Tetracene Derivatives Research Articles

Exploring the ON/OFF nonlinear optical (NLO) response in tetracene-based chromophores: A DFT study on solvent and frequency-dependent NLO properties for switching applications

Tetracene-based nonlinear optical (NLO) materials are an ambient field of interest in optoelectronic technology. Inspired by this material, we theoretically designed D-D-A framework molecules (ZO and ZO-1 to ZO-16) with auxiliary donor and acceptor screening of solo tetracene linear surface and investigated their reactivity, electrical properties, solvent-dependent optical and ON/OFF NLO properties utilizing DFT simulations. The CPCM and IEFPCM model is used to examine how entire spectrum of medium polarity, ranging from less polar to more polar solvents (chloroform (ε = 4.71) < tetrahydrofuran (ε = 7.43) < DMSO (ε = 46.83 < water (ε = 78.36)) affect the optical absorption and NLO characteristics (βtot, αtot, and μtot) of suggested compounds (ZO and ZO-1 to ZO-16). Furthermore, natural bond orbital analysis (NBO) and topological analysis (MEP, ELF, and LOL) were used to explain the NLO results. Regarding the charge transfer robustness, ZO-9, a promising tetracene derivative, is identified as an appealing second-order NLO candidate, with the lowest energy gap (1.642 eV) and largest λmax (546.692 nm) among all investigated derivatives. Moreover, the solvent-dependent optical absorption spectrum shows that polar solvent (THF) alleviates the λmax from 273.081 nm to 707.511 nm in ZO-11. Similarly, solvent also influences the NLO properties in all designed compounds, especially in ZO-9, which displayed giant βtotal = 7.244 × 105 in chloroform, 8.640 × 105 in THF, 1.153 × 106 in DMSO, and 1.180 × 106 in water as well as in gas (1.993 × 105). Additionally, the results of the second harmonic generation (SHG) β(−2ω, ω, ω) and the electro-optical Pockels effect (EOPE) β(−ω,ω,0) computed at the frequencies of ω = 1064 nm (0.0428 au) and ω = 532 nm (0.0856 au) validates that all tetracene based derivatives are excellent NLO candidates for laser working condition and switching applications.

Principal Singlet Fission Properties Of Twisted Acenes.

Acenes, especially tetracene derivatives, are used as singlet fission materials. The recent synthesis of Dodecaphenyl tetracene (showing end-to-end twist angles of 96-98 degrees) and twisted anthracene derivatives show that the synthesis of twisted linear oligoacenes is possible. Energy calculations and NICS-X-scan studies predict that twisted acenes may be better singlet fission materials compared to their planar analogues.

A Ground-State Dual-Descriptor Strategy for Screening Efficient Singlet Fission Systems.

Exploration of singlet fission (SF) materials is vital for enhancing the photoelectric conversion efficiency of photovoltaic devices, and the development of an effective screening means is in great demand. In this work, we for the first time propose a promising dual-descriptor strategy to predict the SF energetics (ΔESF) from ground-state electronic properties, the gap (GapHL) and exchange energy (KHL) between the highest occupied and lowest unoccupied molecular orbitals (HOMO and LUMO), where GapHL plays a dominant role and KHL acts as a correction. This strategy is statistically verified through exploring the effect of N-doping on the electronic/energetic properties of the N-doped tetracene derivatives and isomers. Several rules of thumb are suggested, and the reliability of this strategy is validated by comparison with experiments. This work proposes a novel strategy for exploring SF chromophores with insights into the SF energetics from ground-state properties and certainly has fundamental interest and generality in exploring efficient SF-capable materials.

N-Heteroacenes as an Organic Gain Medium for Room-Temperature Masers.

The development of future quantum devices such as the maser, i.e., the microwave analog of the laser, could be well-served by the exploration of chemically tunable organic materials. Current iterations of room-temperature organic solid-state masers are composed of an inert host material that is doped with a spin-active molecule. In this work, we systematically modulated the structure of three nitrogen-substituted tetracene derivatives to augment their photoexcited spin dynamics and then evaluated their potential as novel maser gain media by optical, computational, and electronic paramagnetic resonance (EPR) spectroscopy. To facilitate these investigations, we adopted an organic glass former, 1,3,5-tri(1-naphthyl)benzene to act as a universal host. These chemical modifications impacted the rates of intersystem crossing, triplet spin polarization, triplet decay, and spin-lattice relaxation, leading to significant consequences on the conditions required to surpass the maser threshold.

Toward Improving Triplet Energy Transfer from Tetracene to Silicon Using a Covalently Bound Tetracene Seed Layer.

Silicon solar cells are operating close to the theoretical maximum efficiency limit. To increase their efficiency beyond this limit, it is necessary to decrease energy losses occurring for high-energy photons. A sensitizing layer of singlet-fission material can in principle double the current generated by high-energy photons, and significantly reduce energy losses from high-energy photons within the solar cell. Here, we construct a model of such a solar cell, using Si(111) surfaces and tetracene. To increase the energy transfer between the two layers, a series of tetracene derivatives was synthesized, and the molecules were covalently attached onto the silicon surface as a seed layer. Using X-ray diffraction, a shift in crystal structure and ordering of the tetracene close to the seed layer can be observed. Unfortunately, the effect on the energy transfer was limited, showing a need for further investigations into the effect of the seed layer.

QSPR modeling for the prediction of the triplet yield of singlet fission materials

Singlet excitons fission (SF) into triplet excitons can enhance the efficiency of solar cells while reducing the heat loss in light absorption systems, but requires photostable materials with high triplet yield. We use Support Vector Regression (SVR) to establish a Quantitative Structure-Property Relationship (QSPR) model for perdition the triplet yield (ΦSF) of singlet fission materials (tetracene, pentacene, and perylenedimide derivatives, etc.). Minimum redundancy maximum relevance (mRMR), Floating front search (FFS) and Grid-search were used to select property molecular descriptions and parameter optimization, then the SVR model was established to predict the ΦSF of these compounds. The correlation coefficient R values of leave one out cross-validation (LOOCV) test and external validation test set were 0.88 and 0.93, respectively. The results show that the SVR-QSPR model has strong generalization ability, can predict the ΦSF value of singlet fission materials effectively and guide significance for developing highly efficient solar cells.

(Invited) High-Yield and Long-Lived Individual Triplet Exciton Generation Using Covalently-Linked Tetracene Dimers through Intramolecular Singlet Fission

Singlet fission (SF) is a multi-exciton generation process in two neighboring organic chromophores (S1 + S0) where two individual triplet excitons (T1 + T1) are generated from one-photon absorption through a correlated triplet pair (TT) (see: the following equation). Therefore, SF is highly promising for construction of next-generation light energy conversion systems.S1 + S0 → TT → T1 + T1 In addition to the close interaction of two neighboring chromophores, energy-level matching condition between a singlet and two triplet states: [E(S1) ≥ 2E(T1)] are required for efficient SF. Acene derivatives such as pentacene satisfy the above condition. However, the number of high-yield and long-lived triplet excited states through SF using tetracene derivatives is extremely limited because of the acceleration of the reverse reaction: triplet-triplet annihilation.1-2 Namely, the precise structural control of orientation and distance between two nearby tetracene units is required for long-lived individual triplets through SF. In this presentation, we mainly focus on the high-yield and long-lived individual triplet exciton generation through intramolecular SF (ISF) using a series of phenylene-spacer-bridged tetracene dimers.3 References Nakamura, S.; Sakai, H.; Nagashima, H.; Kobori, Y.; Tkachenko, N. V.; Hasobe, T. ACS Energy Lett. 2019, 4, 26-31.Saegusa, T.; Sakai, H.; Nagashima, H.; Kobori, Y.; Tkachenko, N. V.; Hasobe, T. J. Chem. Soc. 2019, 141, 14720-14727.Nakamura, S.; Sakai, H.; Nagashima, H.; Fuki, M.; Onishi, K.; Khan, R.; Kobori, Y.; Tkachenko, N. V.; Hasobe, T. Phys. Chem. C 2021, 125, 18287-18296.

Regioselective Fluorination of Acenes: Tailoring of Molecular Electronic Levels and Solid-State Properties.

Optoelectronic properties of molecular solids are important for organic electronic devices and are largely determined by the adopted molecular packing motifs. In this study, we analyzed such structure‐property relationships for the partially regioselective fluorinated tetracenes 1,2,12‐trifluorotetracene, 1,2,10,12‐tetrafluorotetracene and 1,2,9,10,11‐pentafluorotetracene that were further compared with tetracene and perfluoro‐tetracene. Quantum chemical DFT calculations in combination with optical absorption spectroscopy data show that the frontier orbital energies are lowered with the degree of fluorination, while their optical gap is barely affected. However, the crystal structure changes from a herringbone packing motif of tetracene towards a planar stacking motif of the fluorinated tetracene derivatives, which is accompanied by the formation of excimers and leads to strongly red‐shifted photoluminescence with larger lifetimes.

(Invited) Tetracene Molecular Architectures for High-Yield and Long-Lived Individual Triplet States through Singlet Fission

Singlet fission (SF) is a multi-exciton generation process in two neighboring organic chromophores (S1 + S0) where two individual triplet excitons (T1 + T1) are generated from one-photon absorption through a correlated triplet pair (TT). Therefore, SF is highly promising for construction of next-generation solar energy conversion systems such as photovoltaics and photocatalysis. In addition to the close interaction of two nearby molecules, energy-level matching condition between a singlet and two triplet states: [E(S1) ≥ 2E(T1)] are required. Acene derivatives such as pentacene and tetracene satisfy the above condition. However, the number of high-yield and long-lived triplet excited states through SF using tetracene derivatives is extremely limited because of the acceleration of the reverse reaction: triplet-triplet annihilation. Namely, the precise structural control of orientation and distance between two nearby tetracene units is definitely required for long-lived individual triplets through SF. In this presentation, we mainly focus on the tetracene molecular assemblies for high-yield and long-lived individual triplet states through SF using a series of covalently-linked dimers1 and tetracene-modified gold nanoclusters.2 References Nakamura, S.; Sakai, H.; Nagashima, H.; Kobori, Y.; Tkachenko, N. V.; Hasobe, T. ACS Energy Lett. 2019, 4, 26-31.Saegusa, T.; Sakai, H.; Nagashima, H.; Kobori, Y.; Tkachenko, N. V.; Hasobe, T. J. Chem. Soc. 2019, 141, 14720-14727.

Triplet energy migration pathways from PbS quantum dots to surface-anchored polyacenes controlled by charge transfer.

Sensitization of molecular triplets using PbS quantum dots (QDs), followed by efficient triplet fusion, has been developed as a novel route to near-infrared-to-visible photon upconversion. Fundamentally, however, the mechanisms of triplet energy transfer (TET) from PbS QDs to surface-anchored polyacence acceptors remain highly debated. Here we study and side-by-side compare the kinetic pathways of TET from photoexcited PbS QDs to surface-anchored tetracene and pentacene derivatives using broad-band transient absorption spectroscopy spanning multiple decades of timescales. We find that the TET pathways are dictated by charge-transfer energetics at the QD/molecule interface. Charge transfer from QDs to tetracene was strongly endothermic, and hence spectroscopy showed one-step transformation from QD excited states to tetracene triplets in 302 ns. In contrast, hole transfer from QDs to pentacene was thermodynamically favoured and was confirmed by the formation of pentacene cation radicals in 13 ps, which subsequently evolved into pentacene triplets through a 101 ns electron transfer process. These results not only are consistent with a recently-established framework of charge-transfer-mediated TET, but also provide a route to manipulate triplet sensitization using lead-salt QDs for efficient upconversion of near-infrared photons.

Effect of Sulfur Substitution on Charge Transport Ability of Benzopyrazine-Fused Tetracene Derivatives: A Theoretical Study

Effect of Sulfur Substitution on Charge Transport Ability of Benzopyrazine-Fused Tetracene Derivatives: A Theoretical Study

Synthesis, Hirshfeld Surface Analysis and DFT Studies of Ethano-tetracyclic Tetracene Derivatives

The syntheses of ethano-tetracyclic tetracenes; 14-cyano-5,12-dihydro-5,12-ethanotetracen-14-yl acetate (2a and 2b) and 5,12-dihydro-5,12-ethanotetracen-13-one (3) are reported. The tetracenes isomers 2a and 2b are equally obtained via DA reaction and the tetracene 3 is synthesized from the alkaline hydrolysis of 2a and 2b. The DFT calculations of tetracenes isomers 2a and 2b are performed and gave good agreement to the experimental result. The structure of tetracene 3 is elucidated by X-ray technique and its intermolecular interactions are determined by Hirshfeld surface analysis. The crystal system of tetracene 3 is orthorhombic with a Pca21 space group; a = 28.589 (5) A, b = 6.5023 (14) A, c = 7.5101 (11) A, V = 1396.1 (4) A3, Z = 4. This is the first report describing syntheses Ethano-tetracyclic tetracenes 2a, 2b, 3. DFT studies were used to explain the reaction regioselectivity of the two tetracene isomers 2a, 2b. The x-ray is performed to elucidate the structure of tetracene 3. Hirshfeld surface analysis is performed to determine the intermolecular interactions in the crystal structure of the tetracene 3.

Thermally stable organic thin film transistors based on 2-(anthracen-2-yl)tetracene

Abstract Organic semiconductors with high mobility and high thermal stability are of great importance for practical application of organic electronics. To explore new semiconductors by taking advantage of the intrinsic properties of tetracene molecule, herein, we report the design and synthesis of a novel p-type tetracene derivatives, 2-(anthracen-2-yl)tetracene (TetAnt). Top contact organic thin-film transistors (OTFTs) based on TetAnt show a hole mobility of up to 0.79 cm2 V−1 s−1. In addition, a high mobility of ~0.4 cm2 V−1 s−1 is maintained even after thermal stressed to a high temperature of 290 °C, indicating the excellent thermal stability of TetAnt.

Mersaquinone, A New Tetracene Derivative from the Marine-Derived Streptomyces sp. EG1 Exhibiting Activity against Methicillin-Resistant Staphylococcus aureus (MRSA).

New antibiotics are desperately needed to overcome the societal challenges being encountered with methicillin-resistant Staphylococcus aureus (MRSA). In this study, a new tetracene derivative, named Mersaquinone (1), and the known Tetracenomycin D (2), Resistoflavin (3) and Resistomycin (4) have been isolated from the organic extract of the marine Streptomyces sp. EG1. The strain was isolated from a sediment sample collected from the North Coast of the Mediterranean Sea of Egypt. The chemical structure of Mersaquinone (1) was assigned based upon data from a diversity of spectroscopic techniques including HRESIMS, IR, 1D and 2D NMR measurements. Mersaquinone (1) showed antibacterial activity against methicillin-resistant Staphylococcus aureus with a minimum inhibitory concentration of 3.36 μg/mL.

Singlet Fission in Self-assembled Amphipathic Tetracene Nanoparticles: Probing the Role of Charge-transfer State

Two tetracene derivatives with PEG group of different lengths (PhTc-PEG-1 with short PEG chain and PhTc-PEG-2 with long PEG chain) have been synthesized and fabricated into nanoparticles with re-precipitation method. Spherical nanoparticle is formed for these two compounds in water as revealed by scanning electron microscopy. Steady-state absorption and fluorescence spectra demonstrates that the interaction between the adjacent tetracene units in these two nanoparticles is relatively strong, but the interaction in PhTc-PEG-2 nanoparticle is weaker than that of PhTc-PEG-1 nanoparticle. Transient absorption experiment reveals that singlet fission (SF) can be conducted in these two nanoparticles via a real charge-transfer (CT) intermediate state resembled that in same tetracene core without PEG chain (PhTc). However, the SF yields of these nanoparticles are relatively low, suggesting that the formation of the real CT state is unfavorable for the occurrence of SF. Moreover, the weaker interaction in PhTc-PEG-2 nanoparticle leads to a relatively low SF yield compared to that of PhTc-PEG-1 nanoparticle, suggesting that the long PEG chain should be avoided when modifying SF chromophore for preparing colloidal nanoparticles with the goal of achieving efficient SF.

(Invited) High-Yield Singlet Fission of Tetracene Derivatives Utilizing Organic-Inorganic Hybrid Systems for Light Energy Conversion

Singlet fission (SF) is highly expected to improve the solar energy conversion properties by generating two excitons from one photon absorption. Among various organic compounds, acene derivatives such as tetracene and pentacene are promising for occurrence of efficient SF. Pentacene derivatives sufficiently meet the energy-level matching condition between a singlet and two triplet states: [E(S1) ≥ 2E(T1)]. Although tetracene is well-kwown as a good candidate for SF, the number of high-yield and long-lived triplet excited states through SF is extremely limited because of the relative acceleration of the reverse triplet-triplet annihilation (TTA) considering the above-mentioned energy matching condition. Consequently, the precise control of orientation and distance between two neighboring Tc units is definitely required for long-lived individual triplets through SF but not correlated triplet pair. Because the longer lifetime of the individual triplet states is useful for efficient light energy conversion.Therefore, we first demonstrate the quantitative sequential process from intramolecular SF to intermolecular two-electron transfers using 2,2′-biphenyl-bridged tetracene dimer (Tet-BP-Tet). The obtained high-yield and long-lived triplet excited states of Tet-BP-Tet by intramolecular SF (quantum yield of individual triplet states: ΦT = 175 ± 5% and lifetime of individual triplet states: τT = 0.29 ms) resulted in the quantitative intermolecular two-electron transfer process with chloranil in benzonitrile (electron transfer yield: ΦET = 173 ± 5%).1 Then, we also propose a novel supramolecular strategy utilizing the mixed self-assembled monolayers (SAMs) with two different chain lengths. Specifically, mixed tetracene-SAMs on gold nanoclusters, which are prepared by a tetracene-modified hetero-disulfide with two different chain lengths, attain high-yield SF (Φ SF: ~90%) and individual triplet yields (Φ Τ: ~160%).2 References Nakamura, S.; Sakai, H.; Nagashima, H.; Kobori, Y.; Tkachenko, N. V.; Hasobe, T. ACS Energy Lett. 2019, 4, 26-31.Saegusa, T.; Sakai, H.; Nagashima, H.; Kobori, Y.; Tkachenko, N. V.; Hasobe, T. J. Am. Chem. Soc. 2019, 141, 14720-14727.

Pyrene-stabilized acenes as intermolecular singlet fission candidates: importance of exciton wave-function convergence

Singlet fission (SF) is a photophysical process considered as a possible scheme to bypass the Shockley–Queisser limit by generating two triplet-state excitons from one high-energy photon. Polyacene crystals, such as tetracene and pentacene, have shown outstanding SF performance both theoretically and experimentally. However, their instability prevents them from being utilized in SF-based photovoltaic devices. In search of practical SF chromophores, we use many-body perturbation theory within the GW approximation and Bethe–Salpeter equation to study the excitonic properties of a family of pyrene-stabilized acenes. We propose a criterion to define the convergence of exciton wave-functions with respect to the fine k-point grid used in the BerkeleyGW code. An open-source Python code is presented to perform exciton wave-function convergence checks and streamline the double Bader analysis of exciton character. We find that the singlet excitons in pyrene-stabilized acenes have a higher degree of charge transfer character than in the corresponding acenes. The pyrene-fused tetracene and pentacene derivatives exhibit comparable excitation energies to their corresponding acenes, making them potential SF candidates. The pyrene-stabilized anthracene derivative is considered as a possible candidate for triplet–triplet annihilation because it yields a lower SF driving force than anthracene.

Identifying high-mobility tetracene derivatives using a non-adiabatic molecular dynamics approach

Alkylated tetracenes offer an attractive route towards flexible columnar organic electronics applications with unprecedented hole mobilities and robust charge transfer mechanisms.

Reduced Knoevenagel Reaction of Acetetracenylene-1,2-dione with Acceptor Units for Luminescent Tetracene Derivatives.

Acetetracenylene-1,2-dione reacted with 3-ethylrhodanine in the presence of piperidine and Hantzsch ester via a Knoevenagel condensation-reduction sequence to give a tetracene-rhodanine adduct. This reduced Knoevenagel product exhibited magenta luminescence with a fluorescence quantum yield of φ = 0.34 and fluorescence lifetime of τ = 13.2 ns in toluene. Electrochemical studies and charge carrier transport measurements revealed ambipolar properties with hole and electron mobilities of 5.1 × 10-7 and 1.6 × 10-4 cm2/(V s), respectively.

Electrocatalytic hydrogen production using [FeFe]-hydrogenase mimics based on tetracene derivatives

The synthesis, structure, physical properties, and electrocatalytic hydrogen production of tetrathiatetracene ligand based [FeFe]-hydrogenase mimic molecules were investigated.