Calcium Complexes Research Articles

Physicochemical characteristics of the complexes of simvastatin and atorvastatin calcium with hydroxypropyl-β-cyclodextrin produced by mechanochemical activation

In the present work, inclusion complexes of simvastatin (SIM), atorvastatin calcium (ATV) with hydroxypropyl-β-cyclodextrin (HP-β-CD) have been prepared using mechanochemistry technique to improve solubility of the two drugs and enhance their oral bioavailability. The interactions of the drugs with HP-β-CD were investigated by DSC, XRD, SEM and 1HNMR. The stoichiometry of the inclusion complexes was determined by phase-solubility analysis. Furthermore, molecular docking study showed that the whole SIM molecule was completely embedded into the HP-β-CD cavity, and the part of the ATV molecule was most likely inserted into the cavity of HP-β-CD. The parallel artificial membrane permeability assay (PAMPA) revealed a strong increasing of SIM permeability in the presence of HP-β-CD in comparison with pure SIM used as a control. The pharmacokinetic study in vivo revealed that the bioavailability of mechanochemical treatment samples was significantly increased compared with that of the net drugs. On the other hand, the rapid storage assay (+40 °C for 3 months) showed that the chemical stability of inclusion complexes was higher than pure drugs. Therefore, the mechanochemically synthesized complexes of SIM/HP-β-CD and ATV/HP-β-CD could be a promising approach for the oral delivery of SIM and ATV for enhanced bioavailability.

Cobalt (II), zirconium(IV), calcium(II) complexes with dipicolinic acid and imidazole derivatives: X-ray studies, thermal analyses, evaluation as in vitro antibacterial and cytotoxic agents

Four coordination complexes, [2-mimH]2[Co(pydc)2][ClO4]. H2O (1), [2-mimH]2[Zr(pydc)3] (2), [imiH]2[Zr(pydc)3].4H2O (3) and [Ca(pydcH2)2(H2O)]2[Co(pydc)2]2·6H2O (4) have been prepared from the reaction between proton-transfer compounds containing pyridine-2,6-dicarboxylic acid (pydcH2) with 2-methylimidazole (2-mim) and imidazole (imi) in 1:2 M ratio and metal salts. These compounds have been characterized by spectroscopic methods and single crystal X-ray diffraction technique was used to determine their structures. Also, thermal analyses (TGA/DTA) were carried out on all the synthetic compounds. Then the agar dilution and diffusion methods were used to determine the antibacterial activity of the ligands and their complexes on the growth profile of two pathogenic Gram-positive bacteria namely Staphylococcus aureus and Bacillus cereus and also two Gram- negative bacteria namely Escherichia coli and Klebsiella oxytoca. The highest antibacterial activity was exhibited by (pydcH2) and complex (2) at MIC values between 75 and 175 μg/mL. These two compounds exhibited stronger effects than gentamicin as a standard drug toward Klebsiella oxytoca. The anti-proliferative activity of compounds was evaluated in vitro using oxaliplatin as a positive control against MCF7 (a human breast cancer), HL60 (a human lymphocyte) and HT29 (a human colon adenocarcinoma) cell lines. Selective and significant cytotoxic effect of complex (4) was observed on MCF7 cells (IC50 = 10 μM, Cell viability 62.12%).

Spectrophotometric and Potentiometric Analysis of Calcichrome and Its Complex With Calcium Ion

It was confirmed in this research that the ligand calcichrome formed stable complex with calcium ion at pH of 8.5 which verified by UV/Vis and FTIR spectral analysis and the complexation occurred via hydroxyl groups .
 The stoichiometric ratio of the formed complex was found to be 1:1 by mole ratio and continuous variation methods . Dry ashing method of the complex and flame emission photometric analysis offered a calcium percentage in calcium complex equal 4.5% with an error of 2.41% due to experimental errors .

The effect of chlorhexidine on dental calculus formation: an in vitro study

BackgroundChlorhexidine gluconate (CHG) has been proven to be effective in preventing and controlling biofilm formation. At the same time, an increase in calculus formation is known as one of considerable side effects. The purpose of this study was to investigate whether mineral deposition preceding a calculus formation would occur at an early stage after the use of CHG using an in vitro saliva-related biofilm model.MethodsBiofilms were developed on the MBEC™ device in brain heart infusion (BHI) broth containing 0.5% sucrose at 37 °C for 3 days under anaerobic conditions. Biofilms were periodically exposed to 1 min applications of 0.12% CHG every 12 h and incubated for up to 2 days in BHI containing a calcifying solution. Calcium and phosphate in the biofilm were measured using atomic absorption spectrophotometry and a phosphate assay kit, respectively. Morphological structure was observed using a scanning electron microscope (SEM), and chemical composition was analyzed with an electron probe microanalyzer (EPMA).ResultsThe concentrations of Ca and Pi following a single exposure to CHG increased significantly compared with the control. Repeatedly exposing biofilms to CHG dose-dependently increased Ca deposition, and the amount of Ca was five times as much as that of the control. Pi levels in CHG-treated biofilms were significantly higher than those from the control group (p < 0.05); however, the influence of the number of exposures was limited. Analyses using an SEM and EPMA showed many clusters containing calcium and phosphate complexes in CHG-treated biofilms. Upon composition analysis of the clusters, calcium was detected at a greater concentration than phosphate.ConclusionsFindings suggested that CHG may promote mineral uptake into the biofilm soon after its use. It is necessary to disrupt the biofilm prior to the start of a CHG mouthwash in order to reduce the side effects associated with this procedure. The management of patients is also important.

Analysis of the Differences in the Microbial Community and Structure of Calcified ONP Granular Sludge and Bagasse Granular Sludge

Anaerobic biological technology has been widely used in the treatment of high-concentration organic wastewater such as old newspaper (ONP) pulping wastewater and bagasse spray washing wastewater before pulping. However, due to the high calcium content and complex chemical properties of the ONP pulping wastewater, granular sludge calcification occurs during the anaerobic treatment, which has negative effects. In contrast, calcification does not occur in the bagasse spray washing wastewater. Therefore, a comparative analysis of the biological flora and structure of the granular sludge for these two types of wastewater can provide theoretical and data support for revealing the cause of calcification of granular sludge. The results indicate a considerable difference between the anaerobic granular sludge for the treatment of bagasse spraying wastewater (B-GS) and the treatment of ONP pulping wastewater (P-GS). The microorganisms in the B-GS were mainly Bactericides (25.4%), Proteobacteria (20.2%), Hyd24－12 (14.4%), Chloroflexi (10.6%), and Firmicutes (8.9%). The microorganisms in the P-GS were mainly Bacteroidetes (20.4%), Chloroflexi (19.5%), Proteobacteria (19.3%), Firmicutes (6.2%), Spirochaetae (4.8%), Actinobacteria (4.4%), and Lentisphaerae (4.3%). Methanomassiliicoccus were detected only in the P-GS. The methanogens had a higher relative abundance in the P-GS (50%), and only a small fraction (10%) of methanogens was detected in the B-GS.

Synthesis and molecular structures of YbII and Ca bis(amidinate) complexes containing the tridentate amidinate ligand [2,6-Pri2C6H3NC(But)NC6H4OMe-2

New bis(amidinate) complexes of calcium, [2,6-Pri2C6H3NC(But)NC6H4OMe-2]2Ca(DME) (2), and divalent ytterbium, [2,6-Pri2C6H3NC(But)NC6H4OMe-2]2Yb (4), were synthesized by the transamination of the bis(amide) derivatives [(Me3Si)2N]2M(THF)2 (M = Ca, Yb) with two equivalents of amidine 2,6-Pri2C6H3N=C(But)N(H)C6H4OMe-2, in which one nitrogen atom bears an o-methoxyphenylene moiety capable of coordinating a metalion. An X-ray diffraction study showed that, despite very similar ionic radii of Ca2+ and Yb2+, the amidinate ligands in complexes 2 and 4 bind to these ions in different coordination modes. In the calcium complex, both ligands adopt a κ2-N, O-chelating coordination mode. In the divalent ytterbium compound, one ligand is chelating and binds to the metalion in a κ2-N, O-coordination mode, while the second ligand is coordinated via both the N and O (κ2) atoms and the arene ring of the 2,6-Pri2C6H3 moiety (η6-coordination mode).

Structure and Inhibitor Specificity of L,D-Transpeptidase (LdtMt2) from Mycobacterium tuberculosis and Antibiotic Resistance: Calcium Binding Promotes Dimer Formation.

The final step of peptidoglycan (PG) synthesis in all bacteria is the formation of cross-linkage between PG-stems. The cross-linking between amino acids in different PG chains gives the peptidoglycan cell wall a 3-dimensional structure and adds strength and rigidity to it. There are two distinct types of cross-linkages in bacterial cell walls. D,D-transpeptidase (D,D-TPs) generate the classical 4➔3 cross-linkages and the L,D-transpeptidase (L,D-TPs) generate the 3➔3 non-classical peptide cross-linkages. The present study is aimed at understanding the nature of drug resistance associated with L,D-TP and gaining insights for designing novel antibiotics against multi-drug resistant bacteria. Penicillin and cephalosporin classes of β-lactams cannot inhibit L,D-TP function; however, carbapenems inactivate its function. We analyzed the structure of L,D-TP of Mycobacterium tuberculosis in the apo form and in complex with meropenem and imipenem. The periplasmic region of L,D-TP folds into three domains. The catalytic residues are situated in the C-terminal domain. The acylation reaction occurs between carbapenem antibiotics and the catalytic Cys-354 forming a covalent complex. This adduct formation mimics the acylation of L,D-TP with the donor PG-stem. A novel aspect of this study is that in the crystal structures of the apo and the carbapenem complexes, the N-terminal domain has a muropeptide unit non-covalently bound to it. Another interesting observation is that the calcium complex crystallized as a dimer through head and tail interactions between the monomers.

Thermodynamic Study on the Protonation and Na+, Ca2+, Mg2+-Complexation of a Biodegradable Chelant (HEIDA) at Different Ionic Strengths and Temperatures

A potentiometric method has been used for the determination of the protonation constants of N-(2-hydroxyethyl)iminodiacetic acid (HEIDA or L) at various temperatures 283.15 ≤ T/K ≤ 383.15 and different ionic strengths of NaCl(aq), 0.12 ≤ I/mol·kg−1 ≤ 4.84. Ionic strength dependence parameters were calculated using a Debye–Huckel type equation, Specific Ion Interaction Theory and Pitzer equations. Protonation constants at infinite dilution calculated by the SIT model are $$ \log_{10} \left( {{}^{T}K_{1}^{\text{H}} } \right) = 8.998 \pm 0.008 $$ (amino group), $$ \log_{10} \left( {{}^{T}K_{2}^{\text{H}} } \right) = 2.515 \pm 0.009 $$ and $$ \log_{10} \left( {{}^{T}K_{3}^{\text{H}} } \right) = 1.06 \pm 0.002 $$ (carboxylic groups). The formation constants of HEIDA complexes with sodium, calcium and magnesium were determined. In the first case, the formation of a weak complex species, NaL, was found and the stability constant value at infinite dilution is log10KNaL = 0.78 ± 0.23. For Ca2+ and Mg2+, the CaL, CaHL, CaL2 and MgL species were found, respectively. The calculated stability constants for the calcium complexes at T = 298.15 K and I = 0.150 mol·dm−3 are: log10βCaL = 4.92 ± 0.01, log10βCaHL = 11.11 ± 0.02 and $$ \log_{10} \beta_{\text{Ca{L}}_{2}} $$ = 7.84 ± 0.03, while for the magnesium complex (at I = 0.176 mol·dm−3): log10βMgL = 2.928 ± 0.006. Protonation thermodynamic functions have also been calculated and interpreted.

1,2-Bis(anilido)ethane Complexes of Calcium and Potassium: Synthesis, Structures, and Catalytic Activity

The metalation of 1,2-bis(anilino)ethane with excess KH leads to the formation of the potassium complex [(thf)3K2{1,2-(PhN)2C2H4}] (1). Complex 1 quantitatively reacts with anhydrous CaI2 in THF yielding insoluble KI and dinuclear [(thf)5Ca2{1,2-(PhN)2C2H4}2] (2) after crystallization from a mixture of THF and hexane. Addition of N,N,N′,N′′,N′′′,N′′′-hexamethyltriethylenetetraamine (hmteta) yields [(hmteta)Ca{1,2-(PhN)2C2H4}] (3). The complexes 1 and 2 proved to be inactive as catalysts in hydroamination reactions of diphenylbutadiyne with secondary amines. However, a mixture of 1 and 2 (K:Ca ratio of 2:1) mediated the addition of N-methyl-aniline and 1,2-bis(anilino)ethane to one of the C≡C triple bonds of diphenylbutadiyne. Addition of 18-crown-6 ether (18C6) leads to the formation of the sparingly soluble potassium complex [{(18C6)K}2{1,2-(PhN)2C2H4}] (5) and the insoluble calcium complex [(18C6)Ca{1,2-(PhN)2C2H4}] (6). The calciate-mediated hydroamination reaction is regiocontrolled, but E- and Z-isom...

Ring Opening Polymerization and Copolymerization of Cyclic Esters Catalyzed by Group 2 Metal Complexes Supported by Functionalized P-N Ligands.

We report the preparation of alkali and alkaline earth (Ae) metal complexes supported by 2-picolylamino-diphenylphosphane chalcogenide [(Ph2P(=E)NHCH2(C5H4N)] [E = S (1-H); Se (2-H)] ligands. The treatment of the protic ligand, 1-H or 2-H, with alkali metal hexamethyldisilazides at room temperature afforded the corresponding alkali metal salts [M(THF)2(Ph2P(=E)NCH2(C5H4N)] [M = Li, E = S (3a), Se (3b)] and [{M(THF) n(Ph2P(=E)NCH2(C5H4N)}2] [M = Na, E = S (4a), Se (4b); M = K, E = Se (5b)] in good yield. The homoleptic Ae metal complexes [κ2-(Ph2P(=Se)NCH2(C5H4N)Mg(THF)] (6b) and [κ3-{(Ph2P(=Se)NCH2(C5H4N)}2M(THF) n] (M = Ca (7b), Sr (8b), Ba (9b)] were synthesized by the one-pot reaction of 2-H with [KN(SiMe3)2] and MI2 in a 2:2:1 molar ratio at room temperature. The molecular structures of the protic-ligands 1-H and 2-H, as well as complexes 3a,b-5a,b and 6b-9b were established using single-crystal X-ray analysis. The Ae metal complexes 6b-9b were tested for ring-opening polymerization (ROP) of racemic lactide ( rac-LA) and copolymerization of rac-LA and ε-caprolactone (ε-CL) at room temperature. In the ROP of rac-LA, the calcium complex 7b exhibited high isoselectivity, with Pi = 0.89, whereas both the barium and strontium complexes showed lower isoselectivity with Pi = 0.78-0.62. In the copolymerization of rac-LA and ε-CL, both barium and strontium complexes proved to be efficient precatalysts for the formation of the block copolymer rac-LA-CL, but the reactivity of 9b was found to be better than that of 8b. All the polymers were fully characterized using differential scanning calorimetry, thermogravimetric analysis, and gel permeation chromatography analyses. Kinetic studies on the ROP reaction of LA confirmed that the rate of polymerization followed the order Ba ≫ Sr ≈ Ca.

Synthesis and retarder mechanism study of a novel amphoteric composite high temperature-resistant retarder for oil well cement.

An amphoteric composite polymer (hereinafter referred to as PAADM) as a high temperature-resistant cement retarder was prepared by in situ intercalated polymerization method with 2-crylamido-2-methylpropanesulfonic acid (AMPS), acrylic acid (AA) and two diallyl dimethyl ammonium chloride (DMDAAC) as monomers, and modified montmorillonite as an active polymerization filler. The synthetic composite polymer was characterized by Fourier transform infrared spectroscopy (FT-IR), H nuclear magnetic resonance (H-NMR), X-ray diffraction (XRD) and thermogravimetric analysis (TGA). The results of the aforementioned characterization showed that the synthesized copolymer (PAADM) has an intercalation/exfoliation composite structure and excellent thermal stability. Performance evaluation evidenced that the cement slurry containing PAADM has good retarding property in the range of 120–200 °C, and demonstrated the rapid development of compressive strength under high temperature and low temperature conditions, this property could guarantee that the retarder PAADM could be applied to the construction of deep wells and long interval wells. Moreover, the retarding mechanism of PAADM was studied through calcium binding capacity, adsorption amount, zeta potential, XRD and SEM analysis, and it was found that “adsorption deposition” and “calcium complexation” should be responsible for this retarder delaying the hydration process of cement grains.

Effects of Formation Brine Compositions on Effectiveness of Low Salinity Brine Injection in Carbonate Reservoir

Nowadays, Low Salinity Waterflooding (LSWF) is considered as one of the most effective techniques to enhance oil recovery. Essential mechanism is a Multi-Ion Exchange (MIE). In carbonate formation, collaboration of Potential Determining Ions (PDI) with rock surface and crude oil results in adjustment of surface equilibrium. These ions in injected brine are thoroughly investigated but effects from formation brine are not well documented. In this study, ratio of divalent ions including calcium and magnesium ions in formation brine is studied. Results from imbibition test shows that formation brine containing calcium ion to magnesium ion ratio of 1:1 yields response to LSWF. Oppositely, formation brines with high ratios of 10:1 and 15:1 do not respond to LSWF. As calcium ion in connate water diffuses to injected water, high calcium ion will exhibit dissolution mechanism of rock surface which is part of oil recovery mechanisms. Formation brine with high calcium ion is therefore not recommended for LSWF. High portion of magnesium ion in formation brine does not affect effectiveness of LSWF. Dissolution of magnesium from rock may be obstructed but oil can still be liberated from calcium carboxylate complex and dissolution of calcium. Coreflood test shows similar result which confirms previous explanation.

Metals Complexes Formed with Oleanolic Acid

The oleanolic acid possesses diverse pharmacological properties, it is considered as a good starting material for creating new compounds. The oleanolic acid isolated of Plumeria obtusa leaves was used as raw material to obtained calcium, magnesium, zinc, nickel and copper complexes. The structures of complexes were confirmed by HRMS, 1H NMR, and 13C NMR. Five new compounds were synthesized to promote increased biological activity of oleanolic acid and PCR assays for the different type of cancer.

Redox transmetallation approaches to the synthesis of extremely bulky amido-lanthanoid(ii) and -calcium(ii) complexes.

Redox transmetallation protolysis reactions between HgPh2, elemental metals, M = Ca, Eu, or Yb, and the bulkyl arylsilylamine PhL†H (HN(SiPh3)(Ar†), Ar† = C6H2Pri{C(H)Ph2}2-4,2,6), or the borylsilylamine PhLBoH (HN(SiPh3){B(DipNCH)2}, Dip = C6H3Pri2-2,6) pro-ligands yielded complexes incorporating doubly deprotonated, N,C-chelating amido/organyl ligands, viz. [M(L-H) (thf)x]n, L-H = PhL†-H (1-3) or PhLBo-H (4-5); M = Ca (1, 4), Eu (2) or Yb (3, 5); x = 0 (5) or 2 (1-4); n = 1 (1-4) or 2 (5). Structural differences between 4 and 5 represent a rare divergence in the chemistry of divalent calcium and ytterbium. Utilisation of a less hindered bis(aryl) amine, DLMH (HN(Dip)(Mes), Mes = C6H2Me3-2,4,6) in a similar reaction yielded a three-coordinate, trigonal planar ytterbium complex [Yb(DLM)2(thf)] (6). Direct redox transmetallation reactions between an amido-mercurial iodide [(MeL†)HgI] (7, MeL† = -N(SiMe3)(Ar†)) and ytterbium or europium metal afforded homoleptic [Yb(MeL†)2] (8) and heteroleptic [{Eu(MeL†)(μ-I)(thf)}2] (9) respectively. This study highlights the versatility of redox transmetallation pathways to amido-lanthanoid complexes, especially where such compounds are difficult to access using conventional salt metathesis pathways.

In vitro digestion profile and calcium absorption studies of a sea cucumber ovum derived heptapeptide-calcium complex.

In this study, a novel calcium-binding heptapeptide (NDEELNK) that is released during the trypsin hydrolysis of sea cucumber ovum was identified by peptidomics. The calcium binding mode, in vitro digestion profile and calcium absorption of the NDEELNK-calcium complex were investigated. The NDEELNK peptide could spontaneously bind calcium with a 1 : 1 stoichiometry, and the calcium-binding site might involve the carboxyl oxygen and amino nitrogen atoms of two glutamic acid and one aspartic acid residues in the NDEELNK peptide. The NDEELNK-calcium complex underwent disaggregation and self-aggregation in a mesh of smaller size during simulated gastrointestinal digestion, clarified by dynamic light scattering and confocal laser-scanning microscopy. In addition, the NDEELNK-calcium complex could be conducive to calcium absorption across Caco-2 cell monolayers. The findings from this research suggest possible utilization of hydrolyzed peptides from sea cucumber ovum as dietary supplements to improve calcium absorption.

Well-defined styryl and biphenyl calcium complexes from dilithio compounds and calcium iodide: synthesis, structure and reactivity toward nitrous oxide.

Efficient synthesis and structure elucidation of carbon-calcium σ-bonded compounds are of remarkable interest and importance in organometallic chemistry of the heavier s-block metals. In this paper, we report that styryl and biphenyl calcium complexes with well-defined structures can be facilely obtained via metathesis reaction between their corresponding dilithio compound and calcium iodide. Single-crystal X-ray structural analysis of these calcium complexes revealed their unique iodide-bridged or dicalcium-bridged structures. Their reactivity toward nitrous oxide was disclosed.

Alkaline earth metal complexes stabilized by amidine and guanidine ligands: synthesis, structure and their catalytic activity towards polymerization of rac-lactide.

A series of amidine ligands RAmDIPP (R is backbone substituent, R = 2-methylpyridine (HL1), N,N,2-trimethylaniline (HL2), N,N-dimethylpropan-1-amine (HL3); DIPP (2,6-diisopropylphenyl) is N substituent) and a (Z)-1,1-diethyl-2,3-bis(2-methoxyphenyl)guanidine ligand (HL4) have been synthesized. Reaction of HL1-HL4 with Ca[N(SiHMe2)2](THF) or Ca[N(SiMe3)2](THF)2, respectively, afforded complexes 1-8 (1: [L1AmDIPPCa(SiHMe2)2]2, 2: L1AmDIPPCaN(SiMe3)2·(THF)2, 3: L2AmDIPPCaN(SiHMe2)2·(THF)2, 4: L2AmDIPPCaN(SiMe3)2·(THF), 5: L3AmDIPPCaN(SiHMe2)2·(THF)2, 6: L3AmDIPPCaN(SiMe3)2·(THF)2, 7: [L4CaN(SiHMe2)2]2, 8: [L4CaN(SiMe3)2]2). All the complexes were well-defined by NMR spectrum analyses and the molecular structures of 3 and 5-8 were further determined by single crystal X-ray diffraction analyses. In combination with an excess of PhOH as the chain transfer agent, complexes 1-8 catalyzed immortal ring-opening polymerization of rac-lactide in a controlled manner and exhibited moderate catalytic activity at room temperature. The end-group fidelity of the resultant polymer was certified by NMR and MALDI-TOF mass spectra.

Synchrotron infrared microspectroscopy reveals the response of Sphagnum cell wall material to its aqueous chemical environment

Environmental contextSphagnum moss is a widespread species in peatlands globally and responsible for a large fraction of carbon storage in these systems. We used synchrotron infrared microspectroscopy to characterise the acid-base properties of Sphagnum moss and the conditions under which calcium uptake can occur (essential for plant tissue integrity). The work allows a chemical model for Sphagnum distribution in the landscape to be proposed. AbstractSphagnum is one the major moss types responsible for the deposition of organic soils in peatland systems. The cell walls of this moss have a high proportion of carboxylated polysaccharides (polygalacturonic acids), which act as ion exchangers and are likely to be important for the structural integrity of the cell walls. We used synchrotron light source infrared microspectroscopy to characterise the acid-base and calcium complexation properties of the cell walls of Sphagnum cristatum stems, using freshly sectioned tissue confined in a flowing liquid cell with both normal water and D2O media. The Fourier transform infrared spectra of acid and base forms are consistent with those expected for protonated and deprotonated aliphatic carboxylic acids (such as uronic acids). Spectral deconvolution shows that the dominant aliphatic carboxylic groups in this material behave as a monoprotic acid (pKa=4.97–6.04). The cell wall material shows a high affinity for calcium, with a binding constant (K) in the range 103.9–104.7 (1:1 complex). The chemical complexation model developed here allows for the prediction of the chemical environment (e.g. pH, ionic content) under which Ca2+ uptake can occur, and provides an improved understanding for the observed distribution of Sphagnum in the landscape.

A new calcium 2,5-dihydroxybenzoate: Synthesis, characterization and antioxidant studies and stress mediated cytotoxity in MCF-7 cells

The structure and composition of the calcium 2,5-dihydroxybenzoate (calcium gentisate) were studied by single-crystal and powder X-ray diffraction. Single-crystal X-ray analysis revealed that the compound crystallizes in the orthorhombic space group Pbcn. The Ca(II) cation is coordinated in a monodentate fashion by two symmetry-related gentisate anions and five water molecules. The metal ion and one of the water molecules are located on a 2-fold rotation axis. The adjacent monomeric units are assembled into a 3-D supramolecular framework via O–H…O hydrogen bonds. Comparison of the experimental powder pattern with that simulated from single-crystal X-ray data confirmed the purity and homogeneity of the sample. The FT-IR, UV/VIS, 1H and 13C NMR spectra of the calcium 2,5-dihydroxybenzoic acid were registered and analysed. Moreover the effect of calcium complex and 2,5-dihydroxybenzoic acid on basic oxidative stress parameters, such as thiol group content and lipid peroxidation in the human breast cancer cells MCF-7 was studied. The antiradical and ferric reducing power of these compounds was measured by DPPH, CUPRAC and FRAP methods. The chemical reactivity parameters (e.g. HOMO and LUMO orbitals, ionization potential, electron affinity) for Ca 2,5-dHB and 2,5-dHB were calculated at B3LYP/6-311++G∗∗ level of theory and discussed in relation to their antioxidant properties.

Fabrication and characterization of magnesium and calcium trimesate complexes via ion-exchange and one-pot self-assembly reaction

Using two different synthesis methods, two diversified magnesium and calcium complexes were successfully prepared. When the ion exchange method was used, C9H14MgO11.H2O and C18H30Ca3O24 complexes were obtained. When the one-pot self-assembly reaction was used, C18H34Mg3O26.4H2O and C9H12CaO10 complexes were produced. The structural characterizations were performed by using X-ray diffraction, FT-IR and elemental analyses. Thermal behavior of complexes were also determined via TGA method. The both complexes of magnesium and calcium trimesate have micro and mesoporosity with low porosity because of hydrogen bonds. Then hydrogen storage capacities of complexes were also determined. The differences in synthesis method result in the differences on complexes structure, morphology (shape, particle size and specific surface area) and hydrogen storage capacities.