Jing-can Qin

Design and synthesis of a chemosensor for the detection of Al3+ based on ESIPT

In this study, a simple fluorescent sensor 2-hydroxybenzcarbaldehyde-(2-methylquinoline-4-formyl) hydrazone (HL) has been designed, synthesized and characterized by 1H-NMR, IR, ESI-MS. Upon addition of Al3+, HL shows a large fluorescence enhancement (220-fold) at 484 nm. The reasons for this phenomenon are attributed to formation of a 1:1 complex (Ka = 5.6 × 104), which inhibits the excited-state intramolecular proton transfer (ESIPT) process and photo-induced electron transfer (PET) process. Other metal ions including Ba2+, Ca2+, Cd2+, Co2+, Cr3+, Hg2+, K+, Mg2+, Mn2+, Na+, Ni2+, Pb2+ and Zn2+, have almost no influence on the fluorescence. The lowest detection limit for Al3+ is calculated to be 7.2 × 10−7 M in ethanol.

The design of a simple fluorescent chemosensor for Al3+/Zn2+via two different approaches

In this study, we have developed a simple fluorescent sensor, 7-(2′,4′-dihydroxybenzylideneimino)-4-methyl coumarin, which shows a high selectivity towards Al3+/Zn2+ over a wide range of metal ions. On the one hand, the fluorescence intensity of the probe shows significant fluorescence enhancement in the presence of Al3+ at 427 nm (λex = 357 nm), which might be mainly attributable to the hydrolysis of imines. On the other hand, the receptor exhibits a selective response to Zn2+ at 489 nm (λex = 405 nm), and a photoinduced electron transfer process (PET) is proposed to explain the observed spectral response.

Two Schiff-base fluorescent sensors for selective sensing of aluminum (III): Experimental and computational studies.

Two Schiff-base fluorescent sensors have been synthesized, which both can act as fluorescent probes for Al(3+), upon addition of Al(3+), they exhibit a large fluorescence enhancement which might be attributed to the formation of 1:1 ligand-Al complexes which inhibit photoinduced electron transfer (PET) progress, and that the proposed binding modes of the sensors and Al(3+) are identified by theoretical calculations.

Ratiometric fluorescent probe for Al3+ based on coumarin derivative in aqueous media

In this study, a novel ratiometric chemosensor for Al3+ (HL) which contains coumarin and naphthalene moieties has been designed and synthesized on the basis of the mechanism of internal charge transfer (ICT). On addition of Al3+, the receptor exhibits a strong, increasing fluorescent emission centered at 525 nm at the expense of the fluorescent emission of HL centered at 481 nm in ethanol and water (9:1, v/v). This phenomenon is attributed to formation of a 1:1 complex (Ka = 1.03 × 104), which inhibits internal charge transfer (ICT).

A novel pyrazine derivative as a "turn on" fluorescent sensor for the highly selective and sensitive detection of Al3+

In this study, a novel pyrazine-derived fluorescent sensor bearing the furan unit (1) has been designed, synthesized and characterized. This sensor 1 showed large enhancement in the fluorescence emission intensity at 517 nm in the presence of Al3+ and it also showed high selectivity and sensitivity for Al3+ over other common environmentally and biologically important metal ions, as the detection limit of 1 towards Al3+ could reach 10−7 mol L−1. Moreover, the enhancement of fluorescence emission intensity was attributed to the chelation-enhanced fluorescence (CHEF) phenomenon upon complexation of 1 with Al3+.

Design of a novel Schiff-base fluorescent sensor for Al3+: experimental and computational studies

A novel Schiff-base fluorescent sensor (HL) for Al3+ has been synthesized. The addition of Al3+ results in a significant increase of its fluorescent intensity at 420 nm in ethanol, however, other metal ions have almost no influence on the fluorescence. The reason for this phenomenon might be attributed to the formation of a 1 : 1 stoichiometric L–Al complex which inhibits the photo-induced electron transfer (PET) process. More importantly, the proposed binding mode of L–Al(III) is further identified by theoretical calculations.