Synchronous Fluorescence Determination of Al3+ Using 3-Hydroxy-2-(4-Methoxy Phenyl)-4H-Chromen-4-One as a Fluorescent Probe

Fabrication of a New Coumarin Based Fluorescent "turn-on" Probe for Distinct and Sequential Recognition of Al3+ and F- Along With Its Application in Live Cell Imaging

A new coumarin based fluorescent switch PCEH is fabricated which displays high selective sensing towards Al3+ among other metal cations at physiological pH. On gradual addition of Al3+, PCEH shows a brilliant "turn-on" emission enhancement in MeOH/H2O (4/1, v/v) solution. This new fluorescent switch is proven to be a reversible probe by gradual addition of F- into the PCEH-Al3+ solution. Detection limit as well as binding constant values are calculated to be in the order of 10-9 M and 104 M-1 respectively. We have also explored its potential as a biomarker in the application of live cell imaging using breast cancer cells (MDA-MB-231 cell).

Synthesis, Characterization, Analytical Application, and Theoretical Studies of a Schiff Base, (E)-2-(2-aminophenylthio)-N-(Thiophen-2-yl-methylene) Benzenamine

In this study, a new Schiff base, (E)-2-(2-aminophenylthio)-N-(thiophen-2-yl-methylene) benzenamine was synthesized for selective detection of Hg2+. This Schiff base was characterized by proton nuclear magnetic resonance (1HNMR), carbon-13 nuclear magnetic resonance (13CNMR), and Fourier-transform infrared (FTIR) spectroscopy. Binding interaction between (E)-2-(2-aminophenylthio)-N-(thiophen-2-yl-methylene)benzenamine and various metal ions has been studied by UV-Vis spectroscopic measurements and shows promising coordination towards Hg2+ and almost no interference from other metal ions (Ag+, Mn2+, Fe3+, Al3+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Fe2+ and Cr3+).This Schiff base exhibiting detection limit of 3.8 × 10- 8 M. The Schiff base newly synthesized in this study was successfully applied to the determination of Hg2+ in water samples. In addition to the experimental study, a theoretical study was conducted using Gaussian 09 program to support the experimental findings. FTIR, NMR, bond angle, bond length, torsional angles, and structural approximation were studied using theoretical consideration.

Fluorescence "Turn-off" Sensing of Iron (III) Ions Utilizing Pyrazoline Based Sensor: Experimental and Computational Study

A simple pyrazoline-based ''turn off'' fluorescent sensor 5-(4-methoxyphenyl)-3-(5-methylfuran-2-yl)-1-phenyl-4,5-dihydro-1H-pyrazole (PFM) was synthesized and well characterized by different techniques such as FT-IR, ¹H-NMR, ¹³C-NMR, and mass spectrometry. The synthesized sensor PFM was utilized for the detection of Fe³⁺ ions. Fluorescence emission selectively quenched by Fe³⁺ ions compared to other metal ions (Mn²⁺, Al³⁺, Fe²⁺, Hg²⁺, Cu²⁺, Co²⁺, Ni²⁺, Cd²⁺, Pb²⁺, and Zn²⁺) via paramagnetic fluorescence quenching and showed good anti-interference ability over the existence of other tested metals. Under optimum conditions, the fluorescence intensity of sensor quenched by Fe³⁺ in the range of 0 to 3 μM with detection limit of 0.12 μM. Binding of Fe³⁺ ions to PFM solution were studied by fluorescent titration, revealed formation of 1:1 PFM-Fe metal complex and binding constant of complex was found to be of 1.3 × 10⁵ M^-1. Further, the fluorescent sensor has been potentially used for the detection of Fe³⁺ in environmental samples (river water, tap water, and sewage waste water) with satisfactory recovery values of 99-101%.