Synthesis,crystal structures and sensitivity to sunlight of two Ag (I) photoresponsive metal–organic complexes

Two Ag (I) photoresponsive metal–organic complexes have been constructed from viologen derivatives 1, 1″-[1, n-phenylene-bis(methylene)]bis-4, 4′-bipyridinium-bisbromide (n = 2 and 3) cationic ligands and silver bromide upon slow self-assembly at room temperature. They are characterized by single crystal X-ray diffraction, powder X-ray diffraction, thermal gravimetric analysis (TGA), UV–vis, IR and ESR spectra. Compound 1 is a 3D folding framework and compound 2 contains a 1D inorganic chain constructed by (AgBr₃)^2 − polyhedral units. In addition, the photochromic behaviors of compounds 1 and 2 were also investigated, and they show different and obvious fast photoresponse rate under sunlight.     

Chemical vapor deposition of ordered structures in YAG–alumina eutectic system

The eutectic structure of metals and ceramics is the result of a self-organization phenomenon in which multiple solid phases solidify with an ordered structure from a liquid phase. Hence, a melt-solidification process was the only way to generate ordered structures in a ceramic eutectic system. Here, we prepared ordered structures of Y₃Al₅O₁₂ (YAG)–Al₂O₃ composites via chemical vapor deposition in the YAG–Al₂O₃ eutectic system. Spatially periodic YAG rod and lamellar structures were generated in an alumina matrix homoepitaxially grown on the sapphire substrates on the Al₂O₃-rich side of the eutectic composition, whereas α-Al₂O₃ rod and lamellar structures were generated in a YAG matrix on the Y₂O₃-rich side. The results reveal that the pattern formation of ordered structures in a ceramic eutectic system can occur not only during in the melt-solidification process but also during the vapor deposition process. The Ce³⁺-doped YAG–Al₂O₃ composite film converts some of the blue light into yellow light, allowing some of it to pass through, and emitting white light. The Eu³⁺-doped YAG–Al₂O₃ composite film can be utilized as a scintillation screen for a high-resolution X-ray imaging test to see though a semiconductor storage device.     

Synthesis of a gold(I) complex with a (thio)phosphine-modified β-cyclodextrin

A gold(I) complex with the bidentate ligand 6^A-S-[2-(diphenylphosphino)-ethyl]thio-β-cyclodextrin has been prepared. The complex has been studied by mass spectrometry as well as IR and NMR spectroscopy. The influence of the ligand:metal ratio on the coordination mode has also been examined.     

Surface Energy and Thermal Stability Studies of Poly(dimethyl siloxane)–Poly(alkyl(meth)acrylate) Copolymers

The correlation between the surface energy and thermal stability of polymers plays an important role in engineering of plastic materials. In this work, microstructural characteristics of copolymers of poly(dimethyl siloxane) with benzyl methacrylate, ethyl methacrylate, and methyl acrylate are correlated with their surface energy and thermal stability. The poly(dimethyl siloxane) segments in the copolymer chains affected the hydrophobic behavior. The surface energy of the synthesized copolymers decreased by increasing segments of alkyl methacrylates. The thermal stability of copolymers suggesting that heat resistance of poly(dimethyl siloxane) copolymers used in this correlation can be improved by adjusting the units of alkyl methacrylates in copolymers.     

Syntheses,structures and photoluminescence of Ln(III)–Cu(I) coordination polymers based on benzimidazole-5-carboxylate and oxalate ligands

Three novel Ln(III)–Cu(I) coordination polymers, namely [LnCu(Hbic)₃(ox)_0.5] [Ln = Sm (1), Dy (2), Hbic = benzimidazole-5-carboxylate, ox = oxalate] and [EuCu(Hbic)₂(ox)H₂O]·2H₂O (3) have been hydrothermally synthesized and stucturally characterized. Both complexes 1 and 2 display the same unusual 2D layer heterometallic coordination frameworks that are built up by dimeric [Ln₂(Hbic)₆] cores and oxalate ligands by sharing Cu(I) ions. Complex 3 represents 1D polymeric chain architecture constructed from Eu₂Cu₂ ring units and oxalate ligands. Furthermore, the luminescent property of complex 3 has also been investigated.     

Catalytic hydration of alkynes to ketones by a salen–gold(III) complex

A general atom-economical approach for the synthesis of ketones is demonstrated through hydration of a wide range of alkynes catalyzed by a salen–gold(III) complex in the presence of trifluoroacetic acid as the cocatalyst. Various terminal and internal alkynes were suitable substrates for the catalytic system.     

Cyclopolymerization of cinnamate ester derivatives of alkyl α-(hydroxymethyl) acrylates

Summary Three new monomers for cyclopolymerization were synthesized using phase transfer catalysis of ethyl -(chloromethyl) acrylate (ECMA), t-butyl -(bromomethyl) acrylate (TBBMA) and isobornyl -(bromomethyl)acrylate (IBBMA) with cinnamic acid sodium salt. Bulk and solution polymerization at 70–80°C using AIBN gave soluble cyclopolymers with Mn=13650 and Mw=36540 for the ethyl ester, Mn=47700 and Mw=86900 for the t-butyl ester and Mn=3500 and Mw=4650 for the isobornyl ester monomer. The ester polymerizabilities decreased with increasing substituent bulkiness. FTIR spectra showed ca 30 to 93% cyclic units depending on the concentration of the monomer used in polymerizations. DSC thermograms showed that alkyl group size had little effect on Tg's, with values of 151°C, 156°C, and 164°C for the ethyl, t-butyl and isobornyl esters, respectively.     

V–I characteristics of solid polymer electrolytic (SPE) dehumidifier

Measurements of the V–I characteristics of a solid polymer electrolytic (SPE) dehumidifier were done using a modified SPE dehumidifier with four electrodes which included two electrodes to carry the main current and the other two electrodes to measure the voltages applied to the electrical double layer, which are the boundary voltages between the electrodes and the SPE membrane. The measured results were analyzed using the Butler-Volmer equation to examine the validity of the measurements. The current flowing in the dehumidifier is produced by the decomposition of water near the anode. Therefore, under a steady-state condition, the current should be proportional to the supply rate of water to the anode. On the other hand, a two-layer model for the SPE dehumidifier presented in our previous article showed that the current flowing in the dehumidifier was roughly proportional to the water content in the vicinity of the anode. These results were introduced for interpretation of the V–I measurements of the SPE dehumidifier. It was concluded that the dehumidifier current was expressed in the form of a Butler-Volmer equation as a function of the electrode boundary voltages which were the voltages across the boundary between the electrodes and the SPE membrane. An experimental formula for the current under a steady-state condition was developed as a function of the water content near the anode and the boundary voltages.     

Polyimide/nano-TiO2 hybrid films having benzoxazole pendent groups: In situ sol–gel preparation and evaluation of properties

Polyimide/titania (PI/TiO₂) nanocomposite films have been successfully fabricated through the in situ formation of TiO₂ within a PI matrix via sol–gel method. Poly(amic acid) (PAA), which is the precursor of PI, was successfully synthesized by mixing pyromellitic dianhydride (PMDA), with equimolar amount of a diamine monomer having a pendent benzoxazole unit and two flexible ether linkages in N,N-dimethylformamide (DMF) solvent. Tetraethyl orthotitanate [Ti(OEt)₄] and acetylacetone were then added to the resulted PAA. After imidization at high temperature, PI/TiO₂ hybrid films were formed. The structure and morphology of the hybrid nanocomposites with different titania contents (0 wt%, 5 wt%, 10 wt%, and 15 wt%) were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, and transmission electron microscopy. The results indicate that the TiO₂ nanoparticles were homogeneously dispersed in the hybrid films. The thermogravimetric analysis of nanocomposites confirms the improvement in the thermal stability with the increase in the percentage of titania nanoparticle. Transmission electron microscopy showed that the nanoparticles with an average diameter of 25–40 nm were dispersed in the polymer matrix.     

A heterobimetallic copper(I)–silver(I) complex spanned by 4,4′-bipyridine

Cationic heterobimetallic {[P(C₆H₄CH₂NMe₂-2)₃]Ag-bipy-Cu[P(C₆H₄CH₂NMe₂-2)₃]}²⁺(OTf⁻,PF₆⁻) (5) (bipy = 4,4^′-bipyridine, OTf=OSO₂CF₃) is accessible by the subsequent reaction of [P(C₆H₄CH₂NMe₂-2)₃]AgOTf (1) with bipy (2) to afford {[P(C₆H₄CH₂NMe₂-2)₃]Ag(bipy)}⁺(OTf⁻) (3), which on treatment with equimolar amounts of {[P(C₆H₄CH₂NMe₂-2)₃]Cu}⁺(PF₆⁻) (4) produces 5. In 5 the respective group-11 metal(I) centres are bridged by the π-conjugated organic ligand bipy. The electrochemical behaviour of 5 is reported.     

(en)Mn2(V2O7): A 3D manganese vanadate built by Mn–O layers and two types of pillars of V2O7 and en bridges

An unexpected 3D manganese vanadate (en)Mn₂(V₂O₇) (1) (en = ethylenediamine) has been hydrothermally obtained by H₂E₂Ge₂O₃ (E = ? CH₂CH₂COO^?) ligands and well-prepared mixture of V–Mn-amine and characterized by IR spectroscopy, elemental analysis, thermal stability and powder X-ray diffraction. Single-crystal X-ray diffraction analysis reveals that the structure is a novel pillared-layer, in which MnO₅N octahedra are corner-linked to form an infinite sheet with 4-membered rings (MRs) and further condensed to the 3D framework. The most prominent feature of 1 is the connection between the sheets via double bridges, namely, inorganic V₂O₇ dimeric units and organic en molecules. It is noteworthy that inorganic and organic double bridges between sheets have not been seen in manganese vanadates.     

Influence of solubility parameter difference between monomer and porogen on structures of poly (acrylonitrile–styrene-divinylbenzene) resins

In this work, the acrylonitrile (AN)-styrene (St)-divinylbenzene (DVB) resin was synthesized via suspension polymerization in the presence of inert porogens as diluent. The relationship of the solubility parameter (SP) of the materials and the porous properties of the resin was investigated. These porous spherical resin particles (0.25–0.84 mm) can be used as precursors of amidoxime resin which has a high metal ion chelating efficiency. The results showed that the porous properties (surface area and mean pore width) of the resin changed with variation in the compatibility between monomers and porogens. According to the the BET theory to N₂ sorption and scanning electron microscopy (SEM), the specific surface area of the obtained beads was strongly dependent on the compatibility of the components of the system and achieved values from 3.3 to 66.8 m²/g. The surface area of the terpolymer beads was found to rise with a decrease in the content of acrylonitrile or an increase in the SP of the porogens. However, the variation of the pore size was just the opposite. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 46979.     

Syntheses,structures and magnetic properties of two new heterometallic complexes constructed from a tripodal ligand N-(carbamoylmethyl)iminodiacetato(2−) (ADA)

Two new three-dimensional complexes formulated as [Na₂M(ADA)₂(H₂O)₄]_n (M = Ni(1), Co(2); ADA = N-(carbamoylmethyl)iminodiacetato dianion) have been synthesized under hydrothermal conditions and characterized by elemental analysis, IR, TG analysis and X-ray diffraction. Compounds 1 and 2 are isostructural and crystallize in the triclinic system, space group $P\overline{1}$. ADA ligand acts as chelating and bridging functions featuring a novel hexadentate binding mode. Magnetic measurements show that there is weak ferromagnetic interactions between the adjacent Ni(II) ions in 1.     

Measurement of real-time flow structures in gas–liquid and gas–liquid–solid flow systems using electrical capacitance tomography (ECT)

The real-time cross-sectional distributions of the gas holdups in gas–liquid and gas–liquid–solid systems are measured using electrical capacitance tomography. For the gas–liquid system, air as the gas phase and both Norpar 15 (paraffin) and Paratherm as the liquid phases are used. Polystyrene beads whose permittivity is similar to that of Paratherm are used as the solid phase in the gas–liquid–solid system. The three-phase system is essentially a dielectrically two-phase system enabling measurement of the gas holdup in the gas–liquid–solid system independent of the other two phases. A new reconstruction algorithm based on a modified Hopfield dynamic neural network optimization technique developed by the authors is used to reconstruct the tomographic data to obtain the cross-sectional distribution of the gas holdup. The real-time flow structure and bubbles flow behavior in the two- and three-phase systems are discussed along with the effects of the gas velocity and the solid particles.     

Ru(II)–CO complexes of thioarylazoimidazoles: Syntheses,structures, spectroscopy and DFT calculation

The complexes, cis-(CO)-trans-(Cl)-[Ru(SRaaiNR)(CO)₂Cl₂] (2) and trans-(Cl)-[Ru(SRaaiNR)(CO)Cl₂] (3) (SRaaiNR = 1-alkyl-2-{(o-thioalkyl)phenylazo}imidazoles; R = Me (1a) and Et (1b)) have been synthesized and characterized. The structural confirmation is achieved by single crystal X-ray structure determinations. The complexes show Ru(III)/Ru(II) couple and ligand reductions. Electronic structure and spectral properties of the complexes have been explained with the DFT and TDDFT calculation.     

Electrochemical study of β-diketonatobis(triphenylphosphite)rhodium(I) complexes

The electrochemical behaviour of the series of ten [Rh(RCOCHCOR′)(P(OPh)₃)₂] complexes with R, R′ = CF₃, CF₃ (1), CF₃, CH₃ (2), CF₃, Ph (C₆H₅) (3), CF₃, Fc (ferrocenyl = (C₅H₅)Fe(C₅H₄)) (4), CH₃, Ph (5), CH₃, CH₃ (6), Ph, Ph (7), Fc, CH₃ (8), Fc, Ph (9) and Fc, Fc (10) were studied in acetonitrile containing 0.100 mol dm⁻³ tetra-n-butylammonium hexafluorophosphate as supporting electrolyte utilizing a glassy carbon working electrode. Results are consistent with Rh(I) being first oxidized in an electrochemically irreversible two-electron transfer process at peak anodic potentials ranging E_pa(Rh) = 0.124–0.881 V vs. Fc/Fc⁺. For the ferrocene-containing complexes (4), and (8)–(10) the rhodium oxidation was followed by the electrochemically reversible oxidation of the ferrocenyl group in a one-electron transfer process at a slightly more positive potential. Relationships were established between the electrochemical quantity E_pa(Rh) and kinetic parameter log k₂ as well the sum of experimental group electronegativities (Gordy Scale) of the R and R′ groups (χ_R + χ_R′), the Hammett σ values (σ_R + σ_R′) and the Lever ligand parameter E_L for the [Rh(RCOCHCOR′)(P(OPh)₃)₂] complexes: E_pa(Rh) (vs. Fc/Fc⁺/V) = 0.31 (χ_R + χ_R′)–1.09 = 0.56 (σ_R + σ_R′) + 0.28 = S_M (ΣE_L) + (I_M − 0.66 V) = −0.23 log k₂ − 0.03 (k₂ = second order rate constant for the oxidative addition of methyl iodide to rhodium). A profound shift of E_pa(Rh) to a more positive potential was observed for Rh(I) substrates containing β-diketonato ligands with increasing electronegative substituents R and R′. An exponential dependence of E_pa(Rh) on the pK_a of the β-diketone was obtained.     

Synthesis of a star-shaped polymer having tris (β-diketonato)chromium(III) at the center core

Summary The metal-centered star-shaped polymer was prepared by coordination of p-(1,3-butanedionyl)-terminated poly(oxyethylene) with Cr(III) ion. The structure was confirmed by GPC analysis and IR spectra. The resulting polymer complex was well-soluble in various organic solvents and water. Received: 1 June 1998/Accepted: 9 July 1998