Sonochemical synthesis of two nanostructured silver(I) coordination polymers based on semi-rigid bis(benzimidazole) ligands

Nanoparticles of two silver(I) coordination polymers (CPs), [Ag₂(L1)₂(DCTP)]_n (1) and [Ag₂(L2)(DCTP)]_n (2) (L1 = 1,3-bis(5,6-dimethylbenzimidazol-1-ylmethyl)benzene, L2 = 1,4-bis(benzimidazol-1-yl)-2-butene, H₂DCTP = 2,5-dichloroterephthalic acid), were synthesized by the sonochemical approach and hydrothermal method. Both CPs were characterized by elemental analysis, IR spectra, single-crystal X-ray diffraction, scanning electron microscopy (SEM), and thermogravimetric analyses (TGA). CP 1 exhibits a 2D 4-connected sql net with the point symbol {4⁴.6²}. While CP 2 displays a 2D 3,4-connected 3,4L13 net with the point symbol {4.6²}₂{4².6².8²}. The structural diversity indicates that semi-rigid bis(benzimidazole) co-ligands play important roles in tuning the structures of the mixed Ag(I) CPs. The ultrasound irradiation time, temperature, and power showed significant effects on the morphology and growth process of the nanoparticles of two silver(I) CPs. The luminescence and photocatalytic properties of the nanoparticles of CPs 1–2 on the degradation of methyl blue (MB) were also investigated in detail.     

Synthesis and fluorescence study of water-soluble conjugated polymers for efficient FRET-based DNA detection

Two cationic conjugated polyelectrolytes (CPs, P1i and P2i) were synthesized and examined as a fluorescence resonance energy transfer (FRET) donor to fluorescein (Fl)-labeled single-stranded DNA (ssDNA–Fl) using steady-state and time-resolved photoluminescence (PL) spectroscopy. The two polymers have the same π-conjugation with the main structural difference being the presence of the spiro-anthracenyl substituents orthogonal to the polymer backbone of P2i. These spiro-substituents can function as a molecular spacer that increases the intermolecular separation in the electrostatic complex with ssDNA–Fl. We measured almost complete PL quenching of the excited Fl1 after electrostatic complexation with P1i (PL lifetime 4 ns → 78 ps) and relatively moderate quenching with P2i (PL lifetime 4 ns → 552 ps). A quenching efficiency (Φ_eT) of 98% and 86% was obtained for P1i/ssDNA–Fl and for P2i/ssDNA–Fl, respectively. Both systems have same thermodynamic driving force for quenching as a result of them having the same electronic structures. This discrepancy can be explained in terms of the reduced quenching (via electron transfer, eT) by the increased D–A distance due to the existence of spiro-attached molecular spacers in P2i. It shows that thermodynamically favorable eT quenching can be controlled kinetically by modulating the D–A intermolecular distance using molecular spacers, which suggests an important molecular design guideline for efficient CPs-based DNA detection.     

On the superconductivity and structural properties of YBa2Cu3 − xCdxO7 − y

A series of superconducting cuprates with the nominal composition YBa₂Cu_3 − xCd_xO_7 − yand the effect of Cd substitution on Cu sites in this compound is presented. X-ray powder diffraction patterns for these cadmium cuprates with reduced diamagnetism indicate an orthorhombic unit cell like-perovskite structure for (0 ≤ x ≤ 0.15), while for higher Cd concentration, i.e.x = 1.0 the material is polyphasic. The observed superconducting transition temperature of the samples is nearly the same ([formula] K), except for (x = 1.0) whereT_cdrops to 72 K and a transition from metallic to semiconducting behavior of the normal state of the resistivity is observed. Such a decrease inT_cfor higher Cd concentration could be attributed to the presence of the green phase in this composition.     

Sonochemical synthesis and structural characterization of a new nanostructured Co(II) supramolecular coordination polymer with Lewis base sites as a new catalyst for Knoevenagel condensation

A new Co(II) mixed-ligand coordination supramolecular polymer with composition [Co₂(ppda)(4-bpdh)₂(NO₃)₂]_n (1) (where, ppda = p-phenylenediacrylic acid, 4-bpdh = 2,5-bis(4-pyridyl)-3,4-diaza-2,4-hexadiene) was synthesized using solvothermal, mechanochemical and sonochemical methods. Compound 1 and the new nanostructure have been characterized by single-crystal X-ray, infrared spectroscopy (IR), powder X-ray diffraction (PXRD) analysis and scanning electron microscopy (SEM). The thermal stability of compound 1 was also studied by thermal gravimetric analysis (TGA). The surface area of these compounds was determined by BET. The single-crystal X-ray data shows a new interesting two-dimensional coordination polymer (CP). In addition, the effect of various sonication concentrations of initial reagents, power of ultrasound irradiation and also the time on the size and morphology of nano-structured coordination polymer 1 were evaluated. Moreover, it has been demonstrated that the nanostructure of the CP1 can be used as a catalyst in Knoevenagel condensation reaction.     

Synthesis,characterization and luminescence study of dimethyl[N-arylmethylenethiobenzahydrazonato]indium

Five dimethylindium complexes of type Me₂InL [L = N-(4-methoxy)benzylidenethiobenzahydrazonato (1), N-(3,4-dimethoxy)benzylidenethiobenzahydrazonato (2), N-(4-N,N-dimethylamino)benzylidenethiobenzahydrazonato (3), N-(2-naphthyl)methylene thiobenzahydrazonato (4) and N-(9-anthryl)methylenethiobenzahydrazonato (5)] have been synthesized by reaction of trimethylindium with appropriate N-arylmethylenethiobenzahydrozones. The complexes obtained have been characterized by elemental analysis, ¹H NMR, IR and mass spectroscopy. Compounds 1–5 emit blue colors at λ_max = 432–479 nm when irradiated by UV light. The electroluminescent (EL) properties of 1–5 were examined by fabricating EL devices using 1–5 as emitter, respectively. The EL bands are located in the green region (513–578 nm).     

Sonochemical synthesis of two new nano structure zinc(II) 1,10-phenanthroline coordination supramolecular compounds: New precursors to produce nano-sized zinc(II) oxide

Nanoparticles of two zinc(II) coordination supramolecule compounds (CSCs), [Zn(L)Cl2] (1) and [Zn(L)Br2] (2) L = 1,10-phen = 1,10-phenanthroline ligand, have been synthesized by use of a sonochemical process and characterized by scanning electron microscopy (SEM), X-ray powder diffraction (XRPD), Fourier transform infrared (FTIR) spectroscopy and elemental analyses. The single crystal X-ray data of compounds 1 and 2 imply that the Zn⁺² ions are four coordinated. Topological analysis shows that the compound 1 and 2 are new topology for net: 1,3M4-1. Nanoparticles of zinc(II) oxide have been prepared by calcination of two different zinc(II) CPs at 500 °C that were characterized by scanning electron microscopy (SEM), X-ray powder diffraction (XRD) and IR spectroscopy.     

Growth,structure and physical properties of single crystals of pure and Pb-doped Bi-based high Tc superconductors

Single crystals of (Bi_1−xPb_x)₂Sr₂Ca₂Cu₃O_10+δ (x = 0 and 0.16) (sizes up to 3 × 2 × 0.1 mm³) have been grown by means of a newly developed “vapour-assisted travelling solvent floating zone” technique (VA-TSFZ). Post-annealing under high pressure of O₂ (up to 10 MPa at T = 500 °C) was applied to enhance T_c (up to 111 K) and improve the homogeneity of the crystals (ΔT_c ⩽ 1 K). The structure of both Pb-free and Pb-doped Bi-2223 was refined for the first time from single crystal X-ray diffraction (XRD) data. The unit cell of the average structure is pseudo-tetragonal with a = 5.4210(7), b = 5.4133(6) and c = 37.010(7) Å, and a = 5.395(1), b = 5.413(1) and c = 37.042(11) Å, for the Pb-free and the Pb-doped phase, respectively. An incommensurate modulation in the direction of one of the short cell vectors has been defined (q ∼ 0.21 a¹), however, the structure can be conveniently described in a supercell with a fivefold volume (a = 27.105(4) Å). With respect to the “non-modulated” structure, one additional oxygen atom for ten initial O was found to be inserted into the BiO layers. The superconducting anisotropy of Bi-2223 was found to be ∼50, from measurements of the lower critical field. The anisotropy of Bi-2223 is significantly reduced compared to that of Bi-2212, and this accounts for the enhanced irreversibility fields in Bi-2223. Furthermore, Bi-2223 has a higher critical current density, and a reduced magnetic relaxation rate compared to Bi-2212, which are both signatures of more effective pinning in Bi-2223 due to its reduced anisotropy.     

UV–Vis and NMR spectroscopic investigations on effective and selective non-covalent interactions between fullerenes and calix[6]arene

Ground state non-covalent interactions between a macro cyclic calixarene receptor, namely, 4-tert-butylcalix[6]arene (1), and fullerenes (C₆₀ and C₇₀) were studied in toluene medium by absorption spectrophotometric method. Absorption band due to the charge transfer (CT) transition have been observed in the visible region between fullerenes and 1. Utilizing the CT absorption bands, various important physicochemical parameters like oscillator strength, resonance energy, transition dipole strength of the fullerene-1 complexes and ionization potential of 1 is determined in present investigations. From Jobs method of continuous variation, it is observed that both C₆₀ and C₇₀ form stable 1:1 complexes with 1. The most fascinating feature of the present study is that 1 binds selectively C₇₀ compared to C₆₀ as obtained from binding constant (K) data of C₆₀–1 (K_C60–1) and C₇₀–1 (K_C70–1) complexes, i.e., K_C60–1 = 32,400 dm³·mol^? 1 and K_C70–1 = 110,000 dm³.mol^? 1 and selectivity (K_C70–1/K_C60–1) = 3.4. ¹H NMR analysis provides very good support in favor of strong binding between C₇₀ and 1.     

Sonochemical synthesis of a new nano-sized cerium(III) supramolecular compound; Precursor for nanoceria

Using a sonochemical method, nanoparticles of a new Ce(III) supramolecular compound, (NAMH⁺)₂[Ce₄(pydc)₆(pydcH)₂(H₂O)₈]·8H₂O (1), (H₂pydc = 2,6-pyridinedicarboxylic acid, NAM = nicotinamide), have been synthesized. Compound 1 was characterized by scanning electron microscopy (SEM), X-ray powder diffraction (XRPD), FT-IR spectroscopy and elemental analyses, and its structure was determined by X-ray crystallography. It has been revealed that its structure consists of tetra-nuclear building units that extend to a 3D supramolecular network via non-covalent interactions mainly hydrogen bonding. The thermal stability of complex 1 both for its crystals and nanostructures has been studied by the thermal gravimetric (TG) method and compared with each other. The role of ultrasound irradiation power and the concentration of initial reactants on the size and morphology of the nano-structured complex 1, has been investigated. Ceria nanoparticles were obtained upon the calcination of complex 1 at 800 °C under atmospheric air. Furthermore, the fluorescent properties of complex 1 at room temperature were studied.     

Anomalous high salt conductivity in primary diamines as solvents

It is shown that the conductivities of LiBF₄, LiPF₆, LiN(SO₂CF₃)₂ (LiTFSI), NaPF₆, KPF are abnormally high in two diamine solvents: ethylenediamine (EDA) and 1,3-diaminopropane (1,3 DAP). This is particularly evident for KPF₆, κ_MAX(EDA) = 35 mS cm^− 1 and κ_MAX(1,3 DAP) = 17.4 mS cm^− 1. Compared to three other organic solvents having the same viscosity, η ≅ 1.6 cP, but higher relative permittivity, NMF ε = 186.9, NMP ε = 32, γ-Bu ε = 39.1, the maxima of conductibility of EDA and 1,2 DAP, which have a low relative permittivity, ε ≅ 13–11, are largely superior or equal to those of NMF, NMP, γ-Bu. For KPF₆, κ_MAX(NMF) = 15.4mS cm^− 1, κ_MAX(NMP) = 7.8 mS cm^− 1 and κ_MAX(γ-BL) = 10.8 mS cm^− 1. We assume that this is due to a non-Stokesian conductivity mechanism.     

Sonochemical synthesis of nano-scale mixed-ligands lead(II) coordination polymers as precursors for preparation of PbO and PbBr(OH) nano-structures; thermal,structural and X-ray powder diffraction studies

Nano-structures of two new lead(II) two-dimensional coordination polymers, [Pb₂(2-pyc)₂(I)₂]_n (1) and [Pb₂(2-pyc)₂(Br)₂]_n (2), {2-Hpyc = 2-pyridinecarboxilic acid } were synthesized by a sonochemical method that produce the coordination polymers at nano-size. The new nano-structures were characterized by scanning electron microscopy, X-ray powder diffraction, IR spectroscopy and elemental analyses. Compounds 1 and 2 were structurally characterized by single crystal X-ray diffraction and consist of two-dimensional polymeric units. The thermal stability of compounds 1 and 2 were studied by thermal gravimetric and differential thermal analyses. PbO and PbBr(OH) nano-structures were obtained by calcination of the nano-structures of compounds 1 and 2 at 400 °C, respectively.     

Synthesis and characterization of nano-peanuts of lead(II) coordination polymer [Pb(qcnh)(NO3)2]n with ultrasonic assistance: A new precursor for the preparation of pure-phase nano-sized PbO

A sonochemical method was used to synthesize nano-peanuts of a new lead(II) coordination 1D polymer, [Pb(qcnh)(NO₃)₂]_n (1), where qcnh = 2-quinolincarbaldehyde nicotinohydrazide. The compound was characterized by scanning electron microscopy (SEM), elemental analysis, IR spectroscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray powder diffraction (XRD), and single crystal X-ray analysis. The X-ray structure revealed that the Pb(II) atom is coordinated by one oxygen and three nitrogen atoms from two qcnh ligands and five oxygen atoms from three nitrate ligands in an 8 + 1 fashion with a PbN₃O₆ donor set. One of the PdN distances in the vicinity of the central atom is a bit longer (Pb1N1 = 2.939(4) Å), which shows the effect of the 6s² lone electron pair localized within the valence shell of the lead(II) atom. PbO nanoparticles were obtained by thermolysis of 1 at 180 °C with oleic acid as a surfactant. The average diameter of the nanoparticles was estimated by XRD to be 28 nm. The morphology and size of the prepared PbO nanoparticles were further studied using SEM.     

Sonochemical synthesis and characterization of new nanostructures cobalt(II) metal-organic complexes derived from the azo-coupling reaction of 4-amino benzoic acid with anthranilic acid,salicylaldehyde and 2-naphtol

Nanostructures of three new cobalt(II) complexes, (CoL₁)·0.5DMF·1.5MeOH (1), [H₂L₁ = 5-(4-Carboxy phenyl azo) anthranilic acid], (Co(L₂)₂)·1.5MeOH (2), [HL₂ = 5-(4-Carboxy phenyl azo) salicylaldehyde] and (Co(L₃)₂)·0.5 DMF·0.5MeOH (3), [HL₃ = 1-(4-Carboxy phenyl azo) 2-naphtol], have been synthesized by the reaction of H₂L₁, HL₂ and HL₃ with Co(OAc)₂·4H₂O through sonochemical process. Calcination of the nano-sized compounds 1–3 yield Co₃O₄ nanoparticles at 450 °C under air atmosphere. These nanostructures were characterized by X-ray powder diffraction (XRD) and Scanning Electron Microscopy (SEM). Thermal stability of compounds 1–3 was studied by thermogravimetric (TG) and differential thermal analyses (DTA).     

Sonochemical synthesis of nanoscale mixed-ligands lead(II) coordination polymers as precursors for preparation of Pb2(SO4)O and PbO nanoparticles; thermal,structural and X-ray powder diffraction studies

Nano-structures of two new Pb(II) two-dimensional coordination polymers, [Pb(μ-4-pyc)(μ-NCS)(μ-H₂O)]_n (1) and [Pb(μ-4-pyc)(μ-N₃)(μ-H₂O)]_n (2), 4-Hpyc = 4-pyridinecarboxylic acid were synthesized by a sonochemical method. The new nano-structures were characterized by scanning electron microscopy, X-ray powder diffraction, IR spectroscopy and elemental analyses. Compounds 1 and 2 were structurally characterized by single crystal X-ray diffraction and consist of two-dimensional polymeric units. The thermal stability of compounds 1 and 2 were studied by thermal gravimetric and differential thermal analyses and compared. Pb₂(SO₄)O and PbO nanoparticles were obtained by calcination of the nano-structures of compounds 1 and 2 at 600 °C, respectively.     

Influence of the orthorhombic distortion on the van Hove singularities in the DOS and ARPES spectra of layered cuprates

Four atom states Cu3d_{x² −  y²}, Cu4s, O_a2p_xare involved in a tight-binding model for the superconducting CuO₂plane. The orthorhombic distortion is taken into account by the differences of Cu–O hopping amplitudes and single-site oxygen energies ε_aand ε_bof two oxygen positions in the elementary cell as well. An effective ‘oxygen’ Hamiltonian including only the electron amplitudes at the oxygen ions is derived. Simple expressions for the constant energy contours and the Fermi surface are obtained and they qualitatively describe the photoemission spectra. Extended saddle points nearp = (π,0) andp = (0,π) are observed in qualitative agreement with the ARPES data. The van Hove singularities of the density of states (DOS) related to the extended saddle points are calculated by a Monte Carlo method. It is found that the splitting of the singularity of the DOS at the bottom of the conduction band is created by the energy difference ε_a −  ε_b = 2δ.     

Enhanced mangnetoelectric voltage in multiferroic particulate Ni0.83Co0.15Cu0.02Fe1.9O4−δ/PbZr0.52Ti0.48O3 composites – dielectric,piezoelectric and magnetic properties

Multiferroic particulate composites of Ni_0.83Co_0.15Cu_0.02Fe_1.9O_4−δ– NCCF and lead zirconate titanate (PZT) were prepared conventional ceramic method. The generic formulae x NCCF + (1−x) PZT where x = 0.1, 0.2, 0.3, 0.4, 0.5 and 0.6 mole fractions. The presence of two phases in multiferroic was confirmed with XRD technique. The dielectric constant and loss tangent were studied as a function of frequency (100 Hz to 1 M Hz) and temperature (30–500 °C). The piezoelectric coefficient d₃₃ were also studied on these particulate composites. The hysteresis behaviour was studied to understand the magnetic properties such as saturation magnetization (Ms) and magnetic moment (μ_B). The static magnetoelectric (ME) voltage coefficient was measured as a function of dc magnetic bias field. A high value of ME output (3151 mV/Oe.cm) was obtained in the composite containing 50% highly magnetostrictive ferrite component NCCF – 50% highly piezoelectric ferroelectric component PZT. These multiferroic particulate composites are used as phase shifters, magnetic sensors, cables etc.     

Structural changes in ab-plane of Zn doped Bi-2212 HTSC single crystals

Single crystals of undoped and 1% Zn-doped Bi-2212 are grown by self-flux slow cooling method under similar growth conditions. T_c(ΔT_c) are found to be 84 K (2 K) and 82 K (8 K) for undoped and doped samples respectively. Effect of Zn doping on structure and modulation is studied. Different change in the value of a- and b-axes are observed resulting in a transformation of structure from tetragonal to orthorhombic one. However, no effective change in modulation is there. Distortions are compared in c- and b-axes for undoped and doped samples. The asymmetry in position and intensity of satellite peaks has been discussed. The value of a in excess of b has been reported for the first time. These results are discussed in terms of valancy, coordinates and position of occupancy of Zn ions vis-à-vis those of Cu⁻ ions in Cu–O plane of the structure.     

Sonochemical synthesis and characterization of nano-sized lead(II) 3D coordination polymer: Precursor for the synthesis of lead(II) oxybromide nanoparticles

Nanoparticles of a three-dimensional coordination polymer, [Pb(L)(μ₂-Br)(H₂O)]_n (1), (L^? = 1H-1,2,4-triazole-3-carboxylate), have been synthesized by an ultrasonic method and characterized by scanning electron microscopy, X-ray powder diffraction, IR spectroscopy and elemental analyses. The thermal stability of compound 1 both its bulk and nano-size has been studied by thermal gravimetric (TG) and differential thermal (DTA) analyses and compared each other. Concentration of initial reagents effects and the role of power ultrasound irradiation on size and morphology of nano-structured compound 1, have been studied. Calcination of the compound 1 at 500 °C under air atmosphere yields Pb₃O₂Br₂ nanoparticles.     

Determination of rifampicin based on fluorescence quenching of GSH capped CdTe/ZnS QDs

Aqueous glutathione (GSH)-capped CdTe/ZnS QDs with the diameter of 3–4 nm were synthesized. The fluorescence of CdTe/ZnS QDs at 577 nm was quenched in the presence of rifampicin (Rfp), with excitation wavelength at 350 nm. The mechanism of the interaction of CdTe/ZnS QDs with Rfp was investigated. Under the optimal conditions, the calibration plot of ln(F₀/F) was linear in the range 0.83–56 μg mL^?1 with concentration of Rfp, and the detection limit was 0.25 μg mL^?1. The proposed method was successfully applied to the determination of Rfp in its commercial capsules, and satisfactory results were obtained. The recovery of the method was in the range 98.6–103.2%.