Poly(4-vinylpyridine) as ligand for Au(I) and Zn(II) cations: luminescent metal-containing polymers

Crystal structures of four gold(I) complexes [AuL 2]+[AuX 2]- and a by-product (L·LH+)[AuBr2]- (L = substituted pyridine, X = Cl or Br)

Bis(2-methyl-pyridine)-gold(I) di-bromido-aurate(I), [Au(C6H7N)2][AuBr2], (1), crystallizes in space group C2/c with Z = 4. Both gold atoms lie on twofold axes and are connected by an aurophilic contact. A second aurophilic contact leads to infinite chains of alternating cations and anions parallel to the b axis, and the residues are further connected by a short H⋯Au contact and a borderline Br⋯Br contact. Bis(3-methyl-pyridine)-gold(I) di-bromido-aurate(I), [Au(C6H7N)2][AuBr2], (2), crystallizes in space group C2/m with Z = 2. Both gold atoms lie on special positions with symmetry 2/m and are connected by an aurophilic contact; all other atoms except for one methyl hydrogen lie in mirror planes. The extended structure is closely analogous to that of 1, although the structures are formally not isotypic. Bis(3,5-di-methyl-pyridine)-gold(I) di-chlor-ido-aurate(I), [Au(C7H9N)2][AuCl2], (3) crystallizes in space group P with Z = 2. The cation lies on a general position, and there are two independent anions in which the gold atoms lie on inversion centres. The cation and one anion associate via three short H⋯Cl contacts to form a ribbon structure parallel to the b axis; aurophilic contacts link adjacent ribbons. Bis(3,5-di-methyl-pyridine)-gold(I) di-bromido-aurate(I), [Au(C7H9N)2][AuBr2], (4) is isotypic to 3. Attempts to make similar compounds involving 2-bromo-pyridine led instead to 2-bromopyridinium di-bromido-aurate(I)-2-bromo-pyridine (1/1), (C5H5BrN)[AuBr2]·C5H4BrN, (5), which crystallizes in space group P with Z = 2; all atoms lie on general positions. The 2-bromo-pyridinium cation is linked to the 2-bromo-pyridine mol-ecule by an N-H⋯N hydrogen bond. Two formula units aggregate to form inversion-symmetric dimers involving Br⋯Br, Au⋯Br and H⋯Br contacts.

Investigating the Impact of Packing and Environmental Factors on the Luminescence of Pt(N^N^N) Chromophores

Four Pt(II)(N^N^N) compounds featuring DMSO coordination at the fourth position were synthesized. Ligands varied in terms of pyridyl central ring (hydrogen/chlorine substituent) and lateral rings (triazoles with CF3 substitution or tetrazoles). Coordination to pyridine yielded tetra-nitrogen coordinated Pt(II) complexes or Pt-functionalized polymers using commercial 4-pyridyl polyvinyl (PV) or dimethylaminopyridine. Luminescence behaviors exhibited remarkable environmental dependence. While some of the molecular compounds (tetrazole derivatives) in solid state displayed quenched luminescence, all the polymers exhibited 3MMLCT emission around 600 nm. Conversely, monomer emission was evident on poly(methyl methacrylate) or polystyrene matrices. DFT calculations were used to analyze the aggregation of the complexes both at the molecular level and coordinated to the PV polymer and their influence on the HOMO-LUMO gaps.

Entanglement-Enhanced Water Dissociation in Bipolar Membranes with 3D Electrospun Junction and Polymeric Catalyst

With the use of bipolar membranes (BPMs) in an expanding range of applications, there is an urgent need to understand and improve the catalytic performance of BPMs for water dissociation, as well as to increase their physical and chemical stability. In this regard, electrospinning BPMs with 2D and 3D junction structures have been suggested as a promising route to produce high-performance BPMs. In this work, we investigate the effect of entangling anion and cation exchange nanofibers at the junction of bipolar membranes on the water dissociation rate. In particular, we compare the performance of different tailor-made BPMs with a laminated 2D junction and a 3D electrospun entangled junction, while using the same type of anion and cation exchange polymers in a single/dual continuous electrospinning manufacturing method. The bipolar membrane with a 3D entangled junction shows an enhanced water dissociation rate as compared to the bipolar membrane with laminated 2D junction, as measured by the decreased bipolar membrane potential. Moreover, we investigate the use of a third polymer, that is, poly(4-vinylpyrrolidine) (P4VP), as a catalyst for water dissociation. This polymer confirmed that a 3D entangled junction BPM (with incorporated P4VP) gives a higher water dissociation rate than does a 2D laminated junction BPM with P4VP as the water dissociation catalyst. This work demonstrates that the entanglement of the anion exchange polymer with P4VP as the water dissociation catalyst in a 3D junction is promising to develop bipolar membranes with enhanced performance as compared to the conventionally laminated membranes.

Copper(II) complexes bearing cyclobutanecarboxylate and pyridine ligands: a new series of dinuclear paddle-wheel complexes

Four members of a new series of paddle-wheel copper(II) complexes bearing cyclobutanecarboxylate as bridging ligand with pyridine derived ligands in axial positions are reported. They have been characterised by FTIR-ATR, UV–Vis spectroscopy, mass spectrometry, and single crystal X-ray diffraction. The synthesis is straight-forward by combining the carboxylic acid, copper(II) acetate, and a slight excess of a pyridine ligand. The molecular structures of three complexes reveal a coordination mode expected for such type of dinuclear copper(II) carboxylates.

Graphic abstract

Recent advances in metallopolymer-based drug delivery systems

Metallopolymers (MPs) or metal-containing polymers have shown great potential as new drug delivery systems (DDSs) due to their unique properties, including universal architectures, composition, properties and surface chemistry. Over the past few decades, the exponential growth of many new classes of MPs that deal with these issues has been demonstrated. This review presents and assesses the recent advances and challenges associated with using MPs as DDSs. Among the most widely used MPs for these purposes, metal complexes based on synthetic and natural polymers, coordination polymers, metal-organic frameworks, and metallodendrimers are distinguished. Particular attention is paid to the stimulus- and multistimuli-responsive metallopolymer-based DDSs. Of considerable interest is the use of MPs for combination therapy and multimodal systems. Finally, the problems and future prospects of using metallopolymer-based DDSs are outlined. The bibliography includes articles published over the past five years.