Facile synthesis of novel zinc-based infinite coordination polymer nanoparticles

Lanthanide coordination polymers@CuO nanoparticles: Enhanced self-cascade nanoenzyme activity and ratiometric fluorescence assay of glutathione

Tandem enzyme can catalyze some cascade reactions with high efficiency, and some few tandem enzyme-like mimics have been discovered recently. Further improving the catalytic efficiency of tandem nanoenzymes with facile method may undoubtedly promote and broaden their applications in various fields. In this work, cupric oxide nanoparticles (CuO NPs) with dual-functional enzyme mimics were synthesized using the rapid deposition method in advance, which simultaneously combined with lanthanide infinite coordination polymers (Ln ICPs) during the self-assemble of Tb3+, guanine-5'-triphosphate (GTP) and auxiliary ligand terephthalic acid (TA). Excitingly, the obtained Tb-GTP/TA@CuO ICPs, not only displayed obviously enhanced tandem catalytic activity compared with pure CuO NPs, but also provided a versatile ratiometric platform for ultrahigh selective and sensitive detection of glutathione (GSH) under single-wavelength excitation. A good linear relationship between the ratio signal and the GSH concentration was spanning from 0.001 to 20 μM with an impressive detection limit of 0.50 nM. This study opens a new and universal avenue for preparing integrated multifunctional probes by coupling of nanoenzyme catalytic activity with superior luminescent Ln ICPs through facile method.

Cu2+-Regulated reversible coordination interaction of GQD@Tb/GMP ICP nanoparticles: towards directly monitoring cerebrospinal acetylcholinesterase as a biomarker for cholinic brain dysfunction

This work demonstrates a new strategy for sensing cerebrospinal acetylcholinesterase (AChE) as a cholinergic biomarker for brain dysfunction based on graphene quantum dot (GQD)-functionalized lanthanide infinite coordination polymer (Ln-ICP) nanoparticles. The ICPs used in this work were comprised of two components, i.e. a supramolecular Ln-ICP host formed by the coordination between the GMP ligand and central metal ion Tb3+, and guest GQDs with abundant functional groups, which were utilized as antenna ligands to further sensitize the fluorescence of Tb/GMP. Upon excitation at 300 nm, the obtained GQD@Tb/GMP ICP nanoparticles exhibited enhanced green fluorescence from Tb/GMP. With the addition of Cu2+, the competitive coordination between Cu2+ and GQDs weakened the antenna effect, leading to a decrease in the fluorescence of GQD@Tb/GMP ICPs. However, in the presence of thiocholine (TCh), a thiol-containing compound hydrolyzed from acetylthiocholine (ATCh) by AChE, a stronger coordination interaction between Cu2+ and TCh occurred, resulting in the restoration of the fluorescence of GQD@Tb/GMP ICPs. Using the method established herein, the cerebrospinal AChE fluctuation of rats with acute organophosphorus pesticide (OP) poisoning or chronic Alzheimer's disease (AD) could be monitored. This study essentially provides a novel approach to realize the direct monitoring of a biomarker for brain dysfunction by regulating the competitive coordination interaction reversibly, which is critical in the early diagnosis and therapy of brain diseases.

Designing a New Efficient Photocatalyst Based on Functionalization of Zn-Infinite Coordination Polymer with Ru(acac)3 Complex for Dye Degradation in Aqueous Solutions: Charge Separation Effect

A new Zn-containing infinite coordination polymer, Zn-ICP, functionalized with Ru(acac)₃ complex was designed and utilized as an efficient visible light photocatalyst for dye degradation in aqueous solutions. Incorporation of Ru(acac)₃ not only extended the light absorption of the Zn-ICP to the visible region but also led to electron-hole separation. Upon visible light illumination, photoinduced electron transfer from excited state of Zn-ICP to Ru(acac)₃ occurred, resulting in electron-hole separation as indicated by photoluminescence and electrochemical impedance spectroscopy. The obtained Ru-Zn-ICP revealed enhanced visible light photocatalytic activity in degradation of organic pollutants compared to pristine Zn-ICP owing to photoinduced electron transfer in the Ru-Zn-ICP system and efficient separation of photogenerated electron-hole pairs. The prepared Ru-Zn-ICP photocatalyst was readily recycled without major loss of activity in the successive cycles.

A new water-insoluble coordination polymer as efficient dye adsorbent and olefin epoxidation catalyst

A new water-insoluble bi-metallic coordination polymer was simply prepared via polymerization-precipitation of molybdenum complex building blocks with Zn²⁺ cation. The linker was a di-carboxylic acid consisting of two coordination sites i.e. N,O and COO^- suitable for coordinating to MoO₂ unit and Zn²⁺, respectively. Characterization of the prepared coordination polymer was carried out with various physicochemical methods which confirmed the proposed structure. The prepared coordination polymer preferentially adsorbed methylene blue (more than 92% of methylene blue after 2 min) relative to methyl orange and can be reused at least four times without any loss of adsorption efficiency. The adsorption process of both dyes followed the pseudo-second order kinetic equation. Additionally, the obtained coordination polymer catalyzed epoxidation of olefins with tert-butylhydroperoxide (TBHP) quantitatively with excellent selectivity (>99%) under mild reaction conditions.

Zinc-Containing Coordination Polymer as a Suitable Precursor for Solid State Synthesis of ZnO

Uniform zinc-containing infinite coordination polymer (ICP) nanoparticles were achieved via a straightforward and rapid precipitation method in 5min, from a bi-thioglycolate functionalized salpn ligand (salpn=N,N′-bis(salicylidene)-1,3-propanediamine) as linker and zinc acetate. Characterization of the resulting product was performed by CHN elemental analysis, inductively coupled plasma–optical emission spectroscopy, FT-IR spectroscopy, thermogravimetric analysis, electron microscopies (FE-SEM and HR-TEM), and photoluminescence spectroscopy. Elemental analyses verified the proposed structure for the ICP with a 1:2 ratio of the salpn type ligand and Zn2+ ion. FE-SEM, TEM, and AFM analyses unveiled the existence of nanoparticles with diameters of ~30nm. PL spectroscopy showed a blue shift in emission peak of the ICP with regards to the organic ligand. The obtained ICP was utilized as a precursor to synthesize ZnO nanoparticles with wurtzite structure. An increase in bandgap of the prepared ZnO nanoparticles was observed in comparison with bulk ZnO as a result of quantum confinement of photogenerated electron–hole pairs. This method can be exploited for the synthesis of other coordination polymer micro/nanostructures.

Rapid production of cadmium infinite coordination polymer nanofiber via solvent induced precipitation method

The precipitation synthesis of cadmium infinite coordination polymer (Cd-ICP) nanofibers with a high degree of uniformity is reported. The elemental analyses (CHN and ICP-OES), energy-dispersive X-ray spectroscopy (EDX) and thermogravimetric analysis (TGA) show that thermally robust monodisperse solid consists of bi-carboxylic acid linker and cadmium ion. The coordination between the Cd²⁺ ion and bi-carboxylic acid linker was investigated by Fourier transform infrared (FT-IR) spectroscopy. The photoluminescence (PL) properties of the Cd-ICP were studied in comparison with those of the bi-carboxylic acid linker. It was shown that the emission intensity of the Cd-ICP is much stronger than linker due to the structural rigidity after the coordination of linker to Cd ions. The field emission scanning electron microscopy (FE-SEM) results show that after calcination of the Cd-ICP the morphology changed from fiber to hexagonal-like disc. Furthermore, the results of UV-Vis spectroscopy show larger band gap for obtained CdO relative to the bulk counterpart.