Perylene Bisimide Dyad Research Articles

Coexistence of Parallel and Rotary Stackings in the Lamellar Crystals of a Perylene Bisimide Dyad for Temperature-Sensitive Bicomponent Emission.

Coexistence of rotationally π-π stacked columns and discrete slip-stacked dimers of perylene bisimide (PBI) chromophores is revealed by single crystal X-ray diffraction in the lamellar crystal of a head-to-tail linked PBI dyad. The rotary π-π stacked columnar moieties show H-type spectral character with relatively higher excitation energy, while the discrete slip-stacked π-π dimers have J-type spectral behavior with lower excitation energy. The lamellar crystals show relatively low photoluminescence efficiency of 12% at room temperature, while this dramatically increases to ∼90% at low temperature (80 K). Both of the rotary and slip-stacked moieties are emissive, and the nonradiative energy transfer processes between them are suppressed at low temperature, ensuring the highly efficient excimer-like long-lived fluorescence.

Water-induced self-assembly of an amphiphilic perylene bisimide dyad into vesicles, fibers, coils, and rings

Bestowing amphiphilicity to specifically designed perylene bisimide dyads enables diverse self-assembly pathways in aqueous media.

Water-induced helical supramolecular polymerization and gel formation of an alkylene-tethered perylene bisimide dyad.

An alkylene-tethered perylene bisimide (PBI) dyad with hydrophilic substituents forms helical supramolecular polymers that can be visualized by AFM in THF-water mixtures. The supramolecular polymers also form thixotropic gel-like lyotropic mesophases in the mixtures.

Probing chirality fluctuations in molecules by nonlinear optical spectroscopy.

Symmetry breaking caused by geometric fluctuations can enable processes that are otherwise forbidden. An example is a perylene bisimide dyad whose dipole moments are perpendicular to each other. Förster-type energy transfer is thus forbidden at the equilibrium geometry since the dipolar coupling vanishes. Yet, fluctuations of the geometric arrangement have been shown to induce finite energy transfer that depends on the dipole variance, rather than the mean. We demonstrate an analogous effect associated with chirality symmetry breaking. In its equilibrium geometry, this dimer is non-chiral. The linear chiral response which depends on the average geometry thus vanishes. However, we show that certain 2D chiral optical signals are finite due to geometric fluctuations. Furthermore, the correlation time of these fluctuations can be experimentally revealed by the waiting time dependence of the 2D signal.

Synthesis and photophysical studies of triazine-linked porphyrin–perylene bisimide dyad with long-lived perylene triplet state

Abstract Porphyrin–perylene bisimide dyad containing a triazine group as the linker was synthesized and characterized. The absorption spectra reveal that there is no appreciable interaction between the ground-state porphyrin and ground-state perylene. The fluorescence spectra illustrate that photoinduced energy transfer takes place from the excited perylene to ground-state porphyrin moiety when excited at 491 nm, while enhanced photoinduced electron transfer occurs from the porphyrin singlets to ground-state perylene moiety in the case of excitation at 423 nm. The kinetic analysis indicates that a long-lived perylene triplet state (146 μs) forms via triplet–triplet energy transfer from the porphyrin to perylene moiety, showing potential applications in the photodynamic therapy. These photochemical events are explained with an energy-level diagram.

Backbone‐Directed Perylene Dye Self‐Assembly into Oligomer Stacks

Arm wrestling: Backbone-directed "arm-to-arm" aggregation of a newly designed perylene bisimide (PBI) dyad with a defined intramolecular space leads to the growth of kinetically stable extended PBI π-stacks. This PBI dyad was shown to assemble into oligomers up to 21 units in length.

Noise-Induced Förster Resonant Energy Transfer between Orthogonal Dipoles in Photoexcited Molecules

We show that Förster resonance energy transfer (FRET) in an orthogonally arranged donor-acceptor pair can be induced by environmental noise, although direct transfer is prohibited. Environmental fluctuations break the strict orthogonal dipole arrangement and cause effective fluctuating excitonic interactions. Using a scaling argument, we show that interaction fluctuations are coupled to those of the energy levels and are strong enough to induce large FRET rates. This mechanism also explains the temperature dependence observed in a recent experiment on a perylene bisimide dyad and predicts a modified distance dependence as compared to standard Förster theory.

Förster Resonant Energy Transfer in Orthogonally Arranged Chromophores

We investigate the ultrafast resonant energy transfer of a perylene bisimide dyad by pump-probe spectroscopy, chemical variation, and calculations. This dyad undergoes transfer with near-unit quantum efficiency, although the transition dipole moments of the donor and acceptor are in a perfectly orthogonal arrangement to each other in the equilibrium geometry. According to the point dipole approximation used in Förster theory, no energy transfer should occur. Experimentally we do, however, find an ultrafast transfer time of 9.4 ps. With the transition density cube approach we show that in the orthogonal arrangement the Coulombic interactions do not contribute to the electronic coupling. Through the change of the spacer in both length and chemical character, we can clearly exclude any Dexter-type energy transfer. The temperature effects on the Förster resonant energy transfer rate demonstrate that energy transfer is enabled through low-frequency ground-state vibrations, which break the orthogonal arrangement of the transition dipole moments. The dyads presented here therefore are a first example that shows with extreme clarity the decisive role vibrational motion plays in energy transfer processes.

Photocyclization Reaction of Diarylethene−Perylenebisimide Dyads upon Irradiation with Visible (>500 nm) Light

Two types of fluorescent diarylethene−perylenebisimide dyads were synthesized and their photochromic performance was studied. The dyads showed an unexpected photochromic reactivity. The photocyclization reaction takes place upon irradiation with visible light (>500 nm), where the diarylethene unit has no absorption. Inferring from the excitation wavelength dependence and oxygen effect, the triplet states of the diarylethene unit are considered to play an essential role in the photocyclization reaction with visible (>500 nm) light.

Excitation Energy Dependence of Photoinduced Processes in Pentathiophene−Perylene Bisimide Dyads with a Flexible Linker

In the present paper, photoinduced processes in the dyad molecules of pentathiophene (5T) and perylene-3,4:9,10-bis(dicarboximide) (PDI) with a flexible alkyl linker (propyl or hexyl) were investigated by using femtosecond laser flash spectroscopy in various solvents. Since absorption of 5T covers the wavelength region where absorption of PDI has minima and fluorescence of 5T overlaps with absorption of PDI, combination of 5T and PDI is favorable to achieve light energy harvesting as well as efficient electron transfer. When the sample was excited at the PDI moiety of the dyad, charge separation occurred almost quantitatively even in nonpolar solvent as well as in polar solvents. When the 5T moiety of the dyad was excited, efficient energy transfer to the PDI moiety from which charge separation occurred was confirmed, indicating that 5T acts as an antenna of the charge separation system, like a photosynthesis system of a plant. On the basis of Forster and Marcus theories and the estimated energy and electron-transfer rates, it was indicated that these dyads tend to take a folded structure in all solvents investigated.

Porphyrin-perylene bisimide dyads and triads: synthesis and optical and coordination properties.

[structure: see text] Novel porphyrin perylene dyad and triad dyes have been prepared by the coupling of aminophenyltrisphenylporphyrin and tetraphenoxy-substituted perylenetetracarboxylic acid bisanhydrides in a one-step synthesis. Fluorescence spectra of these compounds reveal features that are attributable to emission of perylene bisimides as well as porphyrin excited states. The self-assembly behavior of zinc-metalated compounds with 4,4'-bipyridine and diazabenzoperylene has been investigated by (1)H NMR spectroscopy in CDCl(3), showing that oligomeric zigzag assemblies are formed.