Nanomolar detection of hypochlorite by a rhodamine-based chiral hydrazide in absolute aqueous media: application in tap water analysis with live-cell imaging.

By employing the oxidation property of hypochlorite (OCl(-)), a novel rhodamine-based hydrazide of the chiral acid ((S)-(-)-2-pyrrolidone-5-carboxylic acid) (RHHP) was designed and synthesized for detection of OCl(-) absolutely in aqueous medium at nanomolar level. The structure of the chiral sensor was also proved by the X-ray crystallography. The bioactivity and the application of the probe for detection of OCl(-) in natural water system have been demonstrated. A plausible mechanism for oxidation of the sensor followed by hydrolysis is also proposed. The sensibility of the receptor toward OCl(-) was studied in absolute aqueous media, and the detection limit of hypochlorite-mediated oxidation to the receptor in nanomolar level makes this platform (RHHP) an ultrasensitive and unique system for OCl(-) oxidation.

A highly selective and sensitive probe for colorimetric and fluorogenic detection of Cd2+ in aqueous media.

A new rhodamine-quinoline based dyad has been synthesized. It shows a highly selective response to Cd(2+) in the presence of other competing metal ions in aqueous media (pH = 7.1). The detection limit of the sensor is in the 10(-7) M level.

Ratiometric and absolute water-soluble fluorescent tripodal zinc sensor and its application in killing human lung cancer cells.

A new "naked-eye" and ratiometric fluorescent zinc sensor (TAQ) of carboxamidoquinoline with 2-chloro-N-(quinol-8-yl)-acetamide as a receptor was designed and synthesized. The sensor shows good water solubility and high selectivity for sensing; about a 15-fold increase in fluorescence quantum yield and a 100 nm red-shift of fluorescence emission upon binding Zn²âº in aqueous HEPES buffer solution are observed. The human lung cancer cell line (A549) activity is also demonstrated.

A differentially selective molecular probe for detection of trivalent ions (Al(3+), Cr(3+) and Fe(3+)) upon single excitation in mixed aqueous medium.

A chemosensor was developed which could selectively detect and differentiate trivalent metal ions (Al(3+), Cr(3+) and Fe(3+)) upon single excitation at two different wavelengths in aqueous medium. This probe selectively detects trivalent ions in the presence of different metal ions in aqueous medium. It shows an excellent performance in the "dipstick" method.

Visual and near IR (NIR) fluorescence detection of Cr3+ in aqueous media via spirobenzopyran ring opening with application in logic gate and bio-imaging.

A new spirobenzopyran derivative (SPNH) was designed and synthesized which was applied in simultaneous colorimetric and NIR fluorescence detections for Cr(3+). This spirobenzopyran receptor is normally colorless in aqueous organic media but the formation of merocyanine occurs by Cr(3+) showing a yellow color. Here the formation of yellow color in UV-vis spectra and strong NIR fluorescence emission at 675 nm makes SPNH a good sensor for Cr(3+) ion. It is also found to be useful in cell imaging and in construction of logic gate. It shows INHIBIT gate in fluorescence and OR gate in absorption. To the best of our knowledge, this is the first report of NIR fluorescence emission of a spirobenzopyran derivative by Cr(3+) and its application to cell-biology and also in the logic gate.

Carbazole based hemicyanine dye for both "naked eye" and 'NIR' fluorescence detection of CN- in aqueous solution: from molecules to low cost devices (TLC plate sticks).

A hybrid carbazole hemicyanine dye (receptor CHD) was developed as a new visible and near infrared chemodosimeter type sensor with high ratiometric selectivity towards cyanide in the presence of other anions in aqueous solution. The chemosensor also showed excellent performance when used in the "dip stick" method, i.e. in solid phase (TLC plates).

Highly reactive (<1 min) ratiometric "naked eye" detection of hypochlorite with real application in tap water.

The de-diaminomaleonitrile reaction in a simple carbazole diaminomaleonitrile hybrid (CDH) was promoted by OCl(-) which disrupted the ICT mechanism by breaking the donor and acceptor linkage. This system utilized an irreversible OCl(-) promoted oxidation reaction and it responded instantaneously at room temperature. The chemosensor also showed excellent performance in tap water and the "dip-stick" method.

Resonance-assisted hydrogen bonding induced nucleophilic addition to hamper ESIPT: ratiometric detection of cyanide in aqueous media.

For ratiometric "naked eye" detection of CN(-), an ESIPT exhibiting benzothiazole receptor (BHI) is designed having one aldehyde group ortho and the other aldehyde para to the OH group respectively. Due to RAHBs, the ortho aldehyde group is highly reactive undergoing nucleophilic cyanide addition selectively, which hampered ESIPT. This is also supported by DFT and TD-DFT calculations.

Dual channel selective fluorescence detection of Al(III) and PPi in aqueous media with an 'off-on-off' switch which mimics molecular logic gates (INHIBIT and EXOR gates).

In this study, we have synthesized a simple Schiff base type isophthaloyl salicylaldehyde hydrazone (ISH) moiety which selectively detects Al(III) and PPi with a fluorescence enhancement at two different wavelengths in aqueous solution. The sensing phenomenon is also reversible and thus the sensor beautifully mimics logic gates (INHIBIT and EXOR gates).

Rapid and ratiometric detection of hypochlorite with real application in tap water: molecules to low cost devices (TLC sticks).

We have designed a chemodosimeter DPNO (weak fluorescence) which can be oxidized to HPNO (strong blue fluorescence) by OCl(-) with high selectivity and sensitivity in a ratiometric approach with a noticeably lower detection limit. The sensor could be useful for the detection of hypochlorites in tap water.

Selective detection and bio-imaging of Pd2+ with novel 'C-CN' bond cleavage of cyano-rhodamine, cyanation with diaminomaleonitrile.

A new rhodamine based chemosensor, cyano-rhodamine, has been designed and synthesized with a green approach which shows a specific 'C-CN' bond breaking with the action of the Pd(2+) ion to produce the specific color and fluorescence of rhodamine 6G itself in solution and in HeLa cells.