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

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

An efficient approach to the synthesis of novel pyrene-fused azaacenes

An efficient approach to the synthesis of novel pyrene-fused azaacene

Synthesis and fluorescence emission properties of 1,3,6,8-tetraarylpyrenes

Synthesis and fluorescence emission properties of 1,3,6,8-tetraarylpyrene

D-π-D chromophores based on dithieno[3,2-b:2',3'-d]thiophene (DTT): Potential application in the fabrication of solar cell

© 2016 Elsevier LtdIn this work, four stable dithieno[3,2-b:2',3'-d]thiophene-based π-extended molecules were designed and synthesized via a Pd-catalysed Sonogashira coupling reaction. The structures of these symmetrical compounds, including dithieno[3,2-b:2',3'-d]thiophene (DTT) as the π-center and various donor (D) groups, were determined on the basis of NMR spectral data, elemental analysis, and X-ray crystallography. The photo-physical properties of the DTT-based derivatives 2 were fully investigated in both solution and the solid state. The notable optical features of their solid-state powders showed significant red-shifts in comparison with the luminescence of their dilute dichloromethane solutions. These results combined with the theoretical calculations indicate that they are promising candidates for several applications in electronic and optoelectronic devices, as well as organic dyes for solar cells

Pyrene-cored blue-light emitting [4]helicenes: synthesis, crystal structures, and photophysical properties

The synthesis, crystal structures and photophysical properties of two types of pyrene-cored blue-light emitting [4]helicenes are reported, in which two naphthalene rings of condensed pyrenes were constructed resulting in helical architectures. The photophysical properties and electrochemical characteristics of these pyrene-cored [4]helicenes were fully investigated in both solutions and films, along with that of the pre-cyclization Q4 products, 4,9- and 4,10-(phenylethenyl)pyrenes

Extended [pi]-conjugated pyrene derivatives: structural, photophysical and electrochemical properties

This article presents a set of extended [pi]-conjugated pyrene derivatives, namely 1,3-di(arylethynyl)-7-tert-butylpyrenes, which were synthesized by a Pd-catalyzed Sonogashira coupling reaction of 1,3-dibromo-7-tert-butylpyrenes with the corresponding arylethynyl group in good yields. Despite the presence of the tert-butyl group located at the 7-position of pyrene, X-ray crystallographic analyses show that the planarity of the Y-shaped molecules still exhibits strong face-to-face [pi]-[pi] stacking in the solid state; all of the compounds exhibit blue or green emission with high quantum yields (QYs) in dichloromethane. DFT calculations and electrochemistry revealed that this category of compound possesses hole-transporting characteristics. In addition, with strong electron-donating (-N(CH3)2) or electron-withdrawing (-CHO) groups in 2 d or 2 f, these molecules displayed efficient intramolecular charge-transfer (ICT) emissions with solvatochromic shifts from blue to yellow (green) on increasing the solvent polarity. Furthermore, the compounds 2 d and 2 f possess strong CT characteristics

Multiple photoluminescence from pyrene-fused hexaarylbenzenes with aggregation enhanced emission features

Multiple photoluminescence, involved in monomer emission, excimer emission and charge transfer emission origin from new pyrene-fused hexaarylbenzenes (HAB) compounds were observed, which were designed and synthesized (in high yield) via the Diels-Alder reaction of bis(2-tert-butylpyren-6-yl)acetylene and tetraphenylcyclopentadienone. Although the distinction of between two molecules arises only from the geometrical position of one of the pyrenes, the NMR spectra, the crystal packing and the physicochemical properties of these pyrene-based HAB hybrids are distinctly different both in their solution state and in aggregation-state. The X-ray diffraction analysis clearly indicated that the pyrene moieties in this system would form different crystal packing in crystal state that can induce a fantastic multiple photoluminescence phenomenon

Vanadyl sulfates: molecular structure, magnetism and electrochemical activity

Reaction of differing amounts of vanadyl sulfate with p-tert-butylthiacalix[4]areneH4 and base allows access to the vanadyl-sulfate species [NEt4]4[(VO)4(μ3-OH)4(SO4)4]·½H2O (1), [HNEt3]5[(VO)5(μ3-O)4(SO4)4]·4MeCN (2·4MeCN) and [NEt4]2[(VO)6(O)2(SO4)4(OMe)(OH2)]·MeCN (3·MeCN). Similar use of p-tert-butylsulfonylcalix[4]areneH4, p-tert-butylcalix[8]areneH8 or p-tert-butylhexahomotrioxacalix[3]areneH3 led to the isolation of [HNEt3]2[H2NEt2]2{[VO(OMe)]2p-tert-butylcalix[8-SO2]areneH2} (4), [HNEt3]2[V(O)2p-tert-butylcalix[8]areneH5] (5) and [HNEt3]2[VIV2VV4O11(OMe)8] (6), respectively. Dc magnetic susceptibility measurements were performed on powdered microcrystalline samples of 1–3 in the T = 300–2 K temperature range. Preliminary screening for electrochemical water oxidation revealed some activity for 2 with turnover frequency (TOF) and number (TON) of 2.2 × 10−4 s−1 and 6.44 × 10−6 (mmol O2/mmol cat.), respectively. The compound 3 showed an improved electrochemical activity in the presence of water. This is related to the increased number and the rate of electrons exchanged during oxidation of V4+ species, facilitated by protons generated in the water discharge process

Lithium calix[4]arenes: structural studies and use in the ring opening polymerization of cyclic esters

We have structurally characterized a number of lithiated calix[4]arenes, where the bridge in the calix[4]arene is thia (–S–, LSH4), sulfinyl (–SO–, LSOH4), sulfonyl (–SO2–, LSO2H4), dimethyleneoxa (–CH2OCH2–, LCOCH4) or methylene (–CH2–, LH4). In the case of L4SH4, interaction with LiOtBu led to the isolation of the complex [Li8(L4S)2(THF)4]·5THF (1·5THF), whilst similar interaction of L4SOH4 led to the isolation of [Li6(L4SOH)2(THF)2]·5(THF) (2·5THF). Interestingly, the mixed sulfinyl/sulfonyl complexes [Li8(calix[4]arene(SO)(SO2)(SO1.68)2)2(THF)6]·8(THF) (3·8THF) and [Li5Na(LSO/3SO2H)2(THF)5]·7.5(THF) (4·7.5(THF) have also been characterized. Interaction of LiOtBu with LSO2H4 and LCOCH4 afforded [Li5L4SO2(OH)(THF)4]·2THF (5·2THF) and [Li6(LCOC)2(HOtBu)2]·0.78THF·1.22hexane (6·0.78THF·1.22hexane), respectively. In the case of LH4, reaction with LiOtBu in THF afforded a monoclinic polymorph [LH2Li2(thf)(OH2)2]·3THF (7·3THF) of a known triclinic form of the complex, whilst reaction of the de-butylated analogue of LH4, namely de-BuLH4, afforded a polymeric chain structure {[Li5(de-BuL)(OH)(NCMe)3]·2MeCN}n (8·2MeCN). For comparative catalytic studies, the complex [Li6(LPr)2(H2O)2]·hexane (9 hexane), where LPr2H2 = 1,3-di-n-propyloxycalix[4]areneH2, was also prepared. The molecular crystal structures of 1–9 are reported, and their ability to act as catalysts for the ring opening (co-)/polymerization (ROP) of the cyclic esters ε-caprolactone, δ-valerolactone, and rac-lactide has been investigated. In most of the cases, complex 6 outperformed the other systems, allowing for higher conversions and/or greated polymer Mn.</p

Host–guest interaction of hemicucurbiturils with phenazine hydrochloride salt

<div><p>The host–guest interactions between phenazine hydrochloride salt (PheH⁺) and hemicucurbit[<i>n</i>]uril (<i>n</i> = 6 or 12) (HemiQ[6 or 12]) have been studied by ¹H NMR, UV–vis, IR, mass spectrometry (MS) and quantum chemistry. In ¹H NMR spectra, the broadening of proton resonances of the hosts suggests the interactions of PheH⁺ with HemiQs. The quantitative stabilities of the host–guest systems have been obtained by UV–vis titration experiments, that is, the stoichiometric interactions of PheH⁺ with HemiQ[6] have been observed with an association constant of <i>K</i>_a = (2.5 ± 1.2) × 10⁶ L mol^− 1, while the 2:1 ratio complexes of PheH⁺ with HemiQ[12] are formed with stepwise association constants of <i>K</i>₁ = (9.2 ± 2.8) × 10⁴ L mol^− 1 and <i>K</i>₂ = (6.4 ± 0.9) × 10⁵ L mol^− 1, respectively, which induce a total association constant of <i>K</i>_a = 5.9 × 10¹⁰ L² mol^− 2. Both the 1:1 and 2:1 complexes have been detected by MS. Quantum chemistry calculations have been used to understand the static structures and thermodynamic stabilities of the supramolecular assemblies.</p></div