A phosphorescent copper(I) complex: Synthesis,characterization, photophysical property,and sensing performance towards molecular oxygen

In this paper, we report the synthesis, crystal structure, photophysical properties, and electronic nature of a phosphorescent Cu(I) complex of [Cu(PYB)(POP)]BF₄, where PYB and POP stand for 2-pyridin-2-yl-1H-benzoimidazole and bis(2-(diphenylphosphanyl)phenyl) ether, respectively. [Cu(PYB)(POP)]BF₄ renders yellow phosphorescence peaking at 561 nm, with a long excited state lifetime of 13.4 μs. Density functional calculation reveals that the emission comes from a triplet metal-to-ligand-charge-transfer excited state. We electrospun composite nanofibers of [Cu(PYB)(POP)]BF₄ and polystyrene, hoping to explore the possibility of using the composite nanofibers as an oxygen sensing material. The finally obtained samples with average diameter of ～900 nm exhibit a maximum sensitivity of 4.20 towards molecular oxygen with short response/recovery time (8 s/16 s) due to the large surface-area-to-volume ratio of nanofibrous membranes. No photobleaching is detected in these samples.     

Nanofibers doped with a phosphorescent iridium complex: Synthesis,characterization, and photophysical property study

In this article, we report a novel Ir(III) complex of Ir(acac)(F-BT)₂ (acac = pentane-2,4-dione, and F-BT = 2-(2-fluorophenyl)benzo[d]thiazole), including its synthesis, characterization, crystal structure, and electronic nature. Data suggest that Ir(acac)(F-BT)₂ molecules crystallize in monoclinic system with double molecules per unit cell, and the onset electronic transition is assigned as a character of metal-to-ligand-charge-transfer. By doping Ir(acac)(F-BT)₂ into a polymer matrix of poly(vinylpyrrolidone) (PVP), we investigate the morphology, emissive character, excited state lifetime, and photostability of the resulting composite nanofibers, as well as those of pure sample. Data comparison suggests that the emission of the composite nanofibers shows a blue shift tendency, the excited state lifetime and photostability of the composite nanofibers become longer and better than those of pure Ir(acac)(F-BT)₂. The rigid framework provided by PVP matrix is responsible for above improvements.     

A series of water soluble RE(III) complexes: Synthesis,characterization, photophysical property and sensing activity towards Cr(III)

In this paper, four water soluble rare-earth(III) fluorescent chemosensors, Na₃RE(PDA)₃ (PDA = pyridine-2,6-dicarboxylic acid, and RE = Sm, Eu, Tb, Dy), are synthesized and characterized. Their excitation and emission spectra, fluorescence responses towards Cr(III), quenching mechanism, oxygen and thermal sensitivity of the complexes are systemically studied. The emission intensity and the excited state lifetimes of the four complexes decrease with increasing concentration of trivalent chromium (Cr(III)). Their sensing behavior towards Cr(III) is investigated by fluorescence spectroscopy. Results suggest that Na₃Dy(PDA)₃ exhibits highest sensitivity and linear spectral response towards Cr(III) (Stern–Volmer constant = 0.461 × 10⁷ L/mol, linearity = 0.996). It is note worthy that oxygen has little effect on the emission of Na₃RE(PDA)₃ complexes. These important advantages make themselves promising candidates to be utilized in actual applications.     

Diamine ligands with multiple coplanar conjugation rings and their phosphorescent copper complexes: Synthesis,characterization, crystal structures,and photophysical property

In this paper, we report a series of diamine ligands with multiple coplanar conjugation rings and their corresponding phosphorescent Cu(I) complexes, including their synthesis, crystal structures, photophysical properties, and electronic nature. Geometric parameters suggest that the Cu(I) center localizes at a distorted tetrahedral geometry within the Cu(I) complexes. Theoretical calculation reveals that all emissions originate from triplet metal-to-ligand-charge-transfer excited state. It is found that the free rotation of conjugation rings may compromise the coplanar plane and thus has little effect on the photophysical property of their corresponding Cu(I) complexes. But excess coplanar conjugation moiety is harmful for emissive state. The detailed quenching mechanism is investigated.     

Oxygen sensing nanofibers doped with red-emitting Eu(III) complex: Synthesis,characterization, mechanism,and sensing performance

In this paper, we synthesize a novel diamine ligand of PIP and its corresponding Eu(III) complex of Eu(DBM)₃PIP, where PIP = 2-phenyl-1H-imidazo[4,5-f][1,10]phenanthroline, and DBM = 1,3-diphenyl-propane-1,3-dione. The UV–Vis absorption spectra, low temperature phosphorescence spectra, energy transfer mechanism, excited state lifetime of Eu(DBM)₃PIP, as well as its photoluminescence spectra, are investigated in detail. Data suggest that the emission of Eu(DBM)₃PIP is quenchable by molecular oxygen due to the back-energy transfer process. By doping Eu(DBM)₃PIP into a polymer matrix of poly(vinylpyrrolidone) (PVP), the oxygen sensing performance of the resulted nanofibrous membrane is investigated. Finally, the 0.6 wt% doped sample exhibits a linear response towards molecular oxygen, with a sensitivity of 3.5 and response/recovery time of 15 s/24 s.     

Synthesis,photophysical and electrophosphorescent properties of a novel fluorinated rhenium(I) complex

A novel fluorinated rhenium complex, i.e., Re-BFPP (BFPP, 2, 3-bis(4-fluorophenyl)pyrazino[2,3-f][1,10]phenanthroline) was designed, synthesized and characterized by ¹H NMR and mass spectroscopy. The light-emitting and electrochemical properties of this complex were studied. The organic light-emitting diodes (OLEDs) employing Re-BFPP as a dopant emitter with the structures of ITO/m-MTDATA (10 nm)/NPB (20 nm)/CBP: X wt.% Re-BFPP (30 nm)/Bphen (10 nm)/Alq₃ (30 nm)/LiF (1 nm)/Al (100 nm) were successfully fabricated and a broad electroluminescent peak at 553 nm was observed. The 10 wt.% Re-BFPP doped device exhibited the maximum luminance of 6342 cd/m² and a peak current efficiency of 17.9 cd/A, corresponding to the power efficiency of 8.1 lm/W.     

A novel Re(I) complex with oxdiazole moiety: Synthesis,characterization, photo- and electro-luminescence properties

In this paper, we report a novel phosphorescent Re(I) complex of Re(CO)₃(OP)Br, where OP = 2-(5-phenyl-[1,3,4]oxadiazol-2-yl)-pyridine, including its photophysical properties, geometric/electronic structures, electrochemical and thermal properties. Experimental data suggest that Re(CO)₃(OP)Br is a promising yellow emitter peaking at 545 nm with short excited state lifetime of ～0.06 μs. The Re(I) center localizes in a distorted octahedral field in Re(CO)₃(OP)Br and the emissive state of Re(CO)₃(OP)Br has metal-to-ligand-charge-transfer character, leading to the room-temperature phosphorescence. Further analysis reveals that Re(CO)₃(OP)Br has HOMO and LUMO energy levels at ?5.90 V and ?3.57 V respectively, as well as its high thermal decomposition temperature of 380 °C. Using Re(CO)₃(OP)Br as a dopant, an electroluminescence peaking at 560 nm is realized, with a maximum luminance of 4300 cd/m² and a maximum current efficiency of 11.3 cd/A.     

Highly efficient organic ultraviolet photodetectors based on a Cu(I) complex

We demonstrate high response visible-blind organic ultraviolet photodetector (UV-PD) using 4,4′,4″-tris[3-methyl-pheny(phenyl)amino]triphenylamine (m-MTDATA) and a novel Cu(I) complex, [Cu(1,2-bis(diphenylphosphino)benzene)(bathocuproine)]BF₄ (CuBB) to act as the electron donor and acceptor, respectively. CuBB behaves high electron mobility and the optimized PD offers a photocurrent up to 173 μA/cm² at ?10 V, corresponding to a response of 251 mA/W under an illumination of 365 nm UV light. We attribute the high response to the high electron transport ability of CuBB, the suppression of radiative decay of m-MTDATA and efficient charge transfer from m-MTDATA to CuBB.     

Synthesis,photophysical and electroluminescent properties of a novel bright light-emitting Eu3+ complex based on a fluorene-containing bidentate aryl phosphine oxide

A novel bidentate aryl phosphine oxide (APO) ligand with fluorene as the chromophore (9,9-diethyl-9H-fluorene-2,7-diyl)bis(diphenylphosphine)oxide (EFDPO), as well as the corresponding Eu³⁺ complex 1 were designed and synthesized. The strong absorption antennae effect of the functional APO ligands was proved. The effect of EFDPO in the intramolecular singlet and triplet energy transfer was also investigated. It is showed that the rigid structure and the appropriate energy levels of EFDPO not only reduce the energy loss induced by the structure relaxation, but also restrain the solvent quenching and facilitate the energy transfer from EFDPO to Eu³⁺. The thermal analysis was also performed to prove the improved thermal stability and phase stability of the complex. The complex exhibited good electroluminescent (EL) performance, such as maximum brightness more than 600 cd m^?2, E.Q.E. around 2% and stable monochromic red emission at 616 nm.     

Reactivity of commercial silicon and silicides towards copper(I) chloride. Effect of aluminium, calcium and iron on the formation of copper silicide

The reaction of CuCl with silicon, containing Al, Fe and Ca as impurities, or with silicides (Si₂Ca, Si₂Fe, Si₂Al₂Ca, Si₈Al₆Fe₄Ca) has been investigated in the temperature range 200–300°C. For the reaction between CuCl and commercial Si, it was found that, at 282°C, aluminium promotes the reaction between Cu₃Si and CuCl while the rate of consumption of Cu₃Si is greatly reduced by the presence of iron. The combined action of these two impurities leads to the formation of more copper–silicon alloy. In the presence of mixed silicides, the reaction with CuCl also leads to the formation of Cu₃Si. For the quaternary Al–Ca silicide containing iron the rate of formation of Cu₃Si is not increased, which allows us to attribute a stabilizing effect to iron.     

Synthesis,characterization, and electrical,electrochemical and gas sensing properties of a novel cyclic borazine derivative containing three phthalocyaninato zinc(II) macrocycles

A novel borazine derivative of trinuclear phthalocyanine has been prepared by following the multistep reactions of unsymmetrically substituted phthalocyanines. 4-(4-Amino-3-nitrophenoxy)phthalonitrile (3) which is one of the precursor molecules of the phthalocyanine was obtained from 4-nitrophthalonitrile (1) and 4-amino-3-nitrophenol (2) with K₂CO₃ in DMF at 50 °C. The zinc(II) phthalocyanine (5) containing an unsymmetrical substituted 4-amino-3-nitrophenoxy group was synthesized by statistical condensation of two different phthalonitriles. 4-(4-Amino-3-nitrophenoxy)phthalonitrile (3) and 4,5-bis(hexylthio)phthalonitrile (4) were cyclotetramerized with zinc acetate in DMF at 170–180 °C to yield 2-(4-amino-3-nitrophenoxy)-9,10,16,17,23,24-hexa(hexylthio)phthalocyanine zinc(II) complex (5), which was then separated by column chromatography on silica gel. The unsymmetrically substituted compound was reduced to the diamine form (6) using hydrazine hydrate in the presence of Pd/C catalyst, and the product was purified with chromatographic separation. Compound 6 was then reacted with triisopropoxyborane in refluxing xylene to give 5H,12H,19H-tris[2-(3,4-diaminophenoxy)-9,10,16,17,23,24-hexa(hexylthio)phthalocyaninato zinc(II) diazaborolo] borazine (7). The resulting product was purified by column chromatography on silica gel. All the target unsymmetrical phthalocyanines and borazine derivative were characterized by elemental analysis, IR, UV–vis, and ¹H NMR. Boron and zinc(II) percents in 7 were quantified with ICP-MS. Impedance spectroscopy and dc measurements were performed on spin coated 5–7 films as a function of temperature (293–400 K). The dc results showed an activated conductivity dependence on temperature. The ac results gave a temperature dependent frequency exponent s. The results were compared with the prediction of the Quantum Mechanical Tunelling and Correlated Barrier Hopping models. The ac conductivity of the films was well represented by the form Aω^s. Gas sensing properties of the films for the volatile organic compounds (VOCs) (chloroform, acetone, carbontetrachloride and ammonia) were also investigated in the temperature range from 293 to 400 K. The operating temperature had a considerable effect on sensing characteristics. Maximum sensitivity to VOCs were observed at room temperature for all films. Cyclic voltammetry of compounds 6 and 7 in solution indicated that these compounds have similar voltammetric behaviour.     

Gold(I) and gold(III) complexes with anionic oxygen donor ligands: hydroxo, oxo and alkoxo complexes

The chemistry of gold(I) and gold(III) hydroxo, oxo and alkoxo complexes containing organic co-ligands is reviewed. Due to the high reactivity of the gold-oxygen bond most of these species can be employed as useful intermediates in many important processes. Alkoxides are by far the most numerous class among these species, and both gold(I) and gold(III) complexes are known with a variety of alkoxides. The recent discovery of the catalytic activity of some gold(I) and gold(III) fluoroalkoxides has enlivened the interest towards this class of compounds leading to new applications for previously known complexes, as is the case for a gold(III) siloxo complex which has found use as a precursor for CVD, as well as for the synthesis of new alkoxo derivatives. Another well represented and well known class of compounds are the gold(I) oxo complexes [O(AuPR₃)₃]⁺ which are the most effective aurating reagents. Gold(III) oxo complexes have been synthesized only recently and much of their chemistry is still largely to be explored. Preliminary studies suggest their potential in the transfer of oxygen atoms. Finally, some cationic gold(III) hydroxo complexes are found to display significant,and in some cases relevant, cytotoxic effects on cancer cell lines.     

Substituent effects on poly(p-phenylenevinylene) backbone,interrupted with silicon atoms: molecular orbital theory

The electronic structures and the structural deformations of silicon containing poly(p-phenylenevinylene) (PPV) polymers have been studied theoretically. The results of the calculations indicate that the regular π conjugated system is effectively interrupted by the organosilicon units yielding a blue emission. It has also been observed that substitution of methoxy on vinylene group caused significant structural deformation of the PPV lumophore, and subsequently, decreased the ionization potential (IP) and increased the electron affinity of the SiBu PPV. Experimentally, it is known that light emitting diodes made of silicon containing copolymers operate at low voltages, due to the reduction of the LUMO level in the luminescence polymers. The flat deformation of the PPV moiety induced a red shift of the absorption maxima. The substitution of phenyl ring on silicon atoms constrained free rotation around the Si C bond increasing the torsional angles of the lumophore and caused slight blue shift of absorption peak. Substitution of the cyano group on the vinylene moiety increased the ionization potential as well as the electron affinity. On the other hand, the electron donating methoxy group decreased the ionization potential and electron affinity. Those calculated results agree well with the experimental observations. The density functional calculation method, which account for electron correlation, yielded much more accurate values for the HOMO–LUMO gap than the Hartree–Fock method.     

Synthesis,characterization and optical studies on Sm~(2+)-doped CdSe nanocrystals:a blueshift and fixed emission with high quantum yields

CdSe:Sm nanocrystals(NCs) were synthesized by a water phase method,and their structures,shapes and optical properties were further characterized.X-ray diffraction(XRD) analysis suggested that both the CdSe and CdSe:Sm NCs contained(111),(220) and(311) lattice planes in the zinc blende structure overlapped with the(002),(110) and(112) lattice planes in the wurtzite structure,and the diameters were about 4.2,3.3 and 2.3 nm for CdSe,CdSe:Sm(8%) and CdSe:Sm(10%) NCs,respectively.All of the CdSe:Sm NCs were monodispersed and uniform spherical nanocrystals.The CdSe:Sm(10%) NCs prepared with different reaction times exhibited constant absorption spectra at 430 nm and a fixed emission peak at581 nm.Compared with those of pure CdSe NCs,the fluorescence emission of CdSe:Sm(10%) NCs blueshifted 20-36 nm,and the absorption peak initially redshifted and then blueshifted with the prolongation of reaction time.In addition,the Sm~(2+) doping decreased the fluorescence lifetime and increased the quantum yields(QYs) of CdSe NCs.The QYs of CdSe:Sm NCs increased initially and then decreased with the increase in the amount of doped Sm~(2+).The initial pH and charge compensator concentration also exhibited significantly enhanced fluorescence emission of CdSe:Sm NCs.     

Synthesis of CETBz-TTF and CESBz-TTF: Preparation, structural and physical properties of their radical salts with paramagnetic Cu(II) complex anions

CETBz-TTF (4,5-bis(cyanoethylthio)benzo-tetrathiafulvalene) and CESBz-TTF (4,5-bis(cyanoethylseleno)benzo-tetrathiafulvalene) 5 have been synthesized from cyano precursor via a cross-coupling reaction. Radical salts with paramagnetic Cu(II) complex anions, such as (CETBz-TTF)₂CuCl₄ 6 and (CESBz-TTF)₂CuCl₄ 7 have been prepared. X-ray crystal structure and physical properties of these new compounds are presented.     

Optical,mechanical, and electrical studies of polymer composites based on charge transfer complex of phenothiazine–iodine with poly(vinyl chloride)

Charge transfer complex (CTC) of phenothiazine and iodine (1:2 molar ratio) was prepared by solvent evaporation method in diethyl ether and its composite with poly(vinyl chloride) was prepared in benzene by diffusion method. Infra-red spectra showed overlapped peaks for both components and intensity of individual component was proportional to feed ratio. Optical photographs and scanning electron microscopy of composites showed template growth and connectivity in insulator matrix was proportional to wt% of CTC. Mechanical strength of composites was found to increase with wt% of PVC. The current–voltage study showed percolation threshold of 8 wt% of CTC. The temperature dependence of conductivity showed semiconducting nature of the materials. Transport property of charges were explained by regression analysis of σ_dc vs. T^?1/1+n data and meets the basis for the Mott's 2D, 3D variable range hopping or thermoionic emission model, depending on temperature and wt% of CTC content. The impedance spectroscopy was performed between 40 Hz–100 kHz range. Circuit elements consists only combination of resistance and capacitance, which showed homogeneous nature of composites. Thermoelectric factor ‘S’ was also evaluated and has value of <1 at 303 K in all cases.     

Novel hexakis (alkylthio) benzene with C3 symmetry: Synthesis,crystal structure and physical properties of a tris-(ethylenedithio) benzene salt : (TEDTB)2BF4

We have synthesized a new hexakis (alkylthio) benzene possessing C₃ symmetry. From this tris-(ethylenedithio) benzene (TEDTB), a radical cation fluoroborate salt of 2.1 stoichiometry, has been prepared and investigated. The room temperature crystal structure shows that this salt crystallizes in an orthorhombic system and presents segregated dimerized stacks of TEDTB. The electric properties exhibit a semiconducting behaviour around room temperature, while low-temperature characteristics need further investigation. We believe that the TEDTB molecule is indicative of a potentially exciting series of donor molecules.     

Two Cd(II) coordination polymers based on asymmetrical Schiff-base ligand with five- and six-membered N-containing heterocyclic rings: Synthesis,crystal structures and luminescent properties

Two cadmium inorganic–organic hybrid coordination polymers [CdL(SCN)₂]_n (1) and [CdLI₂]_n (2), have been synthesized and characterized by IR spectroscopy, elemental analysis, XRPD, thermogravimetric (TG) analyses and X-ray crystallography, where L is 4-(pyridine-4-yl)methyleneamino-1,2,4-triazole. Asymmetrical Schiff-base ligand L acts as a bidentate bridging ligand to bind two Cd(II) centers through two terminal N_triazolyl and N_pyridyl donors in polymers 1 and 2. Polymer 1 displays a new 3D inorganic–organic hybrid network generated through the coordination interactions between Cd-(1,3-μ-SCN⁻) 2D inorganic sheets and bidentate bridging ligands. The structure of polymer 2 is a 3D chiral supramolecular framework which contains helical chains on 2₁ axis. Each Cd(II) center is coordinated by two ligands and two I⁻ donors to attain a distorted tetrahedral environment. The luminescent properties of polymers 1 and 2 were investigated in the solid state at room temperature.     

Synthesis,X-ray structure and luminescent properties of a new 1D terbium(III) coordination polymer based on 2,4-dichlorophenoxyacetate and 4,4′-bipyridine

A new 1D terbium coordination polymer, {[Tb(2,4-dcpa)₃(H₂O)₂]·(4,4′-bpy)_1.5(H₂O)₂}_n (1) [2,4,-dcpa = 2,4-dichlorophenoxyacetate, 4,4′-bpy = 4,4′-bipyridine], was prepared by hydrothermal synthesis and characterized by IR spectroscopy, elemental analysis, thermogravimetric analysis (TGA) and single-crystal X-ray diffraction. Complex 1 exhibits an infinite chain structure with a {Tb₂(2,4-dcpa)₆(H₂O)₄} dimeric repeat unit. Each Tb³⁺ ion is nine-coordinated to two water molecules, one monodentate carboxylate group and four bridging carboxylate groups in which the carboxylate groups are bonded to the terbium ion in one modes: the chelating–bridging tridentate. Three-dimensional fluorescence spectra of 1 were detected at room temperature under the excitation and the emission wavelengths in the range of 420–750 nm with the interval of 5 nm. The lifetime of 1 in solid-state at room temperature up to 1.132 ms. On the other hand, poor luminescence efficiency has been noted for the Tb³⁺-2,4-dcpa complex.