Room Temperature In Solid State Research Articles

The pH-controlled synthesis of three zinc-based complexes modeled by 5-carboxyl-1-carboxymethyl-2-oxidopyridinium with luminescence studies

Three new zinc compounds {[Zn2(ccop)2(4,4′-bpy)]·H2O}n (1), {[Zn(ccop)(bpp)]·H2O}n (2) and [Zn(ccop)(H2O)5]·H2O (3) (H2ccop=5-carboxyl-1-carboxymethyl-2-oxidopyridinium, 4,4′-bpy=4,4′-bipyridine, bpp=1,3-bis(4-pyridyl) propane) have been prepared under hydrothermal conditions at different pH values, and characterized by elemental analysis, IR spectra, thermogravimetric analysis, powder X-ray diffraction, and single-crystal X-ray diffraction. Complex 1 features a 2D (4,4) net when the dinuclear [Zn2(COO)2N2O2] unit is regarded as a quadruply-connected node. Complex 2 also displays a 2D (4,4) net constructed by Zn-carboxylate chains and bpp struts. While 3 is a mononuclear complex which is further assembled into a 3D supramolecular structure through hydrogen boning interactions. All of 1–3 emit the intense indigotin photoluminescence at room temperature in solid state.

Room-temperature solid state synthesis of ZnO/Bi2O3 heterojunction and their solar light photocatalytic performance

ZnO/Bi2O3 heterojunction was prepared by solid state reaction method at room temperature. The as-prepared nanostructures were characterized as the assembled nanosheets of ZnO on which Bi2O3 nanoparticles were well dispersed. Further studies revealed that the morphology and photocatalytic property could be regulated by tuning the amount of Bi2O3. The introduction of Bi2O3 can lead to the enhancement of solar light absorption, and the 5% ZnO/Bi2O3 samples exhibited the best photocatalytic activity under the solar light irradiation. The excellent photocatalytic performances could be ascribed to the synergistic effects of the hierarchical nanostructures and the effective separation of photogenerated carriers. Moreover, the hydroxyl radicals (OH) are found to be the main active species generated in the oxidation reaction of RhB over ZnO/Bi2O3 photocatalyst. Therefore, our work demonstrated a facile way to prepare hierarchical nanostructures with excellent photocatalytic performance using solid state method at room temperature.

Structural, spectral and DFT studies of N-ethyl-2-(4-(phenylamino)-4-thioxobutan-2-ylidene)hydrazinecarbothioamide complexes synthesized by ball milling

Thiosemicarbazone complexes of Ni(II), Co(II), Cu(II) and VO(II) with the N-ethyl-2-(4-(phenylamino)-4-thioxobutan-2-ylidene)hydrazinecarbothioamide (H2L) containing hard-soft NS donor sites were prepared by two different methods, the first was by ball milling as a green strategy and the second was by refluxing as the traditional method. The isolated solid compounds were elucidated by elemental analysis, spectroscopy (1H NMR, IR, UV–visible, ESR, MS spectra), and physical measurements (magnetic susceptibility and molar conductance). IR spectra suggested that the H2L behaved as a neutral or mononegative bidentate ligand depending on the method used. The room temperature solid state ESR spectra of the Cu(II) complex showed dx2-y2 as a ground state, suggesting tetragonally distorted octahedral geometry around Cu(II) center. The DFT was evaluated to confirm the geometry of the investigated compounds. Also, the antimicrobial activity of all compounds was studied using a wide spectrum of bacterial and fungal strains.

Colossal resistance switching and band gap modulation in a perovskite nickelate by electron doping.

The electronic properties of correlated oxides are exceptionally sensitive to the orbital occupancy of electrons. Here we report an electron doping strategy via a chemical route, where interstitial dopants (for example, hydrogen) can be reversibly intercalated, realizing a sharp phase transition in a model correlated perovskite nickelate SmNiO3. The electron configuration of eg orbital of Ni(3+) t2g(6)eg(1) in SmNiO3 is modified by injecting and anchoring an extra electron, forming a strongly correlated Ni(2+) t2g(6)eg(2) structure leading to the emergence of a new insulating phase. A reversible resistivity modulation greater than eight orders of magnitude is demonstrated at room temperature. A solid-state room temperature non-volatile proton-gated phase-change transistor is demonstrated based on this principle, which may inform new materials design for correlated oxide devices. Electron doping-driven phase transition accompanied by large conductance changes and band gap modulation opens up new directions to explore emerging electronic and photonic devices with correlated oxide systems.

Synthesis of Nano-BiFeO3 by Low-heating Temperature Solid State Precursor Method: Using Different Types of Alkali

A new way to prepare BiFeO3 nano-powders by low-heating temperature solid state precursor method is presented in this paper. Room-temperature solid state reaction was adopted to prepare the precursors, which were further calcined in low-heating temperature at 500°C to synthesize nano-BiFeO3. The particle size of BiFeO3, ranging from 18 to 80 nanometers, can be effectively controlled by different alkali in raw materials. Owing to the quantum size effect, the optical band gaps and magnetic characteristics of BiFeO3 increased with the decreasing particle size.

Self-assembly of three d10 metal coordination polymers based on a flexible bis(2-methylbenzimidazole) and dicarboxylate co-ligands

Hydrothermal self-assembly of zinc nitrate with 1,1′-(1,3-propane)bis-(2-methylbenzimidazole) (pbmb) and different dicarboxylic acid ligands gave rise to three new coordination polymers [Zn(pbmb)(hmph)]n (1), {[Zn2(pbmb)(chdc)2]⋅0.5H2O}n (2), [Zn(pbmb)(mip)]n (3) (H2hmph=homophthalic acid, H2chdc=1,4-cyclohexanedicarboxylic acid and H2mip=5-methylisophthalic acid). Both complexes 1 and 3 possess 2D {63} framework and further extend into 3D supramolecular network via CH⋯O hydrogen bonding or π–π stack interactions. While 2 is a 1D double loop-like chain structure, which arranged into a 2D network through CH⋯O hydrogen bonding interactions. Three compounds all exhibit strong photoluminescence at room temperature in solid state and may be good candidates for potential luminescence materials.

A photoluminescent interpenetrating metal–organic frame work based on Cu4I4 and novel azino-quinoline ligand

Synthesis of a novel, triply-interpenetrating metal–organic framework 1.H2O is described here. The coordination polymer was synthesized by simple reaction of Cu2I2 with an azino-quinoline ligand (L1). The X-ray crystal structure analysis reveals that the complex 1.H2O is a 2-D coordination polymer having (4,4′) grid network architecture. The ligand L1 possesses quinoline group and the 2-D structure of 1.H2O contains distorted cubane type Cu4I4 SBU unit. Each of the four Cu(I) ions posses tetrahedral coordination environment. Metal–organic framework in 1.H2O shows strong photoluminescence property at room temperature in solid state and emission spectra shows a blue shift of the peak in comparison to the free azino-quinoline ligand (L1). The coordination polymer 1.H2O was found to be stable up to 290°C.

A thermally labile copper (II) complex with hetero N- and O-donor ligands: Crystal structure, Hirshfeld surfaces, thermal and luminescent properties

A new complex ([Cu(L1)2(H2O]2]⋅2H2O, 1) derived from a hetero N- and O-donor ligand 5-methyl-imidazole-3-carboxylic acid (L1H) has been synthesized and characterized. Comparisons between [Cu(L1)2(H2O]2]⋅2H2O, [Co(L2)(H2O]2⋅H2O (2), and [Cu(L2)2H2O]⋅H2O (L2H=5-methyl-isoxazole-3-carboxylic acid) revealed that the coordinated water molecules play a key role in the construction of crystal structures: two coordinated water molecules in the axial positions lead to single-deck 1D chain and 3D motif while one coordinated water molecule resulted to double-deck 1D chain and 2D stacking motif. Molecular Hirshfeld surfaces revealed that complexes 1 and 2 were supported mainly by H–H, C–H⋯π, and O–H⋯O intermolecular interactions. The room temperature solid state luminescent properties of complexes 1 and 2 were all shown as two distinct bands, which attribute to ligand–metal charge transfer and metal purterbed ligand centered emission.

Synthesis, structures of four coordination compounds constructed from o-methacrylamidobenzoic acid and their relationship between structure and solid state luminescence

Four new coordination compounds, namely, Zn( o -MAABA) 2 (Phen) ( 1 ), [Cd( o -MAABA) 2 · 2H 2 O] 2 ( 2 ), {[Pb 2 Cl 2 ( o -MAABA) 2 (Phen) 4 ]} · 2H 2 O ( 3 · 2H 2 O ), [Pb(NO 3 )( o -MAABA)(Phen)] n ( 4 ), where o -MAABA = o -methacrylamidobenzoic acid and phen=1, 10-phenanthroline, have been synthesized. All compounds were fully confirmed by FT-IR, elemental analysis and TGA analysis. Their structures were determined by single crystal X-ray diffraction, in which compound 1 shows a mononuclear structure, compounds 2 and 3 have binuclear structures and compound 4 shows an infinite chain. In 2 and 4 , the adjacent chains are extended into a 3D supramolecular architecture via π–π interactions. Solid-state room temperature luminescence spectra revealed that emission bands of compound 1 were located at 524 nm ( λ ex =352 nm) and compound 4 at 479 and 584 nm ( λ ex =390 nm) assigned to the excimer formation. The emission at 454 nm ( λ ex =340 nm) of compound 2 was mainly ascribed to the Ligand–Metal Charge Transfer (LMCT). Four coordination compounds constructed by o -methacrylamidobenzoic, phenanthroline and metal ions are reported. The photoluminescent properties is studied, which is affected by the molecular stacking and LMCT.

Synthesis, Characterization and Photoluminescent Property of a Trinucleated Cadmium (II) Coordination Polymer Involving In Situ Ligand Reaction

A novel two-dimensional cadmium complex [Cd3(pzta)2(μ-Cl)4H2O)2]n (1) has been synthesized hydrothermally by the reaction of pyrazine carbonitrile and sodium azide in the presence of cadmium(II) chloride as Lewis acid catalyst. Complex 1 was characterized by elemental analysis, thermal gravimetric analysis, IR spectroscopy and single-crystal X-ray diffraction. Complex 1 crystallizes in triclinic crystal system, having the P $$ \overline{1} $$ space group, which by utilizing hydrogen-bonding extends the molecular complex into 3D hydrogen-bonded metallo-supramolecular networks. It has been shown that N–H–O hydrogen bond based on $$ R_{2}^{2} $$ (26) and $$ R_{2}^{2} $$ (12) supramolecular synthons can be relied upon as effective tools for the assembly and organization of hexa-coordinated complex. Furthermore, compound 1 shows strong photoluminescence properties at room temperature in solid state. The complex Cd3(pzta)2(μ-Cl)4H2O)2]n (1) has been made hydrothermally by the reaction of CdCl2∙H2O, pyrazinecarbonitrile, NaN3, H3PO4 and water at 130 °C in 36 h. In the polymeric structure of 1, hydrogen bonds working in cooperativity with covalent interactions are capable of ‘maneuvering’ complex ions into desirable motifs.

Co(II), Cu(II), Cd(II), Fe(III) and U(VI) complexes containing a NSNO donor ligand: Synthesis, characterization, optical band gap, in vitro antimicrobial and DNA cleavage studies

A new series of [Co(HPTP)Cl(H2O)2], [Cu(HPTP)Cl], [Cd(HPTP)Cl](H2O)4, [Fe(PTP)Cl(H2O)2](H2O), [UO2(HPTP)(OAc)(H2O)2] complexes of Schiff-bases derived from 4-(2-pyridyl)-3-thiosemicarbazide and pyruvic acid (H2PTP) have been synthesized and characterized by spectroscopic studies. Schiff-base exhibit thiol–thione tautomerism wherein sulfur plays an important role in the coordination. The coordination possibility of the Schiff-bases towards metal ions have been proposed in the light of elemental analyses, spectral (IR, UV–vis, 1H NMR, 13C NMR and ESR), magnetic and thermal studies. IR spectra show that H2PTP is coordinated to the metal ions in a mono or binegative tridentate manner. The electronic spectra of the complexes and their magnetic moments provide information about geometries. The room temperature solid state ESR spectra of the Cu(II) complexes show dx2−y2 as a ground state, suggesting square-planar geometry around Cu(II) center. The molecular parameters: total energy, binding energy, isolated atomic energy, electronic energy, heat of formation, dipole moment, HOMO and LUMO were calculated for the ligand and its complexes. Furthermore, the kinetic and thermodynamic parameters for the different decomposition steps were calculated using the Coats–Redfern and Horowitz–Metzger methods. Also, the optical band gap (Eg) of the metal complexes has been calculated. The optical transition energy (Eg) is direct and equals 3.25, 3.26, 3.34 and 3.27eV for Co, Cu, Fe and U complexes, respectively. The synthesized ligand, in comparison to its metal complexes is screened for its antibacterial activity against bacterial species, Bacillus thuringiensis, Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli. The activity data show that the metal complexes to be more potent/antibacterial than the parent Schiff base ligand against one or more bacterial species. Finally, the biochemical studies showed that, Cu, Cd and Fe complexes have powerful and complete degradation effect on DNA.

Room-temperature solid state synthesis of ZnO/α-Fe2O3 hierarchical nanostructures and their enhanced gas-sensing properties

Abstract A facile solid state reaction route was employed to synthesize the ZnO/α-Fe 2 O 3 hierarchical nanostructures by grinding zinc acetate, α-Fe 2 O 3 and sodium hydroxide with proper molar ratios together at room temperatures without any surfactant and template. Their morphological feature was characterized as self-assembled by nanosheets on which α-Fe 2 O 3 nanoparticles were well sprinkled, and it was observed that the amount of α-Fe 2 O 3 added significantly affected the overall morphology. Furthermore, gas-sensing properties of the obtained products were studied. The results demonstrated that the sensors based on ZnO/α-Fe 2 O 3 hierarchical nanostructures exhibited a much higher sensitivity to ethanol vapor than the sensors based on pure ZnO nanostructures and the 2% α-Fe 2 O 3 -added ZnO/α-Fe 2 O 3 nanostructures sensors showed the highest sensitivity. Additionally, the mechanism of gas sensing was also studied.

Intrinsic electrocaloric effect in ultrathin ferroelectric capacitors

Electrocaloric effect in ultrathin SrRuO3/BaTiO3/SrRuO3 capacitors is calculated using a multiscale thermodynamic model. It is found that the electrocaloric coefficient vs working temperature is shifted to higher temperatures with increasing the BaTiO3 layer thickness (above the critical thickness). The electrocaloric effect above the critical thickness is much stronger than that below it. Furthermore, it is demonstrated that a giant electrocaloric effect (3.5 K under 0.24 V) in such capacitors (six BaTiO3 unit cells) at 300 K can be achieved, which suggests that ultrathin ferroelectric capacitors may be promising candidates for room temperature solid-state refrigeration.

Synthesis and structural characterization of several new coordination polymers of 2-(1H-imidazol-1-yl) acetic acid

The combination of the polydentate ligand 2-(1H-imidazol-1-yl) acetic acid (Hima) with metal ions (Pb2+, Li+, Zn2+, Cd2+, Fe2+ and Co2+) leads to seven different coordination polymers: [Pb3(imaH)2Cl6]n (1, layer), [Pb(ima)2(NO3)2]n (2, chain), [Li2H(ima)2(H2O)2Cl]n (3, chain), [Zn(imaH)(ima)Cl]n (4, chain), [Cd(imaH)Cl2]n (5, chain), and [M(ima)2]n (6, M=Fe; 7, M=Co; layer). All compounds were characterized by FT-IR, elemental analysis and TG analysis, and their structures were determined by single crystal X-ray diffraction. According to the structural analysis, compound 1 shows a [Pb3Cl6] layer; compounds 2–4 show an infinite chain, but they were connected with imaH or ima bridges, respectively; compound 5 also has an infinite chain constructed of double chloride bridges; and compounds 6 and 7 exhibit layers without chloride ions involved. In these compounds, the ligand adopts two kinds of forms (anion, ima or zwitterion, imaH) and shows diverse modes of coordination. More interestingly, chloride as the second anion participated in the structural architecture based on its different affinities with metal ions. Solid-state room temperature luminescence spectra revealed that emission bands of compound 1 were located at 455nm, compound 4 at 425nm, and compound 5 at 550nm (λex=390nm), which is mainly assigned to the Ligand–Metal Charge Transfer (LMCT).

Performance evaluation of ZnO–CuO hetero junction solid state room temperature ethanol sensor

A semiconductor ethanol sensor was developed using ZnO–CuO and its performance was evaluated at room temperature. Hetero-junction sensor was made of ZnO–CuO nanoparticles for sensing alcohol at room temperature. Nanoparticles were prepared by hydrothermal method and optimized with different weight ratios. Sensor characteristics were linear for the concentration range of 150–250ppm. Composite materials of ZnO–CuO were characterized using X-ray diffraction (XRD), temperature-programmed reduction (TPR) and high-resolution transmission electron microscopy (HR-TEM). ZnO–CuO (1:1) material showed maximum sensor response (S=Rair/Ralcohol) of 3.32±0.1 toward 200ppm of alcohol vapor at room temperature. The response and recovery times were measured to be 62 and 83s, respectively. The linearity R2 of the sensor response was 0.9026. The sensing materials ZnO–CuO (1:1) provide a simple, rapid and highly sensitive alcohol gas sensor operating at room temperature.

Facile Fabrication of Nanosized Nickel Powder via Solid-State Reaction at Low Heat and its Catalytic Performance

Nano-Nickel (Ni0) powders have been successfully prepared via the reduction of nanosized NiO powders by the solid state reaction. And the nanosized NiO powders were derived from low temperature (350°C) calcinations in muffle in air of nanosized Ni(OH)2 powders firstly prepared by the room temperature solid state reaction between NiSO4•6H2O and NaOH by H2 at 400°C for 4 h. The crystallinity, microstructure of surface and xps property of obtained nickel powders were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). Furthermore, the catalytic activity of the obtained nanosized Ni powders for hydrogenation of nitrobenzene to aniline was investigated. The results show that the spherical Ni parepared in particle sizes ranges from 20 to 25 nm and achieves enhanced catalytic activity for hydrogenation of nitrobenzene to aniline compared with Raney Ni.

Structure and thermal stability of biodegradable Mg–Zn–Ca based amorphous alloys synthesized by mechanical alloying

Abstract Room temperature solid state diffusion reaction induced by mechanical alloying (MA) of elemental blends of Mg, Zn and Ca of nominal composition 60 at.% Mg–35 at.% Zn–5 at.% Ca has been studied. Formation of fully amorphous structure has been identified after 5 h of MA performed in a SPEX 8000M shaker mill, with milling continued up to 8 h to confirm the formation of homogeneous amorphous phase. Thermal stability of the amorphous phase has been studied using differential scanning calorimetry (DSC) and isothermal heat treatment at different temperatures. The amorphous powder consolidated using cold isostatic pressing (CIP) showed an envelope density ∼80% of absolute density, which increased to an envelope density ∼84% of absolute density after sintering at an optimized temperature of ∼523 K for 9 h. Electrochemical bio-corrosion testing of the CIP compacted amorphous pellet as well as the sintered pellet performed in Dulbecco's Modified Eagle Medium, showed improved corrosion resistance in comparison to the as-cast pure Mg. Cytotoxicity testing of the CIP compacted amorphous pellet, performed using the MTT assay with MC3T3 osteoblastic cells, showed low cytotoxicity in comparison to the as-cast pure Mg.

Spectral, magnetic, thermal, molecular modelling, ESR studies and antimicrobial activity of ( E)-3-(2-(2-hydroxybenzylidene) hydrazinyl)-3-oxo- n(thiazole-2-yl)propanamide complexes

( E)-3-(2-(2-hydroxybenzylidene)hydrazinyl)-3-oxo- n(thiazole-2-yl) propane-mide (H 2L) has been prepared and its structure confirmed by elemental analysis, IR and 1HNMR spectroscopy. It has been used to produce diverse complexes with Ni(II), Co(II) and Cu(II) ions. The complexes obtained have been investigated by thermal analysis, spectral studies (IR, UV–visible, ESR), and magnetic measurements. IR spectra suggest that the H 2L acts as a bidentate ligand coordinating via (C N) 1 and (OH) phenolic or deprotonated enolized carbonyl oxygen ( C O ) 1. The electronic spectra of the complexes and their magnetic moments provide information about geometries. The room temperature solid state ESR spectra of the Cu(II) complexes show d x 2− y 2 as a ground state, suggesting tetragonally distorted octahedral or square-planar geometries around Cu(II) centre. The molar conductance measurements proved that the complexes are non-electrolytes. The bond length, bond angle, HOMO, LUMO, dipole moment and charges on the atoms have been calculated to confirm the geometry of the ligand and the investigated complexes. Also, thermal properties and decomposition kinetics of all compounds are investigated. The interpretation, mathematical analysis and evaluation of kinetic parameters ( Ea, A, Δ H, Δ S and Δ G) of all thermal decomposition stages have been evaluated using Coats–Redfern and Horowitz–Metzger methods. Finally, the antimicrobial activity has been tested.

Bivalent transition metal complexes of o-hydroxyacetophenone [N-(3-hydroxy-2-naphthoyl)] hydrazone: Spectroscopic, antibacterial, antifungal activity and thermogravimetric studies

Schiff base complexes of Cu(II), Ni(II) and Zn(II) with the o-hydroxyacetophenone [N-(3-hydroxy-2-naphthoyl)] hydrazone (H 2 o-HAHNH) containing N and O donor sites have been synthesized. Both ligand and its metal complexes were characterized by different physicochemical methods, elemental analysis, molar conductivity ( 1H NMR, 13C NMR, IR, UV–visible, ESR, MS spectra) and also thermal analysis (TG and DTG) techniques. The discussion of the outcome data of the prepared complexes indicates that the ligand behave as a bidentate and/or tridentate ligand. The electronic spectra of the complexes as well as their magnetic moments suggest octahedral geometries for all isolated complexes. The room temperature solid state ESR spectrum of the Cu(II) complex shows d x2− y2 as a ground state, suggesting tetragonally distorted octahedral geometry around Cu(II) centre. The molar conductance measurements proved that the complexes are non-electrolytes. The kinetic thermodynamic parameters such as: E #, Δ H #, Δ G #, Δ S # are calculated from the DTG curves, for the [Ni(H O -HAHNH) 2] and [Zn(H 2 O -HAHNH)(OAc) 2]·H 2O complexes using the Coats–Redfern equation. Also, the antimicrobial properties of all compounds were studied using a wide spectrum of bacterial and fungal strains. The [Cu(H o-HAHNH)(OAc)(H 2O) 2] complex was the most active against all strains, including Aspergillus sp., Stemphylium sp. and Trichoderma sp. Fungi; E. coli and Clostridium sp. Bacteria.

Synthesis, structures, photoluminescence, and theoretical investigations on two new Zn(II)/Mn(II) complexes with pyridine-2-amidoxine and carboxylate ligands

Two new neutral mononuclear Zn(II) and Mn(II) complexes with pyridine-2-amidoxine and carboxylate ligands, [Zn(paH)2(OAc)2]·2CH3OH (paH = pyridine-2-amidoxine, HOAc = acetic acid) (1), and [Mn(paH)2(OAc)2]·C2H5OH·2H2O (2), have been prepared and characterized structurally by X-ray crystallography. 1 and free paH exhibit photoluminescence at room temperature in solid state, which is rare so fare for metal complexes with oxime-based ligand. The emissions of 1 and free paH arise from the metal-perturbed paH-based π → π* ligand-to-ligand charge transfer transition (LLCT) and π → π* charge transfer transition in nature, respectively, in terms of the density functional theory level calculations and molecular orbital analyses. Two new neutral mononuclear Zn (II) and Mn(II) complexes with pyridine-2-amidoxine and carboxylate ligands, [Zn(paH)2(OAc)2]·2CH3OH (paH = pyridine-2-amidoxine, HOAc = acetic acid) (1), and [Mn(paH)2(OAc)2]·C2H5OH·2H2O (2), have been synthesized and characterized structurally. The rarely reported photoluminescent behavior for oxime-based metal complexes has been observed in solid 1, indicating that such neutral mononuclear oxime-based metal complexes are a new class of potential candidates for photoluminescence and/or electroluminescence devices. The photoluminescent property and spectroscopic shifts have been investigated in detail for 1 and free paH ligand by means of the density functional theory level calculations and molecular orbital analyses. The emission for 1 and free paH ligand, are related to the metal-perturbed paH-based π → π* ligand-to-ligand charge transfer transition (LLCT) and π → π* charge transfer transition in nature, respectively.