Synthesis of indolo[3,2-b]carbazole-based new colorimetric receptor for anions: A unique color change for fluoride ions

A novel indolocarbazole-based chemosensor 1 containing hydrogen bond donor moieties has been established as a selective colorimetric and fluorometric sensor for F− in CH3CN/H2O (4:1 v/v). Upon the addition of a series of tetrabutylammonium salts to receptor 1 in aqueous CH3CN, only when the counter ion was F− was a significant color change (from light violet to dark orange) observed

Rare Crystal Structure of Open Spirolactam Ring along with the Closed-Ring Form of a Rhodamine Derivative : Sensing of Cu2+ Ions from Spinach

Crystal structures of a rhodamine derivative in its closed and open spirolactam ring forms were developed, which allows selective and sensitive detection of Cu2+ ions at a micromolar range in neutral medium. The chemosensing properties of the probe through a pentacoordinate Cu2+ ions were proven by spectroscopic and theoretical analysis. The spirolactam ring opening as the Cu2+selective sensor was applied to spinach (Spinacia oleracea) to estimate the accumulation of copper as copper(II) in the plant.peerReviewe

A handy and accessible tool for identification of Sn(II) in toothpaste

An easily accessible colorimetric probe, a carbazole–naphthaldehyde conjugate (CNP), was successfully prepared for the selective and sensitive recognition of Sn(II) in different commercially-available toothpaste and mouth wash samples. The binding mechanism of CNP for Sn2+ was confirmed by UV–Vis, 1H, and 13C NMR titrations. The proposed sensing mechanism was supported by quantum chemical calculations. Selective detection of Sn(II) in the nanomolar range (85 nM), among other interfering metal ions, makes it exclusive. Moreover, Sn2+ can be detected with a simple paper strip from toothpaste, which makes this method handy and easily accessible. The potential application of this system for monitoring Sn2+ can be used as an expedient tool for environmental and industrial purposes.peerReviewe

First Chemosensor for Selective Detection and Quantification of L‑4-Hydroxyproline in Collagen and Other Bio Samples

Amino pyridine-based rhodamine conjugate (APR) has been developed as a first chemosensor for selective detection and quantification of L-4-Hydroxyproline (Hyp). The “turn-on” fluorescence property of the chemosensor makes it unique for easy estimation of Hyp in collagen and biological samples

Differential detection and quantification of cyclic AMP and other adenosine phosphates in live cell

A new naphthol-based rhodamine derivative (NpRD) has been developed for the selective and differential detection of adenosine 3′,5′-cyclic monophosphate (cAMP) and adenosine phosphates (APs) (ATP, ADP, and AMP) from other nucleotides. The simple detection and quantification of cAMP in human blood cells and in other samples based on the ‘turn on’ fluorescence properties of this chemosensor through colorimetry or fluorometry makes it unique for probable application in high throughput screening.peerReviewe

Visualisation of DCP, a nerve agent mimic, in Catfish brain by a simple chemosensor

Abstract A chemosensor, 3-aminophenol-based rhodamine conjugate (ARC) has been developed for visualisation of diethylchlorophosphate (DCP), mimic of a chemical warfare agent, in Catfish brain. The simple detection of DCP by “turn-on” fluorescence property of the chemosensor makes it unique for easy and rapid in vivo and in vitro detection of DCP with the detection limit of 5.6 nM

Reliable fluorescence technique to detect the antibiotic colistin, a possible environmental threat due to its overuse

Colistin, considered a drug of last resort as it is effective towards multidrug-resistant Gram-negative bacterial infections. Oral administration of colistin in the poultry industry is a common practice, not only to prevent and reduce bacterial infections, but also as a rapid-growth promoter. Long-term exposure to any antibiotic will eventually lead to the development of bacterial resistance towards all antibiotics through various mechanisms in the physiological system and environment. Chicken is the most consumed source of animal protein for humans throughout the world. In addition, the manure of poultry, containing traces of the used antibiotics, is being used in farming. Exposure to excess amounts of colistin causes a great concern not only to the humans but to the environment as a whole. In the present contribution, colistin has been detected in chicken hepatocyte cells through in vivo confocal microscopy. In addition, the amount of colistin in the chicken excrements has been estimated. A simple chemosensor NAF, a dye-based on napthaldehyde furfural, was developed for the detection of colistin, supplemented with experimental evidence and theoretical calculations.peerReviewe

Carbazole-driven ratiometric fluorescence turn on for dual ion recognition of Zn²⁺ and Hg²⁺ by thiophene-pyridyl conjugate in HEPES buffer medium: spectroscopy, computational, microscopy and cellular studies

<p>Carbazole-based thiophene-pyridyl conjugate (<b>L</b>) was synthesised and characterised. The complexation between <b>L</b> with Zn²⁺ and Hg²⁺ was studied in HEPES buffer medium by fluorescence, absorption and visual colour change with the detection limit of ~3.7 and ~4.8 μM, respectively. The <b>L</b> detects Zn²⁺ by bringing ratiometric change in the fluorescence signals at 418 and 515 nm, but in the case of Hg²⁺, the signals are observed at 418 and 365 nm, while no new band is observed at 515 nm. The structure of <b>L</b> has been established by single-crystal XRD and that of complexes <b>[ZnL]</b> and <b>[HgL]</b> by density functional theory calculations. TDDFT calculations were performed in order to demonstrate the electronic properties of receptors and their zinc and mercury complexes. The isolated fluorescent complexes <b>[ZnL]</b> and <b>[HgL]</b> were found to be sensitive and selective towards phosphate-bearing ions and sulfide ions, respectively, among the other anions studied. The nanostructural features such as shape and size obtained using atomic force microscopy distinguish <b>L</b> from its complexes formed between <b>L</b> and Zn²⁺ from that formed with Hg²⁺. Moreover, the utility of the conjugate <b>L</b> in showing the zinc recognition in live cells has also been demonstrated using RAW cells as monitored by fluorescence imaging.</p