Xiao-Lei Zhao

Synthesis of several novel coordination complexes: ion exchange, magnetic and photocatalytic studies

Eight new coordination polymers (CPs) based on a V-shaped carboxylate ligand H2L (H2L = 5-(1-oxo-1,3-dihydro-isoindol-2-yl)-isophthalic acid), namely {[Zn(L)(H2O)]·H2O}n (1), {[Zn2(L)2(phen)2(H2O)2]·CH3OH·2H2O}n (2), {[Zn(L)(2,2′-bpy)(H2O)]·H2O}n (3), [Zn2(L)2(4,4′-bpy)]n (4), {[Cu(L)(H2O)]·H2O·0.5(CH3OH)·0.5(DMF)}n (5), [Cu3(L)2(phen)3(ClO4)2]n (6), {[Co(L)(dbpy)(H2O)]·3CH3CN}n (7), and {[Co(L)(phen)(H2O)2]·DMA·3H2O}n (8), have been synthesized and characterized by IR, XRD, TG analysis, elemental analysis and single crystal X-ray diffraction measurement. Reactions of H2L and ZnSO4 with different auxiliary ligands in similar solvents occurred at the temperature of 80 °C, yielding similar 1D chains 1–3 and a three-dimensional (3D) framework 4. Besides, reactions of H2L and Cu2+ in the absence or presence of phen formed CPs of 5 and 6 associated with the reduction of dimensionality of the self-assembled products from 3D to 2D. Complex 5 presents a 3D framework with nanosize channels which are comprised of interlocked six-fold one-dimensional helical chains, while compound 6 shows a 2D structure. Additional reactions of H2L, Co2+ and auxiliary ligands give rise to two structurally related 2D CPs 7 and 8. Single-crystal-to-single-crystal studies show that Zn2+ ions in complexes 1–3 could be partially exchanged with Cu2+ ions. And we elaborated the reasons for different exchange degrees by comparing the coordination energies of Zn2+. Furthermore, by comparing the photoluminescence and photocatalytic mutation results induced by the interconversion of metal ions, we confirm that the property mutation induced by metal ions is greatly controllable and obvious. Magnetic studies show that there are strong antiferromagnetic interactions in 5 and 6. Moreover, complexes 5–8 are also applied to catalyze the reaction of MB under high-pressure mercury lamp irradiation.

Rhodamine 6G hydrazone with coumarin unit: a novel single-molecule multianalyte (Cu2+ and Hg2+) sensor at different pH value

A rhodamine derivative was synthesised via the hydrazone formation of rhodamine 6G hydrazide with 7-diethylamino-3-(1-hydroxy-3-oxobut-1-enyl)-2H-chromen-2-one. As a colourimetric and ratiometric fluorescent probe, the derivative exhibited high selectivity towards Cu2+ in neutral aqueous media. Moreover, the probe sensed Hg2+ with fluorescence enhancement at pH 10. The binding process was confirmed via UV-vis absorption, fluorescence measurements, 1H NMR, mass spectroscopy and density functional theory calculation. To validate the applicability of the probe, the probe was used to detect Cu2+ and Hg2+ ions in actual water samples. The application of the fluorescent sensor in monitoring intracellular Cu2+ in Hela cells has also been demonstrated.

Quinoline containing acetyl hydrazone: An easily accessible switch-on optical chemosensor for Zn2 +

A simple chemosensor, namely, N-((quinolin-8-yl)methylene)acetohydrazide (1) was synthesized and used as an off-on fluorescence sensor, which exhibits high selectivity toward Zn2+ in aqueous media. The probe has large Stokes shift of >200nm, and its detection limit for Zn2+ is 89.3nM. The binding process was confirmed through UV-vis absorption analysis, fluorescence measurements, mass spectroscopy study, 1H NMR spectra and density functional theory calculation. The crystal structures of Zn2+, Ni2+, and Cu2+ complexes based on 1 were determined through X-ray crystallographic analysis. The fluorescent probe was then applied to monitor intracellular Zn2+ in HeLa cells.

A highly sensitive and selective off–on fluorescent chemosensor for hydrazine based on coumarin β -diketone

A coumarin-based sensor C1, namely 3-acetoacetylcoumarin was designed, synthesized and applied for hydrazine detection. Hydrazinolysis of the chemosensor gives a fluorescent coumarin-pyrazole product C1-N2H4 [3-(3-methyl-1H-pyrazol-5-yl)coumarin], and thus resulting in a prominent fluorescence off-on response toward hydrazine under physiological conditions. The probe is highly selective toward hydrazine over cations, anions and other biologically/environmentally abundant analytes. The detection limit of the probe is 3.2ppb. The sensing mechanism was supported by 1H NMR, IR, MS and DFT calculation. The application of the fluorescent probe in monitoring intracellular hydrazine in glioma cell line U251 was also demonstrated.

A simple hydrazone as a multianalyte (Cu2+, Al3+, Zn2+) sensor at different pH values and the resultant Al3+ complex as a sensor for F−

A new colorimetric and fluorescence molecular chemosensor based on triazole hydrazone can be used as a multi-probe for selective detection of Al3+, Zn2+, and Cu2+ by monitoring changes in the absorption and fluorescence spectral patterns. Results show that Al3+ and Zn2+ ions can induce remarkable fluorescence enhancement at pH 6.0 and pH 10.0, respectively, while the addition of Cu2+ ions leads to a significant UV-visible absorption enhancement in the visible range at pH 6.0. In addition, the resultant Al3+ complex could act as an ‘on–off’ fluorescence sensor for F−. The fluorescence sensor was also used to monitor intracellular Al3+, Zn2+, and F− in Hela cells.

Crystal structure of [N,N-bis((pyrrol-2-yl)ethylidene)butane-1,4-diamine-κ4N,N′,N′′,N′′′]-nickel(II), C16H20N4Ni

Abstract C16H20N4Ni, monoclinic, P21/n (no. 14), a = 7.6578(10) Å, b = 17.184(2) Å, c = 11.6581(15) Å, β = 100.837(2)°, V = 1506.7(3) Å3, Z = 4, Rgt(F) = 0.0356, wRref(F2) = 0.0945, T = 296(2) K.