Novel D-π-A dye sensitizers of polymeric metal complexes with phenylethyl or carbazole derivatives as donors for dye-sensitized solar cells: synthesis,characterization, and photovoltaic application

Four novel polymeric metal complexes containing D-π-A type structures were synthesized, characterized and applied as dye sensitizers in dye-sensitized solar cells (DSSCs). The alkoxy benzene or carbazole (CZ) derivative acts as an electron donor (D), C=C acts as π-bridge (π) and the 8-hydroxyquinoline derivative complex acts as electron acceptor. Bipyridine derivative was ancillary ligand as well as providing anchoring group. FT-IR, gel permeation chromatography, thermogravimetric analyses, differential scanning calorimetry, UV–Vis absorption spectroscopy, Elemental analysis, cyclic voltammetry, J-V curves and input photon to converted current efficiency plots were introduced to investigate the four dyes. These dyes exhibit good thermal stability with 5 % weight loss at temperatures (T_d) of around 300 °C. For the DSSCs devices using dyes with CZ derivatives as electron D (P2, P4) exhibited higher power conversion efficiency (PCE) than that with alkoxy benzene (P1, P3). The DSSC based on P4 exhibited the highest PCE value of 2.42 % (J _sc  = 4.93 mA/cm², V _oc  = 0.73 V, FF = 67.2 %) under AM 1.5G solar irradiation. This indicates a new way to design dye sensitizers for DSSCs.     

Synthesis,characterization, and photovoltaic properties of acceptor–donor–acceptor organic small molecules with different terminal electron-withdrawing groups

Two soluble acceptor–donor–acceptor (A–D–A) type organic small molecules, 2,2′-(5,5′-(1E,1′E)-2,2′-(benzo[c][1,2,5]thiadiazole-4,7-diyl)bis(ethene-2,1-diyl)bis(3,4-dihexylthiophene-5,2-diyl))bis(methan-1-yl-1-ylidene)dimalononitrile (BvT-DCN) and 2,2′-(3,3′-(1E,1′E)-2,2′-(5,5′-(1E,1′E)-2,2′-(benzo[c][1,2,5]thiadiazole-4,7-diyl)bis(ethene-2,1-diyl)bis(3,4-dihexylthiophene-5,2-diyl))bis(ethene-2,1-diyl)bis(5,5-dimethylcyclohex-2-ene-3-yl-1-ylidene))dimalononitrile (BT-C6), were synthesized by Knoevenagel condensation reaction based on benzothiadiazole, thiophene, and different terminal electron-withdrawing groups. The acceptor group benzothiadiazole and donor group thiophene inside the molecules are connected by all-trans double bonds, which ensures the benzothiadiazole and thiopene groups are in the same plane and makes the molecules have a relative narrow band gap and absorb sunlight in the long wavelength. The terminal electron-withdrawing groups, malononitrile and 2-(5,5-dimethylcyclohex-2-en-1-ylidene)malononitrile (DCM), are symmetrically introduced into the molecules, respectively, to tune the energy level and extend the absorption of the molecules. The UV–Vis absorption spectrum and cyclic voltammetry measurements indicated that BT-C6 has a lower energy band gap (1.60 eV) than BvT-DCN (1.71 eV), which arises from the stronger electron-withdrawing ability of DCM group in BT-C6 than that of malononitrile group in BvT-DCN. And BvT-DCN and BT-C6 have nearly the same highest occupied molecular orbital energy level, ?5.74 eV for BvT-DCN and ?5.72 eV for BT-C6 due to the same electron–donor group of the two compounds. Bulk heterojunction photovoltaic devices were fabricated using BvT-DCN or BT-C6 as donor and (6,6)-phenyl C₆₁-butyric acid methyl ester as acceptor. The device based on BT-C6 has a higher (~8 times) short circuit current and power conversion efficiency than the device based on BvT-DCN, resulting from the wider solar light absorption of BT-C6 and smaller phase separation dimension of the active layer based on BT-C6.     

The synthesis,characterization, and new optical property of M(Co and Fe)–phenylalanine complexes

In this paper, long flake-like Co(II)–phenylalanine and sphere-like Fe(II)–phenylalanine complexes were successfully synthesized by a refluxing method. The reaction time plays the key role during the whole process of the metal–phenylalanine complexes growth. The intensity of the peaks of metal–phenylalanine in photoluminscence spectra increased twice or more compared with that of pure phenylalanine. This synthesis approach is expected to become an appropriate method for preparation of other metal–organism complexes.     

A green route approach to the synthesis of Ni(II) and Zn(II) templated metal–organic frameworks

A new synthetic route involving mixing of solid reactants followed by heating has been developed for the preparation of two templated metal–organic frameworks (MOFs). [Ni(NO₃)₂(bipy)₂](pyrene)₂ (1) was obtained by mixing together Ni(NO₃)₂·6H₂O, 4,4-bipyridine and pyrene followed by heating at 85 °C for 4 h, while [Zn₂(fumarate)₂(bipy)] (2) was synthesized by mixing together Zn(O₂CCH₃)₂·2H₂O, fumaric acid and 4,4-bipyridine followed by heating at 160 °C for 16 h. The materials were characterized by elemental analysis, FT-IR spectroscopy and X-ray powder diffraction analysis (XRPD). Comparison of XRPD patterns of the materials with patterns simulated from the single crystal X-ray diffraction data, obtained from Cambridge Structural database, allowed identification of the products. Conversion of solid reactants to MOFs occurs spontaneously even when reactants are not mechanically stressed. Overall, the study suggests that MOFs can be synthesized in solid state simply by mixing together appropriate reactants without co-mill (ball-mill). Compared with traditional synthetic techniques such as solvothermal, ball-milling and solution-based, this method is environmentally friendly and highly efficient in the manufacture of these MOFs on a large scale.     

A review of noble metal (Pd,Ag, Pt,Au)–zinc oxide nanocomposites: synthesis,structures and applications

As a promising candidate for future catalytic applications, the noble metal–ZnO nanocomposites are gaining increasing interest due its high catalytic property, and super stability. In this review, the noble metal–ZnO nanocomposites with various composites and structures for catalytic applications will be discussed. We introduce the multi-catalytic properties and design concept of the noble metal–ZnO nanocomposites, and then particular highlight key finding of synthesis method for various noble metal–ZnO nanocomposites. The catalytic activity of noble metal–ZnO nanostructures has been found to rely on not only the species of noble metal but also the architecture of the catalyst material. Moreover, the typical works of modification on noble metal–ZnO nanostructures have been introduced. Critically, the challenges for future research development and our future perspectives are presented.     

Biogenic silica–metal phosphate (metal = Ca,Fe or Zn) nanocomposites: fabrication from rice husk and their biomedical applications

In this investigation, we fabricated biogenic silica–metal phosphate nanocomposites (BSMPNs) using rice husk from agricultural waste as a silica source. The morphologies and dimensions of the synthesized nanocomposites were analyzed using transmission electron microscopy (TEM). Fourier-transform infrared spectroscopy results confirmed that metal phosphate crystals were formed with the biogenic silica. The X-ray diffraction patterns of the BSMPNs showed the presence of hexagonal calcium and iron phosphate and orthorhombic zinc phosphate nanoparticles embedded in the matrix of biogenic silica. The TEM images suggested that spherical and irregularly shaped tiny particles with dimensions between 50 and 100 nm were dispersed in the biogenic silica. The in vitro biological properties of the nanocomposites were studied by a cell viability assay and through the analysis of microscopy images. The cytocompatibility studies proved that the material was nontoxic and had excellent biocompatibility with human mesenchymal stem cells. The synthetic route for these nanocomposites is interesting and may be helpful in the fabrication of various novel silica-based composites and in the exploitation of eco-friendly agricultural biomass. Our results revealed that these nanocomposites can be used in bone tissue engineering.     

Synthesis and characterization of lanthanide(III) complexes with a mesogenic Schiff-base,N,N′-di-(4-decyloxysalicylidene)-2′,6′-diaminopyridine

A mesogenic Schiff-base, N,N′-di-(4-decyloxysalicylidene)-2′,6′-diaminopyridine, H₂ddsdp (abbreviated as H₂L³) that exhibits nematic mesophase, was synthesized and its structure studied by elemental analysis, mass spectrometry, NMR & IR spectral techniques. The Schiff-base, H₂L³, upon condensation with hydrated lanthanide(III) nitrates, yields Ln^III complexes of the general composition [Ln₂(L³H₂)₃(NO₃)₄](NO₃)₂, where Ln = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy and Ho. Among the metal complexes, only that of Ho^III is found to be mesogenic with smectic-X and nematic phases. The IR and NMR spectral data imply a bi-dentate bonding of the Schiff-base in its zwitterionic form (as L³H₂) to the Ln^III ions through two phenolate oxygens, rendering the overall geometry of the complexes to seven-coordinated polyhedron, possibly distorted mono-capped octahedron.     

Triethanolamine copper chloride prepared from zerovalent metal: another polymorph of a known Cu(II) compound or a mixed-valence complex with all-trigonal bipyramidal copper?

Two new copper complexes with triethanolamine (H₃L) have been prepared using copper powder and characterized by X-ray crystallography, IR and EPR spectroscopy. These are [Cu^I(H₃L)Cl]_x⋅[Cu^II(H₂L)Cl]_1−x (X=0; 2/3) (1) and [Cu^II(H₂L)SCN] (2). Both complexes are neutral species and contain copper atoms in trigonal bipyramidal environments. The important dimensions in 1 are Cu-N 2.011(5), 3Cu-O 2.073(3), Cu-Cl 2.239(2) Å and N-Cu-Cl=180.0°; in 2 Cu-N_NCS 1.918(3), Cu-N_H2Tea 1.983(3), Cu-O 2.004(2), 2Cu-O 2.13(1) Å and N_H2Tea-Cu-N_NCS=174.6(1)°. 2 has all the copper atoms in the oxidation state II, while the three-fold symmetry in 1 would suggest that the metal atoms are formally in the oxidation state I. Results of magnetic measurements of several samples of 1 are rationalized by assuming that a continuous range of composition for [Cu^I(H₃L)Cl]_x⋅[Cu^II(H₂L)Cl]_1−x can occur. In the case of x=0, 1 becomes a polymorph of the reported compound [Cu^II(H₂L)Cl].     

Keggin type inorganic–organic hybrid material containing Mn(II) monosubstituted phosphotungstate and S-(+)-sec-butyl amine: Synthesis and characterization

A new inorganic–organic POM-based hybrid material comprising Keggin type mono manganese substituted phosphotungstate and enantiopure S-(+)-sec-butyl amine was synthesized in an aqueous media by simple ligand substitution method. The synthesized hybrid material was systematically characterized in solid as well as solution by various physicochemical techniques such as elemental analysis, TGA, UV–vis, FT-IR, ESR and multinuclear solution NMR (³¹P, ¹H, ¹³C). The presence of chirality in the synthesized material was confirmed by CD spectroscopy and polarimeter. The above study reveals the attachment of S-(+)-sec-butyl amine to Keggin type mono manganese substituted phosphotungstate through N → Mn bond. It also indicates the retainment of Keggin unit and presence of chirality in the synthesized material. An attempt was made to use the synthesized material as a heterogeneous catalyst for carrying out aerobic asymmetric oxidation of styrene using molecular oxygen. The catalyst shows the potential of being used as a stable recyclable catalytic material after simple regeneration without significant loss in conversion.     

Performance measures and metrics in logistics and supply chain management: a review of recent literature (1995–2004) for research and applications

Performance measures and metrics are essential for effectively managing logistics operations, particularly in a competitive global economy. The global economy is featured with global operations, outsourcing and supply chain and e-commerce. The real challenge for managers of this new enterprise environment is to develop suitable performance measures and metrics to make right decisions that would contribute to an improved organizational competitiveness. Now the question is whether traditional performance measures can be used and out of them which ones should be given priority for measuring the performance in a new enterprise environment. Some of the traditional measures and metrics may not be suitable for the new environment wherein many activities are not easily identifiable. Measuring intangibles and nonfinancial performance measures pose the greater challenge in the so-called knowledge economy. Nevertheless, measuring them is so critical for the successful operations of companies in this environment. Considering the importance of nonfinancial measures and intangibles, an attempt has been made in this paper to determine the key performance measures and metrics in supply chain and logistics operations. This is based on a literature survey and some of the reported case experiences. Suggestions for future research directions are also indicated.     

Monodisperse α-Fe(2)O(3)@SiO(2)@Au core/shell nanocomposite spheres: synthesis, characterization and properties

A new hybrid spherical structure α-Fe(2)O(3)@SiO(2)@Au with a size of about 141?nm was designed, with a hematite cubic core surrounded by a thick silica shell and further decorated with gold nanoparticles. The monodisperse α-Fe(2)O(3)@SiO(2) spheres were first prepared by a sol-gel process based on the modified St?ber method. Subsequently, the surface of the α-Fe(2)O(3)@SiO(2) particles was functionalized by-NH(2) functional groups. The electrostatic attraction of -NH(2) groups will attach the negatively charged Au nanoparticles to the amino-functionalized α-Fe(2)O(3)@SiO(2) nanospheres in order to prepare α-Fe(2)O(3)@SiO(2) monodisperse hybrid spheres. The M(H) hysteresis loop for α-Fe(2)O(3)@SiO(2) and α-Fe(2)O(3)@SiO(2)@Au spheres indicates that the nanocomposite spheres exhibit superparamagnetic characteristics at room temperature. The optical properties and the application of these hybrid nanocomposites as catalysts for the conversion of CO to CO(2) have also been studied.     

Polypyrrole–titanium(IV) doped iron(III) oxide nanocomposites: Synthesis,characterization with tunable electrical and electrochemical properties

Titanium(IV)-doped synthetic nanostructured iron(III) oxide (NITO) and polypyrrole (PPy) nanocomposites was fabricated by in situ polymerization using FeCl₃ as initiator. The polymer nanocomposites (PNCs) and pure NITO were characterized by X-ray diffraction, Föurier transform infrared spectroscopy, scanning electron microscopy, electron dispersive X-ray spectroscopy, transmission electron microscopy, etc. Thermo gravimetric and differential thermal analyses showed the enhancement of thermal stability of PNCs than the pure polymer. Electrical conductivity of the PNCs had increased significantly from 0.793 × 10^?2 S/cm to 0.450 S/cm with respect to the PPy, and that had been explained by 3-dimensional variable range hopping (VRH) conduction mechanisms. In addition, the specific capacitance of PNCs had increased from 147 F/g to 176 F/g with increasing NITO content than that of pure NITO (26 F/g), presumably due to the growing of mesoporous structure with increasing NITO content in PNCs which reduced the charge transfer resistance significantly.     

Magnetic and dielectric properties on sol–gel combustion synthesis of Pb(Zr0.52,Ti0.43X0.05)O3 (X = Fe,Ni, and Co) nanoparticles

Pure and X-doped (X = Fe, Ni, and Co) PZT nanoparticles (PZT-NPs) were synthesized by a sol–gel combustion method. The structural characterization of the obtained pure and doped PZT-NPs was carried out by X-ray diffraction (XRD). The crystallite size of the prepared samples was then evaluated by the size strain plot (SSP) method using the XRD results. The average particle sizes of 30–40 nm were measured for pure and doped PZT-NPs by a particle size analyzer. For dielectric measurements, the synthesized powders were pressed into pellets and then sintered at 1250 °C for 2 h. The magnetic properties of the synthesized doped PZT-NPs were studied by a vibration sample magnetometer (VSM) and ferromagnetic behavior was observed.     

Electromagnetic and microwave absorption performance of some transition metal doped La0.7Sr0.3Mn1−xTMxO3±δ (TM = Fe,Co or Ni)

In this study the transition metal doped La_0.7Sr_0.3Mn_1?xTM_xO_3±δ (TM = Fe, Co or Ni, x = 0, 0.2) powders were fabricated by the conventional solid state reaction method. The compositions, morphologies and crystal structures were characterized using different method. The influences of the incorporation of TM into La_0.7Sr_0.3MnO_3±δ on the complex permittivity, complex permeability and microwave absorption performance were investigated in the range of 5.85–18 GHz. It is found that the electromagnetic loss has been enhanced after TM doping. And the microwave absorption properties have been significantly improved. In present study La_0.7Sr_0.3Mn_0.8Fe_0.2O_3±δ had the best microwave absorption properties. The maximum reflection loss was 27.67 dB at 10.97 GHz, and the absorbing bandwidth above 6 dB was 6.80 GHz with 2 mm thickness.     

Cu(II), Co(II) and Ni(II) complexes of –Br and –OCH<Subscript>2</Subscript>CH<Subscript>3</Subscript> substituted Schiff bases as corrosion inhibitors for aluminium in acidic media

A group of Cu(II), Ni(II) and Co(II) complexes of –Br and –OCH₂CH₃ substituted Schiff bases as a new class of corrosion inhibitors for aluminium has been studied in 0.1 M HCl by the addition of 10 ppm compound using potentiodynamic polarization, electrochemical impedance spectroscopy, linear polarization methods and gas evolution tests at 25 °C. The inhibition efficiencies obtained from all methods employed are in good agreement. Results show Ni(II) complex of –OCH₂CH₃ substituted Schiff bases was the best inhibitor with a mean efficiency of 69% at 10 ppm additive concentration. The potentiodynamic polarization curves showed both the cathodic and the anodic processes of aluminium corrosion were suppressed, and the Nyquist plots of impedance gave mainly a capacitive loop. Scanning electron microscopy (SEM) was done from the surface of the exposed sample indicating uniform film on the surface.