Two novel Zn(II) coordination polymers based on trigonal ligand: 4′-(4-pyridyl)-3,2′:6′,3″-terpyridine

Two novel Zn(II) coordination polymers, [Zn₅(pytpy)₈(fum)₄(H₂O)₄(OH)₂]_n · n(CH₃OH) · 2n(H₂O) (1) and [Zn₃(pytpy)₄ (btc)₂]_n · 2n(H₂O) (2) (pytpy = 4′-(4-pyridyl)-3,2′:6′,3″-terpyridine, H₂fum = fumaric acid, H₃btc = 1,3,5-benzenetricarboxylic acid) have been hydrothermally synthesized and structurally characterized. Complex 1 is a 2D layer structure, which is constructed from linear pentanuclear Zn(II) subunits interconnected via bidentate-bridging pytpy ligands and tridentate-bridging fum²⁻ anions. Complex 2 is a 3D network structure, μ₂-pytpy ligands link the layers based on the heart-like hexanuclear subunits to form the 3D network. Both complexes show strong fluorescence emission upon excitation at 310 nm in solid state. Additionally, these two complexes possess great thermal stabilities, especially for 2, the framework is stable up to 350 °C.     

Synthesis of a fluorescent gold(I) complex with a thiosemicarbazone, [Au2(3-NO2-Hbtsc)4]Cl2 · 2CH3CN

Direct reaction of gold(I) chloride with 3-nitrobenzaldehyde thiosemicarbazone (3-NO₂-Hbtsc) in the presence of triphenylphosphine in acetonitrile has yielded ionic complex, [Au₂(3-NO₂-Hbtsc)₄]Cl₂ · 2CH₃CN (1). It exhibited an intense fluorescence band (λ_em) at 383 nm (λ_ex = 300 nm), and two bands of medium intensity at 413 and 436 nm (λ_ex = 350 nm). Complex 1 represents first example of ionic gold(I) complex with a thiosemicarbazone.     

Ditopic, flexible hydrazone-based building blocks with pendant 2,2′:6′,2′′-terpyridine metal-binding domains

The synthesis and characterization of three new bis(2,2′:6′,2′-terpyridine) (tpy) ligands containing different hydrazone spacers between the metal-binding domains are described. Treatment of 1,4-benzenedicarbaldehyde bis(2,2′:6′,2′′-terpyridin-4′-ylhydrazone) (1) with [(tpy)RuCl₃] in the presence of N-ethylmorpholine results in the formation of [(tpy)Ru(μ-1)Ru(tpy)]⁴⁺. Single crystal X-ray diffraction data for [(tpy)Ru(μ-1)Ru(tpy)][PF₆]₄·8MeCN confirm the ability of the hydrazone-based ligand to bridge two ruthenium(II) centres, providing proof-of-principle for the application of this class of flexible ligand in the design of coordination polymers.     

Fast preparation of (111)‐oriented β‐SiC films without carbon formation by laser chemical vapor deposition from hexamethyldisilane without H2

(111)‐oriented β‐SiC films were prepared by laser chemical vapor deposition using a diode laser (wavelength: 808 nm) from a single liquid precursor of hexamethyldisilane (Si(CH₃)₃–Si(CH₃)₃, HMDS) without H₂. The effects of laser power (P_L), total pressure (P_tot) and deposition temperature (T_dep) on the microstructure, carbon formation and deposition rate (R_dep) were investigated. β‐SiC films with carbon formation and graphite films were prepared at P_L ≥ 170 W and P_to ≥ 1000 Pa, respectively. Carbon formation strongly inhibited the film growth. β‐SiC films without carbon formation were obtained at P_tot = 400‐800 Pa and P_L = 130‐170 W. The maximum R_dep was about 50 μm·h^?1 at P_L = 170 W, P_tot = 600 Pa and T_dep = 1510 K. The investigation of growth mechanism shows that the photolytic of laser played an important role during the depositions.     

Synthesis and structural characterization of the Re3 triangular 4,4′-bipyridinium aqua-tris(μ-triiodo)-octachlorotrirhenium dihydrate complex

The Re₃ cluster compound (4,4′-bipyH₂) Re₃Cl₈I₃H₂O · 2H₂O was obtained by thermal reaction of (NH₄)₄[Re₂OCl₁₀] with 4,4′-bipirydine triiodide. The structure of this compound has been established by X-ray measurement. This is the three-centre rhenium cluster with Re centres bonded by iodide bridges. The cations and anions positions are stabilized by hydrogen bonding network.     

Bis(4′-phenyl-2,2′:6′,2″-terpyridine)ruthenium(II): Holding the {Ru(tpy)2} embraces at bay

The solid state structure of [Ru(Phtpy)₂][PF₆]₂ · 4MeCN has been determined (Phtpy = 4′-phenyl-2,2′:6′,2″-terpyridine); [Ru(Phtpy)₂]²⁺ cations pack into sheets by virtue of {M(tpy)₂}₂ embraces, and the MeCN solvent molecules are involved in NH–C interactions which prevent the efficient packing of adjacent sheets. Comparisons with related structures lead to some generalizations about packing motifs in salts containing [M(Phtpy)₂]²⁺ or [M(pytpy)₂]²⁺ cations (pytpy = 4′-pyridyl-2,2′:6′,2″-terpyridine).     

Nanostructured α- and β-cobalt hydroxide thin films

A new perspective in the use of electrochemical methods to deposit cobalt hydroxide thin films is presented. Ordered arrays of α-Co(OH)₂ (hydrotalcite-like (Co-HT)) and β-Co(OH)₂ nanoparticles were synthesized on transparent conductive oxide (TCO) substrates by localized cathodic electrogeneration of hydroxyl via the reduction of NO₂⁻ (or NO₃⁻) ion precursors in solution containing Co²⁺ in very low concentration. The thin films, analyzed by X-ray diffraction and scanning electron microscopy were found to be composed of vertically oriented platelets with the crystallographic c-axis parallel to the substrate surface. Turbostratic disorder was not observed in the films. UV/Vis spectra and thermal gravimetric analyses (TGA) indicated distinct variation between the Co-HT structures. Films deposited at 60 °C using a nitrite precursor generated uniform, vibrant-green mixed-valence Co-HT (Co²⁺/Co³⁺). Nitrate precursors yielded a “hydroxyl-deficient” Co-HT (Co²⁺ only). Films deposited at 95 °C in nitrate solution yielded β-Co(OH)₂. The films obtained in presence of nitrite were thicker than those obtained in nitrate. They were formed of β-Co(OH)₂ and contained traces of Co-HT.     

High‐Speed Preparation of <111>‐ and <110>‐Oriented β‐SiC Films by Laser Chemical Vapor Deposition

Highly oriented <111> and <110> β‐SiC films were prepared on Si(100) single crystal substrates by laser chemical vapor deposition using a diode laser (wavelength = 808 nm) and HMDS (Si(CH₃)₃–Si(CH₃)₃) as a precursor. The effects of laser power (P_L), total pressure (P_tot), and deposition temperature (T_dep) on the orientation, microstructure, and deposition rate (R_dep) were investigated. The orientation of the β‐SiC films changed from <111> to random to <110> with increasing P_L and P_tot. The <111>‐, randomly, and <110>‐oriented β‐SiC films exhibited dense, cauliflower‐like, and cone‐like microstructures, respectively. Stacking faults were observed in the <111>‐ and <110>‐oriented films, and aligned parallel to the (111) plane in the <111>‐oriented film, whereas they were perpendicular to the (110) plane in the <110>‐oriented film. The highest R_dep of the <111>‐oriented β‐SiC film was 200 μm/h at P_tot = 200 Pa and T_dep = 1420 K, whereas that of the <110>‐oriented film was 3600 μm/h at P_tot = 600 Pa and T_dep = 1605 K.     

Light Triggers the Antiproliferative Activity of Naphthalimide-Conjugated (η6-arene)ruthenium(II) Complexes

We report the synthesis and characterization of three half-sandwich Ru(II) arene complexes [(η⁶-arene)Ru(N,N′)L][PF₆]₂ containing arene = p-cymene, N,N′ = bipyridine, and L = pyridine meta- with methylenenaphthalimide (C1), methylene(nitro)naphthalimide (C2), or methylene(piperidinyl)naphthalimide (C3). The naphthalimide acts as an antenna for photoactivation. After 3 h of irradiation with blue light, the monodentate pyridyl ligand had almost completely dissociated from complex C3, which contains an electron donor on the naphthalimide ring, whereas only 50% dissociation was observed for C1 and C2. This correlates with the lower wavelength and strong absorption of C3 in this region of the spectrum (λ_max = 418 nm) compared with C1 and C2 (λ_max = 324 and 323 nm, respectively). All the complexes were relatively non-toxic towards A549 human lung cancer cells in the dark, but only complex C3 exhibited good photocytoxicity towards these cancer cells upon irradiation with blue light (IC₅₀ = 10.55 ± 0.30 μM). Complex C3 has the potential for use in photoactivated chemotherapy (PACT).     

Synthesis and spectroelectrochemistry of dithieno(3,2‐b:2′,3′‐d)pyrrole derivatives

New π‐conjugated polymers containing dithieno(3,2‐b:2′,3′‐d)pyrrole (DTP) were successfully synthesized via electropolymerization. The effect of structural differences on the electrochemical and optoelectronic properties of the 4‐[4H‐dithieno(3,2‐b:2′,3′‐d)pyrrol‐4‐yl]aniline (DTP–aryl–NH₂), 10‐[4H‐dithiyeno(3,2‐b:2′,3′‐d)pirol‐4‐il]dekan‐1‐amine (DTP–alkyl–NH₂), and 1,10‐bis[4H‐dithieno(3,2‐b:2′,3′‐d)pyrrol‐4‐yl] decane (DTP–alkyl–DTP) were investigated. The corresponding polymers were characterized by cyclic voltammetry, NMR (¹H‐NMR and ¹³C‐NMR), and ultraviolet–visible spectroscopy. Changes in the electronic nature of the functional groups led to variations in the electrochemical properties of the π‐conjugated systems. The electroactive polymer films revealed redox couples and exhibited electrochromic behavior. The replacement of the DTP–alkyl–DTP unit with DTP–aryl–NH₂ and DTP–alkyl–NH₂ resulted in a lower oxidation potential. Both the poly(10‐(4H‐Dithiyeno[3,2‐b:2′,3′‐d]pirol‐4‐il)dekan‐1‐amin) (poly(DTP–alkyl–NH₂)) and poly(1,10‐bis(4H‐dithieno[3,2‐b:2′,3′‐d]pyrrol‐4‐yl) decane) (poly(DTP–alkyl–DTP)) films showed multicolor electrochromism and also fast switching times (<1 s) in the visible and near infrared regions. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40701.     

Synthesis of onion-like mesoporous silica from sodium silicate in the presence of α,ω-diamine surfactant

Mesoporous silicas with vesicular and onion-like morphologies were assembled through hydrogen-bonding pathway from sodium silicate as silica source and electrically neutral α,ω-diamine, Jeffamine D2000 surfactant (H₂NCH(CH₃)CH₂[OCH₂CH(CH₃)]₃₃NH₂) as template in aqueous media at different synthesis temperatures (25, 60 and 100 °C). Assembling the material at 100 °C afforded onion-like core shell mesoporous silica, while at relatively lower temperature, e.g. 25 and 60 °C, multilamellar vesicles were obtained. Mesoporous silica with onion-like morphology was also obtained by a two-step synthesis involving an aging period of 20 h at room temperature followed by a hydrothermal stage (1–12 h) at 100 °C. The heavily cross-linked (Q⁴/Q³ ratio of 4.43) onion-like mesophase silica exhibited high hydrothermal stability. The BET surface area, pore volume and KJS (Kruk-Jaroniec-Sayari) pore diameter of the onion-like mesoporous silica were found to be 464 m² g⁻¹, 1.16 m³ g⁻¹ and 7.2 nm, respectively.     

Anion-directed assembly of two novel cadmium(II) complexes constructed by 2,2′-(1,4-butanediyl)bis(1H-benzimidazole) ligand

Depending on the different coordinated anions used, reaction of Cd(II) salt with 2,2′-(1,4-butanediyl)bis(1H-benzimidazole) results in the formation of two coordination polymers: a 1D chain {[Cd(H₂C4BIm)Cl₂] · (H₂C4BIm)}_n (1), and a 2D sheet [Cd(HC4BIm)(NCS)]_n (2) which features distorted 4.8² topology (H₂C4BIm = 2,2′-(1,4-butanediyl)bis(1H-benzimidazole)). The fluorescence properties for both the complexes have been studied.     

Synthesis and X-ray crystal structure determination of monomeric cis-Pd(2,2′-bipyridine)(NO3)2

Complex cis-Pd(2,2′-bipyridine)(NO₃)₂ was synthesized by the reaction of cis-Pd(2,2′-bipyridine)Cl₂ with AgNO₃ in water and crystallized by vapor diffusion of diethyl ether into an acetonitrile solution of the complex. The crystal structure obtained shows that each of the two nitrate ligands are coordinated through oxygen atoms to the Pd(2,2′-bipyridine)²⁺ center in unidentate fashion. IR and ¹H NMR spectral data were also obtained.     

Strong Near‐Infrared Photoluminescence Emission of (003)‐Oriented MgTiO3 Thin Films

In this study, ilmenite‐MgTiO₃ films were sputtered on p‐type Si(111) substrates and the extrinsic effects, such as grain size, crystallinity, and orientation of photoluminescence (PL) properties of the films are discussed. To reduce the effect of oxygen vacancies (act as shallow defects) on PL emissions in the films, oxygen (O₂) was introduced as the sputtering gas and the excitation light source (λ = 532 nm) which has a corresponding energy (hν = 2.33 eV) below the shallow defect states was used. In this study, intense near‐infrared (NIR) PL emission centered at 810.1 nm at room temperature can be observed when the MgTiO₃ thin films exhibit the preferred (003)‐orientation and accompanied by the presence of hexagon‐shaped grains. In this study, the experiment results reveal that the NIR emission intensity of MgTiO₃ films highly depend on crystal orientation and/or grain morphology.     

Photooxidation of N,N-bis(3,5-di-tert.-butylsalicylidene)-1,2-diamino hexane-manganese(III) chloride (Jacobsen catalyst) in chloroform

Mn^III(J-salen)Cl (Jacobsen catalyst) with J-salen=N,N^′-bis(3,5-di-tert.-butylsalicylidene)-1,2-diaminocyclohexane dianion in CHCl₃ is photooxidized by the solvent to a Mn^IV(J-salen) complex, presumably Mn^IV(J-salen)Cl₂, with φ=0.002 at λ_irr=333 nm.     

Growth of Highly Conformal TiCx Films Using Atomic Layer Deposition Technique

TiC_x films were deposited by atomic layer deposition using tetrakis–neopentyl–titanium [Ti(CH₂C(CH₃)₃)₄] and H₂ plasma as the precursor and reactant, respectively. The growth of the rock‐salt–structured TiC_x films was confirmed by X‐ray and electron diffraction. The C‐to‐Ti ratio determined by Rutherford backscattering spectrometry was ~0.52 and the film resistivity was as low as ~600 μΩ cm with a high density of 4.41 g/cm³. The step coverage was approximately 90% over the trench structure (top opening diameter of 25 nm) with an aspect ratio of ~4.5.     

Comparisons of Optical Properties on Meta- and Para-Linkages of Copolymers for Poly(phenylene vinylene) and Poly(phenylene azomethine) with Alkylthio Group at the Side Chain

Three series of soluble copolymers were synthesized: I, poly[m (or p)-phenylene (diacetonitrile) vinylene-co-methoxy-5-(2′-ethylhexylthio)-p-phynylene vinylene] (m-C=C(CN), p-C=C(CN)); II, poly[m (or p)-phenylene azomethine-co-2-methoxy -5-(2′-ethylhexylthio)-p-phenylene azomethine] (m-C=N, p-C=N); III, poly[m (or p)-phenylene vinylene-co-2-methoxy-5-(2′-ethylhexythio)-p-phenyle vinylene] (m-C=C, p-C=C). Of all these copolymers, the copolymers containing meta-linkage showed glass transition temperatures (T_g‘s) approximately 10 ^○C to 30 ^○C lower than those of the corresponding para-linkage copolymers because of lower crystallinity. 5% weight loss of all the copolymers occurred at around 381 to 344 ^○C.Copolymers of the meta-linkage also caused a relative asymmetry and irregularity of the copolymer main chain, thus leading to a decrease of effective conjugation length and a reduction of the molecular aggregation: this subsequently led to less excimer formation. These phenomena can be evidenced from the blue-shift of PL emission, 15 to 49 nm for the meta-linkage copolymers compared with the para-linkage copolymers. In addition, due to the lesser electron-donating capability of the sulfur atom, m-C=C, p-C=C and p-C=N containing the alkylthio group indicated a blue shift of 8 to 24 nm, when compared with those copolymers of similar structures containing the alkyloxy group as reported in the literature. Since series II contains strong electron-withdrawing –C=N– at the main chain, and series I contains even stronger electron-withdrawing cyano group, thus, the observed λ_max are in the order: series I [m-C=C(CN), p-C=C(CN)]>series II [m-C=N, p-C=N]>series III [m-C=C, p-C=C]. Furthermore, since in series II, the lone pair electrons on the –C=N– main chain would overlap partially with the six πelectrons in the phenyl ring, and decrease the coplanar nature of the main chain, thus their PL emission intensities were less than those of series I and III. Finally, a device of the structure (ITO/PEDOT: PSS/m-CC(CN)/LiF/Al) was constructed, and a yellow light of λ_max=570 nm was observed.     

Phase transformations in Sm (α + β)-SiAlON ceramics during post-sintering heat treatments

Phase transformations in Sm (α + β)-SiAlON ceramics during post-sintering heat treatments at 1300 and 1450 °C were investigated using XRD, SEM, TEM and EDS techniques. The transformation from α to β SiAlON, (i.e. α′ to β′) phases was observed at both temperatures. However, other phase transformations occur simultaneously at grain boundaries of the materials and also involve the β′ phase, namely, Glass → SmAlO₃ + β′ and SmAlO₃ + β′ → M′. Their effects on the amount of β′ in the materials must therefore be considered in the study of the α′ to β′ transformation. It is thought that the increase in the β′:(α′ + β′) ratio during a heat treatment process depends not only on the rate of the α′ to β′ transformation, but also on the amount and composition of the intergranular phases.     

Determination of the β ↔ αL′ transition in Ca2SiO4 to 7 KBAR

Differential thermal analysis in hydrostatic apparatus to 7 kbar shows that the β → α_L′ transition temperature in Ca₂SiO₄ linearly increases from 701° ± 2°C at 1 bar at the rate of 10.5 ± 0.5 deg kbar⁻¹. The α_L′ → β transition temperature is observed some 20°–30° lower in temperature than the β → α_L′ transition and no variation in this hysteresis with pressure is indicated.     

Crystallographic Orientation Dependence on Electrical Properties of (Bi,Na)TiO3‐based Thin Films

Orientation‐engineered (La, Ce) cosubstituted 0.94(Bi_0.5Na_0.5)TiO₃–0.06BaTiO₃ thin films were epitaxially deposited on CaRuO₃ buffered (LaAlO₃)_0.3(Sr₂AlTaO₆)_0.35 single‐crystal substrates by pulsed laser deposition. The ferroelectric, piezoelectric, dielectric, and leakage current characteristics of the thin films were significantly affected by the crystallographic orientation. We found that the (001)‐oriented film exhibited the best ferroelectric properties with remnant polarization P_r = 29.5 μC/cm² and coercive field E_c = 7.4 kV/mm, whereas the (111)‐oriented film demonstrated the largest piezoelectric response and dielectric permittivity. The bipolar resistive switching behavior, which is predominantly attributed to a combined effect of ferroelectric switching and formation/rupture of conductive filaments, was observed. The conduction mechanisms were determined to be ohmic conduction and Poole–Frenkel emission at high‐ and low‐resistance states, respectively, in all the films.