A Europium-based MOF Fluorescent Probe for Efficiently Detecting Malachite Green and Uric Acid.

Lanthanide (such as Tb and Eu) metal-organic frameworks (MOFs) have been widely used in fluorescent probes because of their multiple coordination modes and brilliant fluorescence characteristic. Many lanthanide MOFs were applied in detecting metal ions, inorganic anions, and small molecules. However, it's rarely reported that Ln-MOF was devoted to detecting malachite green (MG) and uric acid (UA). We prepared a europium-based metal-organic framework (Eu-TDA) (TDA = 2,5-thiophenedicarboxylic acid group). Luminescence studies demonstrated that Eu-TDA can rapidly detect MG and UA with excellent selectivity and sensitivity, where individual quenching efficiency Ksv (MG: 5.8 × 105 M-1; UA: 4.15 × 104 M-1) and detection limit (MG: 0.0221 µM; UA: 0.689 µM) were regarded as the excellent MOF sensors for detecting MG and UA. The quenching of Eu-TDA's fluorescence emission by MG and UA was likely due to the spectral overlap, energy transfer, and competition. Among 11 metal cations and 14 anions, Eu-TDA can quickly and effectively recognize MG and UA with highly selective and sensitive properties. Our method possesses potential application in detecting UA in human blood and MG in the fishpond.

Self-assembly of a ruthenium-based cGAS-STING photoactivator for carrier-free cancer immunotherapy.

The cGAS (cyclic GMP-AMP synthase)-STING (stimulator of interferon genes) pathway promotes antitumor immune responses by sensing cytosolic DNA fragments leaked from nucleus and mitochondria. Herein, we designed a highly charged ruthenium photosensitizer (Ru1) with a ß-carboline alkaloid derivative as the ligand for photo-activating of the cGAS-STING pathway. Due to the formation of multiple non-covalent intermolecular interactions, Ru1 can self-assemble into carrier-free nanoparticles (NPs). By incorporating the triphenylphosphine substituents, Ru1 can target and photo-damage mitochondrial DNA (mtDNA) to cause the cytoplasmic DNA leakage to activate the cGAS-STING pathway. Finally, Ru1 NPs show potent antitumor effects and elicit intense immune responses in vivo. In conclusion, we report the first self-assembling mtDNA-targeted photosensitizer, which can effectively activate the cGAS-STING pathway, thus providing innovations for the design of new photo-immunotherapeutic agents.

Fluorescence detection of malachite green and cations (Cr3+, Fe3+ and Cu2+) by a europium-based coordination polymer.

Due to remarkable fluorescence characteristics, lanthanide coordination polymers (CP) have been widely employed in fluorescence detection, but it is rarely reported that they act as multifunctional luminescent probes dedicated to detecting malachite green (MG) and various metal ions. A europium-based CP fluorescent probe, Eu(PDCA)2(H2O)6 (PDCA = 2,6-pyridinedicarboxylic acid), has been synthesized and exhibited excellent recognition ability for malachite green and metal cations (Cr3+, Fe3+ and Cu2+) among 11 metal cations, 13 anions and six other compounds. The recognition was achieved by fluorescence quenching when MG, Cr3+, Fe3+ and Cu2+ were added to a suspension of Eu(PDCA)2(H2O)6 respectively. Eu(PDCA)2(H2O)6 is a multifunctional luminescent probe, and displayed high quenching efficiencies K sv (2.10 × 106 M-1 for MG; 1.46 × 105 M-1 for Cr3+; 7.26 × 105 M-1 for Fe3+; 3.64 × 105 M-1 for Cu2+), and low detection limits (MG: 0.039 µM; Cr3+: 0.539 µM; Fe3+: 0.490 µM; Cu2+: 0.654 µM), presenting excellent selectivity and sensitivity, especially for MG. In addition, Eu(PDCA)2(H2O)6 was also made into fluorescent test strips, which can rapidly and effectively examine trace amounts of MG, Cr3+, Fe3+ and Cu2+ in aqueous solutions. This work provides a new perspective for detecting malachite green in fish ponds and heavy metal ions in waste water.

(2-Hy-droxy-acetato-κO)bis-(1,10-phenan-throline-κN,N')copper(II) nitrate.

In the title compound, [Cu(C(2)H(3)O(3))(C(12)H(8)N(2))(2)]NO(3), the Cu(II) atom is coordinated by two phenanthroline (phen) ligands and one carboxyl-O atom of a hy-droxy-acetate anion in a distorted square-pyramidal geometry. The hy-droxy group of the hy-droxy-acetate ligand links with the counter NO(3) (-) anion via a pair of bifurcated O-H⋯O hydrogen bonds. The centroid-centroid distance of 3.5676 (14) Šbetween benzene rings of parallel phen ligands of adjacent mol-ecules suggests the existence of π-π stacking. Weak inter-molecular C-H⋯O hydrogen bonding is also present in the crystal structure.

Two cadmium(II) fluorous coordination compounds tuned by different bipyridines.

Fluorine is the most electronegative element and can be used as an excellent hydrogen-bond acceptor. Fluorous coordination compounds exhibit several advantageous properties, such as enhanced high thermal and oxidative stability, low polarity, weak intermolecular interactions and a small surface tension compared to hydrocarbons. C-H...F-C interactions, although weak, play a significant role in regulating the arrangement of the organic molecules in the crystalline state and stabilizing the secondary structure. Two cadmium(II) fluorous coordination compounds formed from 2,2'-bipyridine, 4,4'-bipyridine and pentafluorobenzoate ligands, namely catena-poly[[aqua(2,2'-bipyridine-κ2N,N')(2,3,4,5,6-pentafluorobenzoato-κO)cadmium(II)]-µ-2,3,4,5,6-pentafluorobenzoato-κ2O:O'], [Cd(C7F5O2)2(C10H8N2)(H2O)]n, (1), and catena-poly[[diaquabis(2,3,4,5,6-pentafluorobenzoato-κO)cadmium(II)]-µ-4,4'-bipyridine-κ2N:N'], [Cd(C7F5O2)2(C10H8N2)(H2O)2]n, (2), have been synthesized solvothermally and structurally characterized. Compound (1) shows a one-dimensional chain structure composed of Cd-O coordination bonds and is stabilized by π-π stacking and O-H...O hydrogen-bond interactions. Compound (2) displays a one-dimensional linear chain structure formed by Cd-N coordination interactions involving the 4,4'-bipyridine ligand. Adjacent one-dimensional chains are extended into two-dimensional sheets by O-H...O hydrogen bonds between the coordinated water molecules and adjacent carboxylate groups. Moreover, the chains are further linked by C-H...F-C interactions to afford a three-dimensional network. In both structures, hydrogen bonding involving the coordinated water molecules is a primary driving force in the formation of the supramolecular structures.

A new five-coordinated copper compound for efficient degradation of methyl orange and Congo red in the absence of UV-visible radiation.

A new copper-based coordination compound Cu2(2,2'-bipy)2(pfbz)4 (1) (where 2,2'-bipy = 2,2'-bipyridine; pfbz = pentafluorobenzoate), was hydrothermally synthesized and structurally characterized. Compound 1 having a binuclear structure consists of two copper cations and two oxygen atoms alternately in a plane square arrangement. In the presence of very small amounts of H2O2, the catalytic properties of compound 1 for the degradation of methyl orange (MO) are excellent in the absence of UV-visible radiation. Moreover, compound 1 presents suitable properties for degradation of Congo red (CR). Our results indicated that the five-coordinated copper compound, 1, will be a promising candidate for efficient degradation of organic dyes.

Poly[(µ-pentafluorobenzoato-κ²O:O')(pentafluorobenzoato-κO)(µ-pyrazine-κ²N:N')copper(II)]: a coordination polymer linked into a three-dimensional network by intermolecular C-H···F-C interactions.

In the title compound, [Cu(C6F5COO)2(C4H4N2)]n, (I), the asymmetric unit contains one Cu(II) cation, two anionic pentafluorobenzoate ligands and one pyrazine ligand. Each Cu(II) centre is five-coordinated by three O atoms from three independent pentafluorobenzoate anions, as well as by two N atoms from two pyrazine ligands, giving rise to an approximately square-pyramidal coordination geometry. Adjacent Cu(II) cations are bridged by a pyrazine ligand and two pentafluorobenzoate anions to give a two-dimensional layer. The layers are stacked to generate a three-dimensional supramolecular architecture via strong intermolecular C-H···F-C interactions, as indicated by the F···H distance of 2.38 Å.