Oxo-Titanium(IV) Complex/Polymer Composites—Synthesis,Spectroscopic Characterization and Antimicrobial Activity Test

The emergence of a large number of bacterial strains resistant to many drugs or disinfectants currently used contributed to the search of new, more effective antimicrobial agents. In the presented paper, we assessed the microbiocidal activity of tri- and tetranuclear oxo-titanium(IV) complexes (TOCs), which were dispersed in the poly(methyl methacrylate) (PMMA) matrix. The TOCs were synthesized in reaction to Ti(OR)₄ (R = ⁱPr, ⁱBu) and HO₂CR’ (R’ = 4-PhNH₂ and 4-PhOH) in a 4:1 molar ratio at room temperature and in Ar atmosphere. The structure of isolated oxo-complexes was confirmed by IR and Raman spectroscopy and mass spectrometry. The antimicrobial activity of the produced composites (PMMA + TOCs) was estimated against Gram-positive (Staphylococcus aureus ATCC 6538 and S. aureus ATCC 25923) and Gram-negative (Escherichia coli ATCC 8739 and E. coli ATCC 25922) bacteria and yeasts of Candida albicans ATCC 10231. All produced composites showed biocidal activity against the bacteria. Composites containing {Ti₄O₂} cores and the {Ti₃O} core stabilized by the 4-hydroxybenzoic ligand showed also high activity against yeasts. The results of investigations carried out suggest that produced (PMMA + TOCs) composites, due to their microbiocidal activity, could find an application in the elimination of microbial contaminations in various fields of our lives.     

Effect of Heat-Treatment on the Mechanism and Kinetics of the Hydrogen Evolution Reaction on Ni—P + TiO2 + Ti Electrodes

Composite Ni—P + TiO₂ + Ti layers were prepared by codeposition of Ni—P alloy with TiO₂ and Ti powders from a solution containing suspension of TiO₂ and Ti particles. The electrodeposition was carried out under galvanostatic conditions at room temperature. The layers exhibited an amorphous Ni—P matrix in which crystalline TiO₂ and Ti were embedded. On the deposit surface, the nonstoichiometric Ti oxide, Ti₁₀O₁₉, and intermetallic compounds, NiTi, formed during the electrodeposition, were also present. The heat treatment of these layers in argon leads to the crystallization of Ni—P matrix and formation of nonstoichiometric Ti oxides, detected by XRD. Electrolytic activity towards the hydrogen evolution reaction (HER) was studied on these electrode materials before and after heat treatment. The mechanism of the HER was also studied, and the kinetic parameters were determined using steady-state polarization and electrochemical impedance spectroscopy (EIS). An increase in activity occurring after heating of Ni—P + TiO₂ + Ti layers is related to TiO₂ reduction and formation of nonstoichiometric Ti oxides: Ti₁₀O₁₉(400 °C), Ti₇O₁₃(500 °C) and Ti₄O₇(800 °C). It is postulated that the increase in electrochemical activity is related to the properties of these oxides and a facility for H reduction/adsorption on their surface, as well as to the presence of NiTi intermetallics as compared with the Ni—P + TiO₂ + Ti electrode.     

Studies on Properties of Rice Straw/Polymer Nanocomposites Based on Polycaprolactone and Fe3O4 Nanoparticles and Evaluation of Antibacterial Activity

Modified rice straw/Fe₃O₄/polycaprolactone nanocomposites (ORS/Fe₃O₄/PCL-NCs) have been prepared for the first time using a solution casting method. The RS/Fe₃O₄-NCs were modified with octadecylamine (ODA) as an organic modifier. The prepared NCs were characterized by using X-ray powder diffraction (XRD), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FT-IR). The XRD results showed that as the intensity of the peaks decreased with the increase of ORS/Fe₃O₄-NCs content in comparison with PCL peaks, the Fe₃O₄-NPs peaks increased from 1.0 to 60.0 wt. %. The TEM and SEM results showed a good dispersion of ORS/Fe₃O₄-NCs in the PCL matrix and the spherical shape of the NPs. The TGA analysis indicated thermal stability of ORS/Fe₃O₄-NCs increased after incorporation with PCL but the thermal stability of ORS/Fe₃O₄/PCL-NCs decreased with the increase of ORS/Fe₃O₄-NCs content. Tensile strength was improved with the addition of 5.0 wt. % of ORS/Fe₃O₄-NCs. The antibacterial activities of the ORS/Fe₃O₄/PCL-NC films were examined against Gram-negative bacteria (Escherichia coli) and Gram-positive bacteria (Staphylococcus aureus) by diffusion method using nutrient agar. The results indicated that ORS/Fe₃O₄/PCL-NC films possessed a strong antibacterial activity with the increase in the percentage of ORS/Fe₃O₄-NCs in the PCL.     

Miscibility and morphology in crystalline/amorphous blends of poly(caprolactone)/poly(4-vinylphenol) as studied by DSC, FTIR, and C solid state NMR

The miscibility and morphology of poly(caprolactone) (PCL) and poly (4-vinylphenol) (PVPh) blends were investigated by using differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy and ¹³C solid state nuclear magnetic resonance (NMR) spectroscopy. The DSC results indicate that PCL is miscible with PVPh. FTIR studies reveal that hydrogen bonding exists between the hydroxyl groups of PVPh and the carbonyl groups of PCL. ¹³C cross polarization (CP)/magic angle spinning (MAS)/dipolar decoupling (DD) spectra of the blends show a 1 ppm downfield shifting of ¹³C resonance of PVPh hydroxyl-substituted carbons and PCL carbonyl carbons with increasing PCL content. Both FTIR and NMR give evidence of inter-molecular hydrogen bonding within the blends. The proton spin-lattice relaxation in the laboratory frame, T₁(H), and in the rotating frame, T_1ρ(H), were studied as a function of the blend composition. The T₁(H) results are in good agreement with thermal analysis; i.e. the blends are completely homogeneous on the scale of 50-80 nm. The T_1ρ(H) results indicate that PCL in the blends has both crystalline and amorphous phases. The amorphous PCL phase is miscible with PVPh, but the PCL crystal domain size is probably larger than the spin-diffusion path length within the T_1ρ(H) time-frame, i.e. larger than 2-4 nm. The mobility differences between the crystalline and amorphous phases of PCL are clearly visible from the T_1ρ(H) data.     

The effect of dense polymer brush on the microfibrillated cellulose for the mechanical properties of poly(ε-caprolactone) biocomposites

Two different cellulosic fibers [pristine microfibrillated celluloses (MFCs) and 2,2-bis(hydroxymethyl)propionic acid-modified MFCs (bis-MPA-modified MFCs)] were grafted by poly(ε-caprolactone) (PCL) molecules through the ring-opening polymerization (ROP) method. The PCL-grafted MFCs were characterized using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and elemental analysis. The results showed that the grafting of PCL on the bis-MPA-modified MFCs was more efficient than that of the pristine MFCs due to the higher density of the activated hydroxyl groups on the bis-MPA-modified MFCs. Furthermore, the numerous PCL chains bound to the bis-MPA-modified MFCs (PCL-g-mMFC) demonstrated the stronger interfacial adhesion between the modified MFC fibers and the PCL matrix, as well as the greatly improved dispersion of the modified MFCs in the PCL matrix of the PCL/cellulose biocomposites.     

Flexible and Asymmetric Ligand in Constructing Coordinated Complexes: Synthesis,Crystal Structures and Fluorescent Characterization

Flexible and asymmetric ligand L [L = 1-((pyridin-3-yl)methyl)-1H-benzotriazole], is used as a basic backbone to construct complicated metal-organic frameworks. Two new polymers, namely, [Ag₂(L)₂(NO₃)₂]_n (1) and [Ag(L)(ClO₄)]_n (2), were synthesized and characterized by X-ray structure analysis and fluorescent spectroscopy. The complex 1 gives an “S” type double helical conformation, whereas complex 2 exhibits a 1D zigzag configuration. Different anions affect the silver coordination geometry and crystal packing topology.     

Impact of the cation field strength on physical properties and structures of alkali and alkaline-earth borosilicate glasses

The impact of the cation field strength (CFS) of the glass network-modifier cations on the structure and properties of borosilicate glasses (BS) were examined for a large ensemble of mixed-cation (R/2)M₍₂₎O–(R/2)Na₂O–B₂O₃–KSiO₂ glasses with M⁺ ={Li⁺, Na⁺, K⁺, Rb⁺} and M²⁺ ={Mg²⁺, Ca²⁺, Sr²⁺, Ba²⁺} from four series of {K, R} combinations of K = n(SiO₂)/n(B₂O₃) = {2.0, 4.0} and R =[n(M₍₂₎O) ?+ ?n(Na₂O)]/n(B₂O₃) = {0.75, 2.1}. Combined with results from La³⁺ bearing glasses enabled the probing of physical-property variations across a wide CFS range, encompassing the glass transition temperature (T_g), density, molar volume and compactness, as well as the hardness (H) and Young's modulus (E). We discuss the inferred composition–structure/CFS–property relationships. Each of T_g, H, and E revealed a non-linear dependence against the CFS and a strong T_g/H correlation, where each property is maximized for the largest alkaline-earth metal cations, i.e., Sr²⁺ and Ba²⁺, along with the high-CFS La³⁺ species. The ¹¹B MAS NMR-derived fractional BO₄ populations decreased linearly with the average M^z+/Na⁺ CFS within both K–0.75 glass branches, whereas the NBO-rich K–2.1 glasses manifested more complex trends. Comparisons with results from RM₂O–B₂O₃–KSiO₂ glasses suggested no significant “mixed alkali effect”.     

Maternal PUFA ω-3 Supplementation Prevents Neonatal Lung Injuries Induced by Hyperoxia in Newborn Rats

Bronchopulmonary dysplasia (BPD) is one of the most common complications of prematurity, occurring in 30% of very low birth weight infants. The benefits of dietary intake of polyunsaturated fatty acids ω-3 (PUFA ω-3) during pregnancy or the perinatal period have been reported. The aim of this study was to assess the effects of maternal PUFA ω-3 supplementation on lung injuries in newborn rats exposed to prolonged hyperoxia. Pregnant female Wistar rats (n = 14) were fed a control diet (n = 2), a PUFA ω-6 diet (n = 6), or a PUFA ω-3 diet (n = 6), starting with the 14th gestation day. At Day 1, female and newborn rats (10 per female) were exposed to hyperoxia (O₂, n = 70) or to the ambient air (Air, n = 70). Six groups of newborns rats were obtained: PUFA ω-6/O₂ (n = 30), PUFA ω-6/air (n = 30), PUFA ω-3/O₂ (n = 30), PUFA ω-3/air (n = 30), control/O₂ (n = 10), and control/air (n = 10). After 10 days, lungs were removed for analysis of alveolarization and pulmonary vascular development. Survival rate was 100%. Hyperoxia reduced alveolarization and increased pulmonary vascular wall thickness in both control (n = 20) and PUFA ω-6 groups (n = 60). Maternal PUFA ω-3 supplementation prevented the decrease in alveolarization caused by hyperoxia (n = 30) compared to PUFA ω-6/O₂ (n = 30) or to the control/O₂ (n = 10), but did not significantly increase the thickness of the lung vascular wall. Therefore, maternal PUFA ω-3 supplementation may protect newborn rats from lung injuries induced by hyperoxia. In clinical settings, maternal PUFA ω-3 supplementation during pregnancy and during lactation may prevent BPD development after premature birth.     

pH-responsive micelles based on (PCL)2(PDEA-b-PPEGMA)2 miktoarm polymer: controlled synthesis,characterization, and application as anticancer drug carrier

Amphiphilic A₂(BC)₂ miktoarm star polymers [poly(ϵ-caprolactone)]₂-[poly(2-(diethylamino)ethyl methacrylate)-b- poly(poly(ethylene glycol) methyl ether methacrylate)]₂ [(PCL)₂(PDEA-b-PPEGMA)₂] were developed by a combination of ring opening polymerization (ROP) and continuous activators regenerated by electron transfer atom transfer radical polymerization (ARGET ATRP). The critical micelle concentration (CMC) values were extremely low (0.0024 to 0.0043 mg/mL), depending on the architecture of the polymers. The self-assembled empty and doxorubicin (DOX)-loaded micelles were spherical in morphologies, and the average sizes were about 63 and 110 nm. The release of DOX at pH 5.0 was much faster than that at pH 6.5 and pH 7.4. Moreover, DOX-loaded micelles could effectively inhibit the growth of cancer cells HepG2 with IC₅₀ of 2.0 μg/mL. Intracellular uptake demonstrated that DOX was delivered into the cells effectively after the cells were incubated with DOX-loaded micelles. Therefore, the pH-sensitive (PCL)₂(PDEA-b-PPEGMA)₂ micelles could be a prospective candidate as anticancer drug carrier for hydrophobic drugs with sustained release behavior.     

Asymmetric Solvation of the Zinc Dimer Cation Revealed by Infrared Multiple Photon Dissociation Spectroscopy of Zn2+(H2O)n (n = 1–20)

Investigating metal-ion solvation—in particular, the fundamental binding interactions—enhances the understanding of many processes, including hydrogen production via catalysis at metal centers and metal corrosion. Infrared spectra of the hydrated zinc dimer (Zn₂⁺(H₂O)_n; n = 1–20) were measured in the O–H stretching region, using infrared multiple photon dissociation (IRMPD) spectroscopy. These spectra were then compared with those calculated by using density functional theory. For all cluster sizes, calculated structures adopting asymmetric solvation to one Zn atom in the dimer were found to lie lower in energy than structures adopting symmetric solvation to both Zn atoms. Combining experiment and theory, the spectra show that water molecules preferentially bind to one Zn atom, adopting water binding motifs similar to the Zn⁺(H₂O)_n complexes studied previously. A lower coordination number of 2 was observed for Zn₂⁺(H₂O)₃, evident from the highly red-shifted band in the hydrogen bonding region. Photodissociation leading to loss of a neutral Zn atom was observed only for n = 3, attributed to a particularly low calculated Zn binding energy for this cluster size.     

Reaction synthesis of several titanium oxides through electrical wire explosion in air and in water

An experimental method to synthesize titanium oxide (Ti–O) through electrical wire explosion was performed. In this study, one experiment was conducted in air atmosphere, and the other with the wire fully dipped in distilled water. In air atmosphere, TiO₂ in anatase and rutile phases with ultrafine spherical particles was recovered. In distilled water, conversely, nanosized Ti–O material was recovered from an unknown phase, possibly a special phase of TiO₂ or a different type of titanium oxide such as Ti_nO or Ti_nO_2n−1. Recovered powders were analyzed using Scanning Electron Microscopy (SEM), High-resolution Transition Electron Microscopy (HR-TEM) and X-ray Diffraction (XRD) techniques.     

Charge states of atoms in ceramic superconductors HgBa2Ca n − 1Cu n O2n + 2, Tl2Ba2Ca n − 1Cu n O2n + 4, and Bi2Sr2Ca n − 1Cu n O2n + 4 (n = 1–3)

The parameters of the electric-field-gradient tensor for copper sites in the HgBa₂Ca _{n ? 1}Cu _n O_{2n + 2}, Tl₂Ba₂Ca _{n ? 1}Cu _n O_{2n + 4}, and Bi₂Sr₂Ca _{n ? 1}Cu _n O_{2n + 4} (n = 1–3) lattices have been determined using ⁶⁷Cu(⁶⁷Zn) Mössbauer emission spectroscopy and calculated in the framework of the point-charge approximation. The agreement between the experimental and calculated parameters has been achieved under the assumption that the holes formed as a result of the decrease in the oxidation state of a part of the mercury, thallium, or bismuth atoms are distributed over the oxygen sites in the Cu-O or adjacent planes. It has been demonstrated that the oxidation state of cations can be controlled in high-temperature superconducting ceramic materials.     

Synthesis and characterization of potential NO donors: novel iron–sulfur nitrosyls containing the μ-N–C–S skeleton

Binuclear paramagnetic nitrosyl iron complexes of “g∼2.03 family” were first synthesized. Their structure and properties differ from those of “the red Roussin salt ethers”. The novel nitrosyl iron complexes: [Fe₂(μ₂-SR)₂(NO)₄]·nH₂O (η¹-S, η¹-N), n=1–2, R – 3-amino-1,2,4-triazolyl (1), 1,2,4-triazolyl (2), 1-methyl-tetrazolyl (3), benzothiazolyl (4) were obtained by the exchange reaction of Na₂Fe₂(S₂O₃)₂(NO)₄ with heterocyclic thiols and studied by methods of EPR, IR and Mössbauer spectroscopy. The molecular structure of complex 1 was determined by X-ray analysis.     

Novel heterometallic Cu/Cd complex containing a unique polymeric ladder-like anion [Cd2(O2CMe)6]2−n derived from elemental copper and cadmium oxide

Copper powder reacts with cadmium oxide and ammonia acetate in methanol solution of ethylenediamine affording {[Cu(en)₂][Cd₂(O₂CMe)₆]}_n in which seven-coordinated cadmium atoms are ligated by three bonding modes of acetate groups forming ladder-like anions [Cd₂(O₂CMe)₆]²⁻_n. The cations [Cu(en)₂]²⁺ are located in the lattice and serve as bridges to connect separate anionic polymer chains into a two- dimensional network via hydrogen bonds.     

The continuing development of Magnéli phase titanium sub-oxides and Ebonex electrodes

Magnéli phase titanium sub-oxides were identified (via X-ray diffraction) in the 1950s as a distinct series of electrically conducting compounds having the general formula Ti_nO_2n−1 where 3 < n < 10. Early research on the characterisation of materials based on Ti_nO_2n−1 has been well documented. This concise review, which is illustrated by data from the literature and our own laboratory, concerns more recent research on Magnéli phase titanium oxide materials. A brief overview of chemical and physical properties is followed by the applications of electrode materials based on these titanium oxides. Energy conversion technologies (particularly batteries and fuel cells) are shown to be a continued area of research that particularly suits the relatively high electrical conductivity and chemical stability inherent in these materials.     

Isolation and structural characterization of the first homoleptic lanthanide–zirconium oxoisopropoxide,La2Zr3O(OPri)16. Combination of an [M4O] tetrahedron with an [MO6] octahedron – A new structure type for pentanuclear alkoxide complexes

The amorphous bimetallic isopropoxides of variable composition LaZr_nO_x(OPrⁱ)_3+4n−2x, where n = 0.5–3 formed on interaction of the two homometallic isopropoxides, La₅O(OⁱPr)₁₃ and Zr(OⁱPr)₄(ⁱPrOH), in solutions in parent alcohol crystallize slowly yielding a bimetallic oxoalkoxide La₂Zr₃O(OPrⁱ)₁₆ (1). In its molecule an octahedrally coordinated zirconium atom is connected via two μ₃-OR and two μ-OR-groups with two lanthanum atoms of a tetrahedral [La₂Zr₂(μ₄-O)] aggregate. This structure type has not been previously observed in the structures of pentanuclear alkoxide aggregates. The conditions leading to formation of 1 from solutions containing the homometallic alkoxides are outlined.     

Structural Diversity of Copper(II) Complexes with 9-Deazahypoxanthine and Their in Vitro SOD-Like Activity

Two structurally different copper(II) complexes of the compositions [{Cu(9dhx)(H₂O)₃}₂(µ-SO₄)₂] (1) and [Cu(9dhx)₂(H₂O)₂(NO₃)₂]·H₂O (2), involving 9-deazahypoxanthine (9dhx; 6-oxo-9-deazapurine; 9-deazahypoxanthine), have been prepared and characterized by elemental analysis, infrared and electronic spectroscopy, electrospray ionisation (ESI) mass spectrometry, thermogravimetric (TG) and differential thermal (DTA) analyses, and cyclic voltammetry. The X-ray structures of complexes 1 and [Cu(9dhx)₂(H₂O)₂(NO₃)₂] (2a) revealed the distorted octahedral geometry in the vicinity of the copper(II) atoms, with the NO₅ and N₂O₄ donor set, respectively. In the dimeric compound 1, the {Cu(9dhx)(H₂O)₃}₂ units are bridged by sulfate groups with the Cu···Cu separation being 5.3446(2) Å. In both structures the 9dhx ligands are coordinated through the N3 atoms of the pyrimidine moieties. The SOD-like activity of complexes 1 and 2 was evaluated in vitro showing moderate effect, with the IC₅₀ values equal to 18.20, and 53.33 μM, respectively.     

A sinusoidal chain constructed from decorated Keggin clusters and {Cu(enMe)2}2+ bridging groups in [Cu(enMe)2(H2O)] [{Cu(enMe)2}{Cu(enMe)2(H2O)W12O40(H2)}] · nH2O

A novel organic–inorganic hybrid material, [Cu(enMe)₂(H₂O)][{Cu(enMe)₂}{Cu(enMe)₂(H₂O)W₁₂O₄₀(H₂)}] · nH₂O (n = 0.33, enMe = 1,2-diaminopropane), has been prepared under mild hydrothermal conditions and characterized by single-crystal X-ray diffraction, IR and magnetic susceptibility measurements. It is revealed that the one-dimensional [{Cu(enMe)₂}{Cu(enMe)₂(H₂O)W₁₂O₄₀(H₂)}]²⁻ chain in the structure shows a unique sinusoidal ruffling, which is constructed from decorated Keggin clusters and {Cu(enMe)₂}²⁺ bridging groups through sharing one terminal and one doubly-bridging oxygen atoms of a cluster. The magnetic measurements show that the compound possesses well-separated Cu²⁺ centers. It was indicated that the hybrid exhibits a good catalytic activity in H₂O₂ decomposition.     

Electrochemical and textural characterization of binary Ru-Sn oxides synthesized under mild hydrothermal conditions for supercapacitors

Hydrous ruthenium-tin oxides (denoted as (Ru-Sn)O₂·nH₂O) were synthesized under a mild hydrothermal condition. The mean particles size of pristine RuO₂·nH₂O, smaller than 3 nm, was decreased with the introduction of Sn into the precursor solutions while it is not significantly affected by varying the Sn content. The textual characteristics of (Ru-Sn)O₂·nH₂O were analyzed through means of X-ray diffraction (XRD), energy-dispersive spectroscopy (EDS), electron diffraction, X-ray photoelectron spectroscopy (XPS), and thermogravimetric analyses (TGA). From the ideal capacitive behavior of pristine oxides with the Ru content ≥40 at.%, hydrothermal synthesis favored the formation of hydrous oxides with a novel structure providing excellent pathways for electron hopping and proton diffusion/exchange during the charge storage/delivery process. The introduction of tin oxide was demonstrated to successfully promote the utilization of oxyruthenium species, reaching a maximum C_S,Ru of ca. 830 F/g for pristine Ru_0.6Sn_0.4O₂·nH₂O (measured at 25 mV/s).     

Synthesis,structure, and photocatalytic hydrogen of three environmentally friendly titanium oxo-clusters

In this paper, three environmentally friendly titanium oxo-clusters, Ti₆O₄(OEt)₄(OPrⁱ)₄(OOCC₆H₅)₈ (1), Ti₆O₄(OEt)₈[OOC(CH₃)₃]₈ (2) and Ti₆O₄(OCH₃)₈[OOC(CH₃)₃]₈ (3), were obtained under three similar solvent-thermal reactions of titanium(IV) isopropoxide, alcohols and carboxylic acids, and structurally characterized by single-crystal X-ray diffraction, TGA and IR analysis. All the compounds were crystallized in the space group P2₁/c and the arrangements of the titanium atoms are similar. In addition, the UV-light photocatalytic hydrogen evolution activities have been observed for them, which showed good photocatalytic activity for hydrogen production from water.