A Highly Fluorescent Pyrene-Based Sensor for Selective Detection Of Fe3+ Ion in Aqueous Medium: Computational Investigations

Host-guest interactions of coumarin-based 1,2-pyrazole using analytical and computational methods: Paper strip-based detection, live cell imaging, logic gates and keypad lock applications

A novel Coumarin-based 1,2-pyrazole, HCPyTSC is synthesised and characterized. The chemosensor has been shown to have efficient colourimetric and fluorescence sensing capabilities for the quick and selective detection of fluoride and copper ions. At 376 and 430 nm, the HCPyTSC exhibits selective sensing for Cu2+ and F- ions. By examining the natural bond orbital (NBO) analysis and the potential energy curve (PES) of the ground state for the function of the C-H bond, it has been determined from the theoretical study at hand that the deprotonation was taken from the 'CH' proton of the pyrazole ring. For F- and Cu2+, the HCPyTSC detection limits were 4.62 nM and 15.36 nM, respectively. Similarly, the binding constants (Kb) for F- and Cu2+ ions in acetonitrile medium were found to be 2.06 × 105 M-1 and 1.88 × 105 M-1. Chemosensor HCPyTSC with and without F- and Cu2+ ions have an emission and absorption response that can imitate a variety of logic gates, including the AND, XOR, and OR gates. Additionally, a paper-based sensor strip with the HCPyTSC was created for use in practical, flexible F- sensing applications. The paper-based sensor was more effective in detecting F- than other anions. The effectiveness of HCPyTSC for the selective detection of F- in living cells as well as its cell permeability were examined using live-cell imaging in T24 cells.

Synthesis of Di(thiophen-2-yl) Substituted Pyrene-Pyridine Conjugated Scaffold and DFT Insights: A Selective and Sensitive Colorimetric, and Ratiometric Fluorescent Sensor for Fe(III) Ions

In this context, we used the multicomponent Chichibabin pyridine synthesis reaction to synthesize a novel di(thiophen-2-yl) substituted and pyrene-pyridine fluorescent molecular hybrid. The computational (DFT and TD-DFT) and experimental investigations were performed to understand the photophysical properties of the synthesized new structural scaffold. The synthesized ligand displays highly selective fluorescent sensing properties towards Fe3+ ions when compared to other competitive metal ions (Al3+, Ba2+, Ca2+, Cd2+, Co2+, Cr3+, Cu2+, Fe2+, Hg2+, Na+, Ni2+, Pb2+, Sr2+, Sn2+ and Zn2+). The photophysical properties studies reveal that the synthesized hybrid molecule has a binding constant of 2.30 × 103 M-1 with limit of detection (LOD) of 4.56 × 10-5 M (absorbance mode) and 5.84 × 10-5 M (emission mode) for Fe3+ ions. We believe that the synthesized pyrene-conjugated hybrid ligand can serve as a potential fluorescent chemosensor for the selective and specific detection of Fe3+ ions.

Iminobenzophenone-thiophen hydrazide schiff base: a selective turn on sensor for paramagnetic Fe3+ ion and application in real sample analysis

A highly selective turn-on sensor for paramagnetic Fe³⁺ ions based on (E)-N'-((2-aminophenyl)(phenyl)methylene)thiophene-2-carbohydrazide is successfully synthesized. The sensor BPTH is significantly selective and sensitive towards Fe³⁺ ions over other interfering metal ions especially Cu²⁺ and Co²⁺ ions with a lowest limit of recognition 1.48 × 10^-7 M. The turn-on sensing mechanism involves enhanced charge transfer. Fe³⁺ ion forms strong binding with the ligand with a K_a value about 8.23 × 10⁴ M^-1 and a 1:1 stoichiometric ratio is confirmed by Job's plot experiment. With Fe³⁺ ion, the yellow ligand BPTH change to a green fluorescent and reversible with 1 equivalent of EDTA. Practical application of sensor is demonstrated in real sample analysis.

Simple Fluorescence Sensing Approach for Selective Detection of Fe3+ Ions: Live-Cell Imaging and Logic Gate Functioning

A pyrene-based fluorescent chemosensor APSB [N-(pyrene-1-ylmethylene) anthracen-2-amine] was designed and developed by a simple condensation reaction between pyrene carboxaldehyde and 2-aminoanthracene. The APSB fluorescent sensor selectively binds Fe³⁺ in the presence of other metal ions. Apart from this, APSB shows high selectivity and sensitivity toward Fe³⁺ ion detection. The detection limit for APSB was 1.95 nM, and the binding constant (K _b) was obtained as 8.20 × 10⁵ M^-1 in DMSO/water (95/5, v/v) medium. The fluorescence quantum yields for APSB and APSB-Fe³⁺ were calculated as 0.035 and 0.573, respectively. The function of this fluorescent sensor APSB can be explained through the photo-induced electron transfer mechanism which was further proved by density functional theory studies. Finally, a live-cell image study of APSB in HeLa cells was also carried out to investigate the cell permeability of APSB and its efficiency for selective detection of Fe³⁺ in living cells.