The solvent influenced coordination variation of flexible ligands to Y(iii) towards MOF structural diversity

Coordination variation by solvent environment change leading to various yttrium-based MOFs with flexible ligands.

New InhA Inhibitors Based on Expanded Triclosan and Di-Triclosan Analogues to Develop a New Treatment for Tuberculosis

The emergence of multidrug-resistant (MDR) and extensively drug-resistant (XDR) tuberculosis (TB) has reinforced the need for the development of new anti-TB drugs. The first line drug isoniazid inhibits InhA. This is a prodrug requiring activation by the enzyme KatG. Mutations in KatG have largely contributed to clinical isoniazid resistance. We aimed to design new ‘direct’ InhA inhibitors that obviate the need for activation by KatG, circumventing pre-existing resistance. In silico molecular modelling was used as part of a rational structure-based drug-design approach involving inspection of protein crystal structures of InhA:inhibitor complexes, including the broad spectrum antibiotic triclosan (TCS). One crystal structure exhibited the unusual presence of two triclosan molecules within the Mycobacterium tuberculosis InhA binding site. This became the basis of a strategy for the synthesis of novel inhibitors. A series of new, flexible ligands were designed and synthesised, expanding on the triclosan structure. Low Minimum Inhibitory Concentrations (MICs) were obtained for benzylphenyl compounds (12, 43 and 44) and di-triclosan derivative (39), against Mycobacterium bovis BCG although these may also be inhibiting other enzymes. The ether linked di-triclosan derivative (38) displayed excellent in vitro isolated enzyme inhibition results comparable with triclosan, but at a higher MIC (125 µg mL−1). These compounds offer good opportunities as leads for further optimisation.

Manganese(II) complexes derived from acyclic ligands having flexible alcohol arms: structural chracterization and SOD and catalase mimetic studies

In this work, a series of seven MnII complexes of noncyclic flexible ligands derived from 2,6-diformylpyridine and ethanolamine or alkyl-substituted ethanolamines were prepared and characterized, six structurally by single-crystal X-ray diffraction studies. The complexes are dichlorido{2,2′-[(pyridine-2,6-diyl)bis(nitrilomethanylylidene)]diethanol}manganese(II), [MnCl2(C11H15N3O2)] or [MnCl2(L1)], (2), bis{μ-2,2′-[(pyridine-2,6-diyl)bis(nitrilomethanylylidene)]diethanol}bis[dithiocyanatomanganese(II)], [Mn2(NCS)4(C11H15N3O2)2] or [Mn2(NCS)4(L1)2], (3), chlorido{1,1′-[(pyridine-2,6-diyl)bis(nitrilomethanylylidene)]bis(propan-2-ol)}manganese(II) chloride monohydrate, [MnCl(C13H19N3O2)(H2O)]Cl·H2O or [MnCl(L2)(H2O)]Cl·H2O, (4), {1,1′-[(pyridine-2,6-diyl)bis(nitrilomethanylylidene)]bis(propan-2-ol)}dithiocyanatomanganese(II), [Mn(NCS)2(C13H19N3O2)] or [Mn(NCS)2(L2)], (5), aquadichlorido{2,2′-dimethyl-2,2′-[(pyridine-2,6-diyl)bis(nitrilomethanylylidene)]bis(propan-1-ol)}manganese(II) 0.3-hydrate, [MnCl2(C15H23N3O2)(H2O)]·0.3H2O or [MnCl2(L3)(H2O)]·0.3H2O, (6), (dimethylformamide){2,2′-dimethyl-2,2′-[(pyridine-2,6-diyl)bis(nitrilomethanylylidene)]bis(propan-1-ol)}dithiocyanatomanganese(II), [Mn(NCS)2(C15H23N3O2)(C3H7NO)] or [Mn(NCS)2(L3)(DMF)], (7), and (dimethylformamide){2,2′-[(pyridine-2,6-diyl)bis(nitrilomethanylylidene)]bis(butan-1-ol)}dithiocyanatomanganese(II) dimethylformamide monosolvate, [Mn(NCS)2(C15H23N3O2)(C3H7NO)]·C3H7NO or [Mn(NCS)2(L4)(DMF)]·DMF, (8). The crystal structure of ligand L1 is also reported, but that of (5) is not. All four ligands (L1–L4) have five potential donor atoms in an N3O2 donor set, i.e. three N (pyridine/diimine donors) and two alcohol O atoms, to coordinate the MnII centre. The N3O2 donor set coordinates to the metal centre in a pentagonal planar arrangement; seven-coordinated MnII complexes were obtained via coordination of two auxiliary ligands (anions or water molecules) at the axial positions. However, in some cases, the alcohol O-atom donors remain uncoordinated, resulting in five- or six-coordinated MnII complexes. The structurally characterized complexes were tested for their catalytic scavenging of superoxide and peroxide. The results indicated that the complexes with coordinated exogenous water or chloride ligands showed higher SOD activity than those with exogenous thiocyanate ligands.

Constructing multi-cluster copper(i) halides using conformationally flexible ligands

Conformationally flexible ligands were used to trap various Cu(i)-halide clusters in one system to obtain multi-cluster copper(i)-halides with distinctive temperature-dependent luminescence.

Dense π-stacking of flexible ligands fixed in interpenetrating Zn(ii) MOF exhibiting long-lasting phosphorescence and efficient carrier transport

Dense π-stacking of flexible ligands fixed in three-fold interpenetrating Zn(ii) MOF exhibits long-lived room temperature phosphorescence lifetime up to 91 ms and efficient electro-hole separation.