Bay-substituted Perylene Diimide Research Articles

Enhancing Oxygen Evolution: Novel Bay-Substituted Perylene Diimide Polymers with Phenol Groups as High-Performance Photocatalysts

Enhancing Oxygen Evolution: Novel Bay-Substituted Perylene Diimide Polymers with Phenol Groups as High-Performance Photocatalysts

Tailoring intersystem crossing of perylenediimide through chalcogen-substitution at bay-position: A theoretical perspective.

Molecular-scale design strategies for promoting intersystem crossing (ISC) in small organic molecules are ubiquitous in developing efficient metal-free triplet photosensitizers with high triplet quantum yield (ΦT). Air-stable and highly fluorescent perylenediimide (PDI) in its pristine form displays very small ISC compared to the fluorescence due to the large singlet-triplet gap (ΔES-T) and negligibly small spin-orbit coupling (SOC) between the lowest singlet (S1) and triplet state (T1). However, its ΦT can be tuned by different chemical and mechanical means that are capable of either directly lowering the ΔES-T and increasing SOC or introducing intermediate low-lying triplet states (Tn, n = 2, 3, …) between S1 and T1. To this end, herein, a few chalcogen (X = O, S, Se) bay-substituted PDIs (PDI-X2) are computationally modeled aiming at introducing geometrical-strain at the PDI core and also mixing nπ* orbital character to ππ* in the lowest singlet and triplet excited states, which altogether may reduce ΔES-T and also improve the SOC. Our quantum-chemical calculations based on optimally tuned range-separated hybrid reveal the presence of intermediate triplet states (Tn, n = 2, 3) in between S1 and T1 for all three PDI-X2 studied in dichloromethane. More importantly, PDI-X2 shows a significantly improved ISC rate than the pristine PDI due to the combined effects stemming from the smaller ΔES-T and the larger SOC. The calculated ISC rates follow the order as PDI-O2 < PDI-S2 < PDI-Se2. These research findings will be helpful in designing PDI based triplet photosensitizers for biomedical, sensing, and photonic applications.

Effect of Substituents at Imide Positions on the Laser Performance of 1,7-Bay-Substituted Perylenediimide Dyes

Perylenediimide (PDI) compounds with no substituents in their core are widely used as the active units of thin-film organic lasers. Recently, bay-substituted PDIs (b-PDIs) bearing two sterically hindering diphenylphenoxy groups at the 1,7-bay positions have received great attention because they show red-shifted emission with respect to bay-unsubstituted PDIs, while maintaining high photoluminescence (PL) quantum yields and low amplified spontaneous emission (ASE) thresholds even at high doping rates. However, their ASE photostability is relatively low compared to that of state-of-the-art PDIs. Thus, the design of b-PDIs with improved ASE photostability remains a challenge. Here, the synthesis of two b-PDIs with phenyl-type substituents at the imide positions is reported. Complete characterization of their optical properties, including absorption, PL, ASE, and transient spectroscopy, supported also by quantum chemical calculations, is performed with the dyes diluted in either a liquid solvent or a polystyrene film. Film experiments were accomplished at very low doping rates, to resemble the isolated molecule behavior, and also in a range of increasing doping rates, to investigate concentration quenching effects. The reported b-PDIs show improved ASE photostability (3-fold) with respect to b-PDIs with aliphatic-type substituents at the imide positions, whilst they show more propensity toward aggregation.

Bay-Substitution Effect of Perylene Diimides on Supramolecular Chirality and Optoelectronic Properties of Their Self-Assembled Nanostructures.

One-dimensional (1D) organic chiral supramolecules have received a great deal of attention for their promising applications in chiral recognition systems, chemical sensors, catalysts, and optoelectronics. Compared to modifications at the imide position of a perylene diimide (PDI), few studies have explored bay substitution of chiral PDIs and their self-assemblies into 1D nanomaterials. Herein, we describe the synthesis of three bay-substituted PDIs and explore the effects of bay substitution on supramolecular chirality by examining circular dichroism spectra and the optoelectronic performance of chiral PDI nanomaterials in phototransistors. Among the three fabricated self-assemblies, nanomaterials based on (R)-CN-CPDI-Ph exhibited the highest electron mobility of 0.17 cm2 V-1 s-1, a low threshold voltage of -1 V, and enhanced optoelectronic performance. For example, the photoresponsivity and external quantum efficiency of (R)-CN-CPDI-Ph assemblies were 4-fold higher than those of (R)-2Br-CPDI-Ph and (R)-2F-CPDI-Ph. All three nanomaterials exhibited fast switching speeds compared with previously reported N-substituted PDIs, suggesting that bay substitution can be an effective means of achieving rapid photoswitching. A comprehensive study using density functional theory calculations and crystal analyses revealed that the enhanced optoelectronic performance of (R)-CN-CPDI-Ph nanomaterials is related to the substitution of CN at the bay position of PDI. This minor change provides simultaneous improvements in electron injectability and structural order. Our findings demonstrate that bay substitution can significantly impact the self-assembly, supramolecular chirality, and optoelectronic properties of PDI nanomaterials.

INSIGHT INTO THE EFFECTS OF BAY-SUBSTITUENTS ON STABLE PERYLENE DIIMIDE RADICAL ANION SALTS

In previous work, the facile method to prepare perylene diimide radical anion salt by alkali treatment was reported. However, the effects of structure on synthetic process of perylene diimide radical anion salt, and the difference of response to Cu 2+ are not thoroughly understood. In this work, two bay-substituted perylene diimide derivatives radical anion salts have been synthesized and characterized in order to study the influence of the bay-substituted groups on the formation condition of the corresponding radical anion salt, and the sensitivity to Cu 2+. The result indicates that the perylene diimide with electron-donating groups (-O-Ph) at bay position was much easier to get the air-stable radical anion salts and had higher sensitivity to Cu 2+ compared to the perylene diimide with electron-withdrawing groups (-Br) at bay position.

Spectroscopic, electrochemical and electrocolorimetric properties of novel 2-(2′-pyridyl)-1H-benzimidazole appended bay-substituted perylene diimide triads

In this study, four new perylene diimide (PDI) derivatives incorporating 2-(2′-pyridyl)-1H-benzimidazole (2PBI) chromophores at the imide positions, in which 1 bearing non-bay-substituted perylene core, and those having four substituents at 1,6,7,12-bay positions of the perylene core, namely 2 bearing electron-withdrawing chlorine atoms, 3 bearing electron-donating 4-methoxyphenoxy groups and 4 bearing non-electron-donating 4-tert-butylphenoxy groups, respectively were synthesized and fully characterized by FT-IR, 1H NMR, 13C NMR, MALDI-TOF mass spectrometry and UV/Vis spectroscopy. The thermal properties were measured by thermogravimetric analysis (TGA) which showed that the materials (1-4) are thermally very stable (Td > 450 °C). DFT was performed for geometry optimizations, and TDDFT was used to compare the calculated and the experimental UV/Vis electronic spectra at the B3LYP/6–311 G(d) level. Detailed measurements were carried out by the use of electroanalytical, spectroscopic and colorimetric techniques in order to understand redox natures, color changes and optoelectronic characters of the novel compounds. These 2PBI-functionalized PDI triads showed reversible reduction processes, chemically stable reduced species and considerably low HOMO-LUMO band gaps, as the new worthy members of photoactive charge transport materials for optoelectronic and photovoltaic systems. In addition, with distinct color changes associated with their redox processes in the solution, these new triads displayed great capacity for application in electrochromic devices. The emission maxima of the compounds were found to be red shifted in the solid state.

7, 8-Dichlorobenzo[ghi]perylenetriimide: A versatile synthon for bay-substituted π-extended perylene dyes

Bay-substituted perylene diimide (PDI) dyes are a subject of great interest in both industrial and academic domains in the past decades. As important laterally extended derivatives of PDI dyes, benzo[ghi]perylenetriimides (BPTIs) have attracted much attention as non-fullerene acceptors, but their scope for applications has been limited by the lack of substitutions at the remaining two bay positions. Herein, we reported a facile synthesis of a novel, highly valuable synthon, 7, 8-dichlorobenzo[ghi]perylenetriimide (2), with two easy leaving chlorine groups at the remaining bay area, which can be further substituted by other functionalized groups through various synthetic strategies. Due to foreseeable applications of core-functionalized BPTIs, this unique synthon is anticipated to open up a fresh ground for optoelectronic materials.

Photothermal conversion performance of perylene diimide radical anion salts modified with tunable moieties

Among photothermal materials, perylene diimide radical anions were promising organic candidates with intense and characteristic near-infrared (NIR) absorption bands and non-fluorescence. Herein, two isolable and ambient stable bay-substituted perylene diimide radical anion salts, namely DBrPDI radical anion salt and TPPDI radical anion salt, were facilely prepared and confirmed by using a very thorough analysis based on the data from UV–Vis/NIR, FL, FTIR, EPR and NMR spectra. Subsequently, two radical anion salts were applied as photothermal conversion agents. DBrPDI radical anion salt exhibited high-performance photothermal conversion in DMF solutions, however a decline in aqueous solution. TPPDI radical anion salt with bulky moieties onto the PDI cores and amine position gave substantial evidence that the photothermal properties could be optimized and enhanced in aqueous solution by modulating the chemical structure of the photothermal conversion agent.

Synthesis and Self-Assembly of Bay-Substituted Perylene Diimide Gemini-Type Surfactants as Off-On Fluorescent Probes for Lipid Bilayers.

Interest in bay‐substituted perylene‐3,4:9,10‐tetracarboxylic diimides (PDIs) for solution‐based applications is growing due to their improved solubility and altered optical and electronic properties compared to unsubstituted PDIs. Synthetic routes to 1,12‐bay‐substituted PDIs have been very demanding due to issues with steric hindrance and poor regioselectivity. Here we report a simple one‐step regioselective and high yielding synthesis of a 1,12‐dihydroxylated PDI derivative that can subsequently be alkylated in a straightforward fashion to produce nonplanar 1,12‐dialkoxy PDIs. These PDIs show a large Stokes shift, which is specifically useful for bioimaging applications. A particular cationic PDI gemini‐type surfactant has been developed that forms nonfluorescent self‐assembled particles in water (“off state”), which exerts a high fluorescence upon incorporation into lipophilic bilayers (“on state”). Therefore, this probe is appealing as a highly sensitive fluorescent labelling marker with a low background signal for imaging artificial and cellular membranes.

Synthesis, characterization of bay-substituted perylene diimide based D-A-D type small molecules and their applications as a non-fullerene electron acceptor in polymer solar cells

Abstract We report a series of bay substituted perylene diimide based donor-acceptor-donor (D-A-D) type small molecule acceptor derivatives such as S-I, S-II, S-III and S-IV for small molecule based organic solar cell (SM-OSC) applications. The electron rich thiophene derivatives such as thiophene, 2-hexylthiophene, 2,2′-bithiophene, and 5-hexyl-2,2′-bithiophene were used as a donor (D), and perylene diimide was used as an acceptor (A). The synthesized small molecules were confirmed by FT-IR, NMR, and HR-MS. The small molecules showed wide and strong absorption in the UV-vis region up to 750 nm, which reduced the optical band gap to

Facile synthesis of an isolable and ambient stable bay-substituted perylene diimide radical anion salt and its optical response to base–acid and metal ions

An isolable and ambient stable bay-substituted perylene diimide adical anion salt was straightforwardly synthesized by base catalysis reduction of N,N-diethylhexyl-1,7-di(pentafluoro-phenoxyl) perylene diimide (DFPDI) in polar solvents, such as acetone, DMF, DMSO, NMP in yields of 48.7 %. Elemental analysis and 1H NMR, 13C NMR and EPR were carried out to confirm the formation of the compounds. Solvent-dependent cyclic voltammetries revealed the only condition for generating DFPDI radical anion in polar solvents—the reduction potential (DFPDI/DFPDI−) is more positive than −0.36 V (vs. Ag/AgCl). Redox studies revealed that DFPDI radical anion was not only ambient stable to moderate oxidants air (O2) and moisture for prolonged existence but also sensitive to strong oxidants-acid H+ and strong oxidization metal ions with low limit value.

1,7‐Bay‐Substituted Perylenediimide Derivative with Outstanding Laser Performance

Efficient ASE at wavelengths >620 nm from PS films doped with a bay-substituted perylenediimide (PDI) derivative is reported. The maximum PDI content is around 40 times larger than in prior studies. The ability to introduce large dye amounts into the film without photoluminescence (PL) quenching allows very high PL and ASE efficiencies with low thresholds. A distributed feedback (DFB) laser device using one of the best-performing films is fabricated and characterized.

Concentration effects on emission of bay-substituted perylene diimide derivatives in a polymer matrix

Reduction of emission quenching in a gain medium based on a dye-doped organic matrix at high doping concentrations is of crucial importance for achieving efficient lasing with a low threshold. In this study, concentration effects on emission properties of bay-substituted perylene diimide derivatives, considered to be promising for lasing application, are reported. Dynamics of emission spectra, quantum yield, lifetime, amplified spontaneous emission, amplified spontaneous emission threshold and photostability of the bromo-, 2,4-di(trifluoromethyl)phenyl- and 4-pyridyl-substituted perylene diimide derivatives in polystyrene films are explored in a wide range of diimide concentrations from 0.06 wt % to 8 wt %. For comparison, emission properties of an unsubstituted perylene diimide derivative are also investigated. An importance of the bay substitution in the perylene diimides is emphasized through i) reduction of emission concentration quenching, which allows for 3–4 times higher doping levels as compared to the doping with an unsubstituted perylene diimide, ii) observation of amplified spontaneous emission at one order of magnitude higher concentrations with reasonable thresholds (up to 200–300 kW/cm 2), and iii) high photostability, which is one order of magnitude higher than that of other bay-substituted perylene diimides and various organic compounds. The results imply potential of the perylene diimide substitution at the bay position for tailoring molecular packing and emission properties via steric hindrance effects, and suggest the bay-substituted perylene diimides may be useful as active media for lasing applications.

Effect of substituents on the electron transport properties of bay substituted perylene diimide derivatives

Electron donating substituents such as 3,4,5-trimethoxy phenyl (PDI1), thiophene (PDI2), 6-methoxy naphthyl (PDI3), 5-hexyl dithiophene (PDI4) and thioanthrenyl (PDI5) moieties incorporated at the bay region of N,N′-dodecylperylene diimide (PDI) derivatives have been synthesized and characterised. The absorption maxima of PDI1–5 showed a bathochromic shift with considerable peak broadening and merging of vibronic fine structure as compared to that of PDI. The photoinduced intramolecular charge transfer (ICT) from electron donating substituents to the perylene-acceptor has been observed from fluorescence self-quenching. The molecules are stable up to 400 °C and amorphous in nature. The cyclic voltammetry results revealed that the oxidation potential can be tuned by the electron donating capacity of the substituents and the dithiophene-attached perylene derivative (PDI4) showed a very low band gap of 1.57 eV. The electron transporting properties have been studied using xerographic time-of-flight method and the highest electron mobility reached up to 4.4 × 10−4 cm2V−1 s−1 at 6.4 × 105 V cm−1 for 1,7-di(3,4,5-trimethoxyphenyl)perylene diimide (PDI1) under ambient conditions.