Cationic schiff base amphiphiles and their metal complexes: Surface and biocidal activities against bacteria and fungi

Growth Inhibition of Sulfate-Reducing Bacteria during Gas and Oil Production Using Novel Schiff Base Diquaternary Biocides: Synthesis, Antimicrobial, and Toxicological Assessment

Upstream crude oil production equipment is always exposed to destruction damagingly which is caused by sulfate-reducing bacterium (SRB) activities that produce H₂S gas, which leads to increased metal corrosion (bio-fouling) rates and inflicts effective infrastructure damage. Hence, oil and gas reservoirs must be injected with biocides and inhibitors which still offer the foremost protection against harmful microbial activity. However, because of the economic and environmental risks associated with biocides, the oil and gas sectors improve better methods for their usage. This work describes the synthesis and evaluation of the biological activities as the cytotoxicity and antimicrobial properties of a series of diquaternary cationic biocides that were studied during the inhibition of microbial biofilms. The prepared diquaternary compound was synthesized by coupling vanillin and 4-aminoantipyrene to achieve the corresponding Schiff base, followed by a quaternization reaction using 1,6-bromohexane, 1,8-bromooctane, and 1,12-bromododecane. The increase of their alkyl chain length from 6 to 12 methylene groups increased the obtained antimicrobial activity and cytotoxicity. Antimicrobial efficacies of Q1-3 against various biofilm-forming microorganisms, including bacteria and fungi, were examined utilizing the diameter of inhibition zone procedures. The results revealed that cytotoxic efficacies of Q1-3 were significantly associated mainly with maximum surface excess and interfacial characteristics. The cytotoxic efficiencies of Q1-3 biocides demonstrated promising results due to their comparatively higher efficacies against SRB. Q3 exhibited the highest cytotoxic biocide against the gram +ve, gram -ve, and SRB species according to the inhibition zone diameter test. The toxicity of the studied microorganisms depended on the nature and type of the target microorganism and the hydrophobicity of the biocide molecules. Cytotoxicity assessment and antimicrobial activity displayed increased activity by the increase in their alkyl chain length.

Corrosion Control of Carbon Steel in Water-Based Mud by Nanosized Metallo-Cationic Surfactant Complexes During Drilling Operations

In this work, three nanometal complexes named cetyltrimethyammonium dibromodichloro zincate (CT-Zn), cetyltrimethyammonium dibromodichloro cuprate (CT-Cu), and cetyltrimethyammonium dibromodichloro manganesate (CT-Mn) were prepared, characterized, and evaluated as corrosion inhibitors for carbon steel in water-based mud (WBM). The chemical structure of the prepared complexes was confirmed by the use of Fourier transform infrared spectroscopy, Raman spectroscopy, elemental analysis, atomic absorption spectroscopy, dynamic light scattering, and thermogravimetric analysis techniques. The surface tension of the complexes was measured. The critical micelle concentrations and some of the surface properties were also determined. The compounds were evaluated as corrosion inhibitors for carbon steel in the prepared WBM using potentiodynamic polarization and weight loss methods during the static and dynamic conditions of the drilling operations. The results indicated that the prepared metal complexes showed high anticorrosion action as the inhibition efficiency increased gradually with the increase in the concentrations of the prepared complexes until it reached the maximum value (93.1%) at 300 ppm for CT-Cu. The order of inhibition efficiency of these inhibitors was as follows: CT-Cu > CT-Zn > CT-Mn. The polarization curves showed that these complexes acted as mixed-type inhibitors. According to the results, the adsorption of these compounds obeyed Langmuir adsorption isotherm. Surface analysis of the carbon steel samples was investigated using scanning electron microscopy, energy dispersive X-ray, and X-ray diffraction techniques. Rheological properties, gel strength, thixotropy, and filtration properties were also measured according to American Petroleum Institute specifications.

Supraamphiphilic Systems Based on Metallosurfactant and Calix[4]resorcinol: Self-Assembly and Drug Delivery Potential

Metallic amphiphiles are used as building blocks in the construction of nanoscale superstructures, where the hydrophobic effects induce the self-assembly of the nanoparticles of interest. However, the influence of synergizing multiple chemical interactions on an effective design of these structures mostly remains an open question. In this regard, supraamphiphilic systems based on flexible surfactant molecules and rigid macrocycles are being actively developed, but there are few works on the interaction between metallosurfactants and macrocycles. In the present work, the self-assembly and biological properties of a metallosurfactant with calixarene were studied for the first time. The metallosurfactant, a complex between lanthanum nitrate and two 4-aza-1-hexadecylazoniabicyclo[2.2.2]octane bromide units, and calix[4]resorcinol containing sulfonate groups on the upper rim were used to form a novel supraamphiphilic composition. The system formed was studied using a variety of physicochemical methods, including spectrophotometry, NMR, XRF, and dynamic and electrophoretic light scattering. It was found that the most optimal tetraanionic calix[4]resorcinol to dicationic metallosurfactant molar ratio, leading to mixed aggregation upon ion pair complexation, is 2:3. The mixed aggregates formed in the pentamolar concentration range were able to encapsulate hydrophilic substrates, including the anticancer drug cisplatin, the pure form of which is more cytotoxic toward healthy cells than toward diseased cells. Interestingly, the drug loaded into the macrocycle-metallosurfactant particles was less cytotoxic to a healthy Chang liver cell line and more cytotoxic to tumor M-HeLa cells. This selectivity depends on the amount of cisplatin added. The more drug is added to the macrocycle-metallosurfactant composition, the greater the biological activity against cancer cells. Taking into account that the appearance of resistance of cancer cells to drugs, especially to cisplatin, is one of the most important problems in treatment, the results of this work envisage the potential application of a mixed macrocycle-metallosurfactant system for the design of therapeutic cisplatin compositions.

Multiple Applications of a Novel Cationic Gemini Surfactant: Anti-Microbial, Anti-Biofilm, Biocide, Salinity Corrosion Inhibitor, and Biofilm Dispersion (Part II)

The Egyptian petroleum industries are incurring severe problems with corrosion, particularly corrosion that is induced by sulfidogenic microbial activities in harsh salinity environments despite extensively using biocides and metal corrosion inhibitors. Therefore, in this study, a synthesized cationic gemini surfactant (SCGS) was tested as a broad-spectrum antimicrobial, anti-bacterial, anti-candida, anti-fungal, anti-biofilm (anti-adhesive), and bio-dispersion agent. The SCGS was evaluated as a biocide against environmental sulfidogenic-bacteria and as a corrosion inhibitor for a high salinity cultivated medium. The SCGS displayed wide spectrum antimicrobial activity with minimum bactericidal/fungicidal inhibitory concentrations. The SCGS demonstrated anti-bacterial, anti-biofilm, and bio-dispersion activity. The SCGS exhibited bactericidal activity against environmental sulfidogenic bacteria and the highest corrosion inhibition efficiency of 93.8% at 5 mM. Additionally, the SCGS demonstrated bio-dispersion activity against the environmental sulfidogenic bacteria at 5.49% salinity. In conclusion, this study provides a novel synthesized cationic surfactant with many applications in the oil and gas industry: as broad-spectrum antimicrobial and anti-biofilm agents, corrosion inhibition for high salinity, biocides for environmentally sulfidogenic bacteria, and as bio-dispersion agents.

Synthesis, Spectral Characterization, and Thermal and Cytotoxicity Studies of Cr(III), Ru(III), Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) Complexes of Schiff Base Derived from 5-Hydroxymethylfuran-2-carbaldehyde

Coordination compounds of Cr(III), Ru(III), Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) ions were synthesized from the furan ligand [5-hydroxymethylfuran-2-yl-methyleneaminoquinolin-2-one] (H-MFMAQ) derived from the condensation of 5-hydroxymethylfuran-2-carbaldehyde and 1-aminoquinolin-2(1H)-one. Elemental analytical data, IR, NMR (1H, 13C, and 15N), EPR, XRD, SEM, TEM, EDX, TGA, mass, molar conductance, magnetic moment, and UV-Visible spectra techniques were used to confirm the structure of the synthesized chelates. According to the data obtained, the composition of the 1 : 1 metal ions : furan Schiff base ligand was found to be [M(MFMAQ)Cl2] (M = Cr(III) and Ru(III)) and [M(MFMAQ)Cl(H2O)]·nH2O in which (M = Mn(II); n=1, Co(II); n=0, Ni(II); n=2, Cu(II); n=0 and Zn(II); n=2.5). The measurements of magnetic susceptibility, ligand field parameter, and reflectance spectra suggested an octahedral geometry for the complexes. Central metals ions and furan Schiff base coordinated via O3 and N donor sites which was observed from IR spectra. The cytotoxic activities of all inspected compounds were evaluated towards human breast (MCF-7) and lung cancer (A549) cell lines.

Investigation of Antimicrobial, Antioxidant, and DNA Binding Studies of Bioactive Cu(II), Zn(II), Co(II), and Ni(II) Complexes of Pyrimidine Derivative Schiff Base Ligand

A new pyrimidine based Schiff base ligand (HL) and its four complexes of type [MLOAc]·nH2O (Cu(II), 1; Zn(II), 2; Co(II), 3; and Ni(II), 4) have been synthesized and characterized by elemental analysis, MS, 1H-NMR, FT-IR, UV-visible, and ESR techniques. The electronic and ESR spectral data suggested that complexes 1–4 possess square planar geometry. Antimicrobial activities of HL and complexes 1–4 were tested against four bacteria (Staphylococcus aureus, Staphylococcus pneumonia, Salmonella enterica typhi, and Haemophilus influenzae) and two fungal strains (Aspergillus flavus and Aspergillus niger). These results show that complexes 1–4 have good antimicrobial activity compared to HL. The DNA cleavage activity of HL and complexes 1–4 was monitored by the agarose gel electrophoresis method. The antioxidant property of the prepared compounds was assessed by using 2,2′-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging method. DNA binding properties of HL and complexes 1–4 have been investigated by electronic absorption technique and viscometric measurements.

Screening the DNA interaction ability and antimicrobial activity of a few novel bioactive complexes tethering N-((2-aminophenyl)(phenyl)methylene)-4-nitroaniline

Few novel transition metal complexes having N-((2-aminophenyl)(phenyl)methylene)-4-nitroaniline were synthesized and characterized by elemental analyses, IR, (1)H and (13)C NMR, electronic, EPR and mass spectra, conductivity and magnetic susceptibility measurements. All the metal complexes adopted square planar geometrical arrangements. The DNA-binding properties of the metal(II) complexes have been investigated by electronic absorption, fluorescence, CD spectra, cyclic voltammetry, differential pulse voltammogram and viscosity measurements. The results obtained indicate that these complexes bind to DNA via an intercalation binding mode. DNA cleavage activities indicate that the metal complexes exhibit greater activity than the ligand. The antimicrobial screening reveals that all the metal complexes exhibit better activity than the free ligand.

Subphase exchange experiments with the pendant drop technique

INTRODUCTION

The development of the coaxial double capillary 15 years ago opened up the possibility to undertake accurate desorption and penetration studies of interfacial layers in the pendant drop technique. Drop and bubble methods offer several advantages with respect to other interfacial techniques. They allow a more stringent control of the environmental conditions, use smaller amounts of material and provide a much higher interface/volume ratio than in conventional Langmuir Troughs.

EXPERIMENTAL

The coaxial capillary was developed 15 years ago at the University of Granada as an accessory for the pendant drop surface film balance. It allows exchanging the subphase of the drop without disturbing the surface film and preserving the drop volume throughout the subphase exchange. Hence, this methodology enables one to carry out a great variety of interfacial studies well beyond the usual adsorption profiles. Penetration studies, sequential adsorption measurements, desorption kinetics, reversibility of adsorption and testing of enzymatic treatments on interfacial layers are amongst the principal applications. The coaxial capillary has been recently upgraded to a multi-exchange device which has boosted its applicability. It can be now used to address multilayer formation, create soft interfacial nano-composites such as membranes, polyelectrolyte assemblies and simulate in vitro digestion in a single droplet.

APPLICATIONS

This review aims to compile the experimental work done, using the pendant drop subphase exchange in the last decade, and how its use has provided new insights into the surface/interfacial properties of many different materials. Special emphasis is placed on recent work regarding simulation of in vitro digestion in order to address issues relating to metabolism degradation profiles. The use of this methodology when dealing with interfacial studies allows setting the foundations of interfacial engineering technology. Based on subphase exchange experiments, we aim to develop models for competitive adsorption of different compounds at the interface and build up layer-by-layer interfacial structures. Future challenges comprise the design of finely adjusted nanoengineering systems, based on multilayer assemblies with tailored functionalities, to match the application demand.

A novel, rapid and automated conductometric method to evaluate surfactant-cells interactions by means of critical micellar concentration analysis

Conductometry is widely used to determine critical micellar concentration and micellar aggregates surface properties of amphiphiles. Current conductivity experiments of surfactant solutions are typically carried out by manual pipetting, yielding some tens reading points within a couple of hours. In order to study the properties of surfactant-cells interactions, each amphiphile must be tested in different conditions against several types of cells. This calls for complex experimental designs making the application of current methods seriously time consuming, especially because long experiments risk to determine alterations of cells, independently of the surfactant action. In this paper we present a novel, accurate and rapid automated procedure to obtain conductometric curves with several hundreds reading points within tens of minutes. The method was validated with surfactant solutions alone and in combination with Saccharomyces cerevisiae cells. An easy-to use R script, calculates conductometric parameters and their statistical significance with a graphic interface to visualize data and results. The validations showed that indeed the procedure works in the same manner with surfactant alone or in combination with cells, yielding around 1000 reading points within 20 min and with high accuracy, as determined by the regression analysis.

Synthesis of Some Novel Sulfonamide Derivatives and Investigating their Biocidal Activity in Cooling Towers

A novel series of dibenzothiophenedioxide sulphonamide derivatives were synthesized and tested as antimicrobial agents. The chemical structures of the prepared compounds were confirmed by micro elemental analysis, fourier transform infrared (FT-IR) and proton nuclear magnetic resonance spectroscopy (H-NMR). The surface parameters of two of the prepared compounds were determined at 35°C including, surface tension, effectiveness, maximum surface excess and minimum surface area. Also the standard free energy of micellization and adsorption were recorded. The results showed that the prepared sulphonamides have good surface properties and effective antimicrobial activity against thirty three test organisms isolated from cooling towers.

A novel bioactive tyramine derived Schiff base and its transition metal complexes as selective DNA binding agents

A novel tyramine derived Schiff base, 3-4-dimethoxybenzylidene-4-aminoantipyrinyl-4-aminoethylphenol(L) and a series of its transition metal complexes of the type, ML2Cl2 where, M=Cu(II), Ni(II), Co(II) and Zn(II) have been designed and synthesized. Their structural features and other properties were deduced from the elemental analysis, magnetic susceptibility and molar conductivity as well as from mass, IR, UV-vis, 1H NMR and EPR spectral studies. The binding properties of these complexes with calf thymus DNA (CT-DNA) were investigated using electronic absorption spectroscopy, viscosity measurement, cyclic voltammetry and molecular docking analysis. The results reveal that the metal(II) complexes interact with DNA through minor groove binding. The interaction has also been investigated by gel electrophoresis. Interestingly, it was found that all the complexes could cleave the circular plasmid pUC19 super coiled (SC) DNA efficiently in the presence of AH2 (ascorbic acid). The complexes showed enhanced antifungal and antibacterial activities compared to the free ligand.

Tetradentate schiff base ligands of 3,4- diaminobenzophenone: Synthesis, characterization and thermodynamics of complex formation with Ni(II), Cu(II) and Zn(II) metal ions

Some new symmetrical diimino tetradentate Schiff base ligands were synthesized by the reaction of 3,4-diaminobenzophenone with salicylaldehyde derivatives, such as [N,N?-bis(4-methoxysalicylaldehyde)- 3,4-diaminobenzophenone] (L1), [N,N?-bis(5-methoxysalicylaldehyde)- 3,4-diaminobenzophenone] (L2), [N,N?-bis(5-bromosalicylaldehyde)-3,4- diaminobenzophenone] (L3), [N,N?-bis(5-nitrosalicylaldehyde)-3,4- diaminobenzophenone] (L4). Additionally, a tetradentate Schiff base ligand [N,N?-bis(3-methoxysalicylaldehyde)-3,4-diaminobenzophenone] (L5), was synthesized. All the Schiff bases and their Ni(II), Cu(II) and Zn(II) complexes were characterized using elemental analysis and infrared, electronic, mass and 1H-NMR spectroscopy. The formation constants of the complexes were measured using UV-Vis spectroscopic titration at constant ionic strength 0.1 M (NaClO4), at 25?C in dimethylformamide (DMF) as solvent.