Stability Constants Research Articles

Inclusion Complexes of Ethanamizuril with β- and Hydroxypropyl-β-Cyclodextrin in Aqueous Solution and in Solid State: A Comparison Study

Ethanamizuril (EZL) is a new anticoccidial drug developed by our Shanghai Veterinary Research Institute. Since EZL is almost insoluble in water, we conducted a study to improve the solubility of EZL by forming inclusion complexes with β-cyclodextrin (β-CD) and hydroxypropyl-β-cyclodextrin (HP-β-CD). In this study, we performed molecular docking and then systematically compared the interactions of EZL with β-CD and HP-β-CD in both aqueous solution and the solid state, aiming to elucidate the solubilization effect and mechanism of cyclodextrins (CDs). The interactions were also examined in the solid state using DSC, PXRD, and FT-IR. The interactions of EZL with CDs in an aqueous solution were investigated using PSA, UV-vis spectroscopy, MS, 1H NMR, and 2D ROESY. The results of phase solubility experiments revealed that both β-CD and HP-β-CD formed inclusion complexes with EZL in a 1:1 molar ratio. Among them, HP-β-CD exhibited higher Kf (stability constant) and CE (complexation efficiency) values as well as a stronger solubilization effect. Furthermore, the two cyclodextrins were found to interact with EZL in a similar manner. The results of our FT-IR and 2D ROESY experiments are in agreement with the theoretical results derived from molecular simulations. These results indicated that intermolecular hydrogen bonds existing between the C=O group on the triazine ring of EZL and the O-H group of CDs, as well as the hydrophobic interactions between the hydrogen on the benzene ring of EZL and the hydrogen of CDs, played crucial roles in the formation of EZL/CD inclusion complexes. The results of this study can lay the foundation for the future development of high-concentration drinking water delivery formulations for EZL.

Complexes of Gold(III) with Hydrazones Derived from Pyridoxal: Stability, Structure, and Nature of UV-Vis Spectra.

Pyridoxal and pyridoxal 5'-phosphate are aldehyde forms of B6 vitamin that can easily be transformed into each other in the living organism. The presence of a phosphate group, however, provides the related compounds (e.g., hydrazones) with better solubility in water. In addition, the phosphate group may sometimes act as a binding center for metal ions. In particular, a phosphate group can be a strong ligand for a gold(III) ion, which is of interest for researchers for the anti-tumor and antimicrobial potential of gold(III). This paper aims to answer whether the phosphate group is involved in the complex formation between gold(III) and hydrazones derived from pyridoxal 5'-phosphate. The answer is negative, since the comparison of the stability constants determined for the gold(III) complexes with pyridoxal- and pyridoxal 5'-phosphate-derived hydrazones showed a negligible difference. In addition, quantum chemical calculations confirmed that the preferential coordination of two series of phosphorylated and non-phosphorylated hydrazones to gold(III) ion is similar. The preferential protonation modes for the gold(III) complexes were also determined using experimental and calculated data.

Colloidal titration: From the perspective of stability constants between oppositely charged polyelectrolytes

Abstract Colloidal titration is a unique method to measure the concentration of charged groups based on the association between cationic and anionic colloids. Titrimetry must involve a unidirectional reaction with a large formation constant. However, the underlying polyelectrolyte complex (PEC) for colloidal titration lacks sufficient data regarding the stability constants (KI). To date, the stoichiometry of colloidal titration has not been discussed in relation to KI. Thus, in this paper, we reviewed PEC studies by focusing on KI and discuss colloidal titration comprehensively. The topics include the history of its establishment, the method to calculate KI, and the special characteristics of PEC compared with ion association reactions, the practical use of colloid titration, and the condition by which the stability constant can be increased. In terms of analytical reagents, polyelectrolytes are similar to (but positioned as a subspecies of) ion association reagents. Ionic strength strongly affects KIs values. Excluding coaggregation effects, the maximum values of log10  KI obtained from reliable data were found to decrease linearly with as ionic strength increases logarithmically. The critical line connected with the maximum KI value at each ionic strength can be used as an empirical reference value and facilitate the analytical design of colloidal titration.

Caged anions in bistren cryptands: Determination of the stability constants by cellmetry method

Bistren host ligands can form stable complexes with different types of anions due to their wide range of structural properties capable of constructing a preferred cavity for the guest anion. Employing a newly developed method, (highly) accurate logK values can be calculated. A standard cell size set was used for most of the complexes; however, based on the energy of the host ligands and the type of the guest anions, some trends and correlations were found to determine the relevant cell sizes of some host ligands. The cell size of the complexes and the anions were always the same. Some unanswered questions in previous experimental studies could also be addressed by the results regarding the highly protonated (LH77+) bistren ligands. For larger complexes, a strategy was developed to calculate accurate stability constants. Based on these results, complexes formed by glyphosate were also studied, and their logK values were predicted.

Implication of metal complexes in biology and medicine, the system cadmium (II)/iron (II)/zinc (II) – sarcosine

Implication of metal complexes in biology and medicin, the system cadmium (II)/iron (II) / zinc (II) – sarcosine. A technique involving the use of paper Electrophoretic Technique is described for the study of equilibria in binary complex system in solution. This methodis based upon the migration of a spot of metal ion on a paper strip at different pH values of background electrolyte containing 0.1 mol L -1 perchloric acid and 0.01 mol L -1 sarcosine. A graph of pH against mobility gives information about the binary complexes and permit to calculate their stability constants. The first and second stability constants of [Cd (II) – sarcosine], [Fe (II) – sarcosine] and [Zn (II) – sarcosine] complexes were found to be (3.94 ± 0.03; 2.66 ± 0.07), (3.70 ± 0.01; 2.54 ± 0.03) and (4.39 ± 0.01; 2.74 ± 0.07) logarithm stability constant values for Cd (II), Fe (II) and Zn (II) complexes, respectively at ionic strength 0.1 Mol L -1 and temperature of 35 0 C. The stability constants follow the order: Cd (II) > Fe (II) > Zn (II).

Metal Complexes in Biology and Medicine the System Cadmium (II) / Iron (II) /Zinc (II) - Proline

Metal ions are fundamental elements for the maintenance of the life span’ s of the humans, animals and plants. In coordination compound studies, a knowledge of the magnitude of the stability constants of complexes is necessary for preliminary quantitative treatment. Present work described method that involves the use of paper electrophoretic technique for the study of the equilibria in binary complex systems in solution. This method is based on the movement of a spot of metal ion in an electric field at various pHs of the background electrolyte. A plot of overall mobility of metal / complex ion versus pH was used to obtain information on the formation of binary complexes and to calculate their stability constants. The stability constant of the ML and ML2 complexes of cadmium (II) – proline,iron(II) – proline and zinc(II) – proline, have been found to be (4.61 ± 0.01; 3.04 ± 0.03), (4.21 ± 0.01; 2.89 ± 0.09) and (4.98 ± 0.02; 2.44 ± 0.05) (logarithm constant values), respectively at 35 ºC and ionic strength 0.1 mol L-1. The first and second stability constants follow the order zinc (II) >cadmium (II) > iron (II). Metal complexes can offer their action such as anti-inflammatory, antidiabetic, antimicrobial, anticancer and ant thyroid compounds. Metal based drugs bioactivity can be increase by metal chelation, which in turn increase their absorbance and stability.

Heterocyclic fluorescent Schiff base chemosensors for the detection of Fe(III) and Cu(II) ions.

Two new Schiff bases were synthesized from 1-(2,4-dihydroxyphenyl)ethanone and pyridine derivatives. Both compounds were characterized using infrared, UV-Vis., 1H NMR, 13C NMR and mass spectral studies. Density functional theory (DFT) calculations were performed for both the Schiff bases with 6-31G(d, p) as the basis set. Vibrational frequencies calculated using the theoretical method were in good agreement with the experimental values. Both the Schiff bases were highly fluorescent in nature. The cation-recognizing profile of the compounds was investigated in aqueous methanol medium. The Schiff base 4-(1-(pyridin-4-ylimino)ethyl)benzene-1,3-diol (PYEB) was found to interact with Fe(III) and Cu(II) ions, whereas the Schiff base 4,4'-((pyridine-2,3-diylbis(azanylylidene))bis(ethan-1-yl-1-ylidene))bis(benzene-1,3-diol) (PDEB) was found to detect Cu(II) ions. The mechanism of recognition was established as combined excited state intramolecular proton transfer (ESIPT)-chelation-enhanced fluorescence (CHEF) effect and chelation-enhanced quenching (CHEQ) process for the detection of Fe(III) and Cu(II) ions, respectively. The stability constant of the metal complexes formed during the sensing process was determined. The limit of detection for Fe(III) and Cu(II) ions with respect to Schiff base PYEB was found to be 1.64 ×10-6 and 2.16 ×10-7M, respectively. With respect to Schiff base PDEB, the limit of detection for Cu(II) ion was found to be 4.54 ×10-4M. The Cu(II) ion sensing property of the Schiff base PDEB was applied in bioimaging studies for the detection of HeLa cells.

Room-temperature stable Perillaldehyde—Natural cyclodextrin inclusion complexes: Preparation, characterization, thermal stability, water solubility, antioxidant activity and slow–release performance

The compound Perillaldehyde (PA) is a bioactive constituent found in natural Perilla oil, exhibiting remarkable antibacterial and antioxidant activity. However, the instability of this compound caused by the easy oxidation of its aldehyde and olefin groups imposes limitations on its extensive applications. Therefore, it is crucial to develop effective strategies for enhancing the stability of PA. This study focuses on utilizing a series of natural cyclodextrins (CDs) to synthesize inclusion complexes (ICs) with PA, aiming to improve water solubility and achieve exceptional stability at room temperature, which is essential for their potential applications in biomedicine or food industries. The hydrophobic cavity of CDs can accommodate the hexatomic ring and hydrophobic chains of PA based on the well-known size-matching effect and hydrophobic interaction, thereby forming stable ICs. Additionally, the hydrophilic outer wall of CDs imparts excellent water solubility to ICs. Phase solubility investigations demonstrate successful construction of α-CD-PA IC and β-CD-PA IC with an inclusion ratio of 1:1. Their respective stability constant (KC) are determined as 342 L/mol and 180 L/mol, indicating superior stability for α-CD-PA IC compared to β-CD-PA IC. Conversely, γ-CD with a larger cavity fails to form a stable inclusion complex with PA due to inadequate size matching. Nuclear Magnetic Resonance Hydrogen Spectroscopy (1H and 2D NMR) studies reveal that PA enters the CDs cavity (α-CD or β-CD) from its wide rim with almost the entire molecule being obliquely embedded within it. Thermogravimetry Analysis (TGA) confirm that after inclusion with CDs, PA exhibits expected stability at 25 ℃. Furthermore, CDs-PA ICs demonstrate significantly improved water solubility compared to pure PA along with enhanced antioxidant activity and slow-release performance, rendering them highly favorable for various applications.

Combination Mechanism of Soil Dissolved Organic Matter and Cu2+ in Vegetable Fields, Forests and Dry Farmland in Lujiang County

Dissolved organic matter (DOM) serves as a critical link in the migration and transformation of heavy metals at the soil–solid interface, influencing the migration behaviour and transformation processes of Cu2+ in soil. There have been studies on the combination mechanisms between DOM and Cu2+ in paddy soils. However, the adsorption/complexation and redox processes between DOM and Cu2+ in other agricultural soil types (such as dry farmland and vegetable fields) are unclear. In order to reveal the combination process of DOM with Cu in different agricultural soil types and the dynamic changes in chemical behaviour that occur, this study analysed the variability of DOM components and structure in three soils using three-dimensional fluorescence spectroscopy and X-ray photoelectron spectroscopy. In addition, the priority order of different DOM compounds in combination with Cu and the change process in relation to the Cu valence state in the soil of Lujiang County, Anhui Province, was revealed based on laboratory experiments. The results showed that the composition of soil DOM was mainly composed of humic-like and fulvic-like substances with a clear terrestrial origin and that the organic matter showed a high degree of decomposition characteristics. The results indicated that the composition of soil DOM is mainly composed of humic and fulvic acid-like substances, and they have obvious characteristics of terrestrial origin. In addition, the soil organic matter showed high decomposition characteristics. The complex stability constants (lgKM) of humic acid-like substances with Cu2+ follow the order of forest land (lgKM = 5.21), vegetable land (lgKM = 4.90), and dry farmland (lgKM = 4.88). The lgKM of fulvic acid-like substances with Cu2+ is in the order of dry farmland (lgKM = 4.51) and vegetable land (lgKM = 4.39). Humic acid-like substances in soil DOM combine preferentially with Cu2+, showing a stronger chelating affinity than fulvic acid-like substances. Cu2+ complexes mainly include hydroxyl, phenolic hydroxyl and amino functional groups are included in soil DOM, accompanied by redox reactions. In comparison to dry farmland, the soil DOM in forest and vegetable fields undergoes more intense redox reactions simultaneously with the chelation of Cu2+. Therefore, the application of organic fertilisers to vegetable and forest soils may lead to uncertainties concerning the fate of heavy metals with variable chemical valence. These results contribute to a deeper understanding of the interaction mechanisms between DOM and Cu2+ in agricultural soils.

Investigation of Murexide-Zn(II) Complexes in Water-Isopropanol Mixtures: Spectroscopic Analysis and Stability Studies

This study investigates the complexes formed between murexide and Zn (II) ion in water-isopropanol mixtures using spectroscopic analysis. The impact of varying solvent ratios on the absorption spectrum of murexide and its complexes with Zn (II) ion is examined. Furthermore, the influence of pH, time, and interfering ions on the stability of the complexes is investigated for three different isopropanol-water ratios with varying polarities (8:2, 6:4, and 3:7). The molar ratio and stability constants of these complexes are determined using the continuous variations method. The results indicate that complexes with a molar ratio of 1:2 (ML2) are formed at the ratios 8:2 and 6:4, while a molar ratio of 1:1 (ML) is observed at the ratio 3:7. The formation constants (Kf) for the complexes are found to be 7.32x1010, 1.10x1011, and 3.98x105 for the three ratios, respectively, suggesting an inverse relationship between complex stability and water content in the solvent mixture. Additionally, the spectroscopic method employed is evaluated based on sensitivity (0.0406 ppm⁻¹), detection limit (0.016 ppm), and quantification limit (0.054 ppm). The linear range of concentration, as determined by Beer‒Lambert’s law, spans from 0.2 ppm to 3.93 ppm. 

Novel sight into Mn(II) complexation with some tri- and tetradentate ligands in aqueous solutions. Specific aspects of interacting with β-aminotricarballylic acid

For the first time the XRD data of β-aminotricarballylic acid (BATCA) hydrochloride crystals are obtained. The acid-base properties of BATCA are presented herein, as compared to aspartic (AA), citric (CA), iminodiacetic (IDA), and nitrilotriacetic (NTA) acids. The comprehensive analysis of composition, pH distribution areas, and stability constants of manganese(II) complexes is carried out from the pH-metric titration and NMR relaxation (0.47 T) experiments at 298 K. Equilibrium constants were obtained using the CPESSP and STALABS computer programs. The approach based on the values of the spin–spin and spin–lattice relaxivities ratio (r2/r1) is used to assess the number of water molecules bound to Mn2+ ion in its complexes in aqueous solutions. This information is useful for prediction of increasing the contrast of MRI-images by manganese(II) complexes, as well as for analyzing the diversity of the complex structures in the solutions.

Preorganization Effects on Eu(III) Ion Coordination by Dipyridyl-Phenanthroline Ligands: A Combined Experimental and Theoretical Analysis.

Although 1,10-phenanthroline has been proven to hold a strong complexing capacity for f-block elements and their derivatives have been applied in many fields, research on more highly or completely rigid phenanthroline ligands is still rare due to the challenging syntheses. Here, we reported three tetradentate ligands 2,9-di(pyridin-2-yl)-1,10-phenanthroline (L1), 12-(pyridin-2-yl)-5,6-dihydroquinolino[8,7b][1,10]phenanthroline (L2), and 5,6,11,12-tetrahydrobenzo[2,1-b:3,4-b']bis([1,10]phenanthroline) (L3) with increasing preorganization on the side chain; among which, L3 is fully preorganized. Their complexation reactions with Eu(III) were systematically investigated by electrospray ionization mass spectrometry (ESI-MS), UV-vis titrations, and single-crystal structures. It is found that all three ligands form only 1:1 M/L complexes with Eu(III). The single-crystal structures revealed that the three ligands hold similar coordination modes, while their stability constants determined by UV-vis titrations were L3 (4.80 ± 0.01) > L2 (4.38 ± 0.01) > L1 (3.88 ± 0.01). This trend is supported not only by the thermodynamic stability of rigid ligands compared to free ligands but also by the conclusion that rigid ligands exhibit faster reaction rates (lower energy barrier) than free ligands kinetically. This work is helpful in providing theoretical guidance for the subsequent development of highly preorganized chelating ligands with strong coordination ability and high selectivity for f-block elements.

Insights on Stability Constants and Structures of Complexes between Coumarin Derivatives and Pb(II) in Aqueous Media.

In the frame of a systematic study on the sequestering ability of natural antioxidants towards metal cations, here the complexation of coumarin-3-carboxilic acid (HCCA) with Pb(II) and the overall stability constants of the resulting complexes, at 37 °C and in 0.16 M NaClO4, are discussed. Reaction of Pb(ClO4)2 with HCCA in an aqueous medium at a pH range from 2 to 6 and various ratios (1:1-1:10) yielded the Pb-CCA complexes, which were characterized spectrometrically by laser desorption ionization mass spectrometry (LD-MS). LD-MS has provided the composition and structure of Pb-CCA species according to the speciation model proposed on the basis of the potentiometric data. The graphic representation of the complex's concentration curves is given by the distribution diagram, which provides a whole depiction of the species present in the solution at the selected pH ranges.

Navigating through the coordination preferences of heavy alkaline earth metals: Laying the foundations for 223Ra- and 131/135mBa-based targeted alpha therapy and theranostics of cancer

The clinical success of [223Ra]RaCl2 (Xofigo®) for the palliative treatment of bone metastases in patients with prostate cancer has highlighted the therapeutic potential of α-particle emission. Expanding the applicability of radium-223 in Targeted Alpha Therapy of non-osseous tumors is followed up with significant interest, as it holds the potential to unveil novel treatment options in the comprehensive management of cancer. Moreover, the use of barium radionuclides, like barium-131 and -135m, is still unfamiliar in nuclear medicine applications, although they can be considered as radium-223 surrogates for imaging purposes. Enabling these applications requires the establishment of chelators able to form stable complexes with radium and barium radionuclides. Until now, only a limited number of ligands have been suggested and these molecules have been primarily inspired by existing structures known for their ability to complex large metal cations. However, a systematic inspection of chelators specifically tailored to Ra2+ and Ba2+ has yet to be conducted.This work delves into a comprehensive investigation of a series of small organic ligands, aiming to unveil the coordination preferences of both radium-223 and barium-131/135m. Electronic binding energies of both metal cations to each ligand were theoretically computed via Density Functional Theory calculations (COSMO-ZORA-PBE-D3/TZ2P), while thermodynamic stability constants were experimentally determined for Ba2+-ligand complexes by potentiometry, NMR and UV–Vis spectroscopies. The outcomes revealed malonate, 2-hydroxypyridine 1-oxide and picolinate as the most favorable building blocks to design multidentate chelators. These findings serve as foundation guidelines, propelling the development of cutting-edge radium-223- and barium-131/135m-based radiopharmaceuticals for Targeted Alpha Therapy and theranostics of cancer.

The accurate assessment of the chemical speciation of complex systems through multi-technique approaches

Abstract Chemical speciation studies, i.e., the study of the distribution of an element or compound among its various species in a system of interest, are of fundamental importance. Chemical speciation investigations can be performed mainly by either the direct measurement of the chemical species by different analytical techniques, or by chemical modeling through equilibrium thermodynamic data, based on the use of stability constants (and other thermodynamic parameters) of the formed species. For these purposes, a series of techniques can be used. As soon as the complexity of the systems of interest increases, the need for more detailed information arises. As such, a multi-technique approach is essential to derive complementary data to define a chemical system. In this tutorial review we analyzed the most common instrumental techniques employed for chemical speciation studies and equilibrium data analysis. The main advantages and disadvantages of potentiometry, voltammetry, coulometry, UV–vis spectrophotometry, spectrofluorimetry, NMR, EPR, ITC, HRMS and quantum mechanical calculations, together with brief mention to other less common techniques, are discussed together with a series of practical examples of their application. The main aim of this tutorial review is to provide a practical guide to all scientists interested in the field.

Effect of ultrasonic pretreatment on the structure and emulsion stability of epigallocatechin-3-gallate and rice bran protein complex

To enhance the emulsion stability of RBP, the mixed solution of epigallocatechin-3-gallate (EGCG) and rice bran protein (RBP) was pretreated by increasing ultrasonic power (200–500 W). Ultrasonic pretreatment decreased the α-helix/β-sheet ratio (P < 0.05), and caused red-shift absorption peaks of intrinsic fluorescence and UV absorption spectroscopy of EGCG-RBP complex. With increasing ultrasonic power, combined phenol content, particle size, absolute value of ζ-potential, free –SH content, and surface hydrophobicity of EGCG-RBP complex initially rose, and subsequently dropped (P < 0.05). Compared with the EGCG-RBP complex without ultrasonic pretreatment, emulsifying activity index increased from 37.68 m2/g to 42.51 m2/g, and emulsion stability index increased from 123.00 min to 326.43 min as ultrasonic power was 425 W. The centrifugal stability constant, emulsion separation rate, and emulsion particle size initially dropped, and subsequently rose with increasing ultrasonic power. The emulsion stability of EGCG-RBP complex was correlated with particle size, absolute value of ζ-potential, α-helix/β-sheet ratio, free –SH content, and surface hydrophobicity (P < 0.05). Overall, ultrasonic pretreatment enhanced the EGCG-RBP interaction by regulating the absolute value of ζ-potential, flexibility and surface hydrophobicity of EGCG-RBP complex, thus improving emulsion stability, which provided a theoretical foundation for expanding the application of RBP in foodstuffs.

Fabrication, physicochemical characterization and theoretical studies of some new mixed ligands complexes based on N-(1H-benzimidazol-2-yl)-guanidine and 1, 10-phenanthroline: DNA interaction, biological applications and molecular docking approach

The fabrication and structural identification of mixed ligand chelates resulting from 1-(1H-benzimidazol-2-yl) guanidine (BIG = main ligand) and 1,10-Phenanthroline (phen) (secondary ligand). The tested compounds were investigated using TGA, CHN, spectra analysis (FT-IR, Mass spectra, NMR), melting point, magnetic moments, molar conductance, Ultraviolet–Visible spectroscopy as well computational studies. The conductance results showed that the tested Pd(II), VO(II) and Ag(I) chelates have electrolytes in fresh solutions of DMSO lies in the range 38.12–118.87 Ω−1 cm2 mol−1 except, Cu(II) chelate is a non-electrolyte it is value equal 15.16 Ω−1 cm2 mol−1. FT-IR spectrum displays that the tested main ligand is coordinated with metal ions in a bi-dentate behavior with N, N donor sites of the HN=C and C=N. While the second ligand coordinated with metal ions through its N2 atom in the pyridine ring. Moreover, the obtained analytical data regarding complexation in solution, molar ratio and continuous variation methods suggest 1M: 1 L molar ratio. Also the stability constant of tested complexes was identified in solution state and the formation constants (Kf) were evaluated by applying continuous-variation method. Stability of complexes was arranged by BIGPAg > BIGPVO > BIGPCu > BIGPPPd in agreement with Kf values. The pH profile revealed that the wide range of pH stability of the tested complexes is at pH = 4- 10 in most of them. Magnetic and electronic spectra are applied to deduce the coordinating ability of the tested ligands and the geometric structure of the studied chelates. That data of magnetic susceptibility for ternary mixed chelates are locked to an octahedral geometry for Cu(II) & VO(II) chelates due to the data of (μeff = 1.8 and 1.83 B.M) respectively and Pd(II) and Ag(I) chelates are diamagnetic with square planar and tetrahedral geometry, respectively. The TGA study of these studied complexes displays that the hydrated H2O, acetate, nitrate, and acetylacetonate anions are removed in the first (45°C-180°C) and second degradation steps followed directly by degradation of the studied ligands in the following stages. The thermodynamic factors, like ΔS*, ΔH*, E*, A and ΔG* are evaluated from the TGA curves and explained. The DFT/B3LYP computation method was applied for the estimation of the MEP, (HUMO & LUMO) energy for the studied compounds. In-silico assay was executed by two different approaches over compounds to evaluate their biological behavior and degree of interaction with biological systems, before practical application. BIGPPd complex displayed priority in interaction with various protein. In-vitro assay was then carried out for compounds against different microbes and BIGPPd showed high antimicrobial activity with inhibition zones are established to be 45.75 ± 0.10 and 41.95 ± 0.05 mm against B. Cereus and G. Candidum at 25 µg/mL. Also, their cytotoxic behavior was examined against MCF-7, HepG2 and HCT-116 carcinoma cell lines, high cytotoxicity was clearly recorded with BIGPPd complex with IC50% are established to be (5, 6.25 and 7.14 µg/mL) respectively. Furthermore, antioxidant activity was examined, and the complexes exhibited high reactivity with trapping free radicals. The BIGPPd exhibited significant free radical scavenging activity with an IC50 value of 20.15 μg/ml. The interaction of metal chelates with DNA was detected by gel electrophoreses, viscosity and spectral studies. Spectrophotometric titration and viscosity studies expose that each of tested complex is an avid binder to DNA. The intrinsic binding constants were calculated for all the tested compounds could bind to Ct-DNA generally through replacement, intercalative mode & minor groove binding of interactions with the sequence: BIGPVO (6.05×104) > BIGPCu > BIGPPd> BIGPAg >BIG (1.16×103). This may be due to enhanced hydrophobic & electrostatic interaction of aromatic rings. Finally, such complexes may be considered as a promising bioactive agent.

Highly efficient recovery of vanadium from Abu Zeneima ferruginous siltstone, Southwestern Sinai, Egypt, by a novel polyimine‐based chelating ligand

AbstractTo extract V5+ ions from the ferruginous siltstone in the Abu Zeneima region of Southwestern Sinai, Egypt, a chelating polyimine ligand (PVAm‐Ben) was synthesized via a condensation reaction involving polyvinyl amine and α‐hydroxy ketone (Benzoin). The structure of PVAm‐Ben underwent comprehensive characterization employing various techniques, namely; FT‐IR, 1H‐NMR, 13C‐NMR, and GC/MS analyses. Experimental factors controlling such as pH, time, initial concentration, dosage, temperature, and stripping, were systematically optimized to enhance measurement accuracy. Under conditions of 25°C, 0.015 mol/L, and 30 minutes, PVAm‐Ben/C2H4Cl2 exhibited remarkable retention capacity at pH 3. Linear regression analysis results suggested the release of a mole of H+ during the extraction process. The stability constant (log β = 2.1882) of the PVAm‐Ben/V5+ complex was determined, yielding a value of 154.24. The stoichiometry mechanism between PVAm‐Ben and V5+ ions displayed a linear correlation (slope: 0.9922), signifying 1 mole of PVAm‐Ben reacting with 1 mole of vanadium. The pseudo‐second‐order kinetic model indicated an exothermic, spontaneous, and advantageous extraction process at low temperatures. Efficient stripping of PVAm‐Ben/C2H4Cl2 loaded with vanadium was achieved using 0.05 M NaOH with a 99% efficiency rate. Ultimately, enhanced variables were employed to yield a V2O5 concentrate with a vanadium content of 55% and a purity level of 98.21%.

Enhanced solubility and biological activities of Flufenamic acid through β-Cyclodextrin derivatives inclusion complexes: A comprehensive study

This study explores the formation of inclusion complexes between the solubility enhancement of Flufenamic acid (FNA) and various β-Cyclodextrins (β-CD, Hβ-CD, Mβ-CD, and Sβ-CD) using ultrasonic probe sonication method. The investigation encompasses a multi-faceted analysis, employing UV–Visible, FTIR, XRD, FE-SEM, TGA-DSC techniques and molecular docking studies. The UV–Visible spectra reveal absorption peak shifts and binding constants (Ka) indicate interaction strength, and thermodynamic parameters suggest spontaneous and favorable inclusion processes of β-CDs:FNA. Solid inclusion complexes of β-CDs:FNA were further characterized using FTIR, revealing alterations in functional groups indicative of complex formation. XRD analysis elucidates changes in crystallinity, while FE-SEM provides insights into morphological variations. Thermal stability is assessed through TGA-DSC, demonstrate the impact of inclusion on the complexes stability. Phase solubility diagrams illustrate the improved solubility of FNA in the presence of β-CDs. Mβ-CD:FNA exhibits the highest stability constant (1204 M−1), emphasizing its potential as an effective carrier. The binding energy of Mβ-CD:FNA (−46.72 kcal/mol) was lower than that of β-CD:FNA (−39.03 kcal/mol), Hβ-CD:FNA (−46.40 kcal/mol), and Sβ-CD:FNA (−46.29 kcal/mol), indicating that the hydroxypropyl group substitution enhanced the inclusion ability of β-CDs. Antibacterial activity studies against S. aureus and E. coli highlight enhanced efficacy of inclusion complexes with Mβ-CD:FNA (92.3 ± 0.18 % and 94.2 ± 0.17 %) demonstrating superior antibacterial activity. Cytotoxicity evaluations on HCT-116 cells reveal the safety profile of the β-CDs:FNA inclusion complexes, with Mβ-CD:FNA showing lower toxicity and high cell internalization compared to other formulations. The findings hold promise for applications in drug delivery, antimicrobial packaging, and the broader pharmaceutical and biotechnological fields.

Metal Complexes in Biology and Medicine: The System Cadmium ((II))/ Iron ((II))/ Zinc ((II)) - α - Aminobutenoic Acid

Metal ions play an important role in biological system. The importance of metal ions to essential functions of living systems and for wellbeing of living organisms is well known. Metal ions are fundamental elements for the maintenance of life spans of the human, animals, and plants. Recent advances in inorganic chemistry have made possible formation of number of transition metal complexes with organic ligand of interest, which can be used as therapeutic agent. In coordination compounds studies, knowledge of the stability constants of complexes is necessary for preliminary quantitative treatment. The present technique involving the use of paper electrophoresis is described for the study of equilibria in binary complex systems in solution. The method is based on the movement of a spot of a metal ion in an electric field at various pH’s of background electrolyte. A graph of pH versus mobility was used to obtained information in the binary complexes and to calculate its stability constants. Using this method , the stability constants of binary complexes metal (II) – α – aminobutenoic acid have been determined to be ( 3.78 ± 0.01, 2.48 ± 0.03 ); ( 3.27 ± 0.04, 2.33 ± 0.07 ); and (4.45 ± 0.02, 2.66 ± 0.05); (logarithm stability constant values) for cadmium (II), iron (II) and zinc (II) complexes, respectively, at ionic strength 0.01 Mol / L and a temperature of 35º C.