Kundan Tayade

Highly selective turn-on fluorescent sensor for nanomolar detection of biologically important Zn2+ based on isonicotinohydrazide derivative: application in cellular imaging.

A new Zn(2+) selective chemosensor (3) was synthesized by condensation of commercially available substituted salicylaldehyde and isonicotinohydrazide, and characterized by single crystal X-ray crystallography. Receptor 3 with Zn(2+) exhibited a highly selective and pronounced enhancement in the fluorescence emission among different cations by forming a 2:1 complex. The receptor can detect Zn(2+) up to nanomolar level (6.75 nM) with good tolerance of other metal ions and can be used for in vitro cellular imaging.

An amide based dipodal Zn2+ complex: nano-molar detection of HSO4− in a semi-aqueous system

A new chromogenic dipodal Zn2+ complex (4) bearing an amide group has been synthesized. The anion binding profile of this sensor was investigated with fluorescence and UV-Vis spectroscopy. The receptor 4 has high affinity for HSO4 − with a binding constant of 3.5 × 104 M−1 and a detection limit of 50 nM. The binding ability was confirmed with spectroscopic methods and density functional theory calculation (DFT).

Novel fluorescent chemosensing of CN− anions with nanomolar detection using the Zn2+–isonicotinohydrazide metal complex

A novel chemosensor based on the Zn2+–isonicotinohydrazide complex ‘(ZnL)’ was developed for the selective detection of cyanide (CN−) over other tested anions, such as HSO4−, F−, Cl−, Br−, I−, NO3−, PO43−, SO42−, SCN−, S2−, CH3COO− and H2PO4− in 80% MeOH (organic–aqueous medium). The detection of CN− with (ZnL) could be possible with both UV-visible and fluorescence responses without any interference effects from other anions. This system shows excellent sensitivity with a lower detection limit of 5.49 nM.

Highly selective optical and reversible dual-path chemosensor for cyanide detection and its application in live cells imaging

A new biocompatible fluorescent receptor 1 was synthesized by conjugating diaminomaleonitrile (DMN) with benzothiazole unit, and characterized by single X-ray. In DMF/water (1:1, v/v), the receptor 1 showed a selectivity turn-on fluorescence at 517nm in the presence of CN-. Receptor 1 showed a detection limit down to 0.16µM without any interference from other tested anions. The reversibility and reusability of 1 for the detection of CN- ion was also tested for five cycles indicating the probe 1 could be used in a reversible manner. Importantly, the receptor 1 showed excellent cells viability and was successfully applied for the detection of CN- in live mouse fibroblast cells L929 cells.

Ratiometric fluorescent scaffold giving discrete response towards iodide ion: a combined experimental and DFT study

A novel ratiometric fluorescent receptor (Z)‐2‐(4‐[diethylamino]‐2‐hydroxybenzylideneamino) pyridine‐3‐carbaldehyde (3) bearing one phenolic OH and one aldehyde group as recognition sites was synthesized and characterized. The anion recognition behaviour of receptor 3 was evaluated by various spectroscopic (UV‐visible, fluorescence and 1H nuclear magnetic resonance) methods and was validated by computational studies. The receptor showed fast response time, excellent selectivity and reproducibility towards iodide ion detection among the other surveyed anions, with a binding constant of 6.12 × 104 M−1 and a detection limit of 0.24 μM, thus confirming its potential applicability as a fluorescent sensor for iodide Copyright

Selective ciprofloxacin antibiotic detection by fluorescent siderophore pyoverdin

Fluorescent siderophore pyoverdin (PVD) was produced from a soil isolate Pseudomonas monteilii strain MKP 213. The PVD was purified near to homogeneity and applied for the fluorescent chemosensing of various antibiotics in aqueous solution (pH=7.0). Upon addition of ciprofloxacin, PVD showed new UV-vis absorption bands at 252 and 321nm due to an internal charge transfer mechanism. Also, the addition of ciprofloxacin induced a highly selective fluorescence enhancement of PVD with a 13nm blue shift from 458 to 445nm. The combination of a long peptide chain along with the chromophore unit of PVD generates a converging cleft for ciprofloxacin recognition with LOD and LOQ of 7.13μM and 21.6μM, respectively without interference from other studied antibiotics. The association constant (Ka) of PVD with ciprofloxacin was calculated to be as low as 1.40×10(5)M(-1) using Benesi-Hildebrand plot depicting its significance in detection. The pharmaceutical tablet analysis measures the sensing with negligible matrix effect and quantitative recovery.

A new lawsone azo-dye for optical sensing of Fe3+ and Cu2+ and their DFT study

Abstract A new lawsone-based azo-dye 2-hydroxy-3-((pyridin-2-ylmethyl)diazenyl)naphthalene-1,4-dione (1) was synthesized and applied for sensing of metal ions. Receptor 1 showed selective fluorescent and colorimetric response for the detection of Cu2+ and Fe3+ over other tested metal ions. The fluorescence intensity of 1 was significantly quenched allowing detection of Fe3+ and Cu2+ down to 0.61 and 6.06 μM, respectively. The binding has been established by fluorescence spectroscopic method. Receptor 1 provided a 1 : 1 binding scaffold for recognition of Fe3+ and Cu2+ ions with the association constant of 3.33 × 106 and 3.33 × 105 M−1, respectively. The B3LYP/6-31G/LANL2DZ method was employed for the optimization of 1 and 1·Fe3+ and 1·Cu2+.

Cu2+-driven metallo-supramolecular self-assembly and its application in sensing of hydroxyl ion

Abstract The dinuclear copper complex receptor (R) was synthesized using the ligands 4-(di-ethyl-amino)-2-hydroxybenzaldehyde and benzo [d] thiazol-2-amine. The single crystal X-ray analysis of the homoleptic bis(μ-oxo)dicopper (II) complex indicated that the ligands are coordinated in an anti-configuration to each other and have adopted a distorted square-pyramidal environment around the Cu2+ ion. The X-ray solid state structural analysis and DFT reveals no direct Cu…..Cu linkage within the complex. The anion recognition ability of the R was studied by UV–vis and fluorescence spectroscopic in acetonitrile. The results indicated that the new complex R displays a sturdy sympathy and selectivity for hydroxide ion.