Showed Photoluminescence Properties Research Articles

Biofilm Demolition by [AuIII(N N)Cl(NHC)][PF6]2 Complexes Fastened with Bipyridine and Phenanthroline Ligands; Potent Antibacterial Agents Targeting Membrane Lipid.

The development of new antibacterial drugs is essential for staying ahead of evolving antibiotic resistant bacterial (ARB) threats, ensuring effective treatment options for bacterial infections, and protecting public health. Herein, we successfully designed and synthesized two novel gold(III)- NHC complexes, [Au(1)(bpy)Cl][PF6]2 (2) and [Au(1)(phen)Cl][PF6]2 (3) based on the proligand pyridyl[1,2-a]{2-pyridylimidazol}-3-ylidene hexafluorophosphate (1⋅HPF6) [bpy=2,2'-bipyridine; phen=1,10-phenanthroline]. The synthesized complexes were characterized spectroscopically; their geometries and structural arrangements were confirmed by single crystal XRD analysis. Complexes 2 and 3 showed photoluminescence properties at room temperature and the time-resolved fluorescence decay confirmed the fluorescence lifetimes of 0.54 and 0.62 ns respectively; which were used to demonstrate their direct interaction with bacterial cells. Among the two complexes, complex 3 was found to be more potent against the bacterial strains (Staphylococcus aureus, Gram-positive and Pseudomonas aeruginosa, Gram-negative bacteria) with the MIC values of 8.91 μM and 17.82 μM respectively. Studies revealed the binding of the complexes with the fundamental phospholipids present in the cell membrane of bacteria, which was found to be the leading cause of bacterial cell death. Cytotoxicity was evaluated using an MTT assay on 293 T cell lines; emphasizing the potential therapeutic uses of the Au(III)-NHC complexes to control bacterial infections.

Three-Dimensional Bimetallic Ammonium K-Eu Nitrate with a Rare (6,6)-Connected Ion Topology Exhibiting Structural Phase Transition and Photoluminescence Properties.

A K-Eu bimetallic ammonium metal-nitrate three-dimensional (3D) framework incorporating R-N-methyl-3-hydroxyquinuclidine, (RM3HQ)2KEu(NO3)6 (RM3HQ = R-N-methyl-3-hydroxyquinuclidine, 1), was characterized and reported. Distinguishing from the former hybrid rare-earth double perovskites, 1 adopts a mixed corner- and face-sharing K+/Eu3+-centered polyhedral connectivity to form a 3D inorganic framework, showing a rare (6, 6)-connected ion topology with a 66 framework. Notably, 1 exhibits clear phase transition, and the switchable thermodynamic behavior is confirmed by variable-temperature dielectric measurements and second-harmonic generation response. Moreover, 1 also shows photoluminescence properties. The activator Eu3+ plays a crucial role in this process, leading to a significant narrow emission at 592 nm with a photoluminescence quantum yield (PLQY) of 20.76%. The fluorescence lifetime (FLT) of 1 is 4.32 ms. This finding enriches the bimetallic hybrid system for potential electronic and/or luminescence applications.

Unveiling the Structural and Optical Properties of Samarium Titanates Pyrochlore, Sm2Ti2O7

A magnetic system whose geometry prevents all pairwise spin interactions from being fulfilled simultaneously to minimize the energy is said to be frustrated. These systems are prevalent throughout all disciplines of physical and chemical study. This article reports a detailed structural and optical analysis of such frustrated Sm2Ti2O7 (STO), a pyrochlore structure. The ordered pyrochlore, STO of cubic symmetry, space group Fd3¯m [no. 227], has been synthesized using the standard solid-state reaction method. The Tauc’s plot reveals a direct band gap value of 3.8 eV from ultraviolet-visible reflectance data. Photoluminescence studies for STO using 280 nm excitation wavelength show the most intense emission peak at 395 nm, 468 nm, and other weak emissions at 368 nm, 412 nm, 430 nm, 449 nm, and 514 nm corresponding to the respective electronic transitions, indicates that the materials show photoluminescence properties. However, the unique characteristics of Sm2Ti2O7, including its wide band gap, photoluminescence, and high refractive index, make it a promising candidate for various magneto-optical, solid oxide fuel cell device fabrication applications.

Extension of Pt–Ag cluster units by incorporating silver salts

Abstract A sterically controlled Z-shaped Pt2Ag2 complex showed a metalation reaction with a Ag ion via the formation of the thermodynamically unfavorable Pt2Ag2 complex with U-shaped configuration. Multiple dative bond formation between Pt and an additional Ag ion endowed enough thermodynamic stability on the Pt2Ag3 cluster to overcome the unfavorable steric effect from bulky substituents on the ligands in the U-shaped structure. A single crystal X-ray structural analysis revealed dimerized structure of the cationic Pt2Ag3 complex units bridged by [Ag2(OTf)4]2− (OTf− = triflate anion) via strong Ag–π coordination with pyrazole moiety in the solid state. The heteropolynuclear complexes showed photoluminescence properties depending on the structure of the Pt–Ag clusters.

Evaluation of ferric ion molar concentration effect on morphological and opto-electrochemical properties of FexNi1-xO composite thin films

The impact of a significantly lower ferric (Fe3+) ion concentration on the structural, morphological, optical, and electrochemical properties of spin-coated FexNi1-xO thin films cast on Indium Tin Oxide (ITO) glasses was scrutinized and then compared with a higher ferric (Fe3+) ion concentration. After a careful structural study of the FexNi1-xO thin films by X-ray diffraction (XRD) analysis, the film surface was further analyzed by atomic force microscopy (AFM), field emission scanning electron microscopy (FE-SEM) study, and X-ray photoelectron spectroscopy (XPS). Even for a noticeably small amount of substituted Ni2+ metal cations by Fe3+, degradation of the host crystal lattice was surprisingly higher. The influence of Fe3+ ions on the optical properties of FexNi1-xO ITO thin films was studied using UV–visible absorption spectra and Raman spectra. Both unsubstituted and Fe-substituted NiO ITO thin films showed photoluminescence properties. Changes in resistance values in pristine and FexNi1-xO thin films were monitored by an electrochemical impedance spectroscopy (EIS) study. Fe-substituted NiO thin films with a lower molar concentration showed better electrochemical performance as compared to those with a higher molar concentration of Fe3+ ions. This fact was further reinforced through a current-voltage (IV) study and a cyclic-voltagram (CV) study.

Structural, physicochemical and anticancer study of Zn complexes with pyridyl-based thiazolyl-hydrazones

Thiazolyl-hydrazones (THs) exhibit a wide spectrum of biological activity that can be enhanced by complexation with various metal ions. Zn(II) complexes with α-pyridine-1,3-TH ligands may represent an alternative to the standard platinum-based chemotherapeutics. In addition, they show photoluminescence properties and thus can be regarded as multifunctional materials. In this study, we synthesized and characterized three neutral Zn(II) complexes (1–3) with pyridine-based TH ligands HLS1‒3 in order to investigate the influence of the ligands charge on the structure and intermolecular interactions in the solid state, and consequently photophysical properties. The deprotonation of the ligands mainly affects the relative energies of electronic levels in the complexes, compared to cationic counterparts, resulting in similar photoluminescence mechanisms and quantum yields with a small shift in emission energy. The influence of the substitution at the ligands’ periphery on the selected quantum molecular descriptors of the complexes is localized to the substitution site. Also, the substituents did not considerably influence the redox responses of the complexes. However, predominant spectral changes were observed in the course of the first reduction and oxidation processes which caused distinct spectral color changes indicating their possible functionality for electrochromic applications. In addition, complex 1 showed antiproliferative activity with GI50 values below 2 µM on all tested cancer cell lines.

Photoluminescence and Induction Heating Studies of Fe3O4@CaWO4:5Dy3+ Magnetic-Luminescent Nanocomposite for Hyperthermia Application

A 5 at.% Dy3+ ions doped CaWO4 nanoparticles (CaWO4:5Dy) were synthesized by hydrothermal method using polyethylene glycol (PEG) as solvent medium and capping agent. The phase purity and crystalline properties of the prepared nanoparticles were obtained from the XRD analysis. TEM images revealed that the CaWO4:Dy3+ have particles of size approximately in the range 30-50 nm. The prepared magnetic luminescence nanocomposite exhibits a high saturation magnetization. The prepared nanocomposite can achieve hyperthermia temperature (42 ºC) in a short period by applying the alternating magnetic field, externally. The nanocomposite also shows photoluminescence properties. Nanomaterials described in this work can be used for optical imaging as well as hyperthermia applications.

Melt and solution processable novel photoluminescent polymer blends for multifaceted advanced applications

To overcome the limitation of traditional photoluminescent materials, a cost-effective photoluminescence polymer was synthesized by a simple and one-step technique using benzyl alcohol as the starting material and aqueous sulfuric acid as the catalyst. The synthesized photoluminescent polymer showed photoluminescence properties independent of the excitation wavelength together with high thermal stability and excellent mechanical properties. The synthesized photoluminescent polymer was incorporated into different polymers viz. thermoplastic as well as thermoset polymers by melt and solution processes, respectively, to achieve photoluminescent polymer blends. The thermal, mechanical, and photoluminescent properties of the fabricated blends were improved or remained almost the same with the photoluminescence polymer contents, strongly proving that the photoluminescent polymer was well dispersed in the polymeric matrix. The potential applications of the photoluminescence polymer blends were investigated for 3D printing and a fluorescent ink. The study paves a way for the development of photoluminescent materials for various applications.

Effect of alkyl substituent on molecular configuration in a Cu(II) complex: Synthesis of Cu and CuO nanoparticles using a single, solid-source precursor

A new hydrazone-type ligand, methyl 4-(pyridine-4yl-methylene) hydrazinecarboxylate (C8H9N3O2; 4-pymc) and its Cu(II) complex [Cu(4-pymc)2(CH3COO)2(H2O)] (1) were prepared and characterized. The structure of 1 comprises monomers in which Cu is five-coordinated with a distorted square pyramidal structure. Oxygen atoms of two monodentate acetate anions and a pair of nitrogen atoms from pyridine rings form the basal plane. The apical position is filled by a water molecule. Further, the TEM images demonstrated successful preparation of both Cu (~35 nm) and CuO (~95 nm) nanoparticles (NPs) using the single source as-prepared Cu(II) complex via a thermal decomposition approach simply by changing the atmospheric conditions (i.e., vacuum and air atmospheres) under which the Cu(II) complex was calcined for 1 h at 400 °C. Furthermore, the TG-DTA studies indicate that 1 underwent endo- followed by exo-thermic decomposition to form CuO as the end residue in an air atmosphere. The production of Cu and CuO NPs was corroborated by powder x-ray diffraction (PXRD) analysis. The sharp and high intensity PXRD peaks of the calcined samples corroborated that the formed NPs had no impurity and high crystallinity. Furthermore, both ligand and Cu(II) complex showed photoluminescence properties. Also, we demonstrated that the prepared 1 can act as a single, solid-source precursor to form both Cu and CuO NPs.

Electronic, Structural and Functional Versatility in Tetrathiafulvalene-Lanthanide Metal-Organic Frameworks.

Tetrathiafulvalene-lanthanide (TTF-Ln) metal-organic frameworks (MOFs) are an interesting class of multifunctional materials in which porosity can be combined with electronic properties such as electrical conductivity, redox activity, luminescence and magnetism. Herein a new family of isostructural TTF-Ln MOFs is reported, denoted as MUV-5(Ln) (Ln=Gd, Tb, Dy, Ho, Er), exhibiting semiconducting properties as a consequence of the short intermolecular S⋅⋅⋅S contacts established along the chain direction between partially oxidised TTF moieties. In addition, this family shows photoluminescence properties and single-molecule magnetic behaviour, finding near-infrared (NIR) photoluminescence in the Yb/Er derivative and slow relaxation of the magnetisation in the Dy and Er derivatives. As such properties are dependent on the electronic structure of the lanthanide ion, the immense structural, electronic and functional versatility of this class of materials is emphasised.

Influence of Sulfur Oxidation State and Substituents on Sulfur-Bridged Luminescent Copper(I) Complexes Showing Thermally Activated Delayed Fluorescence.

Copper(I) complexes are seen as more sustainable alternatives to those containing metal ions such as iridium and platinum for emitting devices. Copper(I) complexes have the ability to radiatively decay via a thermally activated delayed fluorescence (TADF) pathway, leading to higher photoluminescent quantum yields. In this work we discuss six new heteroleptic Cu(I) complexes of the diphosphine-diimine motif. The diphosphine ligands employed are (oxidi-2,1-phenylene)bis(diphenylphosphine) (DPEPhos), and the diimine fragments are sulfur-bridged dipyridyl ligands (DPS) which are functionalized at the 6,6'-positions of the pyridyl rings (R = H, Me, Ph) and have varying oxidation states at the bridging sulfur atom (S, SO2). The proton (Cu-DPS, Cu-DPSO2) and phenyl (Cu-Ph-DPS, Cu-Ph-DPSO2) substituted species are found to form monometallic complexes, while those with methyl substitution (Cu-Me-DPS, Cu-Me-DPSO2) are found to have a "Goldilocks" degree of steric bulk leading to bimetallic species. All six Cu(I) complexes show emission in the solid state, with the photophysical properties characterized by low temperature steady-state and time-resolved spectroscopies and variable temperature time-correlated single photon counting. Cu-DPS, Cu-DPSO2, Cu-Me-DPS, Cu-Me-DPSO2, and Cu-Ph-DPSO2 were shown to emit via a TADF mechanism, while Cu-Ph-DPS showed photoluminescence properties consistent with triplet ligand-centered (3LC) emission.

Electrophoretic size fractionation of graphene oxide nanosheets

Size fractionation of polydispersed graphene oxide (GO) into highly monodispersed fractions by electrophoresis is reported. The smallest fraction with nanosheets of approximately the same size shows photoluminescence properties.

Supported cobalt nanoparticles on graphene oxide/mesoporous silica for oxidation of phenol and electrochemical detection of H2O2 and Salmonella spp

Graphene oxide/silica-cobalt (GO/Si10Co) mesostructured nanocomposite was prepared via simple sol-gel method followed by hydrothermal treatment. Calcination of the material at 540 °C for 24 h gave reduced graphene oxide/silica-cobalt (rGO/Si10Co). The FT-IR and Raman spectroscopies of the GO/Si10Co confirms the interaction between graphene oxide, silica and cobalt. The characteristic structure of the mesoporous silica with parallel and cylindrical pores stacked in a hexagonal array, the graphene sheet and the distribution of cobalt nanoparticles were clearly viewed through FESEM, TEM and EDS-mapping analyses. The BET specific surface areas were found to be 588 m2 g−1 for GO/Si10Co and 843 m2 g−1 for rGO/Si10Co. Nitrogen sorption analysis exhibits that both the materials having type IV isotherms with H1 hysteresis loops, revealed the mesoporosity nature of the materials. The synergistic effect between GO sheets, silica and Co species fashioned the multifunctional applications of the synthesized materials. Under optimal experimental conditions, the GO/Si10Co showed excellent catalytic activity toward the liquid-phase oxidation of phenol with H2O2. Furthermore, rGO/Si10Co mesostructured nanocomposite showed good electrocatalytic activity towards the reduction of H2O2 as compared to GO/Si10Co due to the large surface area, excellent electrical conductivity and enhanced electrochemical activity. The developed nanocomposites were also tested as an aptasensor, and it is demonstrated a low detection limit of ∼101 cfu mL−1 towards Salmonella spp. The EIS result indicates, the electron transfer was blocked as more Salmonella spp was captured on the rGO/Si10Co-aptamer/GCE electrode. Besides, the nanocomposites also showed photoluminescence properties in visible range due to the cobalt nanoparticles and magnetic properties. These properties are important for applications in optoelectronics and biological labelling.

Synthesis, structure, and photoluminescence properties of bis[2-(1,3-benzoxazol-2-yl-κN)-4,5-dichloro-3-(ethoxycarbonyl)phenolato-κO]zinc(II)

The structure of bis[2-(1,3-benzoxazol-2-yl-κN)-4,5-dichloro-3-(ethoxycarbonyl)phenolato-κO]-zinc(II) was determined by IR and 1H and 13C NMR spectroscopy, and its structural characteristics were estimated by quantum chemical calculations. The complex showed photoluminescence properties.

Synthesis and Characterization of New Mesomorphic Azo Compounds and Study their Photoluminesecence Properties

The preparation of a new Azo compounds of highly conjugated dimeric and polymeric liquid crystal to achieve the crystalline characteristics Which have structures assigned based on elemental analysis, IR 1HNMR and CHNS-O while mesogenic properties have been set for DSC and hot-stage polarizing optical microscopy. The compounds show enantiotropicnematic phase being displayed. The compounds show photoluminescence properties in the organic solution at room temperature, with the fluorescence band centered around 400 nm.

Synthesis and Characterization of New Mesomorphic Azo Compounds and Study their Photoluminesecence Properties

The preparation of a new Azo compounds of highly conjugated dimeric and polymeric liquid crystal to achieve the crystalline characteristics Which have structures assigned based on elemental analysis, IR 1HNMR and CHNS-O while mesogenic properties have been set for DSC and hot-stage polarizing optical microscopy. The compounds show enantiotropicnematic phase being displayed. The compounds show photoluminescence properties in the organic solution at room temperature, with the fluorescence band centered around 400 nm.

Thermo-selective Tm(x)Ti(1-x)O(2-x/2) nanoparticles: from Tm-doped anatase TiO2 to a rutile/pyrochlore Tm2Ti2O7 mixture. An experimental and theoretical study with a photocatalytic application.

This is an experimental and theoretical study of thulium doped TiO2 nanoparticles. From an experimental perspective, a method was used to synthesize thulium-doped TiO2 nanoparticles in which Tm(3+) replaces Ti(4+) in the lattice, which to our knowledge has neither been reported nor studied theoretically so far. Different proportions of anatase and rutile phases were obtained at different annealing temperatures, and XRD and Raman spectroscopy also revealed the presence of a pyrochlore phase (Tm2Ti2O7) at 1173 K. Thus, the structure of the Tm-doped nanoparticles was thermally-controlled. Furthermore, XPS showed the presence of Tm(3+) in the samples synthesized, which produces oxygen vacancies to maintain the local neutrality in the lattice. The presence of Tm(3+) in the samples led to changes in the UV-Vis absorption spectra, so they showed photoluminescence properties and new states in the band gap, which produce a new lower energy electronic transition than the main TiO2 one. Periodic DFT calculations were performed to understand the experimentally produced structures. The production of oxygen vacancies was analysed and the changes generated in the structure were fully detailed. The DOS and PDOS analyses confirmed the experimental results obtained using UV-Vis spectroscopy, and showed that the new electronic states in the band gap are due to interactions of the f state of Tm and the p state of O. Likewise, the charge study and the ELF analysis indicate that when Tm is introduced into the TiO2 structure, the Ti-O bond around the oxygen vacancy is strengthened. Finally, an example of a photocatalytic application was developed to show the high efficiency of the samples due to the heterojunction in the interfaces of the phases in the samples, which improved the charge separation and the good charge carrier mobility due to the presence of the pyrochlore phase, as was also shown theoretically.

Ferroelectric (Na1/2Bi1/2)TiO3 thin films showing photoluminescence properties

Polycrystalline lead-free (Na1/2Bi1/2)TiO3 (NBT) ferroelectric thin films doped with 1 mol% of rare earth (RE) elements are processed on Pt-terminated silicon substrates using a solution deposition method. The thin films that exhibit single-phase perovskite structure show photoluminescence properties with highest intensities in the wavelength range between 700 and 850 nm, depending on RE element. The ferroelectric properties of the pure NBT film (Pr: 20.5 µC cm−2, Ec: 150 kV cm−1) are somewhat decreased for the doped films, which is ascribed to decreasing of the number of Bi lone pairs through the substitution of Bi with RE elements in the perovskite lattice.

Synthesis of novel symmetrical tetra- and hexacatenar di-amides containing 1,3,4-thiadiazole units and a study of their mesomorphic and luminescence properties

Novel tetra- and hexacatenar materials based on di-amides derived from 4-aminophenyl-1,3,4-thiadiazole derivatives have been synthesised (series 2a–f, 3a-f and 4a–f) and their mesomorphic properties have been studied by differential scanning calorimetry, polarised optical microscopy and X-ray diffraction. All compounds in series 2a–f and 3a–f display an enantiotropic hexagonal columnar phase. With the exception of 4d and 4f, which are non-mesomorphic, all compounds in series 4a–f display enantiotropic hexagonal columnar mesomorphism. The mesomorphic properties were found to be dependent on the length, number of alkoxy chains attached at the end of the rigid core and on the nature of the central ring (benzene in series 2a–f, thiophene in series 3a–f and cyclohexane in series 4a–f). These compounds also show photoluminescence properties in the visible region. A thermogravimetric analysis was also performed.

Five new mononuclear zinc(II) complexes with a tetradentate N-donor Schiff base: Syntheses, structures and influence of anionic coligands on the luminescence behaviour and supramolecular interactions

The present report describes the syntheses, structures and luminescence properties of five mononuclear complexes, [Zn(L)Cl]ClO4 (1), [Zn(L)Br]ClO4 (2), [Zn(L)I]ClO4 (3), [Zn(L)N3]ClO4 (4), and [Zn(L)(NCS)](SCN) (5), derived from the tetradentate ligand L, N,N′-bis(2-pyridylmethylene)-1,3-propanediamine. The geometry around the Zn2+ centre is best described as square pyramidal, although significant distortion towards the trigonal pyramidal geometry is noticed, especially for the halide complexes, of the later, the chloro (1) and bromo (2) complexes are isostructural and isomorphous. The stabilization of the crystal lattices is maintained by interesting, relatively strong hydrogen bonds and π⋯π interactions which lead to various supramolecular architectures. All the five complexes show photoluminescence properties and their trend can be correlated with the position of the apical anionic coligands in the spectrochemical series of ligands.