Stable Co(II)-based coordination polymer as fluorescence sensor for the discriminative sensing of biomarker methylmalonic acid.

Three novel Co-based coordination polymers including {[Co(L)(µ3-O)1/3]2}n (1), {[Co(L)(bimb)]}n (2) and {[Co(L)(bimmb)1/2]}n (3) (H2L = 2,6-di(4-carboxylphenyl)-4-(4-(triazol-1-ylphenyl))pyridine), bimb = 1,4-bis(lmidazol) butane, bimmb = 1,4-bis(imidazole-1-ylmethyl)benzene) were successfully prepared under solvothermal conditions and characterized. Single-crystal X-ray diffraction analyses revealed that 1 possesses a 3D architecture composed of a trinuclear cluster [Co3N3(CO2)6(µ3-O)], 2 exhibits a 2D new topological framework with the point symbol (84·122)(8)2, whereas 3 shows a unique six-fold interpenetrated 3D framework with a (63·82·10)2(63)2(8) topology. Impressively, all of them can function as a highly selective and sensitive fluorescent sensor for the biomarker methylmalonic acid (MMA) via fluorescence quenching. The low detection limit, reusability and high anti-interference performance together make 1-3 become promising sensors for the practical detection of MMA. Furthermore, the successful application of MMA detection in urine sample was demonstrated, which may be a potential candidate for the further development of clinical diagnostic tools.

Three-Dimensional Cadmium-Organic Framework with Dual Functions of Oxygen Evolution in Water Splitting and Fenton-like Photocatalytic Removal of Organic Pollutants.

Metal-organic frameworks (MOFs) have exhibited appreciable potential as catalytic agents in the field of material science. The research of new MOFs with dual functions in electrocatalysis and photocatalysis under ultraviolet (UV) irradiation is extremely pivotal for renewable energy applications. Hence, we synthesized a series of three-dimensional MOFs, namely, [Cd(bimb)2(HITA)2]n (Cd-MOF 1), {[Cd(bimb)6](NO3)2}n (Cd-MOF 2), and [Cd(bimb)4(ONO2)2]n (Cd-MOF 3) (bimb = 1,4-bis(imidazol-1-ylmethyl)benzene; H2ITA = 5-hydroxyisophthalic acid), with applicability in the oxygen evolution reaction process and Fenton-like photocatalysis. The obtained results show that Cd-MOF 1 exhibited the most remarkable catalytic performance, affording a current density of 10 mA cm-2 at a very low overpotential of 279 mV and the smallest Tafel slope of 85.13 mV dec-1. Meanwhile, these MOFs can generate hydroxyl radicals (•OH) under UV light irradiation with the existence of H2O2, enabling the rapid degradation of organic pollutants. This study provides a valuable direction for producing multifunctional and environmentally friendly catalysts.

One-step synthesis of a carbon dot-based fluorescent probe for colorimetric and ratiometric sensing of tetracycline.

Carbon dots (CDs) with blue fluorescence were synthesized using indole-3-butyric acid and l-tryptophan using a one-step hydrothermal method. The CDs were further employed as a fluorescent sensor with high selectivity for colorimetric and ratiometric detection of tetracycline (TC) in water. The limit of detection (LOD) was found to be 0.33 µM for TC with R2 = 0.98387. Besides, the CDs could be applied in practical water samples and showed good recovery.

Zn-MOFs based luminescent sensors for selective and highly sensitive detection of Fe3+ and tetracycline antibiotic.

Either reduced or excessive metal ions level in biological systems might induce serious metabolic diseases, and the abuse of antibiotics has seriously affected the environment. Despite the significant progress in the development of fluorescence probes over the past decade, the ability to sensitively and selectively detect these metal ions and antibiotics remains a pressing problem. Herein, we demonstrated some effective fluorescence probes for sensing metal ions and antibiotics, six novel and stable Zn(II) metal-organic frameworks (Zn-MOFs), namely [Zn3(L)2(1,4-bimb)3]n (1), [Zn3(L)2(4,4'-bbibp)2(H2O)2]n·2(CH3CN) (2), [Zn(HL)(4,4'-bidpe)]n (3), [Zn(HL)(4,4'-bibp)]n (4), [Zn(HL)(3,5'-bip)]n (5) and [Zn(HL)(1,3'-bit)]n (6) (flexible H3L = 5-(2-carboxylphenoxy)isophthalic acid, semi-flexible 1,4-bimb = 1,4-bis(imidazol-l-ylmethyl) benzene, rigid 4,4'-bbibp = 4,4'-bis(benzoimidazo-1-ly)biphenyl, semi-flexible 4,4'-bidpe = 4,4'-bis(imidazolyl)diphenyl ether, rigid 4,4'-bibp = 4,4'-bis(imidazolyl)biphenyl, rigid 3,5'-bip = bis(1-imidazoly)pyridine and rigid 1,3-bit = 1,3-bis(l-imidazoly)toluene) have been successfully synthesized via solvothermal conditions and further characterized by IR spectra, elemental analysis, powder X-ray diffraction (PXRD), single-crystal X-ray diffraction, and thermogravimetric (TG) analysis. These Zn MOFs have exhibited diversely architectural frameworks via the assistant N-donor ligands: 1, 2, 5 and 6 show unprecedented topological networks, 1 affords a 3-nodal (3, 4, 4)-connect 2-fold interpenetrating topology structure with the Point Schläfli symbol of (5·6·7·92·10)2(5·6·7)2(5·73·82), 2 shows a 3-nodal (3, 4, 6)-c topology with (4·82)2(42·811·10·12)(86), 5 and 6 display 3-nodal (2, 2, 4)-c topology with (2·44·6)(2)(4). 3 and 4 show 4-connected sql topology with (44·62). As expected, Zn MOFs 1-6 not only revealed a highly sensitive and selective fluorescence quenching effect on Fe3+ ions in aqueous solution, but also toughed the interference of a myriad of other metal ions. It is noteworthy that they could also be used as luminescent sensors for detection of tetracycline antibiotic.

Urease inhibition studies of six Ni(II), Co(II) and Cu(II) complexes with two sexidentate N2O4-donor bis-Schiff base ligands: An experimental and DFT computational study.

Six novel complexes, [Ni(C36H34N2O10)]·2.25CH3OH·0.5C4H10O (1), [Co(C36H34N2O10)] (2), [Cu(C36H34N2O10)]·2CH3OH (3), [Ni(C36H32N2O8Cl2)]·2CH3OH (4), [Co(C36H32N2O8Cl2)]·4CH3OH (5) and [Cu(C36H32N2O8Cl2)]·2CH3OH (6) with two sexidentate N2O4-donor bis-Schiff base ligands (C36H34N2O10 = 1,2-bis(2-methoxy-6-formylphenoxy)ethane-l-tyrosine; C36H32N2O8Cl2 = 1,2-bis(2-methoxy-6-formylphenoxy)ethane-l-4-chlorophenylalanine) have been synthesized and structurally characterized. Theoretical calculation of the six complexes was carried out by density functional theory (DFT) Becke's three-parameter hybrid (B3LYP) method employing the 6-3lG basis set, indicating that the calculation results are in accordance with experimental results. Moreover, the inhibitory activities of complexes 1-6 were tested in vitro against jack bean urease. At the same time, molecular docking was investigated to determine the probable binding mode. The experimental values and docking simulation exhibited that complexes 3 and 6 showed strong inhibitory activity (IC50 = 10.36 ± 1.13, 15.63 ± 3.04 µM) compared with the positive reference acetohydroxamic acid (IC50 = 26.99 ± 1.43 µM). Their structure-inhibitory activity relationship was further discussed from the perspective of molecular docking and theoretical calculation.