Perylene Diimide Research Articles

End-to-End Bent Perylene Bisimide Cyclophanes by Double Sulfur Extrusion.

Bending inherently planar π-cores consisting of only six-membered rings has traditionally been challenging because a powerful transformation is required to compensate for the significant strain energy associated with bending. Herein, we demonstrate that sulfur extrusion can achieve substantial molecular bending of a perylene structure to form a substructure of a Vögtle belt, a proposed yet hitherto elusive carbon nanotube fragment. Bent perylene bisimide (PBI) derivatives were synthesized through a double-sulfur-extrusion reaction from the corresponding sulfur-containing V-shaped precursors with an internal alkyl tether. The effect of bending the inherently planar PBI core, which is a recent topic of interest for the design of advanced organic electronic and optoelectronic materials, was investigated systematically. Increasing the curvature leads to a red shift in the absorption and emission spectra, while the fluorescence quantum yields remain high. This stands in contrast with the nonemissive features of previously reported nonplanar PBI derivatives based on conjugative tethers. Detailed photophysical measurements indicated that the increasing curvature with shorter alkyl tethers (i) slightly facilitates intersystem crossing and (ii) significantly suppresses the internal conversion in the excited state of the present bent PBI derivatives. The latter characteristics originate from the restricted dynamic motion associated with the charge-transfer (CT) character between the core chromophores and the N-aryl units.

Synthesis of Thionated Perylenediimides: State of the Art and First Investigations of an Alternative to Lawesson's Reagent.

Perylenediimides (PDIs) are composed of a central perylene ring, on which are grafted two imide groups at the peri positions. Thionated PDIs are characterized by the substitution of one or more oxygen atoms of these imide functions with sulfur atoms. This structural modification alters the electronic properties with a redshift of the optical absorption accompanied by modification of the charge transport characteristics compared to their non-thionated counterparts. These properties make them suitable candidates for applications in optoelectronic devices, such as organic light-emitting diodes and organic photovoltaics. Moreover, the presence of sulfur atom(s) can favor the promotion of reactive oxygen species production for photodynamic and photothermal therapies. These thionated PDIs can be synthesized through the post-functionalization of PDIs by using a sulfurizing reagent. Nevertheless, the main drawbacks remain the difficulties in adjusting the degree of thionation and obtaining tri- and tetrathionated PDIs. Up to now, this thionation reaction has been described almost exclusively using Lawesson's reagent. In the current study, we present our first investigations into an alternative reagent to enhance selectivity and achieve a greater degree of thionation. The association of phosphorus pentasulfide with hexamethyldisiloxane (Curphey's reagent) clearly demonstrated higher reactivity compared with Lawesson's reagent to attain multi-thionated PDIs.

A perylene diimide probe for NIR-II fluorescence imaging guided photothermal and type I/type II photodynamic synergistic therapy

Phototherapy has garnered significant attention in the past decade. Photothermal and photodynamic synergistic therapy combined with NIR fluorescence imaging has been one of the most attractive treatment options because of the deep tissue penetration, high selectivity and excellent therapeutic effect. Benefiting from the superb photometrics and ease of modification, perylene diimide (PDI) and its derivatives have been employed as sensing probes and therapeutic agents in the biological and biomedical research fields, and exhibiting excellent potential. Herein, we reported the development of a novel organic small-molecule phototherapeutic agent, PDI-TN. The absorption of PDI-TN extends into the NIR region, which provides feasibility for NIR phototherapy. PDI-TN overcomes the traditional Aggregation-Caused Quenching (ACQ) effect and exhibits typical characteristics of Aggregation-Induced Emission (AIE). Subsequently, PDI-TN NPs were obtained by using an amphiphilic triblock copolymer F127 to encapsulate PDI-TN. Interestingly, the PDI-TN NPs not only exhibit satisfactory photothermal effects, but also can generate O2•- and 1O2 through type I and type II pathways, respectively. Additionally, the PDI-TN NPs emit strong fluorescence in the NIR-II region, and show outstanding therapeutic potential for in vivo NIR-II fluorescence imaging. To our knowledge, PDI-TN is the first PDI derivative used for NIR-II fluorescence imaging-guided photodynamic and photothermal synergistic therapy, which suggests excellent potential for future biological/biomedical applications.

Tuning Structure and Properties of a Ferromagnetic Organic Semiconductor via a Magnetic Field-Modified Reduction Process

The development of novel synthesis and assembly strategies is critical to achieving a ferromagnetic organic semiconductor with high Curie temperature. In this study, we report a high magnetic field (HMF)-modified solvothermal approach for the reduction in neutral perylene diimide (PDI) into the dianion species to prepare the PDI magnets comprising radical anions after subsequent oxidation processes. The PDI materials, assembled from the dianion solution by an HMF-modified reduction, exhibit a smaller crystallite size and an enlarged distance of the π-π stacking in the PDI aggregates. Furthermore, the PDI magnets obtained from the process under a 9T field reveal weakened ferromagnetism and the rapid degradation of electrical conductivity compared to those prepared without a magnetic field. Based on spectral and structural characterizations, such performance deterioration originates from the enhanced instability of the radical anions exposed to air, as well as the decreased crystallinity for the radical PDIs synthesized from the HMF-modified reduction process. This work demonstrates that magnetic fields offer an effective way in the material synthesis process to manipulate the structure and magnetic properties of the radical-based organic magnets.

Reinforcing Carrier‐Free Photothermal Nanodrugs Through Flavonol‐Driven Assembly

AbstractCarrier‐free nanodrugs that integrate chemodrugs and other therapeutic agents demonstrate good efficacy and minimized side effects, showing promise for combined therapy. However, a key challenge lies in enhancing the bioavailability and therapeutic potential of the nanodrugs through a controllable assembly process. Herein, a carrier‐free photothermal nanodrug (ZPQ NPs) is constructed through flavonol‐driven assembly with amine‐substituted perylene diimide for enhanced chemo‐photothermal combined cancer therapy. The flavonol, particularly quercetin, facilitates J‐aggregation of perylene diimide derivatives within the nanodrug and contributes to multiple improvements, including red‐shifted absorption, enhanced fluorescence intensity, improved photothermal conversion efficiency as well as excellent photostability. Moreover, the nanodrug also demonstrates enhanced cellular uptake and intracellular reactive oxygen species scavenging capability. The combination of quercetin and photothermal effect effectively kills cancer cells, as well as alleviates inflammation following photothermal therapy. Guided by in vivo fluorescence imaging, the application of ZPQ NPs results in complete tumor elimination and effectively inhibits tumor recurrence through chemo‐photothermal combined therapy. This work presents a straightforward strategy for constructing carrier‐free nanodrugs that exhibit simultaneous enhancements in both photophysical properties and biological activity.

Role of Intragap States in Sensitized Sb-Doped Tin Oxide Photoanodes for Solar Fuels Production.

In view of developing photoelectrosynthetic cells which are able to store solar energy in chemical bonds, water splitting is usually the reaction of choice when targeting hydrogen production. However, alternative approaches can be considered, aimed at substituting the anodic reaction of water oxidation with more commercially capitalizable oxidations. Among them, the production of bromine from bromide ions was investigated long back in the 1980s by Texas Instruments. Herein we present optimized perylene-diimide (PDI)-sensitized antimony-doped tin oxide (ATO) photoanodes enabling the photoinduced HBr splitting with >4 mA/cm2 photocurrent densities under 0.1 W/cm2 AM1.5G illumination and 91 ± 3% faradaic efficiencies for bromine production. These remarkable results, among the best currently reported for the photoelectrochemical Br- oxidation by dye sensitized photoanodes, are strongly related to the occupancy extent of ATO's intragap (IG) states, generated upon Sb-doping, as demonstrated by comparing their performances with PDI-sensitized analogues on both undoped SnO2- and TiO2-passivated ATO scaffolds by means of (spectro)electrochemistry and electrochemical impedance spectroscopy. The architecture of the ATO-PDI photoanodic assembly was further modified via the introduction of a molecular iridium-based water oxidation catalyst, thus proving the versatility of the proposed hybrid interfaces as photoanodic platforms for photoinduced oxidations in PEC devices.

Synthesis of Perylene Diimide Modified by POSS and its Assembly Behavior in Solution and SBS Matrix

In this work, Perylene diimide derivatives 1,7- POSS-PDI-C12 (PPC) were synthesized using 1,7-Br-PDI- C12, 18-crown-6 ether as phase transfer agent, K2CO3 as catalyst and THF as solvent in a reaction system. Subsequently, the POSS-SH group was successfully introduced into the perylene imide bay site in high yield. The chemical structure and molecular weight of the products were characterized by 1H-NMR, 13C-NMR, MALDI-TOF MS and FT-IR. The self-assembly behavior in different solvents was studied using the research solution self-assembly method. PPC remained in a single monomolecular state due to the bulky POSS group, which introduced large steric hindrance in the molecular packing, leading to the weakening of the π–π interactions. Then, the Composite thin films containing PPC in SBS was prepared. PPC do not exhibit significant force-chromic behavior owing to the dispersion of single- molecule states. This shows that in the construction of mechanochromic materials, chromophore molecules need to have a certain degree of aggregation in the matrix, but the aggregation degree should not be too high.

Self-Aggregation, Enhanced Guest-Binding Behavior, and Anion-Induced Agglutination of Cyclophane Dimers Linked with Florescent Perylene Diimide.

Cationic, anionic, and nonionic cyclophane dimers, 1a, 1b, and 1c, covalently linked with fluorescent perylene diimide were synthesized, respectively, as a host for aggregation-induced multivalent effects on guest-binding. These PDI-linked cyclophane dimers 1a and 1b, especially 1c, formed self-aggregates in H2O-rich solvents through π-stacking interactions. Critical aggregation concentrations of 1a, 1b, and 1c in H2O were 4.0 × 10-6, 4.0 × 10-6, and less than 0.1 × 10-6 M, respectively. The self-aggregates of the PDI-linked cyclophane dimers in H2O were several hundred nanometers in size by DLS and TEM measurements. In an aggregated state, 1a exhibited guest-binding abilities toward hydrophobic guests, such as 6-p-toluidinonaphthalene-2-sulfonate and 6-anilino-naphthalene-2-sulfonate. Moreover, anion-induced agglutination of 1a was observed upon the addition of phosphate ions, and its effectiveness was as follows: ATP > ADP > H2P2O72- > AMP ≈ PO43- > HPO42- > H2PO4-. The contribution of the adenine base of the nucleotides as a guest moiety used for effective agglutination was confirmed by 1H NMR spectroscopy.

Crystallization-driven tuneable lasing of perylene doped into the nematic liquid crystal

Versatile devices with tunable capabilities for controlling lasing wavelength and intensity are in high demand. Liquid crystals (LCs) exhibit immense potential for such applications, offering fine-tuning possibilities through external factors. On the other hand, laser technology is currently a research hotspot in optoelectronics, and also in practical applications. The recent market introduction of laser television marks a significant stride toward making such advanced technology accessible in every household. In synergy with laser pumping, the LCs unquestionably can be rediscovered. This study presents a comprehensive investigation into the crystallization phenomenon within a host-guest device, compact in size, free from moving parts, and integrating the liquid crystalline (LC) matrix doped with 3,4,9,10-tetra-(3-alcoxy-carbonyl)-perylene (THCP) dye. The focus lies in examining the influence of varying dye concentrations on multicolor fluorescence, lasing behavior, and device morphology. The systematic analysis of Random Lasing (RL) energy thresholds and the impact of DC voltage on light intensity modulation is demonstrated. Morphological changes were monitored in real-time using optical microscopy techniques, including crossed polarizer, and fluorescence imaging under 450 nm excitation. Utilizing advanced Transmission Electron Microscopy (TEM) techniques, we explore exceptional insights into our set of devices, providing novel information about the THCP crystallization process for the first time in the literature. To gain a comprehensive understanding of the crystal forming and molecular geometry we examined additionally the THCP dye, using X-ray diffraction and Raman spectroscopy. Furthermore, we showcase that varying the pumping energy enables multicolor tuning in the fabricated systems, presenting an attractive feature in the context of laser display technologies.

Efficient Electron Transfer Driven by Excited-State Structural Relaxation in Corrole-Perylenedimiide Dyad.

A sterically encumbered trans-A2B-corrole possessing a perylenediimide (PDI) scaffold in close proximity to the macrocycle has been synthesized via a straightforward route. Electronic communication as probed via steady-state absorption or cyclic voltammetry is weak in the ground state, in spite of the corrole ring and PDI being bridged by an o-phenylene unit. The TDDFT excited-state geometry optimization suggests after excitation the interchromophoric distance is markedly reduced, thus enhancing the through-space electronic coupling between the corrole and the PDI. This is corroborated by the strong deviation of the emission spectrum originating from both PDI and corrole in the dyad. Selective excitation of both donor and acceptor units triggers efficient sub-picosecond electron transfer and hole transfer, respectively, followed by fast charge recombination. In comparison to previously studied corrole-PDI dyads, both charge separation and charge recombination occur faster, because of the structural relaxation in the excited state.

Fluorescence Turn-on Detection of Perfluorooctanoic Acid (PFOA) by Perylene Diimide-Based Metal-Organic Framework.

A novel, water-stable, perylene diimide (PDI) based metal-organic framework (MOF), namely, U-1, has been synthesized for selective and sensitive detection of perfluorooctanoic acid (PFOA) in mixed aqueous solutions. The MOF shows highly selective fluorescence turn-on detection via the formation of a PFOA-MOF complex. This PFOA-MOF complex formation was confirmed by various spectroscopic techniques. The detection limit of the MOF for PFOA was found to be 1.68 μM in an aqueous suspension. Upon coating onto cellulose paper, the MOF demonstrated a significantly lower detection limit, down to 3.1 nM, which is mainly due to the concentrative effect of solid phase extraction (SPE). This detection limit is lower than the fluorescence sensors based on MOFs previously reported for PFAS detection. The MOF sensor is regenerable and capable of detecting PFOA in drinking and tap water samples. The PDI-MOF-based sensor reported herein represents a novel approach, relying on fluorescence turn-on response, that has not yet been thoroughly investigated for detecting per- and polyfluoroalkyl substances (PFAS) until now.

Insight into bay-/end-substituted perylene diimide and its S-scheme heterojunction for enhanced photocatalytic H2O2 production under visible-light irradiation

Here, 1D bis(N-carboxymethyl) peryleneimide (H2PDI), 0D 1,6,7,12-tetrachloro-bis(N-carboxymethyl) peryleneimide (4Cl-H2PDI), and 2D 4Cl-H2PDI/graphene quantum dot (4Cl-H2PDI/GQD) nanostructures are synthesized and carefully analyzed. The effect of bay-/end-substitution and S-scheme heterojunction of PDI-based materials as main catalysts on the photocatalytic H2O2 evolution is first studied through the oxygen reduction reaction (ORR). Under the visible-light irradiation (> 420 nm), 4Cl-H2PDI and 4Cl-H2PDI/GQD as photocatalysts exhibit the ∼7 and ∼16 times H2O2 evolution rate than H2PDI (1059.6 vs. 2484.0 vs. 160.0 µM g−1 h−1), respectively. The systematical experiments reveal that 4Cl-H2PDI and 4Cl-H2PDI/GQD should prefer a two-step single-electron ORR process, while H2PDI may involve a 4e‒ water oxidation and one-step 2e‒ ORR process. Further experiments confirm that the bay-substitution and GQD doping of H2PDI can promote the generation, transportation, and separation of photogenerated electrons and holes, and prolong the carrier lifetime. This work provides insight into PDI-based photocatalytic H2O2 production.

Probing Excited State Delocalization and Charge Separation in Hierarchical Perylene Diimide Materials with Time-Resolved Broadband Microscopy

Probing Excited State Delocalization and Charge Separation in Hierarchical Perylene Diimide Materials with Time-Resolved Broadband Microscopy

Dynamic two-dimensional covalent organic frameworks.

Porous covalent organic frameworks (COFs) enable the realization of functional materials with molecular precision. Past research has typically focused on generating rigid frameworks where structural and optoelectronic properties are static. Here we report dynamic two-dimensional (2D) COFs that can open and close their pores upon uptake or removal of guests while retaining their crystalline long-range order. Constructing dynamic, yet crystalline and robust frameworks requires a well-controlled degree of flexibility. We have achieved this through a 'wine rack' design where rigid π-stacked columns of perylene diimides are interconnected by non-stacked, flexible bridges. The resulting COFs show stepwise phase transformations between their respective contracted-pore and open-pore conformations with up to 40% increase in unit-cell volume. This variable geometry provides a handle for introducing stimuli-responsive optoelectronic properties. We illustrate this by demonstrating switchable optical absorption and emission characteristics, which approximate 'null-aggregates' with monomer-like behaviour in the contracted COFs. This work provides a design strategy for dynamic 2D COFs that are potentially useful for realizing stimuli-responsive materials.

Noncovalent synthesis of homo and hetero-architectures of supramolecular polymers via secondary nucleation

The synthesis of supramolecular polymers with controlled architecture is a grand challenge in supramolecular chemistry. Although living supramolecular polymerization via primary nucleation has been extensively studied for controlling the supramolecular polymerization of small molecules, the resulting supramolecular polymers have typically exhibited one-dimensional morphology. In this report, we present the synthesis of intriguing supramolecular polymer architectures through a secondary nucleation event, a mechanism well-established in protein aggregation and the crystallization of small molecules. To achieve this, we choose perylene diimide with 2-ethylhexyl chains at the imide position as they are capable of forming dormant monomers in solution. Activating these dormant monomers via mechanical stimuli and hetero-seeding using propoxyethyl perylene diimide seeds, secondary nucleation event takes over, leading to the formation of three-dimensional spherical spherulites and scarf-like supramolecular polymer heterostructures, respectively. Therefore, the results presented in this study propose a simple molecular design for synthesizing well-defined supramolecular polymer architectures via secondary nucleation.

Molecular Docking Study of Binding of Perylene Di-imide to a Bio Molecular Human Telomeric G-quadruplex

Human telomeres are comprised of d(TTAGGG) repeats involved in the formation of G-quadruplex DNA structures. Ligands stabilizing these G-quadruplex DNA structures are potential inhibitors of the cancer cell-associated enzyme telomerase. In human cells , telomerase adds multiple copies of the 5’-GGTTAG-3’ motif to the end of the G-strand of the telomere and in the majority of tumor cells it results over-expressed. Several structural studies have revealed a diversity of topologies for telomeric quadruplexes, which are sensitive to the nature of the cations present, to the flanking sequences, and probably also to concentration, as confirmed by the different conformations deposited in the Protein Data Bank (PDB). The existence of different polymorphism in the DNA quadruplex and the absence of a uniquely precise binding site give rise to check docking approach . As target we have selected six different experimental models of the human telomeric sequence d[AG3(T2AG3)3] based on three G-tetrads and as ligands the perylene di-imide . We checked out molecular docking simulation of binding of perylene di-imide to a slected G-quadruplex using dock 6.9 to examine whether or not to reproduced the loop binding mode of perylene di-imide. The simulation gave the two highest rank docking pose of perylene di-imide and the binding mode were external stacking on the terminal guanine tetrade and the groove binding.

Self-Assembly Behavior, Aggregation Structure, and the Charge Carrier Transport Properties of S-Heterocyclic Annulated Perylene Diimide Derivatives.

The construction of high-performance n-type semiconductors is crucial for the advancement of organic electronics. As an attractive n-type semiconductor, molecular systems based on perylene diimide derivatives (PDIs) have been extensively investigated over recent years. Owing to the fascinating aggregated structure and high performance, S-heterocyclic annulated PDIs (SPDIs) are receiving increasing attention. However, the relationship between the structure and the electrical properties of SPDIs has not been deeply revealed, restricting the progress of PDI-based organic electronics. Here, we developed two novel SPDIs with linear and dendronized substituents in the imide position, named linear SPDI and dendronized SPDI, respectively. A series of structural and property characterizations indicated that linear SPDI formed a long-range-ordered crystalline structure based on helical supramolecular columns, while dendronized SPDI, with longer alkyl side chains, formed a 3D-ordered crystalline structure at a low temperature, which transformed into a hexagonal columnar liquid crystal structure at a high temperature. Moreover, no significant charge carrier transport signal was examined for linear SPDI, while dendronized SPDI had a charge carrier mobility of 3.5 × 10-3 cm2 V-1 s-1 and 2.1 × 10-3 cm2 V-1 s-1 in the crystalline and liquid crystalline state, respectively. These findings highlight the importance of the structure-function relationship in PDIs, and also offer useful roadmaps for the design of high-performance organic electronics for down-to-earth applications.

Brominated Quaternary Ammonium Salt-Assisted Hybrid Electron Transport Layer for High-Performance Conventional Organic Solar Cells.

Interlayer engineering is crucial for achieving efficient and stable organic solar cells (OSCs). Herein, by introducing a commercialized brominated quaternary ammonium salt, hexamethonium bromide (HB), into a perylene diimide (PDI)-structured electron transport layer (ETL), a PDINN:HB hybrid ETL with enhanced charge collection ability and environmental/operational stability is realized. Molecular dynamics simulations and Kelvin probe force microscopy indicate that strong polar bromine and amine groups can form extra interfacial dipoles in the hybrid interlayer, while X-ray photoelectron spectroscopy and electron paramagnetic resonance suggest the hybrid ETL can interact with the Ag cathode, thereby regulating the energy level arrangement at the interface. As for the results, the PDINN:HB hybrid ETL enables improved power conversion efficiency (PCE) from 17.8 to 18.4% and 18.8 to 19.4% in PM6:C5-16 bulk heterojunction- and PM6/L8-BO pseudobulk heterojunction-based OSCs, respectively. The versatility of this method is further verified by introducing a range of brominated quaternary ammonium salts into PDINN, in which a superior PCE and stability are all obtained compared to the reference device.

Quaternization of porphyrin conjugated organic polymer as an effective photocatalyst for fast degradation of 2,4-D and BPA

Conjugated organic polymers (COPs) originating from porphyrin and perylene bisimide exhibit promising capacity as photocatalysts benefiting from their inherent semiconducting characteristics, but most of them suffer from the hydrophobic properties, which strongly hinder their surface reactions and photocatalytic performance. To solve this problem, the quaternary ammonium groups were introduced into the porous skeleton of a COP-based photocatalyst (PDIN-Py) through Friedel-Crafts alkylation & Menschutkin reactions to yield a super-hydrophilic COP, denoted as PDIN-PyN+. Apart from the hydrophilicity, such post-modification strategy also enhances the visible light utilization, boosts the photogenerated carriers transport and endows PDIN-PyN+ with more positive zeta potential (21.9 mV), thus enhancing the electrostatic interaction with target anionic model pollutants including bisphenol A (BPA) and 2,4-dichlorophenoxyacetic acid (2,4-D) and improving the photocatalytic degradation performance. The removal efficiency (η) of PDIN-PyN+ towards 2,4-D (150 ppm) and BPA (20 ppm) can reach >99 % within 30 min under the irradiation of visible light, and the PDIN-PyN+ also exhibits excellent reusability and withstands various environmental influencing factors, thereby it shows great potential in real-water treatment scenarios.

Sulfur-substituted perylenediimides: Easy tunability of the electronic character

Perylenediimides (PDIs) are the focus of a huge number of research lines for their awesome properties which can be modulated over a wide range by chemical modification of their structure. However, industrial applications require reduced costs in materials preparation and transformation. In this contribution we explore the ability of sulfur-substituted PDIs to vary their electronic character from strong electron-donating to strong electron-accepting in just one reaction.