Search

This study describes the rational development and synthesis of a benzothiazole-salicylaldehyde Schiff base probe 1. This probe is designed to function as a ratiometric fluorescent probe specifically for detecting ClO− ions, utilizing the imine bond as the fluorophore unit. Upon interaction with ClO− ions, probe 1 exhibits a redshift in its absorption spectrum from 435 nm to 450 nm. Moreover, in its emission spectrum, there is a ratiometric emission enhancement observed at 610 nm, providing a clear indication of the presence of ClO− ions. The sensitivity of probe 1 for detecting ClO− ions is quantified, revealing a lowest detection limit of 5.5 μM, indicating its potential for sensitive detection even at low concentrations of ClO− ions. Additionally, it has been successfully utilized for biological imaging purposes, demonstrating low cytotoxicity, which is crucial for its applicability in biological systems. [ABSTRACT FROM AUTHOR]

We report the synthesis of probe 2 for the fluorescence “turn-on” detection of Al3+ ions in CH3OH. Probe 2 has been designed via utilizing the aggregation-induced emission properties of the tetraphenylethylene unit, with further enhancement from Schiff base units for the ESIPT phenomenon. Probe 2 exhibits emission at 548 nm (λex = 360 nm), with a large Stokes shift of 188 nm, indicating the ESIPT phenomenon. Probe 2 also exhibits emission enhancement via increasing the H2O ratio up to 70–90% H2O/THF (v/v) and altering the spherical morphology to needle shapes. Probe 2 has been found to be highly selective and sensitive towards Al3+ ions over other metal ions in pure CH3OH using absorption and emission spectroscopy. FESEM analysis revealed that the size of probe 2 increases upon the addition of Al3+ ions. Thus, the fluorescence “turn-on” behaviour of probe 2·Al3+ is due to metal-induced aggregation. [ABSTRACT FROM AUTHOR]

A donor–π–acceptor (D–π–A) dyad 1 has been successfully synthesized by linking phenanthrenequinone as an electron donor unit and anthraquinone as an electron acceptor unit through a phenyl ring. Dyad 1 exhibits intramolecular charge transfer and this is a key factor for the detection of Hg2+ and of the pyrophosphate ion (P2O74−, PPi) in a semi-aqueous medium. Dyad 1 exhibits absorption peaks at 430, 370, and 337 nm and an emission peak at 530 nm (λex = 430 nm). Dyad 1 exhibits a new absorption peak at 390 nm ratiometrically along with emission quenching in the presence of Hg2+ ions while the presence of PPi results in drastic ratiometric changes in the absorption and emission spectra with new peaks at 495 nm and 620 nm, respectively. The quantum yield of dyad 1 on complexation with PPi was also increased from 0.1 (free dyad) to 0.69 (dyad 1·PPi). The lowest detection limits for Hg2+ and PPi were found to be 31 nM and 46.5 nM, respectively. DFT calculations have been performed to develop a mechanism for PPi and Hg2+ ion binding with dyad 1. [ABSTRACT FROM AUTHOR]

A new multifunctional NBD-based probe has been developed having high sensitivity and selectivity towards Cu2+/Ni2+ over other metal ions over a wide pH range. The probe 1 could be used for the simultaneous estimation of Cu2+ and Ni2+ ions through its visible color change from yellow to blue and light green, respectively, in semi-aqueous systems. The binding mode of probe 1 to Cu2+ and Ni2+ was determined to be a 1 : 1 complexation stoichiometry using a Job's plot. Ethylenediamine tetraacetate showed high selectivity towards the in situ prepared Cu2+ complex over the Ni2+ complex, which is applied to distinguish Ni2+ and Cu2+ ions. The detection limits for Cu2+ and Ni2+ ions, 1.8 × 10−7 M and 1.1 × 10−6 M, respectively, were lower than those recommended by the WHO guidelines for drinking water. Moreover, probe 1 could be used as a practical, visible colorimetric test kit for Cu2+ ions. The sensing mechanism of Cu2+ and Ni2+ ions was supported by DFT-calculations. [ABSTRACT FROM AUTHOR]

Dansyl and antipyrine based hybrid molecular architectures were synthesized and their photophysical behavior towards various cations and anions was investigated. The dyad 1 was used for selective estimation of Cu2+ ions as compared to other metal ions and the binding event was indicated through formation of a new absorption band at 465 nm and a decrease in fluorescence intensity at 528 nm. The dyad 1 showed ratiometric fluorescence behavior towards fluoride ions through hydrogen bonding interactions and restricted the photoinduced electron transfer from dansyl to antipyrine moiety to release its fluorescence at 428 nm. The chemical inputs of Cu2+ and F− ions to dyad 1 mimicked a sequence dependent operation of an exclusive-NOR (XNOR) logic gate. [ABSTRACT FROM AUTHOR]