aliphatic amines (primary/secondary/tertiary) and turn-off response toward aromatic amines and hence differentiates between them. Further, the solution-coated portable paper strips of derivative 5 showed pronounced and sensitive response toward aromatic and aliphatic amines with a detection limit in the range of picogram and nanogram level, respectively.

“Not quenched” aggregates of a triphenylene derivative for the sensitive detection of trinitrotoluene in aqueous medium

Triphenylene derivative 4 bearing gallic acid groups at the periphery has been synthesized. Derivative 4 formed “not quenched” porous aggregates in mixed aqueous medium. These aggregates served as potent chemosensors for the selective detection of trinitrotoluene (TNT) in mixed aqueous media and the detection limit in the range of 228.6 × 10−12 g L−1 (228.6 parts per quadrillion) was observed. Interestingly, due to the porous morphology of these aggregates of derivative 4, they could detect TNT in the vapor phase also. In addition, the dip strips coated by the aggregates of derivative 4 could detect TNT in contact mode with detection limits of 22.7 attograms cm−2.