Bis 4,5-diazafluoren-9-one silver(i) nitrate: synthesis, X-ray structures, solution chemistry, hydrogel loading, DNA coupling and anti-bacterial screening

Abstract

Synthesis of bis-4,5-diazafluoren-9-one silver(I) nitrate I, (dafone = 4,5-diazafluoren-9-one) and low temperature X-ray single crystal structure of [Ag(4,5-diazafluoren-9-one) 2 NO 3 ], crystal form 1, and a re-determination of [Ag(4,5-diazafluoren-9-one) 2 ]NO 3 ·H 2 O, crystal form 2 are presented.Crystal form 1 has a distorted trigonal planar coordination geometry around Ag(I) with an N-Ag-N bond angle of 123.45(7)°. Crystal form 2 has a perfect linear coordination around Ag, with N-Ag-N 180.0°. Compound I was characterized by 1 H-NMR, biological activity and ESI-MS in DMSO at room temperature. The biological activity was determined against 6 different resistant clinical isolates; two Gram-positive (Staphylococcus aureus and Streptococcus pyogenes) and four Gramnegative (Pseudomonas aeruginosa, Klebsiella pneumoniae, Proteus mirabilis, and Salmonella sp.) in comparison with 15 known antibiotics used in the treatment of diabetic foot infections.Compound I showed broad spectrum activity against all the test organisms. Proteus mirabilis, Staphylococcus aureus and Proteus mirabilis were the most sensitive clinical isolates (MIC = 4, 6 and 4 µg/ml, respectively). Three different hydrogels containing I or Ag 2 SO 4 were prepared and the antimicrobial activity against Pseudomonas aeruginosa (ATCC 15442) compared, showing more or less equal activity on a weight basis, but I seems to have a significant better performance per silver ion. The Ag(I) complex also binds more effectively to calf thymus DNA than the dafone ligand itself. reaction was performed in an acetonitrile/water mixture at room temperature, only crystals of [Ag(dafone) 2 ]NO 3 ·H 2 O, 2 were formed. But when an ethanol/water mixture was used with heating, prismatic crystals of [Ag(dafone) 2 NO 3 ], 1 and needles of [Ag(dafone) 2 ]NO 3 ·H 2 O, 2 were collected from the same batch. Synthesis of silver loaded hydrogelsTo vary degrees of cross linking of the hydrogels different molecular weights of dimethacrylated PEG (polyethylene glycol) monomers (PEGDMA) were used and three gels containing different ratios of PEGDMA8k, PEGDMA20k, TEGDA (triethylene glycol diacrylate) and PEGDA700 were prepared with water as a solvent.Silver sulphate (2% and 6% by weight) and 1 (2%) with 1% photoinitiator was added and the mixtures cured with a UV Lamp giving nine different gels. Notable differences in appearance of the produced gels were noted: while the gels with 1 were white/transparent much like a nonsilver containing gel, the gels with Ag 2 SO 4 were severely discoloured, see Figure 1. Figure 1. Dimethacrylated PEG gels with left: 2% 1, right: 2% Ag 2 SO 4Crystal Structures The two structures are strikingly different, we will therefore first present each structure and in conjunction make appropriate comments, and thereafter we will bring up the points that are of general interest in dafone coordination chemistry.Crystallographic data and refinement parameters for crystal forms 1 and 2 are listed in Table 1, Accepted manuscript New Journal of Chemistry, 35,[640][641]...

2D Bipyrimidine silver(I) nitrate: Synthesis, X-ray structure, solution chemistry and anti-microbial activity

“…nClO 4 In some related studies the ESI-MS of the silver(I) trifluoromethan sulfonate (AgO 3 SCF 3 ) compound with 3,6-di(2-pyridyl)pyridazine in CH 3 CN were consistent with X-ray crystallography where the same cations [Ag(L) 2 ] + (Ag:L = 1:2) were found [30]. Similarly, the ESI-MS for the compound [Ag(4,5-diazafluoren-9-one) 2 ]NO 3 [21] showed only one strong peak representing the complex [Ag(L) 2 ] + with (Ag: L = 1:2). On the contrary, the ESI-MS for a solution containing AgBF 4 and excess bidentate 1,12-diazaperylene ligand indicate the formation of the 1:1 (90%) Ag:L complex while the expected 1:2 complex is only observed as a minor peak (10%) [31].…”

Synthesis, Crystal Structure, Quantum Chemical Calculations, DNA Interactions, and Antimicrobial Activity of [Ag(2-amino-3-methylpyridine)2]NO3 and [Ag(pyridine-2-carboxaldoxime)NO3]

“…52 It is perhaps significant that these structures, to a varying degree, have Ag…O interactions with a nitrate anion, and that these, and the surrounding crystal packing effects, may play a significant role difficult to model with a simple DFT calculation. In the 4,5-diazafluoren-9-one case there are also two different crystal structures reported, 53 containing two very dissimilar [Ag(4,5-diazafluoren-9-one) 2 ] + complexes. In contrast, but perfectly consistent with this discussion, the almost perfectly linear coordination geometry with negligible nitrate interaction reported by Zhou et al is well reproduce by their DFT calculations.…”

Coordination chemistry and applications of versatile 4,5-diazafluorene derivatives

“…168 The in vitro linear dichroism studies also showed that both dafo and the silver complexes bind to calf thymus DNA, however the complexes showed significantly stronger binding to DNA compared with the free ligand. 168 The free 9-diazo-4,5-diazafluorene can be photochemically activated to release dinitrogen as a byproduct and generate a triplet carbene. 169 Matrix photolysis experiments of complex [Cu(9-diazo-4,5-diazafluorene) 2 (NO 3 ) 2 ] (Fig.…”