Tetracene Research Articles

New promising class of anode materials for Ca-ion battery: polyaromatic hydrocarbons

Using first-principles calculations we propose new anode materials for calcium-ion batteries, namely anthracene (AN), tetracene (TN) and pentacene (PN) crystals. We show that adsorption of calcium atoms on isolated AN, TN and PN molecules is energetically favorable, as well as intercalation into bulk crystals in a wide range of calcium concentrations. For all crystals, volume expansion during intercalation is less than 20% and for pentacene, it is less than 8%. We assess the diffusion and electronic properties of AN, TN and PN. We show that calcium diffusion barriers along the polyacene molecules are less than 0.45 eV, but calcium diffusion is limited by “jumps” between the molecules. Sequential band filling upon increasing levels of intercalation leads to the reentrant semiconducting-metallic-semiconducting behavior. Our results point to the promise of anthracene, tetracene, and pentacene as anodes for calcium-ion batteries.

Pore-Confined π-Chromophoric Tetracene as a Visible Light Harvester toward MOF-Based Photocatalytic CO2 Reduction in Water.

Integrating photoactive π-chromophoric guest molecules inside the MOF nanopore can result in the emergence of light-responsive features, which in turn can be utilized for developing photoactive materials with inherent properties of MOF. Herein, we report the confining of π-chromophoric tetracene (TET) molecules inside the nanospace of postmodified Zr-MOF-808 (Zr-MOF) with MBA molecules (MBA = 2-(5'-methyl-[2,2'-bipyridine]-5-yl)acetic acid) for effectively utilizing its light-harvesting properties toward photocatalytic CO2 reduction. The confinement of the TET molecules as a photosensitizer and the covalent grafting of a catalytically active [Re(MBA)(CO)3Cl] complex, postsynthetically, result in a single integrated catalytic system named Zr-MBA-TET-Re-MOF. Photoreduction of CO2 over Zr-MBA-TET-Re-MOF showed the evolution of 805 μmol g-1 CO with 99.9% selectivity after 10 h of continuous visible light irradiation in water without any additional sacrificial electron donor and having the apparent quantum efficiency of 1.3%. In addition, the catalyst demonstrated an appreciable activity even under direct sunlight irradiation in aqueous medium with a maximum production of 362.7 μmol g-1 CO, thereby mimicking artificial photosynthesis. Moreover, electron transfer from TET to the catalytic center was supported by the formation of photoinduced TET radical cation, as inferred from in situ UV-vis spectra, electron paramagnetic resonance (EPR) analysis, and transient absorption (TA) studies. Additionally, the in situ diffuse reflectance infrared Fourier transform (DRIFT) measurements support that the photoreduction of CO2 to CO proceeds via *COOH intermediate formation. The close proximity of the light-harvesting molecule and catalytic center facilitated facile electron transfer from the photosensitizer to the catalyst during the CO2 reduction.

Reversible control of energy transfer efficiency using thermoresponsive volume-phase-transition gel and application to luminescence chromism

For poly-N-isopropylacrylamide (PNIPA) gels with lower critical solution temperatures (LCSTs), a slight temperature shift dramatically changes the water content inside the gel. Unless bonded chemically, hydrophobic molecules—such as polycyclic aromatic hydrocarbons (PAHs)—added to the PNIPA gel aggregate to form a separate phase when the gel is in the swollen state and diffuse into the gel in the dehydrated state. This phenomenon can be leveraged by incorporating PAHs with energy transfer capabilities, such as anthracene (AN) and tetracene (TE), within a PNIPA gel and using the hydration state of the gel to modulate the distance between these molecules. Using this strategy, we were able to promote energy transfer in the aggregated state and suppress it in the dehydrated state of the gel. The emission from the energy-acceptor TE was dominant under accelerated energy transfer conditions, whereas when energy transfer was suppressed, emission from the AN excited species was also observed. The reversible transfer of energy, controlled by water absorption and dehydration, resulted in unprecedented luminescence chromism.

Structure and photophysics of rubrene–tetracene blends

The application potential of singlet fission (SF), describing the spontaneous conversion of an excited singlet into two triplets, underlines the necessity to independently control SF rates, energetics and the optical band gap. Heterofission, whereby the singlet splits into triplets on chemically distinct chromophores, is a promising approach to control the above-mentioned parameters, but its details are not yet fully understood. Here, we investigate the photophysics of blends of two prototypical SF chromophores, tetracene (TET) and rubrene (RUB) using time-resolved photoluminescence spectroscopy and time-correlated single photon counting to explore the potential for heterofission in combinations of endothermic SF chromophores.

Photoelectron spectroscopy of 5,12-diazatetracene

The electronic structure of 5,12-diazatetracene (DAT) has been studied in the gas phase by UV photoelectron spectroscopy and quantum chemical calculations. The comparison of DAT spectrum with the of spectrum tetracene (TC) shows the shift of outermost π-ionizations towards higher ionization energies and the appearance of nitrogen lone pair ionizations in the second and third spectral bands. The difference between nitrogen lone pair ionization energies is smaller in DAT compared to diaza analogues containing up to three fused rings. The implications for semiconductor properties are discussed.

Dimeric conformation sensitive electronic excited states of tetracene congeners and their unconventional non-fluorescent behaviour

Unconventional non-fluorescent J-aggregates of Tetracene (TC) and Naphtho[2,1,8-qra]tetracene (NT) were witnessed and their consequent dramatic quenching was unravelled by a steady state, time-resolved and transient spectroscopy in conjunction with excited state density functional calculations. The TC O-aggregate with slippage angle $$\uptheta = 22.3^{\circ }< 54.7^{\circ }$$ exhibited substantial transition dipole moment (TDM) for both lower (2.79 D) and higher (1.59 D) energy singlet excitations, while, NT formed an ideal J-aggregate (polarization angle, $$\upalpha \sim 0^{\circ })$$ with a predominant TDM to only a lower excitonic state (2.69 D). Subsequently, their unusual quenching was quantified with large drops in the photoluminescence quantum yields (PLQY) from 0.116 to 0.002 upon TC O-aggregation and from 0.478 to 0.038 upon NT J-aggregation. These intense PL drops were systematically investigated for possible occurrence of excimer-like emission quenching and/or photo-degradation of the TC core unit. In view of the TC O-aggregates exhibiting a perfect energetic balance between the singlet (2.34 eV) and triplet (1.28 eV) energies for singlet fission (SF) and a concomitant delayed fluorescence signal, their $$\hbox {S}_{{1}}$$ decay characteristics were attributed to SF followed by an inverse triplet-triplet recombination. In contrast, the energetic imbalance ( $$\hbox {E}(\hbox {S}_{1}) < \hbox {2xE}(\hbox {T}_{1})$$ ) in NT J-aggregates permitted only forward process of SF and the resulting long-lived triplet formation was traced with a positive transient absorption ( $$\hbox {T}_{1} \rightarrow \hbox {T}_{\mathrm{n}})$$ band at 500 nm. Accordingly, the singlet excited state $$(\hbox {S}_{1})$$ dynamics of TC O- and NT J-aggregates, being largely dominated by SF, depicted a depleted $$\hbox {S}_{{1}}$$ population, accounting for the large deviation from aggregation induced enhanced emission, exhibited by classical dye J-aggregates. Unconventional O- and J -aggregates of Tetracene and Naphtho[2,1,8-qra]tetracene showed non-fluorescent behaviour whose singlet excited state (S $$_{1})$$ dynamics was largely governed by fast Singlet Fission decay, accounting for atypical deviation from the well-established aggregation induced enhanced emission from classical J-aggregates.

Synthesis, Photophysical, Electrochemical and Thermal Study of Biphenyl Luminophors: Green Light Emitting Materials.

Novel luminophors of anthracene (AN) and tetracene (TN) doped biphenyl were prepared using Conventional Solid State reaction technique. Fluorescence spectroscopy, XRD, SEM, TGA-DSC and Cyclic Voltammetry techniques have been employed for photophysical, electrochemical and thermal study. The X-ray diffraction study revealed the formation of homogeneous biphenyl solid solutions with the added guests AN and TN. Fluorescent biphenyl absorbing short wave UV radiation and emitting at long wave UV radiation has been used as a solid matrix. From the fluorescence spectra it is seen that the added guests shifts the UV fluorescence of biphenyl emitting in green region of visible spectrum at 532nm. SEM images of the prepared luminophors showed the crystallites of average size 140nm which makes them suitable candidates for their use in Optoelectronic devices. HOMO and LUMO energy levels of the synthesized luminophors from electrochemical data observed in 5.50-5.64eV and 3.09-3.13eV with band gap 2.37-2.55eV, respectively. TGA-DSC study revealedthe thermal stability of prepared luminophors. Graphical Abstract.

Donor-Acceptor Interaction in Films of Tetracene–Tetracyanoquinodimethane Heterostructures and Composites

The structures and the absorption and photovoltaic spectra of thin films of tetracene (TC) and tetracyanoquinodimethane (TCNQ), as well as the films of their heterostructures (TC/TCNQ) and composites (TC + TCNQ), have been studied. The heterostructures and composites are obtained by the thermal sputtering of the components – successively or simultaneously, respectively – in vacuum. The photovoltaic spectra were measured, by using the condenser method. It is found for the first time that the largest changes ΔD1 in the TC/TCNQ and TC + TCNQ absorption spectra with respect to the sum of the absorption spectra of the components are observed in the intervals of TCNQ dimeric bands at 2.214 eV (ΔD1 &lt; 0) and in all TC bands (ΔD1 &gt; 0). Those changes testify to the formation of charge transfer complexes between the TC (the electron donor) and TCNQ (the electron acceptor) molecules at the interfaces in the TC/TCNQ heterostructures and in the bulk of TC + TCNQ composites, which is also confirmed by the appearance of TC+- and TCNQ−-bands in the photovoltaic spectra of both the heterostructure and composite films. This result is important for a deeper understanding of the operating mechanisms in various potentially imaginable devices based on those heterostructures and composites (solar cells, field-effect transistors, and light-emitting diodes).

Electron transport behavior of quinoidal heteroacene-based junctions: effective electron-transport pathways and quantum interference.

The electron transport behavior through a series of molecular junctions composed of tetracene (TC) and S/O substituted-TC (S/O-TC) has been studied using density functional theory (DFT) combined with the non-equilibrium Green's function (NEGF) method. The unique transport behavior has been interpreted using correlated quantum interference and electron transport pathway models. In the TC system, two dominant electron transfer channels exist as demonstrated by a detailed transmission pathway analysis. In the substituted S/O-TC systems, the electron transport behavior is regulated through either constructive or destructive quantum interference due to the existence of additional p-electrons, leading to a significant diversity of current-voltage curves. Compared to the TC molecule in the bias region from 0 to 1.0 V, an α-connected molecular junction exhibits a greater current, whereas a β-connected molecular junction shows a smaller current. The substitution with O and S atoms shows a minor effect on the conductance of the molecular junctions. In order to clarify the role of heteroatoms, a series of artificial models designed by removing specific sulfur and carbon atoms in α-S-TC have been investigated in detail. The results have demonstrated that only the S heteroatom on one side of the molecule contributes to the junction conductivity through constructive quantum interference. It has also been observed that current exchange occurs between the two electron transfer channels.

Two different ground states in K-intercalated polyacenes

The electronic states of potassium- (K-) intercalated zigzag-type polycyclic aromatic (PLA) hydrocarbon [polyacene PLAs] ${\mathrm{K}}_{x}(\mathrm{PLAs})$ are studied for a series of the four smallest molecules: naphthalene (NN), anthracene (AN), tetracene (TN), and pentacene (PN), focusing on their 1:1 stoichiometric phases. Clear experimental differences are identified between the first group [${\mathrm{K}}_{1}(\mathrm{NN})$ and ${\mathrm{K}}_{1}(\mathrm{AN})$] and the second group [${\mathrm{K}}_{1}(\mathrm{TN})$ and ${\mathrm{K}}_{1}(\mathrm{PN})$] by magnetic, vibrational, and optical measurements. The first group is categorized as a Mott insulator with an antiferromagnetic ground state with energy of \ensuremath{\sim}10 meV, whereas the second group is classified as a band insulator via dimer formation due to the spin Peierls instability. In the latter system, the first thermally accessible triplet states are located far apart from the singlet ground states and are not detected by electron spin-resonance spectroscopy until 300 K being very different from what is observed for the hole-doped PN reported earlier. The results give a new systematic understanding on the electronic states of electron-doped PLAs sensitive to the energetic balance among on-site Coulomb repulsion, bandwidth, and the Peierls instability.

Electrochemical Oxidation of Hazardous Tetracene to Highly Redox Active Anthraquinone and Hydroquinone Derivatives on a Carbon Nanotube‐Modified Electrode and Its Selective Hydrogen Peroxide Sensing

AbstractA simple method for electrochemical oxidation and degradation of carcinogenic tetracene (TC) to surface confined redox active quinone species (TCO) on a pristine‐multiwalled carbon nanotube modified (MWCNT) gold electrode surface (Au/MWCNT) by applying a static potential at 0.9 V vs. Ag/AgCl in pH 7 phosphate buffer solution has been demonstrated. Various physicochemical characterizations of MWCNT@TCO by TEM, FT‐IR, Raman spectroscopy and GC‐MS reveal the presence of two types of redox sites, hydroquinone and anthraquinone derivatives within the MWCNT@TCO. The modified electrode showed selective electrocatalytic reduction and amperometric i–t sensing of H2O2 with a detection limit (signal‐to‐noise=3) of 122 nM.

Systematic Study of the Electronic States in Electron‐Doped Polyacenes

AbstractHigh‐quality polycrystalline polyacenes (PLAs) of anthracene (AN), tetracene (TN), and pentacene (PN) doped with potassium in the 1:1 and 1:2 stoichiometries are prepared and their physical properties are systematically studied by magnetic measurements. The magnetic susceptibilities as a function of temperature for Kx(PLAs) are interpreted in the framework of a band‐filling model. Clear evidence for the occurrence of charge transfer from K to the organic semiconductors is provided. K1(AN) prepared by a solid‐state diffusion process exhibits a pronounced magnetic hump at 140 K, which is associated with antiferromagnetic interactions ascribed to the on‐site Coulomb repulsion in a Mott insulating state, whereas both K1(TN) and K1(PN) show a conventional Curie–Weiss behavior at low temperatures. We successfully demonstrate the tuning of the electronic states of PLA‐type semiconductors in bulk. Comments are given about the possibility of metallic states in potassium‐doped PLAs, which have recently been reported for other polycyclic aromatic hydrocarbons.

A Creative Route to Tetracenes

A Creative Route to Tetracenes

Experimental assessment of nonergodicity in tetracene single crystals

Dielectric spectroscopy is applied to the study of phase transitions in the range from room temperature down to 12 K in single crystals of tetracene (TEN), a well-known material which, like most organic semiconductors, shows polymorphism. The present analysis, through proper experimental procedures, permits us to identify the wide range ($T$ &gt; 150 K) of instabilities and of strong hysteresis effects as clear evidence of a nonergodic state and then also to clarify some open questions, first of all the role of the sample thermal history, including the temperature variation rate and some apparent sample dependence of the results. Furthermore evidence is obtained of two transitions at 144 and 45 K.

Synthesis and Properties of anti/syn-Regioisomeric Mixtures of Alkyl-Substituted Tetracenes

Synthesis and Properties of anti/syn-Regioisomeric Mixtures of Alkyl-Substituted Tetracenes

Human Aryl Hydrocarbon Receptor Ligand Activity of 31 Non-substituted Polycyclic Aromatic Hydrocarbons as Soil Contaminants

Toxic equivalency factors (TEFs) of 31 non-substituted polycyclic aromatic hydrocarbons (PAHs) for the human aryl hydrocarbon receptor (AhR) ligand activity were measured using the yeast recombinant reporter gene assay established by Miller et al., in order to estimate the toxic equivalents of individual PAHs in environmental samples. Ten PAHs showed sigmoid-shape concentration-response curves. An effective concentration to achieve 50% activity obtained with 1 μmol/l benzo[a]pyrene (BaP) (EC50BaP) was calculated by curve fitting, and TEFs were calculated from the ratio of EC50BaP for BaP to that for the chemical studied. The highest TEF was found for naphthacene (NPC) (TEF=35) followed by benzo[b]fluorene (BbFl) (19), benzo[k]fluoranthene (BkF) (11), benz[a]anthracene (BaA) (7.0), benzo[j]fluoranthene (BjF) (4.0), benzo[a]fluorene (BaFl) (1.9), benzo[b]fluoranthene (BbF) (1.4), chrysene (CHR) (1.1), and BaP (1.0). Concentration dependent activities were also observed for indeno[1,2,3-cd]pyrene (IP) and fluoranthene (FLT). The TEFs of IP and FLT were about 0.2 and 0.02, respectively. The other 19 PAHs, naphthalene (NPT), acenaphtylene (ACL), acenaphthene (ACT), fluorene (FLU), anthracene (ANT), phenanthrene (PHN), pyrene (PYR), triphenylene (TRI), benzo[e]pyrene (BeP), perylene (PER), benzo[ghi]perylene (BgP), dibenz[a, h]anthracene (DahA), picene (PIC), coronene (COR), dibenzo[a, e]pyrene (DaeP), dibenzo[a, h]pyrene (DahP), dibenzo[a, i]pyrene (DaiP), dibenzo[a, l]pyrene (DalP) and naphtho[2,3-a]pyrene (NaP), showed little or no activity in the 0.1-1,000 nmol/l range. The toxic equivalents (TEQs) of surface soil were calculated by multiplication of the TEFs with the concentrations in soil samples collected from Kyoto, Japan. The TEQ of BaA showed the highest value of the 16 US Environmental Protection Agency Priority Pollutant PAHs.

Electronic structure and conduction mechanism of donor–bridge–acceptor systems where PPV acts as a molecular wire

Abstract p -Phenylenevinylene (PPV) oligomers behave as molecular wires, although in different ways in different experiments. The donor–bridge–acceptor systems of Davis et al., where a tetracene (TET) donor and a pyromellitimide (PI) acceptor are linked by PPV oligomers of varying lengths, have revealed an unusual donor–acceptor distance dependence in the rate constant for photo-induced electron transfer (ET). Sikes et al. in an electrochemical experiment have found fast tunneling over 28 A through PPV oligomers. In the present paper, we have applied density functional theory and other quantum chemical methods to study the electronic structure of PPV-systems and used these data to make conclusions regarding the conduction mechanisms. Consistent with the earlier interpretations we find that the PPV bridges act as a tunneling medium for ET in the thermal case and for the shorter bridges in the photo-induced case. In the three longer molecules the photo-induced ET is coherent to the bridge molecule, and is followed by fast draining to the acceptor. The electron transfer does not appear to be connected to torsional activation of bridge plane or side groups.

Dependence of electron transfer dynamics in wire-like bridge molecules on donor–bridge energetics and electronic interactions

Electron transfer (ET) reactions in donor–bridge–acceptor (DBA) molecules that occur by means of superexchange interactions between the donor (D) and the bridge (B) molecules depend on the vertical energy gap separating D and B. This dependence modulates the electronic coupling matrix element for ET, and hence the ET rate. However, when the energy gap between D and B is small, the assumptions intrinsic to the simplest superexchange model break down and charge injection from D to B may occur. To investigate this range of possibilities, we synthesized a family of DBA molecules based on a 2,5-bis(2 ′-ethylhexyloxy)-1,4-distyrylbenzene (OPV3) bridge. Three electron donors, zinc 5,10,15,20-tetraphenylporphyrin (ZnTPP), perylene (PER) and tetracene (TET) as well as two electron acceptors naphthalene-1,8:4,5-bis(dicarboximide) (NI) and pyromellitimide (PI) were attached to the OPV3 bridge. The observed ET dynamics of these molecules are sensitive not only to the donor–bridge energy gap, but also to the excited state torsional dynamics between the donor and bridge.

Electrical conductivity of alternate layer deposition of pentancene and tetracene superlattices

AbstractSuperlattice thin films of pentacene (PEN) and tetracene (TET) were fabricated by alternate layer deposition using the sublimation method. The film showed a highly crystalline structure that was due to the strong aggregation tendency of polyacene compounds to form a layered monomolecular column structure. The crystalline structure of the films was drastically changed by doping with iodine. The doped films showed a highly ordered structure where an iodine monomelecular layer was intercalated between molecular columns of acene compounds in both PEN and TET. The doped films exhibited a large lateral conductivity of 10 Ω−1 cm−1 and attained giant anisotropy above 1012. This indicated that molecular columns of TET remained insulating upon doping to form a perfect two‐dimensional conductor in the superlattice thin films.

Chemical Structure- and Time-Dependent Effects of Polycyclic Aromatic Hydrocarbon-Type Inducers on Rat Liver Cytochrome P450, DNA Adducts, and I-Compounds

Chemical Structure- and Time-Dependent Effects of Polycyclic Aromatic Hydrocarbon-Type Inducers on Rat Liver Cytochrome P450, DNA Adducts, and I-Compounds. Moorthy, B., Sriram, P., and Randerath, K. (1994). Fundam. Appl. Toxicol. 22, 549-560.It is well documented that cytochrome P450IA1 (CYP1A1) plays an important role in carcinogen activation. CYP1A1/1A2 induction may serve as a biomarker of exposure to environmental toxins. In order to explore a specific role of CYP1A1 in metabolism of I-compounds (age-dependent indigenous DNA modifications), 2-month-old female Sprague-Dawley rats were treated ip with corn oil (2 ml/kg) or with one of several CYP1A1 inducers, i.e., dibenz[a,c]anthracene (DBA) (93 μmol/kg), benzo[a]pyrene (BP) (93 μmol/kg), naphthacene (NAP) (93 μmol/kg), or β-naphthoflavone (BNF) (140 μmol/kg), once daily for 4 days. Levels of total cytochrome P450 and activities of CYP1A1-associated enzymes, i.e., ethoxycoumarin O -deethylase (ECD) and ethoxyresorufin O-deethylase (EROD), were determined in liver microsomes at 1, 8, or 15 days after the last treatment. DNA adducts and I-compounds were analyzed by nuclease P1-enhanced 32 P-postlabeling. DNA synthesis rate was determined by measuring [3H]methylthymidine incorporation into DNA. Each inducer significantly elevated the total P450 level at 1 day. The enzyme levels in BP-, NAP-, and BNF-treated animals gradually returned to control by 8 and 15 days, but elevated levels persisted in DBA-treated rats. Similar trends were observed for ECD and EROD activities. DBA and BP, but not NAP and BNF, gave rise to several measurable DNA adducts, which persisted throughout the period of study. All P450 inducers, irrespective of adduct formation, strongly depleted both nonpolar and polar I-compounds, the effects being most pronounced at 1 and 8 days. These results imply a specific role for CYP1A1 in the regulation of I-compound metabolism, in addition to PAH activation.