Among different nitro compounds, trinitrophenol (TNP) is the most common constituent to prepare powerful explosives all over the world. A few works on the detection of nitro explosives have already been reported in the past few years; however, selectivity is still in its infant stage. As all the nitroexplosives are highly electron deficient in nature, it is very difficult to separate one from a mixture of different nitro compounds by the usual photoinduced electron transfer (PET) mechanism. In the present work, we have used a bright luminescent, 2,6-diamino pyridine functionalized graphene oxide (DAP-RGO) for selective detection of TNP in the presence of other nitro compounds. The major advantage of using this material over other reported materials is not only to achieve very high fluorescence quenching of ∼96% but also superior selectivity >80% in the detection of TNP in aqueous medium via both fluorescence resonance energy transfer and PET mechanisms. Density functional theory calculations also suggest the occurrence of an effective proton transfer mechanism from TNP to DAP-RGO, resulting in this tremendous fluorescence quenching compared to other nitro compounds. We believe this graphene based composite will emerge a new class of materials that could be potentially useful for selective detection, even for trace amounts of nitro explosives in water.

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The hydrosilylation of olefins by a nickel(ii) catalyst assisted by a redox non-innocent phenalenyl (PLY) ligand is reported.

Selective detection of either mercury (Hg2+) or iodide (I-) ion using fluorescence turn-on or turn-off processes is an important area of research. In spite of intensive research, simultaneous detection of both mercury and iodide using fluorescence turn-off-on processes, high sensitivity and theoretical support concerning the mechanisms are still lacking. In the present work, graphene oxide is functionalized by thymine to realize simultaneous detection of both Hg2+ and I- selectively using fluorescence turn-off-on mechanism. Ultra high sensitivity to the extent of ppb level exploiting large surface area of graphene is achieved. DFT calculations also assist to realize the detailed mechanisms involving this PL quenching and also its regain during sensing of these ions in aqueous solution.

Redox equivalent storage in the phenalenyl backbone towards catalytic multi-electron reduction.

Graphene oxide (GO) enriched in oxygen functionalities is limited in optoelectronic application because of its poor optical behavior. One of the major strategies for developing the optical properties of GO is functionalization. Here, GO sheets are functionalized by aminoazobenzene to achieve an intercalated type structure with interlayer separation of 9.3 Å. Bright green emission is observed in this aminoazobenzene-functionalized GO (AAB-GO). Remarkable enhancement in photoluminescence via surface passivation and excited-state intramolecular proton transfer is noticed in the AAB-GO composite. Density functional theory calculations are also carried out to investigate the stability of the modified structure along with its interlayer separation, the results of which agree well with the experimental results. The estimated energy gap (∼2.73 eV) between the highest occupied molecular orbital and lowest unoccupied molecular orbital is also in agreement with the experimental results (∼2.85 eV) of UV−vis absorption data.

Here we demonstrate a simple, low cost, and green synthetic approach to synthesizing water-soluble, nitrogen-doped, fluorescent carbon quantum dots (NCQDs) from lemon juice and ammonia by hydrothermal treatment. Chemical characterizations and low temperature photoluminescence and photoconductivity results show interesting structural features of the as-prepared NCQDs. These new NCQDs consist of a ring type moiety (porphyrin/chlorin) in the centre surrounded by the graphitic network and serve as an efficient fluorescent probe for label-free, sensitive, and selective detection of Fe 3+ with a detection limit of 140 ppb (2.5 mM), which is remarkably lower than the earlier reports on CQDs-based sensing systems. DFT calculations are carried out to optimise the structural aspects for selective detection of Fe 3+ . This extremely low detection limit (140 ppb) arises due to static quenching in addition to dynamic quenching which generally occurs in most cases.

Four new end-on pseudohalide-bridged dinuclear copper(II) complexes, [Cu2(L(1))2(N3)2]·DMF (1), [Cu2(L(2))2(N3)2] (2), [Cu2(L(3))2(NCS)2] (3), and [Cu2(L(4))2(N3)2] (4) {where HL(1), HL(2), HL(3), and HL(4) are tridentate N2O donor Schiff bases}, are synthesized and characterized. Complexes 1, 2, and 3 possess π···π stacking interactions, while in addition hydrogen-bonding interactions are present in 1 and 3. However, by contrast, complex 4 contains neither type of interaction. Field-induced long-range ferromagnetic ordering beyond 0.9 T is observed in complexes 1 and 2 due to π···π stacking interactions, while ferroelectric ordering is observed in complexes 1 and 3 due to hydrogen-bonding interactions. Most interestingly, complex 1, which contains both π···π stacking and hydrogen-bonding interactions, shows multiferroic behavior as a result of coupling between the dielectric and magnetic fields with 8% change in the magneto-dielectric effect at room temperature. We believe that from this study will emerge a new class of multiferroic materials.