Wen-Juan Ruan

A polypyridyl-pyrene based off-on Cd2+ fluorescent sensor for aqueous phase analysis and living cell imaging

By retaining the quadrapyridyl receptor of polypyridylhexaazatriphenylene (a Cd(2+) sensor reported by us) and extending its chromophoric group with pyrene, a chemical sensor (1) was designed and synthesized in this work. This sensor exhibit selective off-on fluorescence response to Cd(2+) over other metal ions, and the detection limit is as low as 0.02 μM. The Cd(2+) sensing of 1 has high water toleration and can be carried out in the media with the water content up to 70%. Additionally, 1 was successfully applied to the in vivo imaging of intracellular Cd(2+) in living HaLa cells, and showed low cytotoxicity and cell membrane permeability in these experiments. These results suggest that 1 has potential application in the Cd(2+) analysis of environmental and biological samples.

Solvent induced rapid modulation of micro/nano structures of metal carboxylates coordination polymers: mechanism and morphology dependent magnetism

Rational modulation of morphology is very important for functional coordination polymers (CPs) micro/nanostructures, and new strategies are still desired to achieve this challenging target. Herein, organic solvents have been established as the capping agents for rapid modulating the growth of metal-carboxylates CPs in organic solvent/water mixtures at ambient conditions. Co-3,5-pyridinedicarboxylate (pydc) CPs was studied here as the example. During the reaction, the organic solvents exhibited three types of modulation effect: anisotropic growth, anisotropic growth/formation of new crystalline phase and the formation of new crystalline phase solely, which was due to the variation of their binding ability with metal cations. The following study revealed that the binding ability was critically affected by their functional groups and molecular size. Moreover, their modulation effect could be finely tuned by changing volume ratios of solvent mixtures. Furthermore, they could be applied for modulating other metal-carboxylates CPs: Co-1,3,5-benzenetricarboxylic (BTC), Zn-pydc and Eu-pydc etc. Additionally, the as-prepared Co-pydc CPs showed a fascinating morphology-dependent antiferromagnetic behavior.

Two hexaazatriphenylene-pyrene based Hg2+ fluorescent chemosensors applicable for test paper detection

Two chemosensors with large hexaazatriphenylene-pyrene chromophores were designed and synthesized. Both of them exhibit a selective fluorescence quenching response to Hg2+ in aqueous acetonitrile solution, and their detection limits are lower than the toxic level of Hg2+. Additionally, these compounds were successfully used for test paper detection.

Two hexaazatriphenylene based selective off-on fluorescent chemsensors for cadmium(II).

Two hexaazatriphenylene (HAT) derivatives, 2,3,6,7-tetramethyl-10,11-di(pyridin-2-yl)dipyrazino[2,3-f:2,3-h]quinoxaline (1) and 2,3-dimethyl-6,7,10,11-tetra(pyridin-2-yl)dipyrazino[2,3-f:2,3-h]quinoxaline (2), were designed and synthesized. Both 1 and 2 exhibited high off-on fluorescent selectivity for Cd(2+) over many other metal ions, and the detection limits were determined to be 0.6 and 5.0 μM, respectively. The stoichiometry and coordination mode of blue fluorescent 1-Cd(2+) and cyan fluorescent 2-Cd(2+) were determined with fluorescence titration fit, Jobs plot analysis, (1)H NMR titration and X-ray crystallography, and the fluorescence enhancement mechanism was analyzed with density functional theory calculation.

A nanoscale Fe(II) metal–organic framework with a bipyridinedicarboxylate ligand as a high performance heterogeneous Fenton catalyst

With 2,2′-bipyridine-5,5′-dicarboxylate as the ligand, a nanoscale Fe(II) MOF material (Fe-bpydc) was synthesized. Fe-bpydc could activate H2O2 to degrade organic pollutants in near neutral conditions, and its activity and stability are superior to reported results. Interestingly, Fe-bpydc only consumes H2O2 in the presence of organics, leading to high H2O2 utilization efficiency.

C2-symmetrical hexaazatriphenylene derivatives as colorimetric and ratiometric fluorescence chemsensors for Zn2+

Two C2-symmetrical hexaazatriphenylene (HAT) derivatives, 2,3-diphenyl-6,7,10,11-tetra(pyridin-2-yl)dipyrazino[2,3-f:2,3-h]quinoxaline (1) and 2,3,6,7-tetraphenyl-10,11-di(pyridin-2-yl)dipyrazino[2,3-f:2,3-h]quinoxaline (2), were designed and synthesized by the condensation reaction of 1,2-diamines and 1,2-diketones. Both compounds 1 and 2 exhibit sensitive, ratiometric and colorimetric fluorescence selectivity for Zn(2+) ion over alkali ions, alkaline earth ions and a wide range of transition metal ions upon excitation at 350 nm in acetonitrile/water. The interactions between 1 or 2 and Zn(2+) can be observed by naked eyes with an obvious color change of the solution from colorless to yellow. For fluorescence intensity of 2 toward Zn(2+), a good linearity (correlation coefficient R(2)=0.993) was established with a detection limit of 0.095 μM, which is more sensitive than that of 1 (0.2 μM). The binding modes of the free ligands 1 and 2 with Zn(2+) are discussed in context to their photophysical and electrochemical properties as well as single X-ray crystallographic structures of 1, 2 and 1-Zn.

Luminescent Metal‐Organic Framework Based Label‐Free Assay of Polyphenol Oxidase with Fluorescent Scan

Metal-organic frameworks (MOFs) are emerging in recent years as a kind of versatile fluorescent sensing materials, but their application to enzyme assays has rarely been studied. Here, the first example of a MOF-based label-free enzyme assay system is reported. A luminescent MOF was synthesized and applied to the activity analysis of polyphenol oxidase (PPO). With its distinct responses to the phenolic substrate and o-quinone product, this MOF could transduce the extent of PPO-catalyzed oxidation to fluorescence signal and enable the real-time monitoring of this reaction. Wide substrate adaptability and high sensitivity (detection limit=0.00012u2005Uu2009mL-1 ) were exhibited by this method, which meets the requirement of common bioanalysis. Interestingly, by the comparison with molecular capturing reagents, the heterogeneous nature of this MOF-based assay effectively preventing the interaction with the enzyme was proven, thus ensuring the authenticity of results.

Anticancer effect and mechanism of a Se-modified porphyrin Au(III) complex

Au, Se and porphyrin are widely used components in the design of anticancer drugs, but their combination has never been referred to. In this work, a Se-modified porphyrin Au(III) complex, [AuTPP-Se]Cl, was designed and synthesized as a potential anticancer agent. This compound exhibits remarkable antiproliferative activity on all the six tested cancer cells. Its potency on HepG2 is even ten times higher than that of CDDP. The synergistic action among Au, Se and porphyrin components was validated. Mechanism study showed that both the induction of mitochondria-dependent apoptosis and the arrest of cell cycle contribute to the anticancer activity of [AuTPP-Se]Cl.

MOF based fluorescent assay of xanthine oxidase for rapid inhibitor screening with real-time kinetics monitoring

The activity assay of xanthine oxidase (XO) is of great application value in clinical diagnosis because the abnormal level of this enzyme is related to a series of pathological states. In this work, a Zr based metal-organic framework (BTB-MOF) with stable photoluminescence in pure water and buffer solution was synthesized. The examination about the fluorescent responses of this material to xanthine and its oxidation product, uric acid, showed that, although both of them affected the emission of BTB-MOF in quenching form, the efficiencies presented much difference. Taking advantage of this feature, a fluorescent method was developed for the activity assay of XO, that is, BTB-MOF was added to the enzymatic oxidation system as a sensor to transduce the proceeding of the reaction real-timely to the signal of fluorescent intensity change. Our method can work under the interference of normal biologically related species, and precisely reflect XO activity in the range of 0.2-40u202fUu202fL-1 (detection limitu202f=u202f0.004u202fUu202fL-1). With consecutive fluorescence intensity scan, this assay could be applied as a high speed screening method of XO inhibitors with the testing time of 1u202fmin. This work shows the wide potential application of MOFs in enzyme analysis.

Zn(II) porphyrin based nano-/microscale metal–organic frameworks: morphology dependent sensitization and photocatalytic oxathiolane deprotection

With Zn(II) porphyrin as a building block, nano-/microscale MOFs with different morphologies were synthesized as sensitizers for O2 (forming 1O2). The sensitization efficiency was observed to enhance remarkably with the decrease of morphological dimension of the sample. With high sensitization ability, the one-dimensional MOF could selectively photocatalyze the deprotection of oxathiolanes to ketones.