Perylene Diimide Research Articles

Epitaxial growth of copper phthalocyanine on a large single-grain of thin film alkyl perylene diimide

In this work, heteroepitaxial growth of copper phthalocyanine (CuPc) on a large single-grain of thin film N,N’-Di-n-octyl-3,4,9,10-perylenetetracarboxylic diimide (PTCDI-C8) was investigated. Vacuum-deposited PTCDI-C8 thin films at a growth temperature of ∼180 °C exhibited large grain growth of several hundred micrometers or more in size, and their surface consisted of stripe islands with molecular steps. CuPc deposited at 180 °C on this PTCDI-C8 large grain underlayer was found to grow epitaxially with its needle-like crystals dominantly oriented in one unique direction. The mechanism of the observed epitaxy is discussed based on the results of in-plane X-ray diffraction and the initial growth morphology.

A Theoretical Investigation on the Properties of Charge Transport of Hexaazatrinaphthylene Derivatives

AbstractA hexaazatrinaphthylene [HAT] is a well‐known halogenated perylene diimide compound recognized for photochemical stability, high electron affinity, easy functionalization, and high conductivity. Based on density functional theory, optoelectronic and charge transport properties of HAT derivatives with electron‐donating, electron‐withdrawing, and push‐pull substituents, were investigated. The impact of substituting electron‐withdrawing groups (EWG), electron‐donating groups (EDG), and push‐pull substituents on various aspects, including molecular structure, frontier molecular orbitals, ionization energy, electron affinity, reorganization energy, crystal packing, and charge carrier mobility, is investigated. A crystal structure simulation method is employed to optimize potential arrangements of crystal packing for the molecules under examination. The presence of EWG, EDG, and push‐pull substitutions significantly affects the energy and distribution of electron density in the frontier molecular orbitals, leading to alterations in the absorption spectrum and charge transport properties. When adding various substituents to the core system, the different crystal packing motifs and varied intermolecular interactions of the examined molecules result in noticeably different transfer integrals. Due to higher hole reorganization energy and weak HOMO orbital overlapping, HAT derivative molecules exhibit better electron mobility. Among the studied molecules, HAT‐F and HAT‐F‐OCH3 molecules demonstrate better electron mobility with values of 0.49 and 2.36 cm2 V−1 s−1, respectively, and established the n‐channel characteristics.

Perylene diimide covalent organic frameworks super-reductant for visible light-driven reduction of aryl halides

In recent years, there has been a growing interest in the utilization of molecular photocatalysts in their radical ionic forms, especially as visible-light super-reductants. These catalysts exhibit remarkable capabilities in facilitating otherwise inert high-potential organic reactions, such as the reduction of aryl halides to aryl radicals. However, the development of heterogeneous super-reductants has lagged behind due to the deactivation effect caused by molecular aggregation. This study presents a novel approach to address this limitation by heterogenizing perylene diimides (PDIs) super-reductants with a consecutive photo-induced electron transfer mechanism into two-dimensional donor-acceptor (D-A) covalent organic frameworks (COFs). Both COFs, possessing D-A electronic structures and photothermal effects, demonstrated superior visible-light photocatalytic performance compared to their homogeneous counterparts. They achieved up to 99% conversion in the dehalogenation of aryl halides, primarily through a hydrogen atom trapping aryl radical mechanism. Additionally, we conducted a comparative investigation of the excited states of radical anionic D-A-type COFs and DPPDI using femtosecond transient absorption spectroscopy. Notably, the lifetimes of COFs were significantly prolonged, measuring 210 and 260 ps, respectively, compared to the 150 ps lifetime of (DPPDI•−). This study offers valuable insights into the design of efficient free radical ion-type photocatalysts, with potential applications in various chemical transformations.

Sn-fused perylene diimides: Synthesis, mechanism, and properties

The first example of metal Sn-fused perylene diimides (PDI) derivative (Sn-PDI) was designed, synthesized, and investigated. To obtain this type compound, a simple one-pot synthesis, named stannylative cycloaddition reaction, has been successfully developed via a palladium-based catalyst system. The novel mechanism exhibits that the reaction experiences oxidative addition, Pd-cyclization, stannylation, Pd-Sn-cyclization, and reductive elimination processes successively. This stannylative cycloaddition does realize unique σ-π hyperconjugation effect and therefore significantly influencing on the photophysical, electrochemical and excited state properties. Compared with those of PDI, both of the absorption and fluorescence spectra of Sn-PDI display large red-shifts over 20 nm. The electron energy levels of Sn-PDI have changed with an uncommon regulation. And Sn-PDI gives a considerably raised highest occupied molecular orbital (HOMO) level of -6.00 eV More importantly, the singlet excitons of Sn-PDI could efficiently intersystem cross (ISC) into triplet state with a long lifetime of 17.8 µs, which is far longer than that (4.4 ns) of PDI.

Polyoxometalate-dependent Photocatalytic Activity of Radical-doped Perylenediimide-based Hybrid Materials.

Inorganic-organic hybrid materials are a kind of multiduty materials with high crystallinity and definite structures, built from functional inorganic and organic components with highly tunable photochemical properties. Perylenediimides (PDIs) are a kind of strong visible light-absorbing organic dyes with π-electron-deficient planes and photochemical properties depending on their micro-environment, which provides a platform for designing tunable and efficient hybrid photocatalytic materials. Herein, four radical-doped PDI-based crystalline hybrid materials, Cl4-PDI⋅SiW12O40 (1), Cl4-PDI⋅SiMo12O40 (2), Cl4-PDI⋅PW12O40 (3), and Cl4-PDI⋅PMo12O40 (4), were attained by slow diffusion of polyoxometalates (POMs) into acidified Cl4-PDI solutions. The obtained PDI-based crystalline hybrid materials not only exhibited prominent photochromism, but also possessed reactive organic radicals under ambient conditions. Furthermore, all hybrid materials could be easily photoreduced to their radical anions (Cl4-PDI⋅-), and then underwent a second photoexcitation to form energetic excited state radical anions (Cl4-PDI⋅-*). However, experiments and theoretical calculations demonstrated that the formed energetic Cl4-PDI⋅-* showed unusual POM-dependent photocatalytic efficiencies toward the oxidative coupling of amines and the iodoperfluoroalkylation of alkenes; higher photocatalytic efficiencies were found for hybrid materials 1 (anion: SiW12O40 4-) and 2 (anion: SiMo12O40 4-) compared to 3 (anion: PW12O40 3-) and 4 (anion: PMo12O40 3-). The photocatalytic efficiencies of these hybrid materials are mainly controlled by the energy differences between the SOMO-2 level of Cl4-PDI⋅-* and the LUMO level of the POMs. The structure-photocatalytic activity relationships established in present work provide new research directions to both the photocatalysis and hybrid material fields, and will promote the integration of these areas to explore new materials with interesting properties.

Methylation of Si(111) Modulates Molecular Orientation in Perylenediimide Thin Films.

Singlet fission produces a pair of low-energy spin-triplet excitons from a single high-energy spin-singlet exciton. While this process offers the potential to enhance the efficiency of silicon solar cells by ∼30%, meeting this goal requires overlayer materials that can efficiently transport triplet excitons to an underlying silicon substrate. Herein, we demonstrate that the chemical functionalization of silicon surfaces controls the structure of vapor-deposited thin films of perylenediimide (PDI) dyes, which are prototypical singlet fission materials. Using a combination of atomic force microscopy (AFM) and grazing-incidence wide-angle X-ray scattering (GIWAXS), we find terminating Si(111) with either a thin, polar oxide layer (SiOx) or with hydrophobic methyl groups (Si-CH3) alters the structures of the resulting PDI films. While PDI films grown on SiOx are comprised of small crystalline grains that largely adopt an "edge-on" orientation with respect to the silicon surface, films grown on Si-CH3 contain large grains that prefer to align in a "face-on" manner with respect to the substrate. This "face-on" orientation is expected to enhance exciton transport to silicon. Interestingly, we find that the preferred mode of growth for different PDIs correlates with the space group associated with bulk crystals of these compounds. While PDIs that inhabit a monoclinic (P21/c) space group nucleate films by forming tall and sparse crystalline columns, PDIs that inhabit triclinic (P1̅) space groups afford films comprised of uniform, lamellar PDI domains. The results highlight that silicon surface functionalization profoundly impacts PDI thin film growth, and rational selection of a hydrophobic surface that promotes "face-on" adsorption may improve energy transfer to silicon.

Bay-Substitution of Perylene Bisimides with Bidentate Nucleophiles: The Case of Aryloxide Anions.

In this study, we delve into the regioselectivity of nucleophilic reactions involving brominated perylene bisimides (PBIs) and various bidentate aryloxide anions, previously associated with an SRN1 mechanism. We present herein a new perspective, suggesting that a single-electron-transfer aromatic nucleophilic substitution (SeT-SNAr) mechanism is a more plausible scenario. Our study reveals the favorable impact of photostimulation on reaction yields, making our method a convenient approach for accessing O-arylated PBIs.

Enhanced interfacial property and thermal conductivity of pitch-based carbon fiber/epoxy composites via three-layer assembly of PDI/GN/PDI interphase

Π-conjugate perylene diimide (PDI)/graphene (GN)/PDI interphase was designed and constructed on pitch-based carbon fiber (PCF) surface by multi-layer assembly, and the interfacial and thermal conductive performances of PCF/Epoxy (EP) composites with PDI, PDI/GN and PDI/GN/PDI interphase were investigated. Flat nanoscale structures with fragmented and wrinkled GN, PDI nanowires were respectively observed on PCF-GN, PCF-PDI/GN and PCF-PDI surface, while three-dimensional oblique cicada-wing nanostructure of three-layer interphase was constructed on PCF-PDI/GN/PDI surface due to the re-assembly of PDI under confinement constraint of GN substrate. Interlayer shear strength and transverse fiber bundle tensile strength of PCF-PDI/GN/PDI/EP composite were 28.4 %, 9.36 %, 12.0 % and 246 %, 85.8 %, 116 % higher than those of PCF-GN/EP, PCF-PDI/GN/EP and PCF-PDI/EP composites, which were attributed to the improvement of interface adhesion and the effectively buffer stress transfer between carbon fiber and resin matrix by introducing three-layer PDI/GN/PDI interphase. Additionally, PCF-PDI/GN/PDI/EP composites showed the highest heat conduction and thermal conductivity, ascribing to the construction of extra conductive paths and the weakening of phonons scattering from three-dimensional (3D) structure of PDI/GN/PDI interphase, which realized the formation of structure-function integration interphase of pitch-based carbon fiber composites.

Supramolecular Engineering of Ti3C2Tx MXene -Perylene Diimide Hybrid Electrodes for the Pseudocapacitive Electrochemical Storage of Calcium Ions.

The rare combination of metallic conductivity and surface redox activity enables 2D MXenes as versatile charge storage hosts for the design of high-rate electrochemical energy storage devices. However, high charge density metal ions including but not limited to Ca+2 and Mg+2 pose challenges such as sluggish solid-state diffusion and also inhibiting the charge transfer across electrode-electrolyte interfaces. In this work, free-standing hybrid electrode architectures based on 2D titanium carbide-cationic perylene diimide (Ti3C2Tx@cPDI) via supramolecular self-assembly are developed. Secondary bonding interactions such as dipole-dipole and hydrogen bonding between Ti3C2Tx and cPDI are investigated by zeta potential and Fourier-transformed infrared (FTIR) spectroscopy . Ti3C2Tx@cPDI free-standing electrodes show typical volumetric capacitance up to 260 F cm-3 in Mg2+ and Ca2+ aqueous electrolytes at charging times scales from 3minutes to a few seconds. Three-dimensional (3D) Bode maps are constructed to understand the charge storage dynamics of Ti3C2Tx@cPDI hybrid electrode in an aqueous Ca-ion electrolyte. ,Pseudocapacitance is solely contributed by the nanoscale distribution of redox-active cPDI supramolecular polymers across 2D Ti3C2Tx. This study opens avenues for the design of a wide variety of MXene@redox active organic charge hosts for high-rate pseudocapacitive energy storage devices.

Trifluoromethyl‐Substituted Perylene Diimides for Rapid and Sensitive Film‐Based Fluorescence Detection of Methamphetamine and Cocaine Hydrochloride

AbstractFilm‐based fluorescence sensors are attractive for rapid and on‐site detection of illicit drugs, due to their potential for portability, high sensitivity and reusability. Three new bay‐substituted perylene diimide derivatives are synthesized , P1‐CH3 (1‐methyl), P1‐CF3 (1‐trifluoromethyl), and P1‐(CF3)2 (1,7‐di‐trifluoromethyl) that can be solution processed into thin films capable of detecting methamphetamine hydrochloride (MA•HCl) and cocaine•HCl via a luminescence quenching mechanism. The ionization potentials of the materials are sufficiently high to enable photoinduced hole transfer to occur, which led to the luminescence quenching. The trifluoromethyl‐substituted PDIs exhibit superior sensitivity and reversibility of the luminescence quenching process. In particular, P1‐(CF3)2 shows a limit of detection to MA•HCl of ≈100 ng after a 15‐second exposure, and its luminescence can be fully recovered either through mild heating or being placed in an air flow. Furthermore, by using the luminescence quenching and recovery responses of four PDI sensing materials it is possible to differentiate MA•HCl, cocaine•HCl, from aspirin, caffeine, sugar, and (sebum) skin oil in around a minute.

Innenrücktitelbild: Molecular Engineering of Perylene Diimide Polymers with a Robust Built‐in Electric Field for Enhanced Solar‐Driven Water Splitting (Angew. Chem. 8/2024)

Innenrücktitelbild: Molecular Engineering of Perylene Diimide Polymers with a Robust Built‐in Electric Field for Enhanced Solar‐Driven Water Splitting (Angew. Chem. 8/2024)

Inside Back Cover: Molecular Engineering of Perylene Diimide Polymers with a Robust Built‐in Electric Field for Enhanced Solar‐Driven Water Splitting (Angew. Chem. Int. Ed. 8/2024)

Inside Back Cover: Molecular Engineering of Perylene Diimide Polymers with a Robust Built‐in Electric Field for Enhanced Solar‐Driven Water Splitting (Angew. Chem. Int. Ed. 8/2024)

Photothermal-assisted S-scheme PDIs/C, N, S-CeO2 derived from MOF-808 (Ce) heterojunction for photocatalytic removal of antibiotics

In this research, an organic supermolecule self-assembly perylene diimides (PDIs) semiconductor was wrapped around the surface of three-dimensional metal oxides frame (C, N, S-CeO2) by oil bath heating method. The photocatalytic ability was determined by the degradation of organic pollutants under visible light. The photodegradation rate of tetracycline (TC) was nearly 80.1% within 30 min, and the apparent reaction rate constant (k) was 15.83 times higher than that of C, N, S-CeO2. Free radical capture experiments and electron spin resonance analysis showed that •O2-, •OH and 1O2 were the main active species. The structure of PDIs/C, N, S-CeO2 maintained stable after four cycles, meanwhile, anti-ion interference experiment illustrated that degradation efficiency was not affected by neutral ionic intensity. Further, the formation pathways of main degradation intermediates during the degradation process and the toxicity prediction of degradation intermediates were proposed. In addition, 10% PDIs/C, N, S-CeO2 could also efficiently degrade other organic pollutants (chlorotetracycline (CTC), ciprofloxacin (CIP), rhodamine B (RhB), methylene blue (MB)). The excellent photocatalytic activity of 10% PDIs/C, N, S-CeO2 was attributed to the matched energy band structure, establishment of multi-dimensional channels, more significant visible light assimilation performance and enhanced photothermal ability. This work provides a new perspective on the construction of n-n S-scheme heterojunction photocatalysts between self-assembled organic supramolecular materials and MOF-derived metal oxides.

One-Step Cascade Synthesis of ortho-bay-Imidazolo-Extended Perylene Biscarboximides (OBISIM) and Their Application as Broad-Spectrum Fluorescent Dyes.

A one-step synthesis of perylene dyes with lateral extension by condensed imidazoles in a cascade reaction of sodium amide and benzonitrile is described in which multiple extensions can be controlled by the reaction conditions. The extensions lead to bathochromic shifts in absorption and fluorescence while maintaining high fluorescence quantum yields. The condensed imidazole units cause additional absorption bands in the hypsochromic visible region, resulting in broad-band absorbers. Multiple extensions of the aromatic system enable the NIR spectral approach of the spectra. Energy transfer (fluorescence resonance energy transfer, FRET) of dyads with perylene biscarboximides is very efficient and achieves quantum yields close to unity regardless of the lengths and orientation of the spacer. Applications as broad-band-absorbing fluorescent dyes, such as in solar collectors, are discussed.

Activation of persulfate by β-PDI/MIL-101(Fe) photocatalyst under visible light toward efficient degradation of sulfamethoxazole

Recently, the removal of antibiotics from wastewater has become increasingly important. Advanced oxidation processes (AOPs) combining persulfate (PS) activation and photocatalysis have been proven as a promising strategy for antibiotics degradation. For the first time, the β-alanine modified perylene diimide derivative (β-PDI) and MIL-101(Fe) were selected to create novel Z-scheme photocatalysts (MPx) by simple milling method based on the electrostatic attraction. The optimal MP50/PS/vis system could remove 99.7 % of SMX within 6 min and the MP50 displayed great recyclability and sustainability. The persulfate as electron scavenger not only inhibited the recombination of photogenerated electron-hole pairs but also generated additional SO4•-, thereby improving the efficiency of SMX degradation. The removal of SMX was simultaneously dependent on radicals (h+, O2•-, SO4•-, and •OH) and non-radical (1O2) pathways, and it is noteworthy that h+ played a major role. LC-MS was applied to investigate the degradation pathways and intermediates of SMX, their toxicities were further studied and the results showed that the MP50/PS/vis system was successful in reducing its biotoxicity and the risk of inducing potentially drug-resistant bacteria. This work provided profound insights into the mechanism of antibiotic degradation by persulfate activating-photocatalysis coupling AOPs.

Structurally Diverse Pyrene-decorated Planar Chiral [2,2]Paracyclophanes with Tunable Circularly Polarized Luminescence between Monomer and Excimer.

We reported the synthesis of a series of structurally diverse CPL-active molecules, in which pyrene units were installed to chiral pm/po-[2,2]PCP scaffolds either with or without a triple bond spacer for pm/po-PCP-P1 and pm/po-PCP-P2, respectively. The X-ray crystallographic analyses revealed that these pyrene-based [2,2]PCP derivatives exhibited diverse structures and crystal packings in the solid phases. The pyrene-based [2,2]PCP derivatives exhibit various (chir)optical properties in organic solutions, depending on their respective structures. In a mixture of dioxane and water, pm/po-PCP-P1 emit green excimer fluorescence, whereas pm/po-PCP-P2 emit blue one. The chiroptical investigation demonstrated that Rp-pm-PCP-P1 and Rp-pm-PCP-P2 exhibited completely opposite CD and CPL signals even they possess the same chiral Rp-[2,2]PCP core. The same argument also holds for other chiral pyrene-based [2,2]PCP derivatives. The theoretical calculation revealed that these unusual phenomena were attributed to different orientation between transition electric dipole moments and the magnetic dipole moments originating from the presence or absence of a triple bond spacer. These pyrene-based [2,2]PCP derivatives display various colours and fluorescence emissions in the solid state and PMMA films, possibly due to the different packings as observed in the crystal structure. Moreover, these compounds also can interact with perylene diimide through π-π interactions, leading to near-white fluorescence.

Synthesis and dark state EPR properties of PDI-trityl dyads and triads.

Covalently-linked chromophore-radical systems with their unique optical and magnetic properties are useful for applications in, e. g., quantum information science. To expand the catalog of molecular systems, we synthesized and characterized six novel chromophore-radical and radical-chromophore-radical systems employing derivatives of perylene diimide (PDI) as the chromophore and trityl as the radical. The EPR properties of these compounds were evaluated in solution at cryogenic and room temperatures. In addition, the electron spin-spin coupling in the two bistrityl systems was investigated using DQC measurements. The presented results serve as a basis for further spectroscopic investigations under photoexcitation of the PDI core.

Synthesis and Characterization of Bola-Amphiphilic Porphyrin-Perylenebisimide Architectures.

We report on the synthesis and characterization of a family of three water-soluble bola-amphiphilic zinc-porphyrin-perylenebisimide triads containing oligo carboxylic-acid capped Newkome dendrons in the periphery. Variations of the perylenebisimide (PBI) core geometry and dendron size (G1 and G2 dendrons with 3- and 9-carboxylic acid groups respectively) allow for tuning the supramolecular aggregation behavior with respect to variation of the molecular architecture. The triads show good solubility in basic aqueous media and aggregation to supramolecular assemblies. Theoretical investigations at the DFT level of theory accompanied by electrochemical measurements unravel the geometric and electronic structure of the amphiphiles. UV/Vis and fluorescence titrations with varying amounts of THF demonstrate disaggregation.

Detection of basic amino acids under highly alkaline conditions using a perylene amine-derived probe

pH plays a crucial part in numerous chemical and physiological processes. In this work, a new perylene diimide derivative that acts as a pH-sensitive dye with Bay Area Carboxylic Acid functionality. The derivative utilizes the outstanding thermal, chemical and photochemical stability found in PDI materials and has remarkable UV–visible absorption and fluorescence emission qualities. Based on these properties, a fluorescent probe (PCA) was synthesised using a perylene tetracarbodiimide (PDI) backbone for the recognition of alkaline pH. In alkaline environments where the pH values are between 10 and 14, the fluorescence intensity significantly decreases, and a blue shift occurs, which is a standard feature of alkaline pH probes. The probe demonstrates exceptional sensing ability within the pH range of 10.00–14.00, with notable stability and reversibility. Encapsulation of the probe in a thin polymer film material enhances the pH sensing capability of the system. New sensor has been developed to detect basic amino acids by utilizing the probes' pH response characteristics. this sensor has also been applied to detect the concentration of arginine.

Energy landscape of perylenediimide chromophoric aggregates.

Understanding the self-assembly of conjugated organic materials at the molecular level is crucial in their potential applications as active components in electronic and optoelectronic devices. The type of aggregation significantly influences the intriguing electronic and optical characteristics differing from their constituent molecules. Perylenediimides (PDIs), electron-deficient molecules exhibiting remarkable n-type semiconducting properties, are among the most explored organic fluorescent materials due to their high fluorescence efficiency, photostability, and optoelectronic properties. PDI derivatives are reported to form well-tailored supramolecular architectures: cofacial with minor slip (H-aggregates), staggered with major slip (J-aggregates), magic angle stacking (M-aggregates), rotated (X-aggregates), rotated orthogonal ((+)-aggregates), etc. H*-aggregates are defined here as an ideal case of H-aggregate with an eclipsed configuration. Although numerous reports regarding the formation and optical properties of various PDI aggregates are known, the key driving force within the PDI units guiding the self-assembly to form distinct aggregate systems remains elusive. To unravel the molecular-level mechanisms behind the self-assembly of PDI units by probing the intermolecular interactions, symmetry-adapted perturbation theory-based energy decomposition, potential energy surface scans, and non-covalent interaction index analyses were employed on PDI dimer models. Quantum theory of atoms in molecules and frontier molecular orbital analyses were implemented on the dimer models to comprehend the effect of heteroatoms and orbital interactions in stabilising the X-aggregates over the other PDI aggregate systems. Competition between the attractive and repulsive non-covalent interactions dictates a stability order of X > H > J > M > (+) > H* for the PDI aggregate system, while in the parent perylene system, the stability order was found to be X > (+) > H > M > J > H*.