Perylene Tetracarboxylic Acid Bisimide Research Articles

Ultrafast exciton delocalization and localization dynamics of a perylene bisimide quadruple π-stack: a nonadiabatic dynamics simulation.

Unraveling the photogenerated exciton dynamics of π-stacked molecular aggregates is of great importance for both fundamental studies and industrial applications. Among various π-stacked molecular aggregates, perylene tetracarboxylic acid bisimide (PBI) based aggregates are regarded as one of the prototypes due to their inherent high fluorescence quantum yield and excellent photostability and flexibility in controlling intermolecular forces via chemical modifications. However, the exciton dynamics of these PBI based aggregates remain elusive up to now. In this work, we have first employed LR-TDDFT-based nonadiabatic dynamics simulations and static electronic structure calculations to investigate the ultrafast exciton dynamics of a newly synthesized perylene bisimide quadruple (PBQ) π-stack. Upon photoexcitation, the S6 to S10 states are the most likely populated excited states, which can be regarded as a combination of local excited (LE) excitons and charge transfer (CT) excitons of those four PBI chromophores. Then, the excited PBQ π-stack relaxes ultrafast to the lowest lying excited S1 state within 500 fs, which is accompanied by the complicated exciton conversion as well as exciton localization/delocalization dynamics. In short, the initially populated hybrid LE and CT excitons convert to the LE excitons of B/C and A/D, in which the LE excitons of B/C contribute the most (∼0.44) while the LE excitons of A/D also have minor contributions (0.21), indicating the formation of the localized excimer state. We use the notations A/B/C/D here to represent the four PBI fragments of PBQ π-stacks along the direction perpendicular to the PBI molecular plane. Additionally, using a recently defined root mean square deviation (RMSD) of electron and hole spatial distributions along three Cartesian coordinates, we could investigate the exciton localization/delocalization dynamics in a quantitative way. Our simulation results indicate that the photoinduced electrons and holes of the PBQ π-stack exhibit an ultrafast localization(∼10 fs)-delocalization(∼60 fs)-localization(∼200 fs) dynamics, during which both LE and CT excitons play crucial roles. Our present work is not only consistent with previous experimental studies, but also provides more detailed insights into the relevant processes, which might be useful for the future design of PBI based optoelectronic devices with improved performances.

Molecular simulation studies of self-assembly for a chromonic perylene dye: All-atom studies and new approaches to coarse-graining

Perylene tetracarboxylic acid bisimides are compounds that show intense visible light absorption and exhibit excellent chemical, photochemical and thermal stability. As such, they have been widely used as dyes and have a range of industrial applications. These dyes have also been investigated for various applications in aqueous media as chromonic liquid crystals: lyotropic systems characterised by the association of aromatic mesogenic cores into stacked structures. In this study, we focus on one perylene dye bis-(N,N-diethylaminoethyl) perylene-3,4,9,10-tetracarboxylic diimide dihydrochloride, PER, and study its self-assembly in aqueous solution through both atomistic and coarse-grained molecular models. All-atom molecular dynamics simulations demonstrate spontaneous self-assembly into chromonic H-aggregate stacks with an interparticle twist between molecules. The coarse-graining of complex chromonic mesogens introduces a wealth of subtle complexities that presents a significant challenge to overcome. Consequently, we developed coarse-grained (CG) models using both bottom-up and top-down approaches: the multiscale coarse-graining method (MS-CG) in the form of hybrid force matching (FM) and the MARTINI 3 force field, respectively. We discuss the successes/deficiencies of these approaches and introduce changes to improve upon their performance and representability. For the MARTINI 3 model, careful optimisation of parameters allows it to exactly reproduce the atomistic self-assembly behaviour including the relevant thermodynamic properties in solution. The bottom-up CG model, produced using a conventional MS-CG treatment, fails to reproduce most of the target properties, but the implementation of the potentials into a combined FM-MARTINI 3 framework allows the recovery of the correct self-assembly behaviour in solution.

Perylene Bisimide In-chain Polyethylene with Unique Self-assembly Nanostructure through Acyclic Diene Metathesis (ADMET) Polymerization

A novel perylene tetracarboxylic acid bisimide (PTCBI) in-chain polyethylene (PE) was first prepared via acyclic diene metathesis (ADMET) polymerization of PTCBI-functionalized α,ω-diene monomer. The polymers could spontaneously self-assemble into hollow cylindrical structures in which the π-π interaction between adjacent PTCBI moieties was enhanced and the electron mobility was possibly promoted. The hydrogenation of as-obtained polymer was readily accomplished, affording the desired precision PTCBI in-chain PE with a saturated backbone, which showed high glass transition temperature (Tg = 63 °C), relatively wide range of light absorption (λ = 200−575 nm), and higher LUMO level (−3.62 eV). It can therefore serve as a superior model for facile construction of functional polyolefin and soluble PTCBI polymer with ordered architecture.

Direct observation of ultrafast coherent exciton dynamics in helical π-stacks of self-assembled perylene bisimides.

Ever since the discovery of dye self-assemblies in nature, there have been tremendous efforts to exploit biomimetic supramolecular assemblies for tailored artificial photon processing materials. This feature necessarily has resulted in an increasing demand for understanding exciton dynamics in the dye self-assemblies. In a sharp contrast with J-type aggregates, however, the detailed observation of exciton dynamics in H-type aggregates has remained challenging. In this study, as we succeed in measuring transient fluorescence from Frenkel state of π-stacked perylene tetracarboxylic acid bisimide dimer and oligomer aggregates, we present an experimental demonstration on Frenkel exciton dynamics of archetypal columnar π–π stacks of dyes. The analysis of the vibronic peak ratio of the transient fluorescence spectra reveals that unlike the simple π-stacked dimer, the photoexcitation energy in the columnar π-stacked oligomer aggregates is initially delocalized over at least three molecular units and moves coherently along the chain in tens of femtoseconds, preceding excimer formation process.

3b14 オリゴシロキサン鎖を有するペリレンテトラカルボン酸ビスイミドの配向処理(分子配向エレクトロニクス,口頭発表,2013年日本液晶学会討論会)

3b14 オリゴシロキサン鎖を有するペリレンテトラカルボン酸ビスイミドの配向処理(分子配向エレクトロニクス,口頭発表,2013年日本液晶学会討論会)

Synthesis of Pyridine-Fused Perylene Imides with an Amidine Moiety for Hydrogen Bonding

Pyridine-fused perylene tetracarboxylic acid bisimides (PBIs) were synthesized via Suzuki-Miyaura coupling and acid condensation. The fused PBIs with electron-donating substituents exhibited an intramolecular charge transfer interaction. One of the N-alkyl substituents was selectively removed with BBr3 to create an amidine guest binding site. A hydrogen bonding interaction with pentafluorobenzoic acid changed the absorption spectra and enhanced fluorescence.

Ultrafast Exciton Self-Trapping upon Geometry Deformation in Perylene-Based Molecular Aggregates.

Femtosecond time-resolved experiments demonstrate that the photoexcited state of perylene tetracarboxylic acid bisimide (PBI) aggregates in solution decays nonradiatively on a time-scale of 215 fs. High-level electronic structure calculations on dimers point toward the importance of an excited state intermolecular geometry distortion along a reaction coordinate that induces energy shifts and couplings between various electronic states. Time-dependent wave packet calculations incorporating a simple dissipation mechanism indicate that the fast energy quenching results from a doorway state with a charge-transfer character that is only transiently populated. The identified relaxation mechanism corresponds to a possible exciton trap in molecular materials.

2b03 オリゴシロキサン鎖を有するペリレンテトラカルボン酸ビスイミドの液晶性と電子輸送性(分子配向エレクトロニクス,口頭発表,2012年日本液晶学会討論会)

2b03 オリゴシロキサン鎖を有するペリレンテトラカルボン酸ビスイミドの液晶性と電子輸送性(分子配向エレクトロニクス,口頭発表,2012年日本液晶学会討論会)

Liquid–crystalline perylene tetracarboxylic acid bisimide bearing oligosiloxane chains with high electron mobility and solubility

Liquid–crystalline perylene tetracarboxylic acid bisimide derivatives 1 and 2 bearing 1,1,1,2,2,3,3-heptamethyltrisiloxane chains at the end of alkyl side-chains have been synthesized. Compound 1 having four trisiloxane chains exhibits a hexagonal columnar phase at room temperature. Time-of-flight measurement reveals that the electron mobility in the columnar phase of compound 1 exceeds 10−3cm2V−1s−1 at room temperature. In contrast, compound 2 bearing two trisiloxane chains is not mesomorphic. These two compounds are soluble in various organic solvents except for alcohols and thin films can be produced by a spin-coating method.

Iridium-Catalyzed Direct Tetraborylation of Perylene Bisimides

The class of dyes known as perylene tetracarboxylic acid bisimide (PBI) has received much attention recently due to their interesting electronic and optical properties. PBI derivatives are typically accessed via electrophilic substitution at the 1-, 6-, 7- and 12-positions around the rim of the bay regions. However, not until recently have the 2-, 5-, 8- and 11-positions been functionalized by alkyl- and arylation. Here, the same authors report the direct iridium-catalyzed tetraborylation of PBIs at the 2-, 5-, 8- and 11-positions (1). In addition to serving as a potentially useful synthetic building block, the borylations also allow subsequent introduction of an oxygen heteroatom at these positions.

Perylene bisimide macrocycles and their self-assembly on HOPG surfaces

Acetylene-linked macrocycles incorporating multiple perylene tetracarboxylic acid bisimide (PBI) chromophores have been synthesised and separated by recycling GPC. The very first example of such macrocycles, i.e., cyclic trimer 5, containing three PBI dyes self-assembles into highly ordered donut-shaped unique hexagonal nanopatterns on HOPG surfaces as revealed by atomic force microscopy (AFM).

Highly fluorescent water-soluble polyglycerol-dendronized perylene bisimide dyes

Water-soluble perylene tetracarboxylic acid bisimides (PBIs) with terminally linked polyglycerol dendrons of four different generations have been synthesized. These PBI dyes reveal a strong dendritic effect, enabling outstanding fluorescence quantum yields in water up to almost 100% for the highest dendron generation.

Understanding Ground- and Excited-State Properties of Perylene Tetracarboxylic Acid Bisimide Crystals by Means of Quantum Chemical Computations

Quantum chemical protocols explaining the crystal structures and the visible light absorption properties of 3,4:9,10-perylene tetracarboxylic acid bisimide (PBI) derivates are proposed. Dispersion-corrected density functional theory has provided an intermolecular potential energy of PBI dimers showing several energetically low-lying minima, which corresponds well with the packing of different PBI dyes in the solid state. While the dispersion interaction is found to be crucial for the binding strength, the minimum structures of the PESs are best explained by electrostatic interactions. Furthermore, a method is introduced, which reproduces the photon energies at the absorption maxima of PBI pigments within 0.1 eV. It is based on time-dependent Hartree-Fock (TD-HF) excitation energies calculated for PBI dimers with the next-neighbor arrangement in the pigment and incorporates crystal packing effects. This success provides clear evidence that the electronically excited states, which determine the color of these pigments, have no significant charge-transfer character. The developed protocols can be applied in a routine manner to understand and to predict the properties of such pigments, which are important materials for organic solar cells and (opto-)electronic devices.

Electronic structure of epitaxial thin films of bay-substituted perylene bisimide dyes

We have investigated epitaxial thin films of three air-stable organic n-type semiconducting perylene tetracarboxylic acid bisimides (PBIs) with fluoroalkyl groups in the imide position with a combination of X-ray, UV, and inverse photoelectron spectroscopy. We explore the applicability of film preparation by organic molecular beam deposition (OMBD) under ultra-high vacuum conditions to these compounds. By means of fluorine and chlorine substituents in the bay area a systematic torsion of the π-conjugated core of these three PBIs is achieved. Accordingly, these molecules offer a model system to analyze the interplay between the molecular conformation, the film structure, and the electronic structure. Our results show that the PBIs can be deposited intact and contamination free by OMBD and relatively smooth films with layer-to-layer growth can be established. Moreover, the valence spectra reveal the effect of the electro-negative bay substituents as well as of the twisting of the perylene core, which leads to energy shifts of the occupied and unoccupied frontier orbitals.

Fluorescent J-type aggregates and thermotropic columnar mesophases of perylene bisimide dyes.

A series of perylene tetracarboxylic acid bisimides 3a-e bearing 3,4,5-tridodecyloxyphenyl substituents on the imide N atoms and zero, two, or four phenoxy-type substituents in the bay positions of the perylene core were synthesized. From investigations of their spectroscopic properties and aggregation behavior in low-polarity solvents by absorption and fluorescence optical spectroscopy, not only were these compounds found to form fluorescent J-type aggregates, but also binding constants for aggregation could be derived which reflect the number and steric demand of the phenoxy substituents for bisimides 3a-d. In the pristine state, 3a-d form thermotropic hexagonal columnar mesophases which exist over a broad temperature range from below -30 degrees C to over 300 degrees C. For the tetraphenoxy-substituted compound 3e, however, a layered crystalline structure was found. This difference in behavior can be explained by the concept of microphase segregation of the aromatic cores of the molecules and the alkyl chains at the periphery. The high stability and bright fluorescence of the mesophase of several of the compounds make them promising for applications as polarizers or components in (opto)electronic devices.

Fluorescent and electroactive cyclic assemblies from perylene tetracarboxylic acid bisimide ligands and metal phosphane triflates.

Tetraaryloxy-substituted perylene tetracarboxylic acid bisimides with one or two 4-pyridyl receptor substituents at the imide functionality were synthesized and employed in transition metal directed self-assembly with Pd(II) and Pt(II) phosphane triflates. Upon mixing of the components, quantitative formation of functional molecular square-type complexes containing four dye molecules and model complexes of a 2:1 (perylene bisimide ligand:transition metal ion) stoichiometry was observed. The isolated metallosupramolecular squares were characterized by 1H and 31P [1H] NMR spectroscopy as well as conventional electrospray ionization (ESI) and ESI-FTICR mass spectrometry, which gave evidence for the structure and the high stability of these giant cyclic dye assemblies (molecular weight (3a) 8172, Pt-Pt corner diagonal ca. 3.4 nm). Studies of the optical absorption and fluorescence properties and the electrochemistry and spectroelectrochemistry of both the perylene bisimide ligands and the perylene bisimide metal complexes show that Pt(II) coordination does not interfere with the optical and electrochemical properties of the perylene bisimide ligands; this gives squares with high fluorescence quantum yields (phiF (3a)=0.88) and three fully reversible redox couples. The latter could be unambiguously related to quantitative formation of perylene bisimide radical cations (E1/2 = +0.93 V vs. Fc/Fc+), radical anions (E1/2= - 1.01 V vs. Fc/Fc+), and dianions (E1/2 = -1.14 V vs. Fc/Fc+); these redox reactions change the charge state of the cyclic assembly from +12 to zero. In contrast, Pd(II) coordination influenced the electrochemical properties of the assembly because of an irreversible palladium reduction at E1/2= -1.15 V versus Fc/Fc+. Finally, dynamic ligand exchange processes between different metallosupramolecular assemblies were investigated by multinuclear NMR and electrospray mass spectrometry. These studies confirmed the reversible nature of the pyridine-Pt(II)/Pd(II) coordination process.

Fluorescent and Electroactive Cyclic Assemblies from Perylene Tetracarboxylic Acid Bisimide Ligands and Metal Phosphane Triflates

Fluorescent and Electroactive Cyclic Assemblies from Perylene Tetracarboxylic Acid Bisimide Ligands and Metal Phosphane Triflates

Hierarchical self-organization of perylene bisimide--melamine assemblies to fluorescent mesoscopic superstructures.

A series of three perylene tetracarboxylic acid bisimide dyes 3a-c bearing phenoxy substituents at the four bay positions of the perylene core were synthesized and their complexation behavior to complementary ditopic dialkyl melamines 8a-c was investigated. Binding constants and Gibbs binding energies for the hydrogen bonds between the imide and the complementary melamine moiety have been determined in several solvents by NMR and UV/Vis titration experiments with monotopic model compounds 5 and 9. The effects of the solvent polarity and specific solvent-solute interactions on the degree of polymerization of (3 x 8)n are discussed, and a general formula to estimate the chain length of [AA-BB]n nylon-type supramolecular polymers is derived. In addition to the formation of a hydrogen-bonded supramolecular chain. pi-pi interactions were observed for perylene bisimide-melamine assemblies 3b x 8b and 3b x 8c in aliphatic solvents. The orthogonal nature of hydrogen bonding and pi-pi interactions leads to three-dimensional growth yielding large-sized aggregates already in dilute solution. On suitable substrates, densely intertwined networks of nano- to mesoscopic strands are formed which have been investigated by electron microscopy, confocal fluorescence microscopy and optical polarization microscopy. The high fluorescence and excellent photostability of these superstructures is promising for future studies on energy migration and artificial light harvesting at the nano- and mesoscopic length scale.