Pyrene Derivatives Research Articles

Study of ultrafast nonlinear optical response and transient dynamics of pyrene derivatives with intramolecular charge transfer characteristics

Two pyrene derivatives 1906 and 1936 with typical charge transfer characteristics were designed and synthesized to study the influence of intramolecular charge transfer (ICT) on the ultrafast nonlinear optical (NLO) absorption. Frontier molecular orbital distribution and hole-electron analysis show that compound 1906 has stronger ICT characteristics than 1936 by introducing the halogen effect. Intense ESA signals in the green region of these pyrene derivatives were observed in the transient absorption spectrum (TAS). The excited state dynamics clearly show singlet-based electronic transitions and relaxation processes. Femtosecond Z-scan experiment at 480 nm indicates the ultrafast NLO absorption performance of these pyrene derivatives can be significantly improved by enhancing the ICT characteristics. The photophysical mechanism is one-photon absorption (OPA) induced excited-state absorption (ESA). As the input intensity is 46.8 GW cm−2, the effective NLO absorption coefficient of 1906 is 7.6 × 10−13 W m−1 which is 6.3 times that of 1936. Our results indicate that these pyrene derivatives are promising potential candidates for ultrafast laser protection applications.

A new mitochondrial probe combining pyrene and a triphenylphosphonium salt for cellular oxygen and free radical detection via fluorescence lifetime measurements

To improve and diversify the quantification of reactive oxygen species (ROS) in mitochondria of single cells, we connected pyrene derivatives (PB) to a triphenylphosphonium salt (TPP+) as a mitochondrial vector forming PB-TPP+ probes. Two pyrene isomers with the n-butyltriphenylphosphonium moieties attached at their 1- or 2- positions were synthesized and characterized. Using the long fluorescence lifetime of pyrene, it was possible to monitor the variation of cellular free radicals and oxygen and to follow the reversibility of both quenchers in real-time. We compared the behavior of these new probes to the previously published pyrene-probes, functionalized by a mitochondrial-penetrating peptide, allowing their transfer to the mitochondria (Mito-PB) or to the cytosolic membrane for pyrene butyric acid (PBA). The high cellular uptake of the new probes allows cells to be loaded with an initial concentration 40 times lower than that for Mito-PB probes, without inducing perturbations in cell growth. The variation in free radicals and oxygen levels was monitored within cells under different stress conditions through the fluorescence lifetime of the new TPP+-based probes giving comparable results to those obtained for MPP-based probes. However, at a loading concentration as low as 25 nM, our technique allows the detection of increased production of free radicals in the mitochondria in the presence of the TPP+ vector, a warning to the user of this well-known vector.

Using click chemistry to study the photoacoustic effect of near-infrared captivating pyrene derivatives

Near-infrared photoacoustic (PA) imaging usually employs near-infrared light-absorbing agents to detect cancer cells/tissue by generating acoustic energy from optical energy. Here, a class of near-infrared dyes, pyrene derivatives with different substitutes, was characterized by PA technology. Interestingly, the click reagents F4-TCNQ could cause the redshift of peaks of the PA intensity of pyrene derivatives. Besides, the symmetric pyrene derivatives had a better PA effect, pyrene accumulation of benzene ring structure also had a certain influence on the PA effect. The systematical study of the near-infrared dyes not only showed the high potential of pyrene derivatives as PA contrast agents but also gave guidelines for designing near-infrared absorbing dyes for high PA intensity in the future.

A Highly Fluorescent Pyrene-Based Sensor for Selective Detection Of Fe3+ Ion in Aqueous Medium: Computational Investigations.

In this work, we introduce a highly selective and sensitive fluorescent sensor based on pyrene derivative for Fe(III) ion sensing in DMSO/water media. 2-(pyrene-2-yl)-1-(pyrene-2-ylmethyl)-1H-benzo[d]imidazole (PEBD) receptor was synthesized via simple condensation reaction and confirmed by spectroscopic techniques. The receptor exhibits fluorescence quenching in the presence of Fe(III) ions at 440nm. ESI-MS and Job's method were used to confirm the 1:1 molar binding ratio of the receptor PEBD to Fe(III) ions. Using the Benesi-Hildebrand equation the binding constant value was determined as 8.485 × 103M-1. Furthermore, the limit of detection (LOD, 3σ/K) value was found to be 1.81µM in DMSO/water (95/5, v/v) media. According to the Environmental Protection Agency (EPA) of the United States, it is lower than the acceptable value of Fe3+ in drinking water (0.3mg/L). The presence of 14 other metal ions such Co2+, Cr3+, Cu2+, Fe2+, Hg2+, Pb2+, K+, Ni2+, Mg2+, Cd2+, Ca2+, Mn2+, Al3+, and Zn2+ did not interfere with the detection of Fe(III) ions. The fluorescence life-time of the receptor PEBD with and without Fe3+ ion was found to be 1.097 × 10-9s and 0.9202 × 10-9s respectively. Similarly, the quantum yield of the receptor PEBD with Fe3+ and without Fe3+ ion was calculated, and found as 0.05 and 0.25 respectively. Computational studies of the receptor PEBD were carried out with density functional theory (DFT) using B3LYP/ 6-311G (d, p), LANL2DZ level of theory.

Delineating the effect of substituent and π-bridge flip on the photophysical properties of pyrene derivatives: answers from DFT/TD-DFT calculations

Delineating the effect of substituent and π-bridge flip on the photophysical properties of pyrene derivatives: answers from DFT/TD-DFT calculations

Ultrastable Conjugated Microporous Polymers Containing Benzobisthiadiazole and Pyrene Building Blocks for Energy Storage Applications.

In recent years, conjugated microporous polymers (CMPs) have become important precursors for environmental and energy applications, compared with inorganic electrode materials, due to their ease of preparation, facile charge storage process, π-conjugated structures, relatively high thermal and chemical stability, abundance in nature, and high surface areas. Therefore, in this study, we designed and prepared new benzobisthiadiazole (BBT)-linked CMPs (BBT–CMPs) using a simple Sonogashira couplings reaction by reaction of 4,8-dibromobenzo(1,2-c;4,5-c′)bis(1,2,5)thiadiazole (BBT–Br2) with ethynyl derivatives of triphenylamine (TPA-T), pyrene (Py-T), and tetraphenylethene (TPE-T), respectively, to afford TPA–BBT–CMP, Py–BBT–CMP, and TPE–BBT–CMP. The chemical structure and properties of BBT–CMPs such as surface areas, pore size, surface morphologies, and thermal stability using different measurements were discussed in detail. Among the studied BBT–CMPs, we revealed that TPE–BBT–CMP displayed high degradation temperature, up to 340 °C, with high char yield and regular, aggregated sphere based on thermogravimetric analysis (TGA) and scanning electron microscopy (SEM), respectively. Furthermore, the Py–BBT–CMP as organic electrode showed an outstanding specific capacitance of 228 F g−1 and superior capacitance stability of 93.2% (over 2000 cycles). Based on theoretical results, an important role of BBT–CMPs, due to their electronic structure, was revealed to be enhancing the charge storage. Furthermore, all three CMP polymers featured a high conjugation system, leading to improved electron conduction and small bandgaps.

Ester-functionalized pyrene derivatives: Effects of ester substituents on photophysical, electrochemical, electrochromic, and electrofluorochromic properties

Multifunctional electrochromic materials are widely used in optoelectronic devices. Pyrene is a π-electron-rich group with fluorescence properties. Ester-functionalized pyrene derivatives potentially have interesting multifunctional properties such as electrochromic and electrofluorochromic characteristics. In this work, mono-, di-, tri-, and tetra-ester-substituted pyrene derivatives were synthesized, and the effects of the number of ester substituents on their photophysical, electrochemical, electrochromic, and electrofluorochromic properties were investigated. The number of ester substituents significantly affected these properties. An increase in the number of ester substituents on the pyrene caused red shifts in the absorption and emission spectra, a decrease in the driving voltage, and changes in the electrochromic colored states and electrofluorochromic performance. Mono-, di-, and tri-ester-functionalized pyrene derivatives showed good electrochromic properties, namely good switching stabilities, high optical contrasts, rapid responses, and high coloration efficiencies. Mono- and tri-ester-functionalized pyrenes gave good electrofluorochromic performances with reversible fluorescence quenching–fluorescence restoring between colored and bleached states during the electrochromic process. Ester-functionalized pyrene derivatives were successfully used in two functional digital displays with vivid colors. These results show that ester-functionalized pyrene derivatives with good electrochromic and electrofluorochromic properties are promising candidates for use in various applications, e.g., digital displays, organic electroluminescence displays, electronic shelf labels, energy-saving windows, and electronic paper.

Tunable Excimer Circularly Polarized Luminescence in Isohexide Derivatives from Renewable Resources.

Organic compounds showing circularly polarized luminescence (CPL) are at the forefront of novel applications and technologies. Here we show the synthesis and chiroptical properties of pyrene and perylene derivatives of inexpensive chiral scaffolds: isomannide and isosorbide. Low‐intensity ECD spectra were obtained, suggesting the absence of chromophore interaction in the ground state, except in the case of isomannide bis‐perylenecarboxylate, whose ECD spectrum showed a positive exciton couplet. All isomannide derivatives, with the only exception of the one containing a pyrenecarboxylate and a perylenecarboxylate, exhibited excimer CPL spectra, whereas isosorbide derivatives did not show any CPL. Isomannide derivatives bearing two pyrenecarboxylate or two pyrenylacetate groups showed positive CPL emission with dissymmetry factors up to 10−2, which depends on the conformational freedom of the appended units. The CPL sign, Stokes shift and order of magnitude of dissymmetry factor were reproduced by excited‐state calculations on a representative compound. Interestingly, the mixed derivative containing pyrenic units with different spacing from the isomannide scaffold showed an oppositely signed excimer band with respect to the homo‐substituted derivatives.

π‐Extended Helical Nanographenes: Synthesis and Photophysical Properties of Naphtho[1,2‐a]pyrenes**

AbstractA mild and efficient synthesis of a broad scope of substituted naphtho[1,2‐a]pyrene derivatives was accomplished in good yields using an InCl3/AgNTf2‐mediated two‐fold alkyne benzannulation reaction. HPLC enantiomeric separation was achieved and the interconversion barriers have been determined. The ECD spectra of two derivatives were recorded and interpreted through TD‐DFT calculations. Raman spectra were also recorded and predicted through DFT calculations.

Switching between intramolecular charge transfer and excimer emissions in solids based on aryl-modified ethynyl‒o-carboranes

Because of its unique electronic properties, o-carborane has attracted attention as a scaffold for constructing solid-state luminescent materials. Here, we report stimulus-responsive luminochromic materials based on polycyclic aromatic hydrocarbon (PAH), such as anthracene and pyrene, modified with the ethynyl-o-carborane unit. Initially, luminochromism originating from switching of different emission mechanisms is described between intramolecular charge transfer (ICT) emission and excimer emission triggered by mechanical stimuli, heat, and vapor annealing regarding the single o-carborane-substituted anthracene. Next, the luminescence properties of two ethynyl-o-carboranes at both ends of PAHs are presented. In particular, multi-step mechanochromic luminescence of the pyrene derivative is explained. Stepwisely changes triggered by weak stimuli that can induce cracking sites, followed by luminochromic behavior and by grinding treatment, which causes phase transition from crystal to amorphous, leading to luminescent mechanism changes from ICT emission to excimer emission.

Strong emission of excimers realized by dense packing of pyrenes in tailored bola-amphiphile nano assemblies

Pyrene is known for the quenched emission of excimers, especially in aqueous solution. Here, we report strong emission of pyrene excimers realized in amphiphile assemblies by controlling the face-to-face distance between the pyrene planes. We find that both the self-assembly behavior and emission properties of a cationic pyrene-containing amphiphile (denoted by PRB) are altered by exchanging the counterions. Upon the addition of sodium mesitylenesulfonate (Na MtS), the excimer emission of pyrene in self-assembled aggregates of PRB is greatly enhanced in aqueous solution. Concomitantly, the disk-like assemblies of PRB are converted to spherical particles, in which the repulsive interactions of the head groups are screened by replacing the counterions of the PRB molecules. The quantum yield of PRB increases from 0.5% to 16.6%, which is attributed to the dense packing of pyrene moieties in the aggregates. This study demonstrates that controlling supramolecular interactions is a feasible avenue to enhance the emission of pyrene excimers in amphiphile assemblies. The face-to-face distance between neighboring pyrenes is reduced The excimer emission of pyrene derivatives was boosted in the aggregated state The quantum yield increases by 2 orders of magnitude to >16% Pyrene is known for the quenched emission of excimers, especially in aqueous solution. Zhao et al. report the enhanced excimer emission of pyrene derivatives by controlling the intermolecular interactions in the aggregated state of assemblies, whereby the quantum yield increased by 2 orders of magnitude to >16%.

Three in One: Stimuli-Responsive Fluorescence, Solid-State Emission, and Dual-Organelle Imaging Using a Pyrene-Benzophenone Derivative.

Small organic luminogens, owing to their contrasting stimuli-responsive fluorescence in solution along with strong emission in aggregated and solidstates, have been employed in optoelectronic devices, sensors, and bioimaging. Pyrene derivatives usually exhibit strong fluorescence and concentration-dependent excimer/aggregate emission in solution. However, the impacts of microenvironments on the monomer and aggregate emission bands and their relative intensities in solution, solid, and supramolecular aggregates are intriguing. The present study delineates a trade-off between the monomer and aggregate emissions of a pyrene-benzophenone derivative (ABzPy) in solution, in the solid-state, and in nanoaggregates through a combined spectroscopic and microscopic approach. The impact of external stimuli (viscosity, pH) on the aggregate emission was demonstrated using steady-state and time-resolved spectroscopy, including fluorescence correlation spectroscopy and fluorescence anisotropy decay analysis. The aggregate formation was noticed at a higher concentration (>10 μM) in solution, at 77 K (5 μM), and in the solid-state due to the π-π stacking interactions (3.6 Å) between two ABzPy molecules. In contrast, no aggregate formation was observed in the viscous medium as well as in a micellar environment even at a higher concentration of ABzPy (50 μM). The crystal structure analysis further shed light on the intermolecular hydrogen-bonding-assisted solid-state emission, which was found to be highly sensitive toward external stimuli like pH and mechanical forces. The broad emission band comprising both monomer and aggregate in the aqueous dispersion of nanoaggregates was used for the specific cellular imaging of lysosomes and lipid droplets, respectively.

Color-tunable emission from violet-blue to pure-blue based on 5,9-disubstituted pyrene derivativesviaengineering of aryl-side groups

By attaching a few kinds of two aryl-side groups into pyrene core at 5,9-positions, five pyrene-based color-tunable blue emitters have been developed for highly efficient nondoped and doped blue OLEDs.

Synthesis of Conjugated Molecules Based on Dithienopyrrole Derivatives and Pyrene as Chemosensor for Mesotrione Detection

The conjugated molecules based on pyrene and dithienopyrrole derivatives including 4-(2-ethylhexyl)-2-(pyren-1-yl)-4H-dithieno[3,2-b:2’,3’-d]pyrrole (EP4HP) and 4-(2-ethylhexyl)- 2,6-di(pyren-1-yl)-4H-dithieno[3,2-b:2’,3’-d]pyrrole (EDP4HP) have been successfully synthesized via C–H direct arylation reaction. The structures of these conjugated molecules were determined via nuclear magnetic resonance and Fourier-transform infrared spectroscopy (FTIR). The optical properties of conjugated molecules were evaluated via ultraviolet visible (UV-Vis) and fluorescence spectroscopies. The conjugated molecules exhibited the efficient fluorescence quenching toward herbicide mesotrione as nitroaromatic pesticides that could be promising candidates as the chemosensor for tracing of nitroaromatic pesticides.

Probing twisted intramolecular charge transfer of pyrene derivatives as organic emitters in OLEDs

Intramolecular charge transfer (ICT) plays a critical role in determining the photophysical properties of organic molecules, including their luminescence efficiencies. Twisted intramolecular charge transfer (TICT) is a process in which structural change accompanies ICT. Herein, we used time-resolved spectroscopy to study TICT in pyrene derivatives that are promising blue organic light emitting diode (OLED) emitter candidates; these derivatives show strong solvent-dependent charge-transfer (CT) behavior with unique fluorescence properties, increased fluorescence intensity in polar solvent. Slight structural changes that do not affect excited state dynamics were observed in nonpolar solvents, while polar solvents were found to affect excited state dynamics and CT characteristics, which affect their unusual fluorescence behavior. The TICT behavior of these pyrene derivatives can be modulated through structural modification. Our study provides valuable guidelines for the control of optical properties, including the luminescence efficiencies of OLED emitters that show TICT characteristics.

A Novel Functional Fluorescent Probe Based on a Pyrene Derivative for Detection of Multi-Pollutants

A Novel Functional Fluorescent Probe Based on a Pyrene Derivative for Detection of Multi-Pollutants

Unravelling the semiconductor properties of mixed stack donor acceptor cocrystals of pyrene derivatives and TCNQ: effect of crystal packing versus super-exchange mechanism

The role of crystal packing and super-exchange mechanism to dictate the semiconductor properties of two mixed DDADDA stack charge transfer cocrystals is elucidated via theoretical study.

A Plasmonic Supramolecular Nanohybrid as a Contrast Agent for Site‐Selective Computed Tomography Imaging of Tumor

AbstractDesign of organic–inorganic hybrids by anchoring of plasmonic materials such as gold nanoparticles (AuNPs) on self‐assembled organic substrates is useful but challenging. Herein, in situ anchoring of plasmonic nanoparticles on the surface of a designed spherical assembly via AuS bond formation is presented. First, a thiol tailed pyrene derivative (2) undergoes solvent dependent self‐assembly, transforming into an organic spherical aggregate (2agg). The thiol (‐SH) rich surface of the organic assembly allows cumulative anchoring of AuNPs on the surface to form an organic–inorganic hybrid (Au@2agg). Further coating of biocompatible polyethylene glycol (PEG) leads to the construction of the final multicomponent system (PEG‐Au@2agg) exhibiting morphological and spectroscopic features. The potential of PEG‐Au@2agg as a bioprobe and a contrast agent is investigated by X‐ray computed tomography (CT) experiments in vivo. High X‐ray attenuation of directly anchored AuNP clusters on the surface of this supramolecular nanohybrids enhances the X‐ray CT contrast and allows tracing of site‐selective accumulation in mouse 4T1 breast tumor. Thus, this approach of designing organic–inorganic nanohybrids paves the way for developing future intelligent multifunctional nanosystems capable of cancer detection and imaging.

Stretching-enhanced emission behavior of polyurethane composites containing pyrene derivatives

A series of mechanoresponsive fluorescence composite films were prepared by doping pyrene (Py) and its derivatives including 1-hydroxypyrene (HPY), 1-pyrenemethanol (PYM) and 1-pyrenylboronic acid (PBA) into thermoplastic polyurethane (PU) via physical blending, respectively. The fluorescence property of the composite films was found to be influenced by the polar group of pyrene derivatives and the content of hard segment of PU. The doped PYM showed a stronger trend to aggregate in PU matrixes, relative to other dyes. Contrary to PU/Py and most of previously reported mechanoresponsive materials, the emission intensity of aggregated PYM molecules in both PU25/PYM and PU50/PYM films exhibited a stretching-enhanced-emission feature. When PU25/PYM was stretched up to 500%, the intensity ratio of its dual emission peaks at 490 and 400 nm increased from 2.3 to 5.3. This interesting mechanoresponsive behavior was related to the formation of strong hydrogen bonding between PYM and hard segment of PU matrixes proved by FT-IR spectrograph. Enhancing instead of reducing the emission intensity of dyes through stretching would be remarkable in the field of mechanoresponsive materials.

Pyrene-Functionalized Fluorescent Nanojars: Synthesis, Mass Spectrometric, and Photophysical Studies.

Nanojars are a class of supramolecular coordination complexes based on pyrazolate, Cu2+, and OH– ions that self-assemble around highly hydrophilic anions and serve as efficient anion binding and extraction agents. In this work, the synthesis, characterization, and photophysical properties of pyrene-functionalized fluorescent nanojars are presented. Three pyrene derivatives, 4-(pyren-1-yl)pyrazole (HL1), 4-(5-(pyren-1-yl)pent-4-yn-1-yl)pyrazole (HL2), and 4-(3-(pyrazol-4-yl)propyl)-1-(pyren-1-yl)-1,2,3-triazole (HL3), and the corresponding nanojars were synthesized and characterized using nuclear magnetic resonance spectroscopy and mass spectrometry. Electronic absorption, steady-state, and time-resolved fluorescence measurements were carried out to understand the interaction between the pyrene fluorophore and copper nanojars. Optical absorption measurements have shown minor ground state interaction between the fluorophore and nanojars. The fluorescence of pyrene is significantly quenched when attached to nanojars, suggesting strong contribution from the paramagnetic Cu2+ ions. Significant static quenching is observed in the case of L1, when pyrene is directly bound to the nanojar, whereas in the case of L2 and L3, when pyrene is attached to the nanojars using flexible tethers, both static and dynamic quenching are observed.