Chao-rui Li

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+.

A highly selective and sensitive fluorescent chemosensor and its application for rapid on-site detection of Al3 +

In this paper, a simple naphthalene-based derivative (HL) has been designed and synthesized as a Al3+-selective fluorescent chemosensor based on the PET mechanism. HL exhibited high selectivity and sensitivity towards Al3+ over other commonly coexisting metal ions in ethanol with a detection limit of 2.72nM. The 1:1 binding stoichiometry of the complex (HL-Al3+) was determined from the Jobs plot based on fluorescence titrations and the ESI-MS spectrum data. Moreover, the binding site of HL with Al3+ was assured by the 1H NMR titration experiment. The binding constant (Ka) of the complex (HL-Al3+) was calculated to be 5.06×104M-1 according to the Benesi-Hildebrand equation. In addition, the recognizing process of HL towards Al3+ was chemically reversible by adding Na2EDTA. Importantly, HL could directly and rapidly detect aluminum ion through the filter paper without resorting to additional instrumental analysis.

A novel chromone and rhodamine derivative as fluorescent probe for the detection of Zn(II) and Al(III) based on two different mechanisms

In this study, a novel fluorescent probe, 6‑hydroxychromone‑3‑carbaldehyde‑(rhodamine B carbonyl) hydrazine (L), for Zn2+ and Al3+ was designed and synthesized. Initially, this probe L exhibited inferior fluorescence emission peak centered at 488 nm in EtOH/HEPES solution (3/1, 10.0 μM HEPES, pH 7.4) when excited at 421 nm. After the addition of Zn2+, this probe L displayed excellent selectivity towards Zn2+ with obvious fluorescence color change from colorless to yellow, which might be attributed to the formation of a 1:1 ligand-metal complex resulting in the inhibition of photo-induced electron transfer phenomenon. Whereas, the prepared Zn2+ complex of L could be used as a ratiometric fluorescent probe to detect Al3+ on the basis of fluorescence resonance energy transfer mechanism. This ligand-metal complex of Zn2+ (LZn) showed high selectivity towards Al3+ with obvious enhancement in fluorescence emission intensity at 580 nm and remarkable decrease in fluorescence emission intensity at 488 nm, and the fluorescence color also changed from yellow to pink. Furthermore, the detection limit of the probe L, LZn towards Zn2+, Al3+ were 1.25 × 10-7 M and 3.179 × 10-6 M, respectively. Additionally, the complexation properties of L towards Zn2+ and LZn towards Al3+ were studied in detail.

Synthesis and Evaluation of Neutral Gd(III), Mn(II) Complexes From DTPA-Bisamide Derivative as Potential MRI Contrast Agents

A strong chelating ligand was synthesized through the modification of DTPA by bioactive 5-fluorouracil derivatives and characterized by means of mass spectra, Fourier transform infrared spectra, elemental analysis, and nuclear magnetic resonance spectroscopy. Its complexes of Gd(III) and Mn(II) were designed as potential MRI contrast agents. Thermodynamic stability constant of the complexes indicated that they were stable enough to prevent the metal ions from releasing. Relaxivity studies showed that the two complexes provided higher T1-weighted relaxivity than that of commercial contrast agent Gd-DTPA and the Mn(II) complex owned much higher T2-weighted relaxation property. Both the Gd(III) and Mn(II) complexes had the advantage of becoming promising T1-weighted MRI contrast agents.