Synthesis and antimicrobial activity of some new benzo and naphthonitrile derivatives

5-Amino-2-aryl-2H-1,2,3-triazole-4-carboxamides: Unique AIEE-gens and selective Hg2+ fluorosensors

A series of fluorescent sensors based on small molecule were designed and fully characterised, demonstrating AIEE effect and revealing an outstanding ability to selectively detect Hg²⁺ ions. The structural and electronic properties were studied through quantum chemical calculations at (Time-Dependent) Density Functional Theory ((TD)-DFT) level. Carboxamides of 2-Aryl-1,2,3-Triazoles (CATs) showed significant differences in their photophysical properties depending on the structure of the substituent at amino function on the C5-atom in the heterocycle. When the tert-cycloalkylamino group (pyrrolidine, piperidine, azepane) was attached, the triazoles exhibited highly intensive blue fluorescence, with quantum yields (QYs) up to 95 % and lifetime up to 6.9 ns in different solvents, whereas the QYs of congeners bearing secondary alkylaminogroups (viz., NHMe, NHC₆H₁₁-cyclo) indicate low QYs (1-10 %). Nevertheless, all types of the obtained fluorophores demonstrated excellent AIEE effect and formed fluorescent nanoparticles in a binary mixtures of organic solvents and water. The introduction of the carboxamide function enhances the sensing properties of 2-aryl-1,2,3-triazoles, providing a selective fluorescence quenching reaction in the presence of Hg²⁺. The fluorescence intensity of the CATs declines with the addition of 1.0 eq. of Hg²⁺ into DMSO-water (v/v, 1:9). The other cations used did not induce any appreciable changes in fluorescence intensity. The CATs form a complex with Hg²⁺ with highly specific detection for Hg²⁺ over other competitive metal ions: the detection limits were determined to be 0.23 and 0.15 μM for the CATs 1b and 2c. The reverse effect was registered with the addition of ethylene diamine sodium salt; meanwhile, the CATs demonstrated more effective coordination with Hg²⁺ in comparison with cysteine. This last finding, as well as the ability to detect Hg²⁺, is very valuable for application within biology and medicine.

Synthesis, computational and antimicrobial evaluation of some new pyridine derivatives

A series of pyridine compounds were prepared by using 3-(dimethylamino)-1-(pyridin-4-yl)prop-2-en-1-one (14) as a precursor. The reaction of 14 with different reagents afforded different new heterocyclic compounds. All the new compounds were characterized by spectroscopic analyses. Moreover, the density function theory study was made to establish the geometry of the tested compounds. The antimicrobial activities of the newly prepared pyridine derivatives were studied against Gram-positive bacteria (Bacillus subtilis and Bacillus thuringiensis) and Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa) and fungi (Fusarium oxysporum and Botrytis fabae) by the minimal inhibitory concentration method. Compounds belonging to the pyran 32, pyridine 33, indenopyran 34, thiazolopyridine 35, and chromene 39 series displayed a high antimicrobial activity. It was found that the experimental results of the biological evaluation were in agreement with the molecular modeling studies.

AgNO3 as Nitrogen Source for Cu-Catalyzed Cyclization of Oximes with Isocyanates: A Facile Route to N-2-Aryl-1,2,3-triazoles

A versatile copper-catalyzed [3 + 1 + 1] annulation of oximes and isocyanates with AgNO₃ is described. In this conversion, AgNO₃ and isocyanates instead of conventional azide or diazonium reagents were used as the nitrogen source. This three-component transformation was achieved by cleaving N-O/C-H/C-N bonds and building C═N/N-N bonds, which provides a strategy to prepare N-2-aryl-1,2,3-triazoles with a good substrate and functional compatibility.

A Compendium of the Most Promising Synthesized Organic Compounds against Several Fusarium oxysporum Species: Synthesis, Antifungal Activity, and Perspectives

Vascular wilt caused by F. oxysporum (FOX) is one of the main limitations of producing several agricultural products worldwide, causing economic losses between 40% and 100%. Various methods have been developed to control this phytopathogen, such as the cultural, biological, and chemical controls, the latter being the most widely used in the agricultural sector. The treatment of this fungus through systemic fungicides, although practical, brings problems because the agrochemical agents used have shown mutagenic effects on the fungus, increasing the pathogen's resistance. The design and the synthesis of novel synthetic antifungal agents used against FOX have been broadly studied in recent years. This review article presents a compendium of the synthetic methodologies during the last ten years as promissory, which can be used to afford novel and potential agrochemical agents. The revision is addressed from the structural core of the most active synthetic compounds against FOX. The synthetic methodologies implemented strategies based on cyclo condensation reactions, radical cyclization, electrocyclic closures, and carbon-carbon couplings by metal-organic catalysis. This revision contributes significantly to the organic chemistry, supplying novel alternatives for the use of more effective agrochemical agents against F. oxysporum.

Heterocycle Compounds with Antimicrobial Activity

Background:

Bacterial infections are a growing problem worldwide causing morbidity and mortality mainly in developing countries. Moreover, the increased number of microorganisms, developing multiple resistances to known drugs, due to abuse of antibiotics, is another serious problem. This problem becomes more serious for immunocompromised patients and those who are often disposed to opportunistic fungal infections.

Objective:

The objective of this manuscript is to give an overview of new findings in the field of antimicrobial agents among five-membered heterocyclic compounds. These heterocyclic compounds especially five-membered attracted the interest of the scientific community not only for their occurrence in nature but also due to their wide range of biological activities.

Method:

To reach our goal, a literature survey that covers the last decade was performed.

Results:

As a result, recent data on the biological activity of thiazole, thiazolidinone, benzothiazole and thiadiazole derivatives are mentioned.

Conclusion:

It should be mentioned that despite the progress in the development of new antimicrobial agents, there is still room for new findings. Thus, research still continues.

Enantioselective cyanation via radical-mediated C-C single bond cleavage for synthesis of chiral dinitriles

Ring-opening reaction via selective cleavage of C–C bond is known as a powerful strategy for construction of complex molecules. Complementary to the ionic process focusing on mostly small ring systems, radical-mediated C–C bond cleavage offers a solution for further diverse enantioselective functionalization benefited from its mild conditions, whereas such asymmetric transformations are still limited to three-membered rings so far. Herein, we describe radical-mediated ring-opening and enantioselective cyanation of four- and five-membered cycloketone oxime esters to access chiral 1,5- and 1,6-dinitriles. Employment of dual photoredox/copper catalysis is essential for the asymmetric ring-opening cyanation of cyclopentanone oxime esters. Both reactions proceed under mild conditions giving chiral dinitriles in high yields and enantioselectivity with low catalyst loading and broad substrate scope. The products dinitriles can be converted to valuable optically active diamides and diamines. Mechanistic studies indicate that the benzylic radical generated via C–C single bond cleavage is involved in the catalytic cycle.

Ring-opening reaction via selective cleavage of C–C bond is a powerful strategy to increase molecular complexity. Here the authors present the facile synthesis of chiral 1,5- and 1,6-dinitriles via the radical-mediated ring-opening and enantioselective cyanation of cycloketone oxime esters.

Synthesis of Pharmacological Heterocyclic Derivatives Based Surfactants

Synthesis of chromenopyrimidine derivatives and the related fused system carried out by the reaction of chromene derivative 1 with various reagents under suitable reaction conditions. Condensation of stearoyl chloride with these heterocycles, then, propoxylated the products using propylene oxide to produce surface active agents having a twofold capacity as surface and antimicrobial dynamic specialists which may be served in the production of medications, pesticides, beautifying agents or may be utilized as an antimicrobial. Some of the surface properties and antimicrobial activity were resolved.

Nanoformulation and antimicrobial evaluation of newly synthesized thiouracil derivatives

The present work reports the synthesis of a new series of pyridopyrimidine derivatives. The newly synthesized compounds were characterized by various analytical and spectral techniques. In addition, their antimicrobial activity was evaluated as well as modeling studies were performed to investigate their ability to recognize and bind to the biotin carboxylase (BC)-active site. The results showed a broad spectrum antibacterial and antifungal profile of the synthesized derivatives. Docking results demonstrated that all members of this class of new derivatives were able to recognize the active site of Escherichia coli BC and form different types of bonding interactions with key active site amino acid residues. Besides the compounds with promising antimicrobial activity in addition to 6-aminothiouracil, as control, were incorporated into polycaprolactone nanoparticles to improve their water solubility, permeability through physiological barriers and consequently enhanced therapeutic efficacy. The compounds-loaded nanoparticles were prepared using single emulsion-solvent evaporation technique, and their diameters were found to be in the range 136 ± 30 to 213 ± 28 nm. Transmission electron microscopy (TEM) showed a spherical and dense morphology of the nanoparticles. The results also showed high entrapment efficiency of the synthesized bioactive compounds in the nanoparticles (85 ± 5% to 91 ± 2%) with a desirable in vitro biodegradation and release profiles.

Inhibition of selected bacterial growth by three hydrocarbons: mathematical evaluation of toxicity using a toxicodynamic equation

The individual toxicity of different hydrocarbons (naphthalene, cyclododecane and aniline) on the growth of selected bacteria (Pseudomonas sp., Phaeobacter sp. and Leuconostoc mesenteroides) was studied by means of a toxicodynamic model combination of two sigmoid equations (logistic and Weibull). All the toxicological effects on growth parameters and kinetic properties were characterized and the global toxicity of such chemicals was evaluated. It was observed that two kinetic parameters (maximum growth and maximum growth rate) were in almost all cases influenced by the hydrocarbons studied. Aniline was less toxic than cyclododecane and naphthalene. The presented approach is a reasonable starting point for understanding and modeling complete and real assessment of chemical toxic effects on bacterial growths. The values of EC50,τ could be used for a most efficient comparison of the individual toxicity of chemicals.

Quantum chemical study on influence of intermolecular hydrogen bonding on the geometry, the atomic charges and the vibrational dynamics of 2,6-dichlorobenzonitrile

FT-IR (4000-400 cm(-1)) and FT-Raman (4000-200 cm(-1)) spectral measurements on solid 2,6-dichlorobenzonitrile (2,6-DCBN) have been done. The molecular geometry, harmonic vibrational frequencies and bonding features in the ground state have been calculated by density functional theory at the B3LYP/6-311++G (d,p) level. A comparison between the calculated and the experimental results covering the molecular structure has been made. The assignments of the fundamental vibrational modes have been done on the basis of the potential energy distribution (PED). To investigate the influence of intermolecular hydrogen bonding on the geometry, the charge distribution and the vibrational spectrum of 2,6-DCBN; calculations have been done for the monomer as well as the tetramer. The intermolecular interaction energies corrected for basis set superposition error (BSSE) have been calculated using counterpoise method. Based on these results, the correlations between the vibrational modes and the structure of the tetramer have been discussed. Molecular electrostatic potential (MEP) contour map has been plotted in order to predict how different geometries could interact. The Natural Bond Orbital (NBO) analysis has been done for the chemical interpretation of hyperconjugative interactions and electron density transfer between occupied (bonding or lone pair) orbitals to unoccupied (antibonding or Rydberg) orbitals. UV spectrum was measured in methanol solution. The energies and oscillator strengths were calculated by Time Dependent Density Functional Theory (TD-DFT) and matched to the experimental findings. TD-DFT method has also been used for theoretically studying the hydrogen bonding dynamics by monitoring the spectral shifts of some characteristic vibrational modes involved in the formation of hydrogen bonds in the ground and the first excited state. The (13)C nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated by the Gauge independent atomic orbital (GIAO) method and compared with experimental results. Standard thermodynamic functions have been obtained and changes in thermodynamic properties on going from monomer to tetramer have been presented.

Synthesis and antimicrobial activity of some novel hydrazide, benzochromenone, dihydropyridine, pyrrole, thiazole and thiophene derivatives

As a part of ongoing studies in developing new potent antimicrobial agents, a novel synthesis of 2-cyano-N-(1-(3-oxo-3H-benzo[f]chromen-2-yl)ethylidene)acetohydrazide (3) has been reported. The latter compound was reacted with different reagents to give new heterocyclic compounds. The structures of the newly synthesized compounds were confirmed by elemental analysis, IR, (1)H NMR, (13)C NMR and mass spectral data. Representative compounds of the synthesized products were tested and evaluated as antimicrobial agents.