Preparation of some novel thiazolidinones,imidazolinones, and azetidinone bearing pyridine and pyrimidine moieties with antimicrobial activity

By aiming to design new antimicrobial agents, we prepared new series of thiazolidin-4-ones (12a–d), imidazolin-4-ones (13a–d), and azetidin-2-ones (14a–d), having pyridine and pyrimidine moieties. Chemical structures of these derivatives were elucidated by the use of spectral and elemental analyses. All the new substituted pyridopyrimidines were subjected to in vitro antimicrobial testing by estimating the zone of inhibition toward Bacillus subtilis and Staphylococcus aureus, as examples of bacterial species, in addition to Aspergillus flavus and Candida albicans, as examples of fungal species. The results of antimicrobial testing detected that all the screened derivatives displayed antibacterial effect; especially azetidin-2-one derivative, ( 14c ), was the most active one. Regarding the antifungal potential, only thiazolidinone derivatives, 12a and 12c, and the imidazolinone, 13c, displayed inhibitory activity toward Aspergillus flavus, while all the tested compounds, 12a–d , 13a–d, and 14a–d, except 14a, produced inhibitory potential toward Candida albicans. Docking studies of the most active antimicrobial agents, 12c, 13c, and 14c, within GLN-6-P, recorded good scores with several binding interactions with the active site.     

Development of a Chitosan/Nickel Phthalocyanine Composite Based Conductometric Micro-sensor for Methanol Detection

Thin-film composite of chitosan/nickel phthalocyanine (NiPc) was electrochemically deposited on the fingers of interdigitated gold electrodes, applying chronoamperometric polymerization technique. The presence of crystallized NiPc in the chitosan was confirmed by EDX and FTIR analysis. Acetone, ethanol, and methanol gas-sensing properties of the films prepared at optimum conditions were studied at atmospheric temperature, through differential measurements at an optimized frequency of 10 kHz, using a lock-in amplifier. The conductometric sensor presents the highest sensitivity of 60.2 μS.cm⁻¹(v/v) for methanol and 700 ppm as the limit of detection. For validation, the methanol content of a commercial rubbing alcohol was determined.     

New fused pyrroles with rA1/A2A antagonistic activity as potential therapeutics for neurodegenerative disorders

Molecular Diversity - In a pilot study, eleven pyrrolopyridine and pyrrolopyrimidine derivatives (specifically, 7-azaindole and 7-deazapurine derivatives) were synthesised by Suzuki cross-coupling...     

Structural studies on Ba(II) adducts of the cytosine nucleobase and its derivative 1-Methylcytosine*

Abstract

The use of the cytosine nucleobase or its 1-Methylcytosine derivative as ligands toward barium(II) cations led to the formation of three compounds, {[Ba(1-Mecyt)(H₂O)X₂]}_n [X=Cl (1), Br (2)], and {[Ba(cyt)₂(H₂O)(ClO₄)₂]}_n (3). Depending on the ligand and the counterion employed, 1–3 exhibit different architectures, which serve as a playground to study how the methyl substitution, together with the nature of the counterion are both significant in the self-assembling process of such species. The effect of the nature and size of the alkaline-earth metal ion on the final structural motif is also evident when comparing these structures with parent complexes of the Ca(II) ion.     

Efficient CO2 Insertion and Reduction Catalyzed by a Terminal Zinc Hydride Complex

The terminal zinc hydride complex [Tntm]ZnH ( 2 ; Tntm=tris(6‐tert‐butyl‐3‐thiopyridazinyl)methanide) is an efficient hydrosilylation catalyst of CO₂ at room temperature without the need of Lewis acidic additives. The inherent electrophilicity of the system leads to selective formation of the monosilylated product (MeO)₃SiO₂CH (at room temperature with a TOF of 22.2 h^?1 and at 45 °C with a TOF of 66.7 h^?1). In absence of silanes, the intermediate formate complex [Tntm]Zn(O₂CH) ( 3 ) is quantitatively formed within 5 min. All complexes were fully characterized by ¹H and ¹³C NMR spectroscopy and single‐crystal X‐ray diffraction analyses. Density functional theory (DFT) calculations reveal a high positive charge on zinc and the increased preference of the ligand to adopt a κ³‐coordination mode.     

[Cd<Subscript>5</Subscript>(OH)(H<Subscript>2</Subscript>O)<Subscript>3</Subscript>][CH<Subscript>3</Subscript>CO<Subscript>2</Subscript>]<Subscript>9</Subscript>, a cadmium hydroxy-acetate compound with a layered network

[Cd₅(OH)(H₂O)₃][CH₃CO₂]₉ crystallizes in the triclinic system, with the space group P , a = 10.897(3) Å, b = 11.035(5) Å, c = 16.061(12) Å, = 96.83(7), = 95.31(8), = 118.22(6) and z = 2. Its structure has been determined using 9497 unique single crystal data. The final refinements let the agreement factors R₁ and wR₂(F²) converge to reach the respective values of 0.0548 and 0.0986. R₁ = 0.0338 for the 7264 unique data with I > 2(I). [Cd₅(OH)(H₂O)₃][CH₃CO₂]₉ is a cadmium hydroxide acetate compound with a bi-dimensional structure in which hydrogen bonds insure cohesion between layers stacked along the [1 10] direction. The inorganic network is built up of layers constituted of CdO₆ octahedra and CdO₇ pentagonal bi-pyramids sharing edge or corner.     

Solid-phase extraction method for determination of volatile compounds in traditional balsamic vinegar

A solid-phase extraction method for the determination of volatile compounds in traditional balsamic vinegar (TBV) has been developed. The optimisation has been carried out using a two-level factorial design expanded further to a central composite design. LiChrolut-EN SPE cartridges were used and the optimised analytical conditions were: 7 g of TBV diluted 1:4, 5 mL of washing water, and elution with 10 mL of dichloromethane. The linear ranges and detection and quantitation limits were adequate for the analysis of the studied compounds in TBV. The accuracy of the method was also studied: recoveries up to 80% and repeatability values lower than 15% were obtained for the majority of the studied compounds. Two TBVs of different age were analysed by the optimised method.     

Spin-counting NMR experiments for the spectral editing of structural motifs in solids

Scalar couplings, recoupled or full dipolar interactions can be used to characterize multinuclear structural molecular motifs in solids, by counting the neighbouring spins in solid-state NMR, opening new ways for the differentiation of overlapping spectral responses which is a limiting factor in many high resolution experiments carried out on disordered systems.     

Optimization of Surfactin Production by <Emphasis Type="Italic">Bacillus subtilis</Emphasis> Isolate BS5

Bacillus subtilis BS5 is a soil isolate that produces promising yield of surfactin biosurfactant in mineral salts medium (MSM). It was found that cellular growth and surfactin production in MSM were greatly affected by the environmental fermentation conditions and the medium components (carbon and nitrogen sources and minerals). Optimum environmental conditions for high surfactin production on the shake flask level were found to be a slightly acidic initial pH (6.5-6.8), an incubation temperature of 30 degrees C, a 90% volumetric aeration percentage, and an inoculum size of 2% v/v. For media components, it was found that the optimum carbon source was molasses (160 ml/l), whereas the optimum nitrogen source was NaNO(3) (5 g/l) and the optimum trace elements were ZnSO(4).7H(2)O (0.16 g/l), FeCl(3).6H(2)O (0.27 g/l), and MnSO(4).H(2)O (0.017 g/l). A modified MSM (molasses MSM), combining the optimum medium components, was formulated and resulted in threefold increase in surfactin productivity that reached 1.12 g/l. No plasmid could be detected in the tested isolate, revealing that biosurfactant production by B. subtilis isolate BS5 is chromosomally mediated but not plasmid-mediated.     

Dicobalt hexacarbonyl complexes of alkynyl imines in a sequential Staudinger/Pauson-Khand process. A route to new fused tricyclic beta-lactams

Dicobalt hexacarbonyl complexes of alkynyl imines were allowed to react with ketenes via Staudinger reaction. Sequential [2 + 2] cycloaddition/Pauson-Khand reaction led to structurally new fused-tricyclic beta-lactams and fused-azabicyclic cyclopentenones. Chemoselectivity, scope, and limitation of the process were investigated.