Microwave-Assisted Method for the Synthesis of Perylene Ester Imides as a Gateway Toward Unsymmetrical Perylene Bisimides

Tuning the Liquid Crystallinity and Electroluminescence via Sulfonation of S-Annulated Perylene Tetraester

This study presents a comparative analysis of S-annulated perylene tetraester (PTE-S) and its sulfone (PTE-SO2) analogue. This sulfone modification reduced melting point and stabilized a room temperature columnar rectangular (Colr) phase in contrast to its parent PTE-S which showed a crystalline behaviour at room temperature. This molecular design also leads to red-shifted absorbance and emission in comparison to PTE-S, along with a tuning of photoluminescence from sky blue to green, achieving an impressive quantum yield of 85 %. OLED devices fabricated using PTE-SO2 as emitter material at concentrations of 0.2, 0.5, and 1 wt.% in CBP as host material. A maximum external quantum efficiency (EQE) of 2.9 % was observed with the 0.5 wt.% PTE-SO2 in CBP with CIE coordinates of (0.45, 0.35), accompanied by an orange luminance of 848 cd/m2. Notably, a device with a 0.5 wt% doping concentration of PTE-S demonstrates an EQE of 3.5 %, and cyan luminance of 2,598 cd/m2.

Asymmetrically Functionalized Electron-Deficient π-Conjugated System for Printed Single-Crystalline Organic Electronics

Large-area single-crystalline thin films of n-type organic semiconductors (OSCs) fabricated via solution-processed techniques are urgently demanded for high-end electronics. However, the lack of molecular designs that concomitantly offer excellent charge-carrier transport, solution-processability, and chemical/thermal robustness for n-type OSCs limits the understanding of fundamental charge-transport properties and impedes the realization of large-area electronics. The benzo[de]isoquinolino[1,8-gh]quinolinetetracarboxylic diimide (BQQDI) π-electron system with phenethyl substituents (PhC2 -BQQDI) demonstrates high electron mobility and robustness but its strong aggregation results in unsatisfactory solubility and solution-processability. In this work, an asymmetric molecular design approach is reported that harnesses the favorable charge transport of PhC2 -BQQDI, while introducing alkyl chains to improve the solubility and solution-processability. An effective synthetic strategy is developed to obtain the target asymmetric BQQDI (PhC2 -BQQDI-Cn ). Interestingly, linear alkyl chains of PhC2 -BQQDI-Cn (n = 5-7) exhibit an unusual molecular mimicry geometry with a gauche conformation and resilience to dynamic disorders. Asymmetric PhC2 -BQQDI-C5 demonstrates excellent electron mobility and centimeter-scale continuous single-crystalline thin films, which are two orders of magnitude larger than that of PhC2 -BQQDI, allowing for the investigation of electron transport anisotropy and applicable electronics.

Perylene tetra-(alkoxycarbonyl) derivative and its copper chelate for selective sensing of fluoride ions

Two novel fluoride ion fluorescent probes (P1 and P2) containing perylene tetra-(alkoxycarbonyl) derivative (PTAC) and its copper chelate were designed and synthesized. The identification properties of the probes were studied by absorption and fluorescence methods. The results showed that the probes were highly selective and sensitive to fluoride ions. ¹H NMR titration confirmed that the sensing mechanism involved the formation of H-bond between the O-H moiety and fluoride ions, and the coordination of copper ion could enhance the H-bond donor capacity of the receptor unit (O-H). The corresponding orbital electron distributions were calculated by density functional theory (DFT). In addition, fluoride ion can be easily detected by probe-coated Whatman filter paper without the need for expensive equipment. Until now, there have been few reports of such probes enhancing the capacity of the H-bond donor based on metal ion chelation. This study will contribute to the design and synthesis of novel sensitive perylene fluoride probes.

Solution-processable organic light-emitting diodes utilizing electroluminescent perylene tetraester-based columnar liquid crystals

Herein, we reveal a homologous series of liquid crystals involving perylene tetraesters as the core connected to the four trialkoxyphenyl units at the periphery using the triazole moiety as the linker. A thorough analysis using differential scanning calorimetry, polarized optical microscopy, and small- and wide-angle X-ray scattering studies confirm that all the mesogens 1a-c hold a stable enantiotropic columnar mesophase. Suitable molecular orbital levels and excellent material photophysical and thermal properties encouraged the study of their electroluminescent properties. Due to this, a well designed solution-processable organic light emitting diode device structure is configured as ITO (125 nm)/poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) (35 nm)/host: x wt% emitter (x = 0.5, 1.0, 3.0, 5.0) (20 nm)/2,2'2''-(1,3,5-benzinetriyl)tris(1-phenyl-1-H-benzimidazole) (TPBi) (40 nm)/lithium fluoride (LiF) (1 nm)/aluminium (Al) (200 nm) using compounds 1a-c as emitters. 4,4',4''-Tris[phenyl(m-tolyl)amino]triphenylamine (m-MTDATA) and 4,4'-bis(N-carbazolyl)-1,1'-biphenyl (CBP) were chosen as two different host materials. The current density-voltage-luminance and current efficacy-luminance-power efficacy plots suggest that m-MTDATA is a better host than CBP. Amongst, device based on 1 wt% emitter 1c doped in the m-MTDATA host matrix displayed the best performance, with a maximum power efficacy of 17.2 lm W^-1, current efficacy of 18.5 cd A^-1, and external quantum efficiency of 6.3%.

Gold nanoparticle-based supramolecular approach for dye-sensitized H2-evolving photocathodes

Solar conversion of water into the storable energy carrier H₂ can be achieved through photoelectrochemical water splitting using light adsorbing anodes and cathodes bearing O₂ and H₂ evolving catalysts, respectively. Herein a novel photocathode nanohybrid system is reported. This photocathode consists of a dye-sensitized p-type nickel oxide (NiO) with a perylene-based chromophore (PCA) and a tetra-adamantane modified cobaloxime reduction catalyst (Co) that photo-reduces aqueous protons to H₂. An original supramolecular approach was employed, using β-cyclodextrin functionalized gold nanoparticles (β-CD-AuNPs) to link the alkane chain of the PCA dye to the adamantane moieties of the cobaloxime catalyst (Co). This new architecture was investigated by photoelectrochemical measurements and via femtosecond-transient absorption spectroscopy. The results show that irradiation of the complete NiO|PCA|β-CD-AuNPs|Co electrode leads to ultrafast hole injection into NiO (π = 3 ps) from the excited dye, followed by rapid reduction of the catalyst, and finally H₂ evolution.

Recent Advances in Heterocyclic Nanographenes and Other Polycyclic Heteroaromatic Compounds

This review surveys recent progress in the chemistry of polycyclic heteroaromatic molecules with a focus on structural diversity and synthetic methodology. The article covers literature published during the period of 2016-2020, providing an update to our first review of this topic (Chem. Rev. 2017, 117 (4), 3479-3716).

A novel colorimetric and fluorescent probe based on a core-extended perylene tetra-(alkoxycarbonyl) derivative for the selective sensing of fluoride ions

A novel fluoride (F⁻) colorimetric and fluorescent probe (P1) based on a core-extended perylene tetra-(alkoxycarbonyl) (PTAC) derivative was developed. The probe exhibited high sensitivity and selectivity for distinguishing F⁻ from other common anions through significant changes of the UV-Vis and fluorescence spectra. Job's plot analysis revealed that the stoichiometry of the P1–F⁻ interaction is 1 : 1. The association constant between P1 and F⁻ was estimated to be 9.7 × 10² M⁻¹ and the detection limit of F⁻ was about 0.97 μM. An approximately 76 nm red-shift in the absorption and fluorescent quenching response was observed when F⁻ was associated with P1. The emission intensity (I₅₇₄) decreased linearly along with the F⁻ concentration from 3 × 10⁻⁵ M to 2 × 10⁻⁴ M. The mechanism of intermolecular proton transfer (IPT) was deduced based on the changes in the absorption, fluorescence, electrochemistry, and ¹H NMR titration spectra. The density functional theory (DFT) theoretical results of the P1–F⁻ complex are in good agreement with the experimental results. The rapid detection of F⁻ ions in the solid state and living cells was also studied.

A colorimetric and fluorescent probe based on a nuclear extended perylene tetra-(alkoxycarbonyl) derivative can be used for the detection of F⁻ in liquid, solid and living cells.

Effect of Photonic Band Gap on Photoluminescence in a Dye-Doped Blue Phase Liquid Crystal

Tunability of fluorescence intensity is an essential parameter for enhancing the versatility of devices like emissive displays and solar cells. Soft photonic crystals, with their tunable photonic band gap (PBG), are highly sought-after systems for such purposes. Here, we report modulation of photoluminescence (PL) intensity in a fluorescent dye-doped blue phase liquid crystal, a 3D soft photonic crystal. On cooling, from the isotropic fluid phase, the PL intensity gets enhanced due to the overlapping of the emission wavelength of the dye with the photonic band edge. However, the PL intensity decreases on the application of an electric field, despite both thermal and electric fields having a similar effect (red shift) on the PBG. The contrasting behavior of PL intensity, also observed in composites obtained by varying the dye and the chiral dopant (handedness), is discussed in terms of scattering pathways for the emitted photons. The time-resolved PL studies show a reduction in the lifetime of the excited species upon cooling, validating the thermal dependence of PL intensity modulation due to Purcell effect. The facile modulation of PL intensity in the dye-doped blue phase system makes it appealing from the point of view of high-performance photonic applications.

Perylene-Based Liquid Crystals as Materials for Organic Electronics Applications

Columnar phases formed by the stacking of disclike molecules with an intimate π-π overlap forms a 1D pathway for the anisotropic charge migration along the columns. Columnar phases have great potential in organic electronic devices to be utilized as active semiconducting layers in comparison to organic single crystals or amorphous polymers in terms of processability, ease of handling, and high charge carrier mobility. Intelligent molecular engineering of perylene and its derivatives provided access to tune the physical properties and self-assembly behavior. The columnar phase formed by perylene derivatives has great potential in the fabrication of organic electronic devices. There are several positions on the perylene molecule, which can be functionalized to tune its self-assembly, as well as optoelectronic properties. Thus, many liquid-crystalline molecules stabilizing the columnar phase, which are based on perylene tetraesters, perylene diester imides, and perylene bisimides, have been synthesized over the years. Their longitudinal and laterally extended derivatives, bay-substituted derivatives exhibiting a columnar phase, are reported. In addition, several liquid-crystalline oligomers and polymers based on perylene derivatives were also reported. All such modifications provide an option to tune the energy levels of frontier molecular orbitals with respect to the work function of the electrodes in devices and also the processability of such materials. In this feature article, we attempt to provide an overview of the molecular design developed to tune the applicable properties and self-assembly of perylene derivatives as well as recent developments related to their application in the fabrication of organic solar cells, organic light-emitting diodes, and organic field-effect transistors.

Progress in the synthesis of perylene bisimide dyes

Rapid progress in the synthesis of perylene bisimide dyes gave an old scaffold new life.