Tetra-μ-benzoato-κ4 O:O′;κ3 O:O,O′;κ3 O,O′:O′-bis­[(benzoato-κ2 O,O′)(1,10-phenanthroline-κ2 N,N′)neodymium(III)]

The complete mol­ecule of the title compound, [Nd2(C7H5O2)6(C12H8N2)2], is generated by a crystallographic inversion center. The two NdIII ions are linked by four bridging benzoate ions, with an Nd⋯Nd separation of 4.0360 (2) Å. As well as the bridging ligands, each NdIII ion is coordinated by one N,N′-bidentate phenanthroline ligand and an O,O′-bidentate benzoate ion. The resulting irregular nine-coordinated geometry of the NdIII ion is completed by seven O and two N atoms. The mol­ecular structure is stabilized by intra­molecular C—H⋯O hydrogen bonds. In the crystal structure, mol­ecules are linked into infinite chains along the c axis by inter­molecular C—H⋯O hydrogen bonds. The crystal structure is consolidated by weak inter­molecular C—H⋯π inter­actions

Tuning the photophysical properties of BODIPY dyes through extended aromatic pyrroles

A series of naphthyl and fluorantho-fused BODIPY dyes have been synthesized by a simple two-step process. These dyes display high molar absorptivities in the far visible region of the spectrum with emission quantum efficiencies at or near unity

Judicious Ligand Design in Ruthenium Polypyridyl CO2 Reduction Catalysts to Enhance Reactivity by Steric and Electronic Effects

A series of RuII polypyridyl complexes of the structural design [RuII(R−tpy)(NN)(CH3CN)]2+ (R−tpy=2,2′:6′,2′′-terpyridine (R=H) or 4,4′,4′′-tri-tert-butyl-2,2′:6′,2′′-terpyridine (R=tBu); NN=2,2′-bipyridine with methyl substituents in various positions) have been synthesized and analyzed for their ability to function as electrocatalysts for the reduction of CO2 to CO. Detailed electrochemical analyses establish how substitutions at different ring positions of the bipyridine and terpyridine ligands can have profound electronic and, even more importantly, steric effects that determine the complexes’ reactivities. Whereas electron-donating groups para to the heteroatoms exhibit the expected electronic effect, with an increase in turnover frequencies at increased overpotential, the introduction of a methyl group at the ortho position of NN imposes drastic steric effects. Two complexes, [RuII(tpy)(6-mbpy)(CH3CN)]2+ (trans-[3]2+; 6-mbpy=6-methyl-2,2′-bipyridine) and [RuII(tBu−tpy)(6-mbpy)(CH3CN)]2+ (trans-[4]2+), in which the methyl group of the 6-mbpy ligand is trans to the CH3CN ligand, show electrocatalytic CO2 reduction at a previously unreactive oxidation state of the complex. This low overpotential pathway follows an ECE mechanism (electron transfer–chemical reaction–electron transfer), and is a direct result of steric interactions that facilitate CH3CN ligand dissociation, CO2 coordination, and ultimately catalytic turnover at the first reduction potential of the complexes. All experimental observations are rigorously corroborated by DFT calculations

Bridging ligands comprising two or more di-2-pyridylmethyl or amine arms: alternatives to 2,2'-bipyridyl-containing bridging ligands

Bridging ligands incorporating 2,2'-bipyridine as a chelating component have been utilised for several decades and are widely employed in coordination chemistry, supramolecular chemistry and materials synthesis. Such ligands form stable 5-membered chelate rings upon coordination to a metal. Two related chelating units, di-2-pyridylamine and di-2-pyridylmethane, which form 6-membered chelate rings when coordinated to a metal, have been studied far less as components of bridging ligands but have recently garnered significant levels of attention. Of around 140 reports on the incorporation of these moieties into bridging ligands some 75% have been published in the last 15 years. This review covers the synthesis of bridging ligands containing di-2-pyridylamine and di-2-pyridylmethane chelating moieties, and a survey of their coordination and supramolecular chemistry. Applications of the resulting systems as structural and functional models of enzyme active sites, and spin-crossover materials, and for investigations into anion-π interactions are covered. © 2011 Elsevier B.V.Christopher J. Sumbyhttp://www.elsevier.com/wps/find/journaldescription.cws_home/500845/description#descriptio

A Cationic Porphyrin, ZnPor, Disassembles <i>Pseudomonas aeruginosa</i> Biofilm Matrix, Kills Cells Directly, and Enhances Antibiotic Activity of Tobramycin

One of the greatest threats to human health is the rise in antibiotic-resistant bacterial infections. Pseudomonas aeruginosa (PsA) is an “opportunistic” pathogen known to cause life-threatening infections in immunocompromised individuals and is the most common pathogen in adults with cystic fibrosis (CF). We report here a cationic zinc (II) porphyrin, ZnPor, that effectively kills planktonic and biofilm-associated cells of PsA. In standard tests against 16–18 h-old biofilms, concentrations as low as 16 µg/mL resulted in the extensive disruption and detachment of the matrix. The pre-treatment of biofilms for 30 min with ZnPor at minimum inhibitory concentration (MIC) levels (4 µg/mL) substantially enhanced the ability of tobramycin (Tobra) to kill biofilm-associated cells. We demonstrate the rapid uptake and accumulation of ZnPor in planktonic cells even in dedicated heme-uptake system mutants (ΔPhu, ΔHas, and the double mutant). Furthermore, uptake was unaffected by the ionophore carbonyl cyanide m-chlorophenyl hydrazine (CCCP). Cells pre-exposed to ZnPor took up the cell-impermeant dye SYTOXTM Green in a concentration-dependent manner. The accumulation of ZnPor did not result in cell lysis, nor did the cells develop resistance. Taken together, these properties make ZnPor a promising candidate for treating multi-drug-resistant infections, including persistent, antibiotic-resistant biofilms

A Cationic Porphyrin, ZnPor, Disassembles Pseudomonas aeruginosa Biofilm Matrix, Kills Cells Directly, and Enhances Antibiotic Activity of Tobramycin

One of the greatest threats to human health is the rise in antibiotic-resistant bacterial infections. Pseudomonas aeruginosa (PsA) is an &ldquo;opportunistic&rdquo; pathogen known to cause life-threatening infections in immunocompromised individuals and is the most common pathogen in adults with cystic fibrosis (CF). We report here a cationic zinc (II) porphyrin, ZnPor, that effectively kills planktonic and biofilm-associated cells of PsA. In standard tests against 16&ndash;18 h-old biofilms, concentrations as low as 16 &micro;g/mL resulted in the extensive disruption and detachment of the matrix. The pre-treatment of biofilms for 30 min with ZnPor at minimum inhibitory concentration (MIC) levels (4 &micro;g/mL) substantially enhanced the ability of tobramycin (Tobra) to kill biofilm-associated cells. We demonstrate the rapid uptake and accumulation of ZnPor in planktonic cells even in dedicated heme-uptake system mutants (&Delta;Phu, &Delta;Has, and the double mutant). Furthermore, uptake was unaffected by the ionophore carbonyl cyanide m-chlorophenyl hydrazine (CCCP). Cells pre-exposed to ZnPor took up the cell-impermeant dye SYTOXTM Green in a concentration-dependent manner. The accumulation of ZnPor did not result in cell lysis, nor did the cells develop resistance. Taken together, these properties make ZnPor a promising candidate for treating multi-drug-resistant infections, including persistent, antibiotic-resistant biofilms