Synthesis,molecular modeling,TD-DFT,antimicrobial, and in vitro therapeutic activity of new spherical nano-sized sulfonamide imine ligands and their zinc (II) and copper (II) complexes

A series of nanometer-sized spherical sulfonamide imine ligands HL ¹ -HL ⁵ and their copper and zinc complexes were synthesized and fully characterized based on elemental analyses, spectroscopic (UV/vis, FT-IR, NMR, EPR, SEM) studies, molar conductance and thermal analyses. Furthermore, computational studies of HL ¹ -HL ⁵ were carried out by the DFT/B3LYP method. TD-DFT, HOMO and LUMO energy values, chemical hardness, electronegativity, electrophilic index, softness, and other parameters were calculated. Screening against several pathogenic microorganisms indicated that HL ¹ exhibited high activity against the tested Gram-negative bacteria relative to other analogues and the inhibition activity is greater than the standard Gentamicin. Analogously, HL ² exhibited high potent activity against the tested Gram-positive bacteria. Copper complexes exhibited a higher potent activity than zinc analogues. Noteworthy, inhibition activity of [Cu ( L ³ )(OAc)] complex is higher than that of the standard Ampicillin. [Cu ( L ² )(OAc)] complex displayed a similar activity of the standard bactericides and fungicides in use. The complexes showed appreciated values of MIC against bacterial strains: B. subtilis (MIC = 0.4 μg / mL), E. coli and S. pneumonia (MIC = 1.95 μg / mL) and P. aeruginosa (MIC = 7.81 μg / mL). in vitro cytotoxic activities study proved that [Cu ( L ³ )(OAc)] complex exhibited appreciable activity versus (HEPG-2); IC₅₀ = 4.8 μg/ml, while [Cu( L ² )(OAc)] complex showed a high activity against (MCF-7); IC₅₀ = 6.2 μg/ml. These results could be considered as new findings of promising antitumor candidates for experimental chemotherapy.     

Development and analysis of a malaria transmission mathematical model with seasonal mosquito life-history traits

In this paper, we develop and analyze a malaria model with seasonality of mosquito life-history traits: periodic-mosquitoes per capita birth rate, -mosquitoes death rate, -probability of mosquito to human disease transmission, -probability of human to mosquito disease transmission, and -mosquitoes biting rate. All these parameters are assumed to be time dependent leading to a nonautonomous differential equation system. We provide a global analysis of the model depending on two threshold parameters and (with ). When , then the disease-free stationary state is locally asymptotically stable. In the presence of the human disease-induced mortality, the global stability of the disease-free stationary state is guarantied when . On the contrary, if , the disease persists in the host population in the long term and the model admits at least one positive periodic solution. Moreover, by a numerical simulation, we show that a sub-critical (backward) bifurcation is possible at . Finally, the simulation results are in accordance with the seasonal variation of the reported cases of a malaria-epidemic region in Mpumalanga province in South Africa.     

Synthesis of Novel Semiconducting Aromatic Polyesteramids Containing Pyridine: Characterization of Nanometer-Sized Rod-Like Analogues and their Copper (II) Complexes

In this paper, new thermally stable isomeric unsubstituted polyesteramides have been successfully prepared by condensation of aromatic acids chlorides namely; isophthaloyl, pyridine-3,5-dicarbonyl and pyridine-2,6-pyridine-dicarbonyl dichlorides with the aminophenol isomers in NMP. Conducting the reaction in NMP/H₂O (90/10 v/v) followed by centrifugal separation furnished the desired polymers as rod-like nanoparticles. The morphology of obtained nanoparticles were studied by SEM. Mixing NMP with H₂O was essential for controlling the particles morphology and as a reaction accelerator.

Pyridine-containing polymers exhibit semi-conducting nature as their conductivities increase with increasing temperature, while no variation of the conductivity with the temperature was observed for their corresponding phenylene analogues. Introduction of the nitro group into the polymer backbone led to a red shift in the absorption and the obtained polymers have a bright yellow color, which is unusual with this polymer group. Copper (II) ions were complexed the polyesteramides-containing nitro group in a (1:1) ratio. Complexes of pyridine-containing polymers exhibit semiconducting nature changed to metallic characters on heating and their conductivities increased tens of magnitudes than their corresponding ligands. These new types of polymeric materials and their nano-sized rods may have numerous applications in nanotechnology and their properties can be tuned for specific applications such as conducting adhesives and coating materials.     

An application of Carlitz's formula

In this note we establish a new transformation formula for the generalized hypergeometric function of two variables. On specializing its parameters, it yields the interesting result:

${}_4\text{F}{}_3\text{γ2β?γ1+}\text{1}\text{2}\text{α,}\text{1}\text{2}\text{+}\text{1}\text{2}\text{α;1}\text{1}\text{2}\text{(1+2β),2+α,1+β;}\text{=}\text{βΓ(2β)Γ(2β?α?γγ)}\text{(β?γ)Γ(2β?α)Γ(2β?γ)}$

. valid for Rl(2β ? α ? γ) > 0. When γ = ?n (a negative integer), it reduces to a result due to Professor Carlitz. Several other new summation formulae for ₅F₄(1), ₄F₃(1) and for the hypergeometric function of two variables are obtained.     

Preparation of a set of selectively protected disaccharides for modular synthesis of heparan sulfate fragments: toward the synthesis of several <Emphasis Type="Italic">O</Emphasis>-sulfonated [β-D-GlcUA-(1→4)-β-D-GlcNAc]OPr types

A concise method for a stereocontrolled synthesis of a set of selectively protected disaccharides is reported. Coupling of the donor 11 onto acceptors 23 and 24, promoted by trimethylsilyl triflate-N-iodosuccinimide (TMSOTf-NIS), generated the disaccharides 25 and 26. Under typical conditions, condensation of the fully protected donor 12 onto acceptors 23 and 24 produced the disaccharides 27 and 28. The building blocks 25–28 were prepared in moderate yields having exclusive β-stereoselectivity. A unique pattern of protecting groups distinguished clearly between positions to be sulfated and functional groups remaining as free hydroxyl groups. Acetyl and/or levulinoyl esters temporarily protected the positions to be sulfated, while benzyl ethers were used for permanent protection. The anomeric positions were protected as allyl ethers, whereas the 4′-positions were masked as p-methoxybenzyl (PMB) ethers. The orthogonality of the PMB and allyl groups can then be used for further elongation of the chain by recurrent deprotection and activation steps. The hydroxyl group, OH-6, of glucosamine moieties was protected as a TBDPS ether to avoid oxidation. A five-step deprotection/sulfonation sequence was applied to the disaccharide 27 to generate the corresponding sulfated [β-D-GlcUA-2-OSO₃Na-(1→4)-β-D-Glc pNAc]-(1→O-Pro) 34.     

A novel anticancer diterpenoid from Jatropha gossypifolia

Jatropha gossypifolia root bark is used in ethnomedicine for bacterial infections and cancer of the lungs. Phytochemical investigation resulted in the isolation and characterization of a potent anticancer and novel lathyrane diterpenoid compound, abiodone, with an unusual methylene group. The structure of this novel compound was established by 1D, and 2D NMR spectroscopic experiments a nd confirmed by X-ray analysis.     

Spectroscopic study of 2-, 4- and 5-substituents on pKa values of imidazole heterocycles prone to intramolecular proton-electrons transfer

New 2-(1H-imidazol-2-yl)phenols (L1Et–L8tBuPt) bearing a phenolic proton in the vicinity of the imidazole base were prepared and characterized. Experimental studies of the dependence of their protonation/deprotonation equilibrium on substituent identities and intramolecular hydrogen bonding tendencies were carried out using electronic absorption spectroscopy at varying pH values. In order to make comparison, 2-(anthracen-10-yl)-4,5-diphenyl-1H-imidazole (L9Anthr) bearing no phenolic proton and 4,5-diphenyl-2-(4,5-diphenyl-1H-imidazol-2-yl)-1H-imidazole (L10BisIm) bearing two symmetrical imidazole base fragments were also prepared and experimentally investigated. DFT calculations were carried out to study frontier orbitals of the investigated molecules. While electron-releasing substituents produced increase in protonation–deprotonation pK_as for the hydroxyl group, values for the imidazole base were mainly affected by polarization of the imidazole ring aromaticity across the 2-imidazole carbon and the 4,5-imidazole carbons axis of the imidazole ring. It was concluded that electron-releasing substituents on the phenol ring and/or electron-withdrawing substituents on 4,5-imidazole carbons negatively affects donor strengths/coordination chemistries of 2-(1H-imidazol-2-yl)phenols, and vice versa. Change of substituents on the phenol ring significantly altered the donor strength of the imidazole base. The understanding of pK_a variation on account of electronic effects of substituents in this work should aid the understanding of biochemical properties and substituent environments of imidazole-containing biomacromolecules.     

Slow magnetic relaxation in mononuclear tetrahedral cobalt(II) complexes with 2-(1H-imidazol-2-yl)phenol based ligands

Three mononuclear cobalt(II) complexes based on the 2-(4,5-diphenyl-1H-imidazol-2-yl)phenol ligand and its nitro and methoxy derivatives have been synthesized and investigated. For two of these complexes, which were derived from the parent ligand and its nitro derivative, the molecular structures have been determined by X-ray crystallography. A distorted tetrahedral coordination environment is observed for the cobalt(II) centers with two bidentate N,O ligands. The magnetic properties have been studied by susceptibility and magnetization measurements revealing the presence of high-spin cobalt(II) ions with a considerable zero-field splitting in the order of D = –35 to –41 cm⁻¹ for the three complexes. With an applied dc field the ac susceptibility data reveal a slow magnetic relaxation which is characteristic for single-molecular magnet (SMM) behavior.