The influence of structural isomerism on fluorescence and organic dye selective adsorption in two complexes based on flexible ligands

One water-stable magnetic coordination polymer material (Fe3O4@PmPD–[Co-BT]) as an efficient adsorbent for rapid dye removal

Benefiting from the framework, Fe₃O₄@PmPD–[Co-BT] has an excellent effect of removing CR from wastewater, and the adsorption capacity was 347.8 mg g⁻¹.

A new three-dimensional cobalt(II) coordination polymer based on V-shaped 3,4'-oxydibenzoate: synthesis, crystal structure and magnetic properties

A new coordination polymer (CP), namely poly[(μ-4,4'-bipyridine)(μ₃-3,4'-oxydibenzoato)cobalt(II)], [Co(C₁₄H₈O₅)(C₁₀H₈N₂)]_n or [Co(3,4'-obb)(4,4'-bipy)]_n (1), was prepared by the self-assembly of Co(NO₃)₂·6H₂O with the rarely used 3,4'-oxydibenzoic acid (3,4'-obbH₂) ligand and 4,4'-bipyridine (4,4'-bipy) under solvothermal conditions, and has been structurally characterized by elemental analysis, IR spectroscopy, single-crystal X-ray crystallography and powder X-ray diffraction (PXRD). Single-crystal X-ray diffraction reveals that each Co^II ion is six-coordinated by four O atoms from three 3,4'-obb^2- ligands, of which two function as monodentate ligands and the other as a bidentate ligand, and by two N atoms from bridging 4,4'-bipy ligands, thereby forming a distorted octahedral CoN₂O₄ coordination geometry. Adjacent crystallographically equivalent Co^II ions are bridged by the O atoms of 3,4'-obb^2- ligands, affording an eight-membered Co₂O₄C₂ ring which is further extended into a two-dimensional [Co(3,4'-obb)]_n sheet along the ab plane via 3,4'-obb^2- functioning as a bidentate bridging ligand. The planes are interlinked into a three-dimensional [Co(3,4'-obb)(4,4'-bipy)]_n network by 4,4'-bipy ligands acting as pillars along the c axis. Magnetic investigations on CP 1 disclose an antiferromagnetic coupling within the dimeric Co₂ unit and a metamagnetic behaviour at low temperature resulting from intermolecular π-π interactions between the parallel 4,4'-bipy ligands.

Upconversion fluorescent aptasensor for bisphenol A and 17β-estradiol based on a nanohybrid composed of black phosphorus and gold, and making use of signal amplification via DNA tetrahedrons

This study describes an upconversion fluorescent aptasensor based on black phosphorus nanohybrids and self-assembled DNA tetrahedrons dual-amplification strategy for rapid detection of the environmental estrogens bisphenol A (BPA) and 17β-estradiol (E2). Tetrahedron complementary DNAs (T-cDNAs) were self-assembled in an oriented fashion on a 2D nanohybrid composed of black phosphorus (BP) and gold to give a materials of architecture BP-Au@T-cDNAs. In parallel, core-shell upconversion nanoparticles were modified with aptamers (UCNPs@apts) and used as capture probes. On complementary pairing, the BP-Au@T-cDNA quench the fluorescence of UCNPs@apts (measured at an excitation wavelength 808 nm and at main emission peaks at 545 nm and 805 nm.) Compared with single-stranded probes based on black phosphorus and gold, the dual-amplification strategy increases quenching efficiency by nearly 25%-30% and reduces capture time to 10 min. This is due to the higher optical absorption of 2D nanohybrid and the reduction of steric hindrance by T-cDNAs. Exposure to BPA or E2 cause the release of UCNPs@apts from the BP-Au@T-cDNAs due to stronger binding between aptamer and analyte. Hence, fluorescence recovers at 545 nm for BPA and 805 nm for E2. Based on these findings, a dually amplified aptamer assay was constructed that covers the 0.01 to 100 ng mL^-1 BPA concentration range, and the 0.1 to 100 ng mL^-1 E2 concentration range. The detection limits are 7.8 pg mL^-1 and 92 pg mL^-1, respectively. This method was applied to the simultaneous determination of BPA and E2 in spiked samples of water, food, serum and urine. Graphical abstract Schematic presentation of novel quenching probes designed by tetrahedron complementary DNAs oriented self-assembled on the surface of black phosphorus/gold nanohybrids. Combined with aptamer-modified upconversion nanoparticles, a dual-amplification self-assembled fluorescence nanoprobe was constructed for simultaneous detection of BPA and E2.

Synthesis, structure and photoluminescence properties of a three-dimensional cadmium(II) (4,5)-connected coordination network

The assembly of coordination polymers from metal ions and organic moieties is currently attracting considerable attention in crystal engineering due to their intriguing architectures and potential applications as functional materials. A new coordination polymer, namely poly[[μ₂-trans-1,2-bis(pyridin-3-yl)ethylene-κ²N:N']bis(μ₄-4,4'-oxydibenzoato-κ⁶O:O,O':O'':O'',O''')dicadmium(II)], [Cd₂(C₁₄H₈O₅)₂(C₁₂H₁₀N₂)]_n or [Cd₂(4,4'-OBB)₂(3,3'-BPE)]_n, has been synthesized by the the self-assembly of Cd(NO₃)₂·4H₂O, 4,4'-oxydibenzoic acid (4,4'-H₂OBB) and trans-1,2-bis(pyridin-3-yl)ethene (3,3'-BPE) under hydrothermal conditions. The title compound was structurally characterized by IR spectroscopy, elemental analysis and single-crystal X-ray diffraction analysis. Each Cd^II centre is coordinated by six carboxylate O atoms from four different 4,4'-OBB^2- ligands and by one pyridyl N atom form a 3,3'-BPE ligand. Adjacent crystallographically equivalent Cd^II ions are bridged by 4,4'-OBB^2- ligands, affording a two-dimensional [Cd(4,4'-OBB)]_n net extending in the ac plane. Neighbouring [Cd(4,4'-OBB)]_n nets are interlinked by 3,3'-BPE along the b axis to form a three-dimensional (3D) [Cd₂(4,4'-OBB)₂(3,3'-BPE)]_n coordination network. In the network, each Cd^II centre is linked by four different 4,4'-OBB^2- ligands and one 3,3'-BPE ligand. Meanwhile, each 4,4'-OBB^2- ligand connects four separate Cd^II ions. Therefore, if the 4,4'-OBB^2- ligands and Cd^II ions are considered as 4- and 5-connecting nodes, the structure of the title compound can be simplified as a 3D (4,5)-connected binodal framework with the rare (4⁴6²)(4⁴6⁶) TCS topology (Pearson, 1985; Blake et al., 2011). The thermal stability and photoluminescence properties of the title compound have also been investigated.

Syntheses, structural diversity, magnetic properties and dye absorption of various Co(ii) MOFs based on a semi-flexible 4-(3,5-dicarboxylatobenzyloxy)benzoic acid

Various polymeric structures of MOFs1–5.