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1.
A series of 4‐X‐1‐methylpyridinium cationic nonlinear optical (NLO) chromophores (X=(E)‐CH?CHC6H5; (E)‐CH?CHC6H4‐4′‐C(CH3)3; (E)‐CH?CHC6H4‐4′‐N(CH3)2; (E)‐CH?CHC6H4‐4′‐N(C4H9)2; (E,E)‐(CH?CH)2C6H4‐4′‐N(CH3)2) with various organic (CF3SO3?, p‐CH3C6H4SO3?), inorganic (I?, ClO4?, SCN?, [Hg2I6]2?) and organometallic (cis‐[Ir(CO)2I2]?) counter anions are studied with the aim of investigating the role of ion pairing and of ionic dissociation or aggregation of ion pairs in controlling their second‐order NLO response in anhydrous chloroform solution. The combined use of electronic absorption spectra, conductimetric measurements and pulsed field gradient spin echo (PGSE) NMR experiments show that the second‐order NLO response, investigated by the electric‐field‐induced second harmonic generation (EFISH) technique, of the salts of the cationic NLO chromophores strongly depends upon the nature of the counter anion and concentration. The ion pairs are the major species at concentration around 10?3 M , and their dipole moments were determined. Generally, below 5×10?4 M , ion pairs start to dissociate into ions with parallel increase of the second‐order NLO response, due to the increased concentration of purely cationic NLO chromophores with improved NLO response. At concentration higher than 10?3 M , some multipolar aggregates, probably of H type, are formed, with parallel slight decrease of the second‐order NLO response. Ion pairing is dependent upon the nature of the counter anion and on the electronic structure of the cationic NLO chromophore. It is very strong for the thiocyanate anion in particular and, albeit to a lesser extent, for the sulfonated anions. The latter show increased tendency to self‐aggregate.  相似文献   

2.
Naphthalene diimide copolymers are attractive n‐type materials due to their high electron affinities, high electron mobilities, and exceptional stability. Herein, we report a series of NDI‐fused‐thiophene based copolymers with each copolymer differing in the number of fused thiophenes in the donor monomer. Increasing the number of fused‐thiophene moieties within an NDI‐copolymer backbone is shown to not only enable tuning of the electronic structure but also improve charge mobilities within the active layer of organic field‐effect transistors. Electron mobilities and on/off ratios as high as 0.012 cm2 V?1 s‐1 and Ion/Ioff > 105 were measured from n‐channel thin‐film transistors fabricated using NDI‐xfTh copolymers. Bulk heterojunction solar cell devices were also fabricated from the NDI‐xfTh copolymer series in blends with poly(3‐hexylthiophene) (P3HT) with PNDI‐4fTh ‐ based devices yielding the largest Jsc (0.57 mA cm?2) and fill factor (55%) in addition to the highest measured PCE for this series (0.13%). © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 4061–4069  相似文献   

3.
The title compound, {(C9H14N)4[Pb3I10]}n, crystallizes as an organic–inorganic hybrid. As such, the structure consists of a two‐dimensional inorganic layer of [Pb3I10]n4n ions extending along [100]. The asymmetric unit contains two independent Pb atoms, viz. one in a general position and the other on an inversion centre. Each Pb atom is octa­hedrally coordinated by six iodide ions and exhibits both face‐ and corner‐sharing with adjacent atoms in the inorganic layer. These anionic layers alternate with 3‐phenyl­propyl­ammonium cations, which hydrogen bond to the iodides. Simple face‐to‐edge σ–π stacking inter­actions are observed between the aromatic rings that stabilize the overall three‐dimensional structure. This net structure has only been observed five times previously.  相似文献   

4.
We report the synthesis, characterization, redox behavior, and n‐channel organic field‐effect (OFET) characteristics of a new class of thieno[3,2‐b]thiophene‐diketopyrrolopyrrole‐based quinoidal small molecules 3 and 4 . Under ambient atmosphere, solution‐processed thin‐film transistors based on 3 and 4 exhibit maximum electron mobilities up to 0.22 and 0.16 cm2 V?1 s?1, respectively, with on‐off current ratios (Ion/Ioff) of more than than 106. Cyclic voltammetry analysis showed that this class of quinoidal derivatives exhibited excellent reversible two‐stage reduction behavior. This property was further investigated by a stepwise reductive titration of 4 , in which sequential reduction to the radical anion and then the dianion were observed.  相似文献   

5.
Sterically unprotected thiophene/phenylene co‐oligomer radical cation salts BPnT.+[Al(ORF)4]? (ORF=OC(CF3)3, n=1–3) have been successfully synthesized. These newly synthesized salts have been characterized by UV/Vis‐NIR absorption and EPR spectroscopy, and single‐crystal X‐ray diffraction analysis. Their conductivity increases with chain length. The formed meso‐helical stacking by cross‐overlapping radical cations of BP2T.+ is distinct from previously reported face‐to‐face overlaps of sterically protected (co‐)oligomer radical cations.  相似文献   

6.
Low‐cost quantum‐dot sensitized solar cells (QDSSCs) were fabricated by using the earth‐abundant element SnS quantum dot, novel TiC counter electrodes, and the organic disulfide/thiolate (T2/T?) redox couple, and reached an efficiency of 1.03 %. QDSSCs based on I?/I3?, T2/T?, and S2?/Sx2? redox couples were assembled to study the role of the redox couples in the regeneration of sensitizers. Charge‐extraction results reveal the reasons for the difference in JSC in three QDSSCs based on I?/I3?, T2/T?, and S2?/Sx2? redox couples. The catalytic selectivity of TiC and Pt towards T2/T? and I?/I3? redox couples was investigated using Tafel polarization and electrochemical impedance analysis. These results indicated that Pt and TiC show a similar catalytic selectivity for I?/I3?. However, TiC possesses better catalytic activity for T2/T? than for I?/I3?. These results indicate the great potential of transition metal carbide materials and organic redox couples used in QDSSCs.  相似文献   

7.
Although the understanding of intermolecular interactions, such as hydrogen bonding, is relatively well‐developed, many additional weak interactions work both in tandem and competitively to stabilize a given crystal structure. Due to a wide array of potential applications, a substantial effort has been invested in understanding the halogen bond. Here, we explore the utility of multinuclear (13C, 14/15N, 19F, and 127I) solid‐state magnetic resonance experiments in characterizing the electronic and structural changes which take place upon the formation of five halogen‐bonded co‐crystalline product materials. Single‐crystal X‐ray diffraction (XRD) structures of three novel co‐crystals which exhibit a 1:1 stoichiometry between decamethonium diiodide (i.e., [(CH3)3N+(CH2)10N+(CH3)3][2 I?]) and different para‐dihalogen‐substituted benzene moieties (i.e., p‐C6X2Y4, X=Br, I; Y=H, F) are presented. 13C and 15N NMR experiments carried out on these and related systems validate sample purity, but also serve as indirect probes of the formation of a halogen bond in the co‐crystal complexes in the solid state. Long‐range changes in the electronic environment, which manifest through changes in the electric field gradient (EFG) tensor, are quantitatively measured using 14N NMR spectroscopy, with a systematic decrease in the 14N quadrupolar coupling constant (CQ) observed upon halogen bond formation. Attempts at 127I solid‐state NMR spectroscopy experiments are presented and variable‐temperature 19F NMR experiments are used to distinguish between dynamic and static disorder in selected product materials, which could not be conclusively established using solely XRD. Quantum chemical calculations using the gauge‐including projector augmented‐wave (GIPAW) or relativistic zeroth‐order regular approximation (ZORA) density functional theory (DFT) approaches complement the experimental NMR measurements and provide theoretical corroboration for the changes in NMR parameters observed upon the formation of a halogen bond.  相似文献   

8.
In order to interpret well whether or not the organic or polymer interfacial layer is effective on performance of the conventional Au/n‐Si (metal semiconductor [MS]) type Schottky barrier diodes (SBDs), in respect to ideality factor (n ), leakage current, rectifying rate (RR ), series and shunt resistances (Rs , Rsh ) and surface states (Nss ) at room temperature, both Au/biphenyl‐CoPc/n‐Si (MPS1) and Au/OHSubs‐ZnPc/n‐Si (MPS2) type SBDs were fabricated. The electrical characteristics of these devices have been investigated and compared by using forward and reverse bias current–voltage (I–V ) characteristics in the voltage range of (?4 V)–(4 V) for with and without (biphenyl‐CoPc) and (OHSubs‐ZnPc) interfacial layers at room temperature. The main electrical parameters of these diodes such as reverse saturation current (I0 ), ideality factor (n ), zero‐bias barrier height (ΦB0 ), RR , Rs and Rsh were found as 1.14 × 10?5 A, 5.8, 0.6 eV, 362, 44 Ω and 15.9 kΩ for reference sample (MS), 7.05 × 10?10 A, 3.8, 0.84 eV, 2360, 115 Ω and 270 kΩ for MPS1 and 2.16 × 10?7 A, 4.8, 0.7 eV, 3903, 62 Ω and 242 kΩ for MPS2, respectively. It is clear that all of these parameters considerably change by using an organic interfacial layer. The energy density distribution profile of Nss was found for each sample by taking into account the voltage dependence of effective barrier height (Φe ) and ideality factor, and they were compared. Experimental results confirmed that the use of biphenyl‐CoPc and OHSubs‐ZnPc interfacial layer has led to an important increase in the performance of the conventional of MS type SBD. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

9.
The structure of the title compound, poly[[[μ3N′‐(3‐cyanobenzylidene)nicotinohydrazide]silver(I)] hexafluoroarsenate], {[Ag(C14H10N4O)](AsF6)}n, at 173 K exhibits a novel stair‐like two‐dimensional layer and a three‐dimensional supramolecular framework through C—H...Ag hydrogen bonds. The AgI cation is coordinated by three N atoms and one O atom from N′‐(3‐cyanobenzylidene)nicotinohydrazide (L) ligands, resulting in a distorted tetrahedral coordination geometry. The organic ligand acts as a μ3‐bridging ligand through the pyridyl and carbonitrile N atoms and deviates from planarity in order to adapt to the coordination geometry. Two ligands bridge two AgI cations to construct a small 2+2 Ag2L2 ring. Four ligands bridge one AgI cation from each of four of these small rings to form a large grid. An interesting stair‐like two‐dimensional (3,6)‐net is formed through AgI metal centres acting as three‐connection nodes and through L molecules as tri‐linkage spacers.  相似文献   

10.
Black crystals of [Rb(crypt‐2,2,2)]4(I5)2(I8) were obtained from a dichloromethane/ethanol solution of RbI, I2 and Kryptofix‐2,2,2®. The crystal structure (monoclinic, P21/c (no. 14), a = 1250.1(1), b = 2555.2(2), c = 2313.4(3) pm, β = 121.45(1)°, V = 6309.9(11)·106 pm3, Z = 2) consists of [Rb(crypt‐2,2,2)]+ cations leaving three‐dimensional channels for the V‐shaped (I5)? and Z‐shaped (I8)2? anions which are isolated from each other.  相似文献   

11.
Ti/MCM‐41 is a well‐known heterogeneous catalyst for alkene epoxidation with organic peroxides. This titanosilicate contains isolated titanium atoms forming part of a framework of mesoporous silica whose structure is formed by parallel hexagonal channels 3.2 nm in diameter. The surface area and porosity of Ti/MCM‐41 are about 880 m2 g?1 and 0.70 cm3 g?1, respectively. These values are among the highest for any material. Herein, we show that Ti/MCM‐41 exhibits photovoltaic activity. Dye‐sensitized solar cells using mesoporous Ti/MCM‐41 (2.8–5.7 % Ti content) as active layer, black dye N3 as photosensitizer and I3?/I? in methoxyacetonitrile as electrolyte exhibit a VOC, JSC and FF of 0.44 V, 0.045 mA cm?2 and 0.33, respectively. These values compare well against 0.75 V, 4.1 mA cm?2 and 0.64, respectively, measured for analogous solar cells using conventional P‐25 TiO2. However, the specific current density (JSC/Ti atom) for the Ti/MCM‐41 is very similar to that of P25 TiO2.  相似文献   

12.
In pH 3.8 acetic acid‐sodium acetate (HAC‐NaAC) buffer solution, laccase exhibited a strong catalytic effect on the H2O2 oxidation of I ? to form I2, and I2 combined with excess I ? to form I3? that reacted with cationic surfactants of tetradecyl dimethylbenzyl ammonium chloride (TDMAC) to produce the (TDMAC‐I3)n association complex particles, which exhibited a strong resonance scattering (RS) peak at 468 nm. Under the chosen conditions, as the concentration of laccase activity increased, the RS intensity at 468 nm (I468 nm) increased linearly. The increased RS intensity ΔI468 nm was linear to laccase activity in the range of 0.08–0.96 U/mL, with a regression equation of ΔI468 nm?88.8U?1.9, and a detection limit of 0.02 U/mL laccase. This proposed method was applied to detect laccase activity in waste water, with satisfactory results.  相似文献   

13.
Poly‐p‐phenylenebenzobisoxazole (PBO) contains a fully conjugated rod‐like backbone entailing excellent optoelectronic properties and superior stabilities. Poly(2,3‐dihydrothieno‐1,4‐dioxin):polystyrenesulfonate (PEDOT:PSS) is a hole transferring medium, which was spun into a thin‐film between PBO and indium‐tin‐oxide to facilitate photovoltaic (PV) effect by forming a donor‐acceptor interlayer to separate and to transport photoinduced charges. Optimum PBO thickness for PV heterojunctions was about 71 nm at which the hole transferring PEDOT:PSS generated the maximum short circuit current (Isc) at a thickness of 115 nm. By using a layer of lithium fluoride (LiF) as an electron transferring layer adhering to Al cathode, the most open circuit voltage (Voc) and Isc were achieved with a LiF thickness of 1–2 nm because of possible electric dipole effect leading to an increase of Voc from 0.7 to 0.92 V and of Isc from about 0.1 to 0.2 μA. No PV response was observed for all PBO homojunctions because of insufficient exciton separation into electrons and holes. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 988–993, 2007  相似文献   

14.
Halide anion‐doped bismuth terephthalate hybrids were synthesized using a facile solvothermal method. Four series of hybrids doped with halide anions X? (F?, Cl?, Br? and I?) were produced by varying the molar ratios (n) of X? relative to Bi(NO3)3 (n = 0.25, 0.5, 0.75 and 1) in dimethylformamide solution. The results indicated that 0.25 equiv. of different halide anion‐doped bismuth terephthalate hybrids, especially BiBDC‐Cl(0.25) and BiBDC‐Br(0.25), exhibited excellent photocatalytic activity under visible light and UV light irradiation. They also exhibited excellent adsorption performance for Rhodamine B which could be attributed to high surface areas and negative charge on the surface of the catalysts. Moreover, the degradation of Rhodamine B under visible light irradiation is a photosensitization process and ?O2? is the most important active species. The halide anion‐doped bismuth terephthalate hybrids are promising photocatalysts for removal of organic pollutants. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

15.
A new two‐photon material, 3E,6E‐bis(2‐pyrid‐4′‐ylvinyl)dibenzothiophene (BPVDBT), has been firstly synthesized by an efficient Pd‐catalyzed Heck coupling route. The single‐ and two‐photon fluorescence, quantum yields, lifetimes, solvent effects of the chromophore were studied in detail and the compound exhibited solvent‐sensitivity. The fluorescence intensity (Iout) and input excitation intensity (Iin) can fit in well with the quadratic parabolas, which indicates that the up‐converted fluorescence was induced by the two‐photon absorption (TPA). TPA cross‐section of BPVDBT has been measured using the two‐photon‐induced fluorescence method, whose value is 14.24×10?50 cm4·s·photon?1·molecule?1 at 750 nm. The experimental results confirm that BPVDBT is a good two‐photon absorbing chromophore with an A‐π‐A type.  相似文献   

16.
Two of the title compounds, namely (E)‐1,2‐bis­(1‐methyl­benzimidazol‐2‐yl)ethene, C18H16N4, (Ib), and (E)‐1,2‐bis­(1‐ethyl­benzimidazol‐2‐yl)ethene, C20H20N4, (Ic), consist of centrosymmetric trans‐bis­(1‐alkyl­benzimidazol‐2‐yl)ethene mol­ecules, while 3‐eth­yl‐2‐[(E)‐2‐(1‐ethyl­benzimidazol‐2‐yl)­ethen­yl]benzimidazol‐1‐ium perchlorate, C20H21N4+·ClO4, (II), contains the monoprotonated analogue of compound (Ic). In the three structures, the benzimidazole and benzimidazolium moieties are essentially planar; the geometric parameters for the ethene linkages and their bonds to the aromatic groups are consistent with double and single bonds, respectively, implying little, if any, conjugation of the central C=C bonds with the nitro­gen‐containing rings. The C—N bond lengths in the N=C—N part of the benzimidazole groups differ and are consistent with localized imine C=N and amine C—N linkages in (Ib) and (Ic); in contrast, the corresponding distances in the benzimidazolium cation are equal in (II), consistent with electron delocalization resulting from protonation of the amine N atom. Crystals of (Ib) and (Ic) contain columns of parallel mol­ecules, which are linked by edge‐over‐edge C—H⋯π overlap. The columns are linked to one another by C—H⋯π inter­actions and, in the case of (Ib), C—H⋯N hydrogen bonds. Crystals of (II) contain layers of monocations linked by π–π inter­actions and separated by both perchlorate anions and the protruding eth­yl groups; the cations and anions are linked by N—H⋯O hydrogen bonds.  相似文献   

17.
Low‐layered, transparent graphene is accessible by a chemical vapor deposition (CVD) technique on a Ni‐catalyst layer, which is deposited on a <100> silicon substrate. The number of graphene layers on the substrate is controlled by the grain boundaries in the Ni‐catalyst layer and can be studied by micro Raman analysis. Electrical studies showed a sheet resistance (Rsheet) of approximately 1435 Ω per □, a contact resistance (Rc) of about 127 Ω, and a specific contact resistance (Rsc) of approximately 2.8×10?4 Ω cm2 for the CVD graphene samples. Transistor output characteristics for the graphene sample demonstrated linear current/voltage behavior. A current versus voltage (IdsVds) plot clearly indicates a p‐conducting characteristic of the synthesized graphene. Gas‐sensor measurements revealed a high sensor activity of the low‐layer graphene material towards H2 and CO. At 300 °C, a sensor response of approximately 29 towards low H2 concentrations (1 vol %) was observed, which is by a factor of four higher than recently reported.  相似文献   

18.
A new benzodithiophene (BDT)‐based polymer, poly(4,8‐bis(2‐ethylhexyloxy)benzo[1,2‐b:4,5‐b′]dithiophene vinylene) (PBDTV), was synthesized by Pd‐catalyzed Stille‐coupling method. The polymer is soluble in common organic solvents and possesses high thermal stability. PBDTV film shows a broad absorption band covering from 350 nm to 618 nm, strong photoluminescence peaked at 545 nm and high hole mobility of 4.84 × 10?3 cm2/Vs. Photovoltaic properties of PBDTV were studied by fabricating the polymer solar cells based on PBDTV as donor and PC70BM as acceptor. With the weight ratio of PBDTV: PC70BM of 1:4 and the active layer thickness of 65 nm, the power conversion efficiency of the device reached 2.63% with Voc = 0.71 V, Isc = 6.46 mA/cm2, and FF = 0.57 under the illumination of AM1.5, 100 mW/cm2. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1822–1829, 2010  相似文献   

19.
A novel silicon‐based compound, 10‐phenyl‐2′‐(triphenylsilyl)‐10H‐spiro[acridine‐9,9′‐fluorene] (SSTF), with spiro structure has been designed, synthesized, and characterized. Its thermal, electronic absorption, and photoluminescence properties were studied. Its energy levels make it suitable as a host material or exciton‐blocking material in blue phosphorescent organic light‐emitting diodes (PhOLEDs). Accordingly, blue‐emitting devices with iridium(III) bis[(4,6‐difluorophenyl)‐pyridinato‐N,C2′]picolinate (FIrpic) as phosphorescent dopant have been fabricated and show high efficiency with low roll‐off. In particular, 44.0 cd A?1 (41.3 lm W?1) at 100 cd m?2 and 41.9 cd A?1 (32.9 lm W?1) at 1000 cd m?2 were achieved when SSTF was used as host material; 28.1 lm W?1 at 100 cd m?2 and 20.6 lm W?1 at 1000 cd m?2 were achieved when SSTF was used as exciton‐blocking layer. All of the results are superior to those of the reference devices and show the potential applicability and versatility of SSTF in blue PhOLEDs.  相似文献   

20.
Poly[aniline(AN)‐co‐5‐sulfo‐2‐anisidine(SA)] nanograins with rough and porous structure demonstrate ultrastrong adsorption and highly efficient recovery of silver ions. The effects of five key factors—AN/SA ratio, AgI concentration, sorption time, ultrasonic treatment, and coexisting ions—on AgI adsorbability were optimized, and AN/SA (50/50) copolymer nanograins were found to exhibit much stronger AgI adsorption than polyaniline and all other reported sorbents. The maximal AgI sorption capacity of up to 2034 mg g?1 (18.86 mmol g?1) is the highest thus far and also much higher than the maximal Hg‐ion sorption capacity (10.28 mmol g?1). Especially at ≤2 mM AgI, the nanosorbents exhibit ≥99.98 % adsorptivity, and thus achieve almost complete AgI sorption. The sorption fits the Langmuir isotherm well and follows pseudo‐second‐order kinetics. Studies by IR, UV/Vis, X‐ray diffraction, polarizing microscopy, centrifugation, thermogravimetry, and conductivity techniques showed that AgI sorption occurs by a redox mechanism mainly involving reduction of AgI to separable silver nanocrystals, chelation between AgI and ? NH? /? N?/? NH2/ ? SO3H/? OCH3, and ion exchange between AgI and H+ on ? SO3?H+. Competitive sorption of AgI with coexisting Hg, Pb, Cu, Fe, Al, K, and Na ions was systematically investigated. In particular, the copolymer nanoparticles bearing many functional groups on their rough and porous surface can be directly used to recover and separate precious silver nanocrystals from practical AgI wastewaters containing Fe, Al, K, and Na ions from Kodak Studio. The nanograins have great application potential in the noble metals industry, resource reuse, wastewater treatment, and functional hybrid nanocomposites.  相似文献   

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