Molecular assemblies of perylene bisimide dyes in water

Perylene bisimides are among the most valuable functional dyes and have numerous potential applications. As a result of their chemical robustness, photostability, and outstanding optical and electronic properties, these dyes have been applied as pigments, fluorescence sensors, and n‐semiconductors in organic electronics and photovoltaics. Moreover, the extended quadrupolar π system of this class of dyes has facilitated the construction of numerous supramolecular architectures with fascinating photophysical properties. However, the supramolecular approach to the formation of perylene bisimide aggregates has been restricted mostly to organic media. Pleasingly, considerable progress has been made in the last few years in developing water‐soluble perylene bisimides and their application in aqueous media. This Review provides an up‐to‐date overview on the self‐assembly of perylene bisimides through π–π interactions in aqueous media. Synthetic strategies for the preparation of water‐soluble perylene bisimides and the influence of water on the π–π stacking of perylene bisimides as well as the resulting applications are discussed.     

Computational studies on optoelectronic and charge transfer properties of some perylene‐based donor‐π‐acceptor systems for dye sensitized solar cell applications

We report DFT studies on some perylene‐based dyes for their electron transfer properties in solar cell applications. The study involves modeling of different donor‐π‐acceptor type sensitizers, with perylene as the donor, furan/pyrrole/thiophene as the π‐bridge and cyanoacrylic group as the acceptor. The effect of different π‐bridges and various substituents on the perylene donor was evaluated in terms of opto‐electronic and photovoltaic parameters such as HOMO‐LUMO energy gap, λ_max, light harvesting efficiency(LHE), electron injection efficiency (Ø_inject), excited state dye potential (E^dye*), reorganization energy(λ), and free energy of dye regeneration (). The effect of various substituents on the dye–I₂ interaction and hence recombination process was also evaluated. We found that the furan‐based dimethylamine derivative exhibits a better balance of the various optical and photovoltaic properties. Finally, we evaluated the overall opto‐electronic and transport parameters of the TiO₂‐dye assembly after anchoring the dyes on the model TiO₂ cluster assembly.     

Spermine‐Functionalized Perylene Bisimide Dyes—Highly Fluorescent Bola‐Amphiphiles in Water

A series of four spermine‐functionalized perylene bisimide dyes without linkers ( 1 ) and with linkers ( 2 – 4 ) between the chromophore and the polyamine was synthesized. Protonation of the spermine moieties resulted in the formation of highly water‐soluble dyes with up to six positively charged ammonium ions. The aggregation behavior of these strongly fluorescent bola‐amphiphiles was studied in pure water as solvent by UV/Vis and fluorescence spectroscopy, and an astonishingly high fluorescence quantum yield of up to Φ_fl=0.90 was observed for PBI 1 . Atomic force microscopy and transmission electron microscopy were applied for the visualization of the aggregates on surfaces. Molecular modeling studies were performed by force‐field calculations to explore the aggregate morphologies, which also provided valuable information on the influence of the additional alkylcarbonyl linkers. Our detailed spectroscopic and microscopic investigations revealed that the excellent optical properties of perylene bisimide chromophores can be used even in pure deionized water if their aggregation is efficiently suppressed.     

Perylene polyphenylmethylsiloxanes for optoelectronic applications

The incorporation of fluorescent organic dyes in an encapsulating matrix represents a route to generate stable and processable materials for optoelectronic devices. Here, we present a method to embed perylene dyes into a high refractive index (HRI) polysiloxane matrix applying an allyl functionalized perylene dye and hydrosilylation chemistry. In a first approach, the dye molecules were covalently integrated into the backbone of linear polyphenylmethylsiloxane chains. The fluorescent and liquid polymers were synthesized with molecular weights from 5660 up to 8400 g mol^?1. In a second approach, the dye itself was used as a cross‐linking agent between linear polyphenylmethylsiloxane chains. These preformed fluorescent batch polymers are liquids with dye concentrations between 0.025 and 8 wt %. The applied synthetic methods incorporated the dye covalently into the polymer structure and avoided the crystallization of the dye molecules and thus the formation of excimers, which would reduce the optical emission. The resulting products can be easily incorporated into curable commercially available HRI polyphenylmethylsiloxane resins. The formed materials are ideal LED encapsulants with a solid and flexible consistency, a uniform dispersion of the dyes, and adjustable mechanical properties, realized by changing the amount of perylene polymers. Further properties of the obtained materials are thermal stabilities up to 478 °C, quantum yields larger than 0.97, and high photostabilities. Thus, the covalent integration of dyes into polyphenylsiloxane structures represents a possible route for the stabilization of the organic dyes against the extreme irradiance and thermal conditions in LED applications. © 2019 The Authors. Journal of Polymer Science Part B: Polymer Physics published by Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 1062–1073     

Color Bricks: Building Highly Organized and Strongly Absorbing Multicomponent Arrays of Terpyridyl Perylenes on Metal Oxide Surfaces

Terpyridine‐substituted perylenes containing cyclic anhydrides in the peri position were synthesized. The anhydride group served as an anchor for assembly of the terpyridyl‐crowned chromophores as monomolecular layers on metal oxide surfaces. Further coordination with Zn²⁺ ions allowed for layer‐by‐layer formation of supramolecular assemblies of perylene imides on the solid substrates. With properly selected anchor and linker molecules it was possible to build high quality structures of greater than ten successive layers by a simple and straightforward procedure. The prepared films were stable and had a broad spectral coverage and high absorbance. To demonstrate their potential use, the synthesized dyes were employed in solid‐state dye‐sensitized solar cells, and electron injection from the perylene antennas to titanium dioxide was observed.     

Polyimide Dendrimers Containing Multiple Electron Donor–Acceptor Units and Their Unique Photophysical Properties

A high‐yielding synthesis of a series of polyimide dendrimers, including decacyclene‐ and perylene‐containing dendrimer D6 , in which two types of polyimide dyes are present, is reported. In these constructs, the branching unit is represented by trisphenylamine, and the solubilizing chains by N‐9‐heptadecanyl‐substituted perylene diimides. The photophysical properties of the dendrimers have been studied by absorption, steady‐state, and time‐resolved emission spectroscopy and pump–probe transient absorption spectroscopy. Photoinduced charge‐separated (CS) states are formed on the femtosecond timescale upon visible excitation. In particular, in D6 , two different CS states can be formed, involving different subunits that decays independently with different lifetimes (ca. 10–100 ps).     

Control of the Interactions in Multichromophores: Novel Concepts. Perylene Bis‐imides as Components for Larger Functional Units

The controlling of the internal interaction in multichromophores leads to functional dyes with novel properties. Such a controlling is demonstrated with perylene dyes and offers a manifold of novel possibilities.     

Bay‐Annulated Perylene Tetraesters: A New Class of Discotic Liquid Crystals

Selenium‐annulated perylene tetraesters that stabilize the hexagonal columnar phase have been synthesized and characterized, and their thermal and photophysical behavior has been determined. The mesophase range decreased with an increase in chain length. A comparative account of the structure–property relationships of this series of compounds with respect to parent perylene tetraesters, N‐ and S‐annulated perylene tetraesters, in terms of their thermal, photophysical and electrochemical behavior is provided. The bay‐annulation of perylene tetraesters is a good option to modify the thermal and photophysical properties of perylene derivatives and it can provide a new avenue for the synthesis of several technologically important self‐assembling perylene derivatives.     

New heterobicationic hemicyanine dyes: Synthesis,spectroscopic properties,and photoinitiating ability

This article describes the synthesis, spectroscopic properties, and free‐radical photoinitiation ability of new heterobicationic hemicyanine dyes. A new synthetic strategy for the preparation of unsymmetrical cyanine dyes has been developed, based on 2‐methylbenzothiazole derivative quaternization by 3‐pyridinium‐1‐bromopropane bromide and subsequent condensation of the resulting product with p‐(N,N‐dimethylamino)benzaldehyde. The tested dyes possess in one molecule two quaternary nitrogen atoms; that is, they are heterobicationic in nature. Novel hemicyanine dyes have been tested as visible‐light photoinitiators of vinyl monomer polymerization. Heterobicationic hemicyanine dyes paired with n‐butyltriphenylborate anions are very efficient photoinitiators of the free‐radical polymerization of trimethylolpropane triacrylate when irradiated with the visible emission of an argon‐ion laser. The photoinitiating abilities of the novel photoredox pairs are compared with the photoinitiation properties of their monocationic equivalent {3‐methyl‐2‐[4‐(N,N‐dimethylamino)styryl]benzothiazolium n‐butyltriphenylborate} as well as a Rose Bengal derivative (a typical triplet‐state photoinitiator). © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6345–6359, 2006     

Regioselective Functionalization of Core‐Persubstituted Perylene Diimides

Regioselective functionalization of core per‐substituted perylene diimides has been achieved efficiently based on a new versatile building block, named tetrabromotetrachloro‐perylene‐3,4:9,10‐tetracarboxylic acid dianhydride (Br₄Cl₄‐PTCDA), which affords a series of novel chromophores with impressive optoelectronic properties. Direct palladium‐catalyzed fourfold intramolecular ring fusion affords successfully unique propeller‐shaped biscarbazole[2,3‐b]carbazole diimides with six annulated rings.     

Photoinduced Electron Transfer in Perylene‐TiO2 Nanoassemblies

The photosensitization effect of three perylene dye derivatives on titanium dioxide nanoparticles (TiO₂ NPs) has been investigated. The dyes used, 1,7‐dibromoperylene‐3,4,9,10‐tetracarboxy dianhydride (1), 1,7‐dipyrrolidinylperylene‐3,4,9,10‐tetracarboxy dianhydride (2) and 1,7‐bis(4‐tert‐butylphenyloxy)perylene‐3,4,9,10‐tetracarboxy dianhydride (3) have in common bisanhydride groups that convert into TiO₂ binding groups upon hydrolysis. The different substituents on the bay position of the dyes enable tuning of their redox properties to yield significantly different driving forces for photoinduced electron transfer (P_eT). Recently developed TiO₂ NPs having a small average size and a narrow distribution (4 ± 1 nm) are used in this work to prepare the dye‐TiO₂ systems under study. Whereas successful sensitization was obtained with 1 and 2 as evidenced by steady‐state spectral shifts and transient absorption results, no evidence for the attachment of 3 to TiO₂ was observed. The comparison of the rates of P_eT (k_PeT) for 1‐ and 2‐TiO₂ systems studied in this work with those obtained for previously reported analogous systems, having TiO₂ NPs covered by a surfactant layer (Hernandez et al. [2012] J. Phys. Chem. B., 117, 4568–4581), indicates that k_PeT for the former systems is slower than that for the later. These results are interpreted in terms of the different energy values of the conduction band edge in each system.     

para‐Quinodimethane‐Bridged Perylene Dimers and Pericondensed Quaterrylenes: The Effect of the Fusion Mode on the Ground States and Physical Properties

Polycyclic hydrocarbon compounds with a singlet biradical ground state show unique physical properties and promising material applications; therefore, it is important to understand the fundamental structure/biradical character/physical properties relationships. In this study, para‐quinodimethane (p‐QDM)‐bridged quinoidal perylene dimers 4 and 5 with different fusion modes and their corresponding aromatic counterparts, the pericondensed quaterrylenes 6 and 7 , were synthesized. Their ground‐state electronic structures and physical properties were studied by using various experiments assisted with DFT calculations. The proaromatic p‐QDM‐bridged perylene monoimide dimer 4 has a singlet biradical ground state with a small singlet/triplet energy gap (?2.97 kcal mol^?1), whereas the antiaromatic s‐indacene‐bridged N‐annulated perylene dimer 5 exists as a closed‐shell quinoid with an obvious intramolecular charge‐transfer character. Both of these dimers showed shorter singlet excited‐state lifetimes, larger two‐photon‐absorption cross sections, and smaller energy gaps than the corresponding aromatic quaterrylene derivatives 6 and 7 , respectively. Our studies revealed how the fusion mode and aromaticity affect the ground state and, consequently, the photophysical properties and electronic properties of a series of extended polycyclic hydrocarbon compounds.     

Photoinduced Charge Separation in a Donor–Spacer–Acceptor Dyad with N‐Annulated Perylene Donor and Methylviologen Acceptor

The first donor–acceptor species in which a strongly emissive N‐annulated perylene dye is connected to a methylviologen electron acceptor unit via its macrocyclic nitrogen atom, is prepared by a stepwise, modular procedure. The absorption spectra, redox behavior, spectroelectrochemistry and photophysical properties of this dyad and of its model species are investigated, also by pump–probe fs transient absorption spectroscopy. Photoinduced oxidative electron transfer from the excited state of the dyad, centered on the N‐annulated perylene subunit, to the appended methyviologen electron acceptor takes place in a few ps. The charge‐separated species recombines in 19 ps. Our results indicate that N‐annulated perylene can be connected to functional units by taking advantage of the macrocyclic nitrogen, an option never used until now, without losing their properties, so opening the way to new designing approaches.     

Synthesis and Spectroscopic Characterization of Fluorophore‐Labeled Oligospiroketal Rods

Fluorescence probes consisting of well‐established fluorophores in combination with rigid molecular rods based on spirane‐type structures were investigated with respect to their fluorescence properties under different solvent conditions. The attachment of the dyes was accomplished by 1,3‐dipolar cycloaddition between alkynes and azides (‘click’ reaction) and is a prime example for a novel class of sensor constructs. Especially, the attachment of two (different) fluorophores on opposite sides of the molecular rods paves the way to new sensor systems with less bulky (compared to the conventional DNA‐ or protein‐based concepts), nevertheless rigid spacer constructs, e.g., for FRET‐based sensing applications. A detailed photophysical characterization was performed in MeOH (and in basic H₂O/MeOH mixtures) for i) rod constructs containing carboxyfluorescein, ii) rod constructs containing carboxyrhodamine, iii) rod constructs containing both carboxyfluorescein and carboxyrhodamine, and iv) rod constructs containing both pyrene and perylene parts. For each dye (pair), two rod lengths with different numbers of spirane units were synthesized and investigated. The rod constructs were characterized in ensemble as well as single‐molecule fluorescence experiments with respect to i) specific rod? dye and ii) dye? dye interactions. In addition to MeOH and MeOH/NaOH, the rod constructs were also investigated in micellar systems, which were chosen as a simplified model for membranes.     

Synthesis and Application of Rylene Imide Dyes as Organic Semiconducting Materials

Rylene imide dyes have been among the most promising organic semiconducting materials for several years due to their remarkable optoelectronic properties and high chemical/thermal stability. In the past decades, various excellent rylene imide dyes have been developed for optoelectronic devices, such as organic solar cells (OSCs) and organic field‐effect transistors (OFETs). Recently, tremendous progress of perylene diimides (PDIs) and their analogues for use in OSCs has been achieved, which can be attributed to their ease of functionalization. In this review, we will mainly focus on the synthetic strategies toward to latest PDI dyes and higher rylene imide analogues. A variety of compounds synthesized from different building blocks are summarized, and some properties and applications are discussed.     

Synthesis and Optical Properties of Water‐Soluble Polyglycerol‐Dendronized Rylene Bisimide Dyes

Four new water‐soluble polyglycerol‐dendronized perylene, terrylene, and quaterrylene bisimides have been synthesized and characterized with respect to their optical properties in polar organic solvents and water by using UV/Vis and fluorescence spectroscopy. All of these dyes were highly soluble in water, but the size of the chosen polyglycerol dendron was only sufficient to completely suppress dye aggregation for the core‐unsubstituted perylene derivative. Their high solubility in water and their absorption and emission wavelengths up to the NIR region make the core‐unsubstituted perylene and terrylene bisimides ideal candidates for applications in bioimaging, whilst the lack of fluorescence for quaterrylene bisimide in all polar solvents does not warrant further investigation of this chromophore in fluorescence and imaging applications. Likewise, tuning of the emission of rylene bisimides towards longer wavelengths by employing electron‐donating bay substituents is not a promising strategy, owing to the lower fluorescence quantum yields in polar solvents and, in particular, in water.     

Synthesis and characterization of colored EUDRAGIT® as enteric coating material

The synthesis of novel polymeric dyes by directly attaching toluidine blue O and MPPD via EDC and CDI coupling is described for polymers with enteric properties [poly(methacrylic acid‐co‐ethyl acrylate)]. The polymeric dyes are analyzed by SEC and UV/Vis measurements as well as investigated regarding their dissolution and permeation characteristics. Almost no changes between the modified and nonmodified polymer could be observed by conventional drug studies and a self‐established method for dissolution rates. Also no influence on the film formation properties was observed by SEM measurements. In vitro toxicity studies showed no increase of toxicity compared to the non modified polymer. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 2386–2393     

1,6‐ and 1,7‐Regioisomers of Dicyano‐Substituted Perylene Bisimides: Synthesis,Optical and Electrochemical Properties

In this study, 1,6‐ ad 1,7‐regioisomers of dicyano‐substituted perylene bisimides (1,6‐ C and 1,7‐ C ) were synthesized and successfully isolated from their regioisomeric mixture using conventional methods of separation, and subsequently characterized by 400 MHz ¹H NMR spectroscopy. This is the first time that the 1,6‐dicyanoperylene bisimide 1,6‐ C has been obtained in pure form. Moreover, the optical and electrochemical properties of 1,6‐ C and 1,7‐ C were found to be virtually the same. Time‐dependent density functional theory calculations performed on both dyes are reported in order to rationalize their electronic structures and optical properties.     

Investigation on Spectroscopic and Laser Properties of Pyrromethene and Perylene Chromophores in Elastic Polymeric Hosts

In this work, two types of chromophore i.e. the pyrromethene and perylene families dyes were doped into elastic polymeric host materials based on polydimethylsiloxane (PDMS), which had been widely employed in various applications. The solubilities, spectroscopic and laser properties of these dyes doped into PDMS matrices were systematically investigated. Tunable laser output with high conversion efficiencies and low laser thresholds were observed and calculated. The laser longevity of pyrromethene dyes doped in PDMS matrices could exceed 1 × 10⁵ pulses through a fast self‐recovery on the laser output with the elapse of aging time. The efficient and stable laser output of the dopants and the flexibility of the PDMS host provided the feasibility of such gain media as mechanically tunable laser sources, which might be employed as cost‐effective components on integrated bio‐chips.     

Synthesis and Photochromic Behavior of Novel Annelated 2H‐Chromenes Derived from Hydroxy‐9H‐xanthen‐9‐ones

The synthesis of four novel pyrano‐xanthenones derived from hydroxy‐9H‐xanthen‐9‐ones is described, and their photochromic properties in solution are reported. All compounds synthesized exhibit a good colorability, making them good potential dyes. The presence of the chromone system fused in the 7,8‐position seems to lead to more stabilized colored forms.