Anthracene Molecules Research Articles

Enhanced photoluminescence emission from anthracene-doped polyphenylsiloxane glass

Anthracene-doped polyphenylsiloxane (PPS) glass containing silver nanoparticles (AgNPs) of appropriate size was synthesized in a form of solid thin films for modifying light emission characteristics. The photoluminescence (PL) emission from the anthracene molecules at ~2.95 eV was resonantly coupled to the localized surface plasmon (LSP) polariton modes that were induced by the excitation of ~30 nm sized AgNPs. The increase in absorption of incident photons within a highly scattering medium, energy transfer from the localized excitons to the LSP modes, and the electrostatic Coulomb effects of the excitons in the presence of metal NPs all resulted in a significant enhancement of PL emission. The PL enhancement is dependent on the concentration of the anthracene molecules. The integrated PL intensity enhancement at the optimum concentration of anthracene molecules in the PPS glass with AgNPs is found to exceed 50.

CHARGE STABILITY AND CONDUCTANCE ANALYSIS OF ANTHRACENE-BASED SINGLE ELECTRON TRANSISTOR

The present paper discusses the investigation of electronic properties of anthracene-based single electron transistor (SET) operating in coulomb blockade region using Density Functional Theory (DFT) based Atomistix toolkit-Virtual nanolab. The charging energies of anthracene molecule in isolated as well as electrostatic SET environments have been calculated for analyzing the stability of the molecule for different charge states. Study also includes the analysis of SET conductance dependence on source/drain and gate potentials in reference to the charge stability diagram. Our computed charging energies for anthracene in isolated environment are in good agreement with the experimental values and the proposed anthracene SET shows good switching properties in comparison to other acene series SETs.

Photo-induced crosslinking and thermal de-crosslinking in polynorbornenes bearing pendant anthracene groups

Functional polynorbornenes bearing anthracene molecules in their side chain were synthesized by ring opening methathesis polymerization (ROMP). The pendant anthracene molecules undergo a [4π+4π] cycloaddition upon irradiation with UV-light, which was studied by means of UV–Vis spectroscopy in thin films of these polymers. This photodimerization reaction also leads to a crosslinking of the macromolecules due to the photodimer formation, resulting in a decrease in solubility of the UV illuminated areas. A thermally induced de-crosslinking could be obtained, revealing the reversibility of this photoreaction. The influence of the flexibility of the macromolecules, i.e. the mobility of the anthracene groups in the polymeric material, on the conversion rate, reversibility and the crosslinking behavior was studied by means of spectroscopy and sol–gel analysis. Furthermore, photo-patterned films were obtained by structured illumination and subsequent development with dichloromethane revealing a negative resist behavior.

Luminescence of Rubrene and DCJTB molecules in organic light-emitting devices

We investigated the optical properties of light emission based on the resonance energy transfer mechanism between two molecules in the host–dopant systems. For this purpose, we fabricated the organic light-emitting devices with the different doped emissive layers. The host matrices were made of 4,4′,4″-tris(carbasol-l-nyl)triphenylamine (TCTA) and 2-methyl-9,10-di(2-naphthyl)anthracene (MADN) molecules and the doped molecules were 5,6,11,12-tetraphenylnaphtacene (Rubrene) and 4-(Dicyanomethylene)-2-tert-butyl-6-(1,1,7,7-tetramethyljulolidin-4-yl-vinyl)-4H-pyran (DCJTB). The concentrations of the doped molecules were 0.1%, 0.3%, 0.5%, and 0.8%. Through spectroscopic analysis using multi-peak fits with a Gaussian function to the emission spectra, we obtained the relative light intensity of the two dopants according to the doping concentrations and examined the relations between the molecular excited energy states and the nature of energy transfer in the host and dopant systems. We show that the luminous efficiency of the devices has a strong correlation between the energy transfer owing to the individual molecular intrinsic properties and the electrical characteristics associated with the bulky properties in the devices.

The Design of UV Absorbing Systems for Horticultural Applications

The synthesis and fluorescence behavior of a series of bis(trisilylalkyl)anthracene molecules is described. The photodegradation of these molecules under UV light has been monitored and compared to a commercially available fluorescent optical brightener. There is a relationship between the structure and the rate of photo decay. The materials with more bulky substituents exhibit the greater stability towards UV. For bis(triphenylsilyl)anthracene the photostability appears to be comparable with a commercially available optical brightener, but the molecule may be susceptible to thermal decay.

Energy transfer induced enhancement of localized exciton emission in ZnO nanoparticle–anthracene hybrid films

AbstractOptically transparent and high‐quality hybrid ZnO nanoparticle and anthracene embedded polyphenylsiloxane (PPS) glass films were spin‐coated on quartz substrates. A strong Förster resonant energy transfer (FRET) process was indicated by the observation of quenching of the ZnO emission and an enhancement of the anthracene emission at room temperature. The efficiency of this energy transfer between ZnO and the S1 vibronic states of the anthracene molecules can be optimized to exceed 90%.magnified imageVisible emission from anthracene only, ZnO only, and the ZnO/anthracene hybrid. The anthracene emission is visibly more intense in the presence of ZnO.(© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Carbon-supported Pd nanoparticles as catalysts for anthracene hydrogenation

The catalytic activity of carbon-supported Pd nanoparticles (NPs) was investigated in the hydrogenation of anthracene at different temperatures and reaction times. These nanocatalysts were prepared by direct reduction of a palladium precursor impregnated on the carbon support. Small spherical and homogenously dispersed Pd NPs were thus achieved. Nanocatalyst performance was evaluated as a function of surface properties, including porosity, defects and Pd NPs population. High conversions and selectivities towards the hydrogenated products without cracking or ring-opening products were achieved. The selectivity of the nanocatalysts to the production of hydrogenated species depended on temperature, reaching a maximum at 300°C. At this temperature and short reaction time, the catalytic activity is thought to have been favored by the presence of a large amount of surface defects in the nanocatalysts that can promote hydrogen transfer to the anthracene molecule. On the other hand, at longer reaction times the porosity and density of Pd nanoparticles on the catalyst were the factors behind the deeper hydrogenation achieved. Finally, a plausible reaction pathway for anthracene hydrogenation in the presence of these Pd nanocatalysts was proposed.

Exohedral functionalization of C60 by [4+2] cycloaddition of multiple anthracenes

By using density functional theory, we have investigated [4+2] cycloaddition of one to four anthracene (ANT) molecules to a C60 fullerene which has been already studied by experimentalists. It was found that the reaction is regioselective and the ANT molecule prefers to be adsorbed atop a C–C bond of the C60 which is shared between two hexagons with reaction energy of −25.2 kcal/mol (for one ANT). The HOMO of the ANT interacts with the LUMO of the C60 via a cycloaddition reaction. Also five regioisomeric bis-adducts of ANT/C60 complexes were compared from stand point of stability. Increasing the number of attached ANTs, the reaction energy becomes less negative. The HOMO–LUMO energy gap of C60 is slightly changed and the potential barrier of the field electron emission from its surface may be reduced upon the reaction.

Fragmentation of anthracene induced by collisions with 40 keV Ar8+ ions

We report on the fragmentation of anthracene molecular ions C14H10r+ as a function of the parent ion initial charge r (= 1–4). Neutral anthracene molecules in the gas phase were ionized and excited in collisions with Ar8+ ions at 40 keV and the mass-to-charge spectra of the parent ions C14H10r+ (1 ⩽ r ⩽ 4) were obtained. Stable molecular ions C14H10r+ (1 ⩽ r ⩽ 3) are observed. Branching ratios for the competitive evaporation (loss of neutral fragments) and fragmentation (charge separation) processes were measured for C14H102+ parent ions. For C14H103+ parent ions, the results indicate that fragmentation is the only dominant process and quasi-symmetric fission is observed.

Effect of Doping (2_Methyl Naphthalene) on Aromatic System (2_Methyl Naphthalene-Anthracene)

In this work, study of absorption and fluorescence spectra for compound (anthracene genitive 2 - methyl naphthalene) dissolved in a polar solvent. The calculated value of the quantity and efficiency found that it increases with ratio doping , and after less than quantity when you reduce the efficiency ratio doping anthracene molecule by molecule 2-methyl naphthalene. Used a diluted concentration to the purpose of minimizing the phenomenon of self-absorption, Calculated the value of the quantity in relation to efficiency anthracene compound dissolved Daye methyl Slfoxayd, the amount of efficiency (qfm=0.32). As a composite record wavelength irritant λex = 365 nm at room temperature. It turns out from this study the presence of my energies activation molecule anthracene doping different proportions of molecule 2 - methyl naphthalene and each activation energy mechanical connecting different which could be interpreted by relying on the theory of packets semiconductor and which proposes a transition charge carriers from the Fermi donor to the packet delivery in the semiconductor negative (n-type) At high temperatures by thermal Excitation.

Benz[ a ]anthracene Biotransformation and Production of Ring Fission Products by Sphingobium sp. Strain KK22

A soil bacterium, designated strain KK22, was isolated from a phenanthrene enrichment culture of a bacterial consortium that grew on diesel fuel, and it was found to biotransform the persistent environmental pollutant and high-molecular-weight polycyclic aromatic hydrocarbon (PAH) benz[a]anthracene. Nearly complete sequencing of the 16S rRNA gene of strain KK22 and phylogenetic analysis revealed that this organism is a new member of the genus Sphingobium. An 8-day time course study that consisted of whole-culture extractions followed by high-performance liquid chromatography (HPLC) analyses with fluorescence detection showed that 80 to 90% biodegradation of 2.5 mg liter(-1) benz[a]anthracene had occurred. Biodegradation assays where benz[a]anthracene was supplied in crystalline form (100 mg liter(-1)) confirmed biodegradation and showed that strain KK22 cells precultured on glucose were equally capable of benz[a]anthracene biotransformation when precultured on glucose plus phenanthrene. Analyses of organic extracts from benz[a]anthracene biodegradation by liquid chromatography negative electrospray ionization tandem mass spectrometry [LC/ESI(-)-MS/MS] revealed 10 products, including two o-hydroxypolyaromatic acids and two hydroxy-naphthoic acids. 1-Hydroxy-2- and 2-hydroxy-3-naphthoic acids were unambiguously identified, and this indicated that oxidation of the benz[a]anthracene molecule occurred via both the linear kata and angular kata ends of the molecule. Other two- and single-aromatic-ring metabolites were also documented, including 3-(2-carboxyvinyl)naphthalene-2-carboxylic acid and salicylic acid, and the proposed pathways for benz[a]anthracene biotransformation by a bacterium were extended.

Photophysical properties of 2-phenylanthracene and its conformationally-stabilized derivatives

A synthetic route to a series of anthracene derivatives consisting of 2-phenylanthracene and its conformationally-stabilized planar derivatives, containing carbon, oxygen, sulphur and nitrogen atoms, is reported. Thermal, optical and electrical properties of the derivatives featuring an extended π-conjugated electron system were also investigated. Experimental results were supplemented by the energy spectra and molecular orbital calculations performed in the framework of density functional theory. Some of the compounds were found to be molecular glasses with glass transition temperatures from 28 to 55 °C as revealed by differential scanning calorimetry. The anthracene compounds in dilute solutions were found to emit in the 400–500 nm wavelength range with the fluorescence quantum yields varying from 0.22 up to 0.46. The solid films of the anthracene derivatives exhibited slightly narrower emission wavelength-tunability with clearly-expressed excimer emission bands (for the benzothiophene- and indole-anthracene compounds) causing a significant lowering of the fluorescence quantum efficiency down to 0.005. Rigidity of the studied anthracene molecules was assessed by evaluating the Huang-Rhys factor (indicating strength of electron-vibrational coupling) from the vibronic profile of the fluorescence spectra, which indicated that the cyclized indole- and benzofuran-anthracenes possess the most rigid molecular structures as opposed to more flexible structures of 2-phenylanthracene and indeno-anthracene. Wet-casted films of the anthracene compounds demonstrated moderate charge carrier drift mobilities, in the order of 10−5–10−4 cm2/V, which are considered as sufficient for light-emitter applications. Moreover, introduction of additional C, O, S and N atoms into 2-phanylanthracene molecule enabled a tuning of the HOMO level from 4.9 up to 5.74 eV, which is crucial for the optimization of hole injection into the active layers, and thus for balancing electron and hole currents in light-emitting devices.

Effects of external electric field on the excitation properties of anthracene molecule

The theoretical investigations on the molecular energy levels, energy gaps, and the singlet-singlet electronic excitation properties (such as absorption spectra, excited energy, oscillator strengths) of the anthracene molecule in different external electric field were carried out by employing density functional theory (DFT) and time-dependent density functional theory (TDDFT) method with 6-311G(d, p) basis set. The stable molecular structure in ground state was optimized by DFT. The calculated results show that the absorption bands of anthracene molecule concentrate in ultraviolet region without external electric field, the absorption peak of which corresponds to the S0→S5 transitions with an excitation wavelength of 234.5 nm. The calculated absorption spectra agree well with the experimental data. Moreover, it is noticeable that the effects of the external electric field on optical properties cannot be neglected. The ultraviolet absorption spectra of anthracene molecule show a red shift into the blue-light region with the increases of electric field intensity. At the same time, the energy gaps between LUMO and HOMO for the anthracene molecule decrease with the increase of external electric field intensity. It can be shown that the anthracene molecule is promising as a useful blue-light emitting material through modulating by an electric field.

Accuracy of density functional theory in the prediction of carbon dioxide adsorbent materials

Density functional theory (DFT) has become the computational method of choice for modeling and characterization of carbon dioxide adsorbents, a broad family of materials which at present are urgently sought after for environmental applications. The description of polar carbon dioxide (CO(2)) molecules in low-coordinated environments like surfaces and porous materials, however, may be challenging for local and semi-local DFT approximations. Here, we present a thorough computational study in which the accuracy of DFT methods in describing the interactions of CO(2) with model alkali-earth-metal (AEM, Ca and Li) decorated carbon structures, namely anthracene (C(14)H(10)) molecules, is assessed. We find that gas-adsorption energies and equilibrium structures obtained with standard (i.e. LDA and GGA), hybrid (i.e. PBE0 and B3LYP) and van der Waals exchange-correlation functionals of DFT dramatically differ from the results obtained with second-order Møller-Plesset perturbation theory (MP2), an accurate computational quantum chemistry method. The major disagreements found can be mostly rationalized in terms of electron correlation errors that lead to wrong charge-transfer and electrostatic Coulomb interactions between CO(2) and AEM-decorated anthracene molecules. Nevertheless, we show that when the concentration of AEM atoms in anthracene is tuned to resemble as closely as possible the electronic structure of AEM-decorated graphene (i.e. an extended two-dimensional material), hybrid exchange-correlation DFT and MP2 methods quantitatively provide similar results.

Dynamics of formation of anthracene anions in molecular clouds and protoplanetary atmospheres

Quantum mechanical scattering calculations are carried out for gas-phase molecules of anthracene, an aromatic system with three condensed aromatic carbon rings, in collision with low-energy electrons. They reveal the presence of various metastable (resonant) anionic states of this prototype species belonging to the larger polycondensed aromatic hydrocarbons deemed to be present in various regions of the interstellar medium. These resonances are analysed in terms of their most likely paths to stabilization into bound anionic molecules or aromatic fragments, while the important role of threshold virtual states is also discussed within the same context.

AROMATIC MOLECULAR JUNCTIONS WITH INERT GASES AS ALLIGATOR CLIPS

In this research paper, we examined the effect of placing the elements of Group 0 as alligator clips with Anthracene molecule binding gold electrodes on the nanometer scale using Extended Huckle Theory (EHT) based semi-empirical model. The electron transport parameters i.e., I-V curves, Conductance-Voltage curves and transmission spectrum were investigated through Anthracene molecule by buffering it between two semi-infinite gold electrodes but via different alligator clips-Helium, Neon, Argon, Krypton, Xenon and Radon, all from Noble gas group or group-0 under finite bias voltages within Keldysh's nonequilibrium green function formalism (NEGF). The simulated results revealed that the Xenon and Radon showed maximum conduction whereas Krypton, Neon, Helium and Argon showed least. The maximum conductance of 0.62G0 and 70.4 μA current was exhibited by Xenon and thus affirmed to be the most optimal alligator clip amongst noble gases at nanometre scale.

Interruption of the inner rotation initiated in isolated electron-driven molecular rotors

An anthracene molecule substituted at the central ring by two aniline moieties able to rotate about the C-N bonds can be considered to be a prototype molecular rotor. Electron attachment into the lowest empty orbitals of this molecule leads to formation of long-lived (microseconds) negative ions. Elimination of a hydrogen molecule from these anions was observed in the gas phase by means of dissociative electron attachment spectroscopy. The experimental findings were interpreted using density functional theory calculations. It was shown that the decay process must be accompanied by formation of a new covalent bond in which one aniline moiety is fixed to the adjacent carbon atom of the anthracene ring. The observed irreversible interruption of the rotational motion could occur in other artificial electron-driven molecular machines provided that suitable atoms approach each other under the rotation.

Molecular-scale bio-sensing using armchair graphene

We evaluate the transport properties performance of armchair graphene nanoribbons (AGNRs) with a bio-molecule assembly as potential molecular-scale biosensors (Anthracene). The bio-molecules are assumed to be absorbed at the edge of an AGNR, and to behave as quasi-1D systems. The transport spectrum and density of states (DOS) are calculated using a single-band tight-binding Hamiltonian representation, and a non-equilibrium Greens function formalism. Doping with boron and nitride atoms and its impact on the transport properties has also been evaluated. Significant changes in transmission and increase in DOS by 200% are observed when the Anthracene molecule is interacting with the AGNR. Boron and Nitrogen doping allow to increase current flows at constant voltage by 50% on average. There results suggest potential significant scope on using AGNRs for bio-devices based on either conductance or electroluminescence.

Aromatic Chromophore-Tethered Schiff Base Ligands and Their Iron(III)/Chromium(III) Salen and Saloph Capped Complexes

Aromatic chromophores; pyrene, phenanthrene, anthracene, naphtalene and benzene-tethered Schiff base ligands and their iron(III)/chromium(III) Salen and Saloph capped complexes have been synthesized. Compounds have been characterized by means of FT-IR Spectroscopy, (1)H-NMR Spectroscopy, Magnetic Susceptibility, Elementel Analsis, TG/DTA measurements. Their fluorescence and absorbance properties have been investigated by Luminescence Spectroscopy and UV-vis Spectroscopy. Generally, ligands show an intense excimer fluorescence emissions in acetonitrile-methanol medium while iron(III) and chromium(III) complexes exhibit low fluorescence's. Intensity compared to ligands iron and chromium centers act as an extra chromophore that quench the pyrene, phenanthrene, anthracene, naphtalene and benzene molecules' singlet state. The mechanism of quenching is attributed to a iron (or chromium)-to-pyrene (or phenanthrene, anthracene, naphtalene and benzene) electronic energy transfer process.

Special Issue: Organic Materials for Electronics

The seminal 1986 paper by Prof. Ching Tang describing organic photocells and the subsequent paper published in 1987 describing organic solar cells were published during the days when most scientists considered organic materials to be not worth the effort. Even the report of polymer transistors in 1988 and polymer LEDs in 1990, by Friend’s group, didn’t make much impact on the perception of the general scientific community. Over the following decade a relatively small group of “fanatics”, most of which being chemists and physicists and a few engineers, devoted their efforts to developing materials and devices that would be good enough to convince more scientists and engineers to join the game. This state of mind may explain why for a long time there were seemingly two cults, one working on small molecules and the other on polymers. As it turned out, the companies that were manufacturing small molecules had a more open view, and it was significantly easier for newcomers to the field to work on small molecules rather than on polymers. The literature concerning engineering of new materials combinations, electrodes, and device structures in the context of small molecules was hence vastly larger compared to that emanating in the context of polymers, a fact that may explain why small-molecule displays have always been one step ahead. Nowadays it doesn’t take a fanatic to work on organic or plastic electronics. There are even some indications for devices made of both polymers and small molecules, but most importantly the field is now diversifying into many directions limited only by the imagination of the scientists involved. This special issue celebrating Professor Ching Tang being awarded the Wolf Prize illustrates a few aspects of this fast evolving field. We have solar cells utilizing indigo which is a natural dye reported to be used as a dying color already in the 13th century, novel PIN diodes based on new materials derived from the good old anthracene molecule, utilization of nature’s expertise in creating organized structures (as in proteins) to induce order in organic electronic materials, and adding metal oxides to the materials’ toolbox to enhance overall performance. The promising field of spintronics or magneto resistance is an example of organics making an impact in areas that were not touched by the community a decade ago. New materials and applications can only make real progress if self-consistent and rigorous tools are developed and/or adapted to this new class of materials/devices, and impedance spectroscopy is a true example of that. Congratulation Ching, 1 Nir Tessler Technion-Israel Institute of Technology Guest Editor