Substituted Pyrene Derivatives Research Articles

Cyano-functionalized carbazole substituted pyrene derivatives for promising organic light-emitting diodes

Balanced charge transport is crucial to realize efficient organic light-emitting diodes. In this work, pyrene derivatives featuring variable number of cyano-functionalized carbazoles are synthesized and characterized by photophysical, electrochemical, thermal and electroluminescence studies. The compounds displayed progressive variation in absorption and emission wavelength reflecting the effect of chromophore loading. The electroluminescence color change from deep blue to green on varying the number/position of cyanocarbazole units on pyrene. 1,6-Disubstituted derivative exhibited blue shift in absorption and emission when compared to the 1,8-analog. The current efficiency and power efficiency of the devices progressively increase on increasing the cyanocarbazole load on pyrene. It is probably originating from the balanced charge transport due to the increase in the number of cyanocarbazole units on pyrene and effective harvest of excitons in emissive layer. The best electroluminescence performance of the doped device fabricated from tetra-substituted derivative (1 wt%) displayed relatively high power efficiency (5.8 lm/W) and current efficiency (9.2 cd/A).

The interactions of probes based on substituted pyrene derivatives in polymer matrices; spectral study

• Pyrene-cholesterol adducts were synthetized and doped to common polymer matrices. • The behavior of various pyrene derivatives were compared based on spectral data. • Their aggregation was evaluated according to UV–vis and static fluorescence spectra. • Lower aggregation in solid matrices was observed for pyrene-cholesterol adducts. • Spectral data analysis allow us to estimate the interaction in polymer/probe mixture Two substituted pyrene derivatives with cholesterol ((3β)-cholest-5-en-3-ol) moiety as esters were synthetized. The spectral properties of the mono-substituted derivatives of pyrene as esters with different linkages to cholesterol via carboxy unit ( PyCACh1 ) and methylene carboxy unit ( PyMECh2 ) are compared with the mono-substituted pyrene derivatives and the parent pyrene in toluene at low concentration and doped in glassy polymer matrices of polystyrene (PS), poly(methyl methacrylate) (PMMA) and polyvinylchloride (PVC) in the concentration range of 0.002–0.06 mol kg −1 . Fluorescence spectroscopy of the pyrene derivatives in polymer matrices reveals changes in the shape of the fluorescence spectra with increasing concentration. Two limiting cases are observed: (1) a medium or large red shift of the entire fluorescence spectrum or (2) the formation of an emission band in the excimer emission region (approx. 500 nm). These changes are less pronounced in the pyrene-cholesterol esters in the PS matrix due to higher compatibility than in PMMA and PVC matrices. Exploitation of these emissions to estimate the interactions of the components in the polymer matrix is discussed.

Synthesis, characterization and solid-state emission properties of arylsilyl-substituted pyrene derivatives

Arylsilyl substituted pyrene derivatives were synthesized via Suzuki-Miyaura and Hagihara-Sonogashira cross-coupling reactions with boronic acid-terminated and ethynyl-terminated tetraphenylsilane at the 1-, 3-, 6- and 8-positions. The spectroscopic properties of the dyes were investigated in various solvents and in films to assess the suitability of these compounds for optoelectronic applications. A triphenylsilylphenyl substituted pyrene was found to exhibit intense emission in the solid state with an absolute fluorescence quantum yield (ΦF) of 0.65. In contrast, the emission properties of a triphenylsilylphenyl(ethynyl) substituted pyrene were found to be somewhat weaker in the solid state (ΦF = 0.16) and solvent polarity dependent in solution. Magnetic circular dichroism (MCD) spectroscopy, cyclic voltammetry, and theoretical calculations have been used to analyze the structure-property relationships with Michl's perimeter model used as a conceptual framework for rationalizing the key trends.

Synthesis, characterization and pharmacological investigations of some novel heterocyclic derivatives incorporating pyrene and sugar moieties

A series of substituted pyrene derivatives 2–15 incorporated heterocyclic and sugar moieties were synthesized and evaluated as antiviral activities using 1-acetylpyrene as a starting material. The structure assignment of the new compounds was based on chemical and spectroscopic evidence. The detailed synthesis, spectroscopic data and pharmacological activities of the synthesized compounds were reported.

Tuning the HOMO–LUMO Gap of Pyrene Effectively via Donor–Acceptor Substitution: Positions 4,5 Versus 9,10

Donor and acceptor substituents were introduced at pyrene's K-regions in order to engineer its optoelectronic properties. A study of the influence of the substitution pattern on the frontier orbitals as well as on the molecular packing is provided. A comparison with the pure donor and acceptor substituted pyrene derivatives highlights the strong impact of the presented donor-acceptor substitution.

Synthesis and photophysical properties of novel butterfly-shaped blue emitters based on pyrene

Using 1,3,5,9-tetrabromo-7-tert-butylpyrene as the bromide precursor, a series of novel butterfly-shaped 1,3,5,9-tetraaryl substituted pyrene derivatives were synthesized by the Suzuki-Miyaura cross-coupling reaction. Their thermal, photophysical, electrochemical and related properties were systematically investigated. All compounds were found to exhibit high thermal stabilities with decomposition temperatures (Td) of up to 300 °C. All compounds show highly blue fluorescence emissions in the spectral region of 412-469 nm in solution (Φf: 0.45-0.92) and 410-470 nm in the solid- state (Φf: 0.48-0.75). It is noteworthy that these butterfly-shaped pyrenes 4 possess low-lying HOMO levels ranging from -4.76 to -5.93 eV, which make them promising candidates in OLED applications.

Novel 4-(2,2-diphenyl-vinyl)-phenyl substituted pyrene derivatives as efficient emitters for organic light-emitting diodes

Two pyrene derivatives (PVPP and TPVPP) bearing 4-(2,2-diphenyl-vinyl)-phenyl side unit were developed for organic light-emitting diodes. Their photophysical, thermal, electrochemical, and electroluminescent properties as well as the film morphologies have been investigated in detail. Both of them exhibit high solid-state quantum yields, good thermal stability, and high glass-transition temperatures in the range of 127–150°C. In particular, it is found that multiple side units can significantly affect the electrochemical properties to improve the electron injection. The LUMO energy level of TPVPP is −2.76eV, which is very close to that of commonly used electron transport materials. The maximum luminance of OLED devices using TPVPP as an emitter layer is 103835cd/m2 with a maximum current efficiency of 5.19cd/A and a maximum power efficiency of 3.38lm/W.

Glass-Forming Carbazolyl and Phenothiazinyl Tetra Substituted Pyrene Derivatives: Photophysical, Electrochemical, and Photoelectrical Properties

Carbazolyl and phenothiazinyl tetra substituted derivatives of pyrene, namely, 1,3,6,8-tetra(9-ethyl-9H-carbazol-3-yl) pyrene (1), 1,3,6,8-tetra(9-ethyl-9H-carbazol-2-yl) pyrene (2), 1,3,6,8-tetra(...

Photophysical and self-assembly properties of asymmetrical multi-aralkyl and arylaldehyde substituted pyrene derivatives

A series of novel asymmetrical pyrene derivatives with aralkyl and aldehyde groups have been successfully synthesized, and their spectroscopic parameters were investigated detailedly. The effects of aralkyl substituent amounts on the electronic absorption and emission spectra have been explored in evaluation of their potential as optical materials components. Moreover, the electrochemical properties of the new pyrene derivatives have been studied for the molecules' HOMO and LUMO levels by cyclic voltammograms. In particular, titration of anhydrous ethanol into dilute CH2Cl2 solution of above compounds, an unusual change of the fluorescence value was observed. The change is believed to correlate strongly to intermolecular charge transfer. The morphological evolution of self-assembled pyrene derivatives with (arylethynyl)aldehyde substituents, from tamen-distinct-like morphologies to vesicular textures, was obtained by increasing aralkyl-substituted fragments. These asymmetrical discotic compounds represent an interesting set of candidates for optoelectronic device components.

Novel asymmetrical pyrene derivatives as light emitting materials: Synthesis and photophysics

A series of novel substituted pyrene derivatives with asymmetrical groups have been successfully synthesized in excellent yield. Structures of the asymmetrical compound were fully characterized by 1H-NMR, IR spectroscopy and mass spectrometry. By introducing ethynyl functions to pyrene, we obtained highly efficient blue and green light emitting materials. It has been demonstrated that the emission characteristics of pyrene derivatives have been bathochromatically tuned in the visible region by extending the π-conjugation. The photophysical properties of these compounds were carefully examined in different organic solvents and different concentrations. The electrochemical properties and geometrical electronic structures of the new pyrene derivatives have been investigated by cyclic voltammograms and density functional theory (DFT) calculations.

Synthesis of unsymmetrically substituted pyrene derivatives through (6-bromo-3,8-dibutylpyren-1-yl)trimethylsilane

A straightforward route to unsymmetrically functionalized pyrene derivatives is described involving the synthesis of key precursor (6-bromo-3,8-dibutylpyren-1-yl)trimethylsilane 1. In a first step bromide 1 was successful in Suzuki–Miyaura, Sonogashira, and Buchwald–Hartwig cross-coupling reactions. Subsequent transformation of the trimethylsilyl group to bromide enabled the introduction of a second variable functional group onto the pyrene skeleton.

Efficient 9-alkylphenyl-9-pyrenylfluorene substituted pyrene derivatives with improved hole injection for blue light-emitting diodes

Two efficient blue-light-emitting materials with stable diarylfluorene and hole-transporting pyrene groups, 9-alkoxyphenyl-9-pyrenylfluorene substituted pyrenes (EHOP1 and EHOP2), have been synthesized by Suzuki coupling reaction and have been fully characterized. They have extreme thermal stability in nitrogen with onset decomposition temperature over 430 °C. They are amorphous materials with Tg of 103 and 191 °C for EHOP1 and EHOP2, respectively. They show stable bright blue emission in the solid state. Due to the non-conjugated pyrene groups at C9 of the fluorene moieties, the absorption spectra of the two compounds showed some characteristic peaks and they showed improved hole-injection ability than conjugated fluorene derivatives. A preliminary simple three-layer blue light-emitting diode, i.e. ITO/TCTA (8 nm)/EHOP1 (30 nm)/BCP (45 nm)/Mg:Ag, was obtained without the need for a hole-injection layer, with high luminance of 11620 cd m−2, turn-on voltage of 4.0 V and current efficiency of 3.04 cd A−1. Furthermore, the device still had a considerable efficiency of 1.74 cd A−1, when the luminescence reaches its maximum.

Dual Fluorescence of Phenyl and Biphenyl Substituted Pyrene Derivatives

The photophysical properties of several acceptor substituted 1-arylpyrene derivatives were investigated. The fluorescence spectra strongly depend on the nature of the aryl moiety and the position and number of methoxycarbonyl acceptor groups. Dual fluorescence, originating from a locally excited and a charge transfer state, was observed for the diester derivatives. The solvent dependence of the dual fluorescence and the slightly curved solvatochromic plots indicate a change of the character of the excited states from solvents of low to high polarity. The rate constants for fluorescence and nonradiative decay were calculated to reveal the nature of the excited-state relaxation, that is, the increase of the mesomeric interactions by geometrical flattening or stabilization of the CT state by further twisting toward perpendicularity. Flattening is the major relaxation pathway of the diester phenylpyrene derivative in nonpolar solvents whereas in highly polar solvents the low value for the fluorescence transit...