1 Ocak 2004 Dergi makalesi Açık Erişim

Zhao, L; Perepichka, IF; Turksoy, F; Batsanov, AS; Beeby, A; Findlay, KS; Bryce, MR

Citation Style Language JSON

{
  "DOI": "10.1039/b401867m", 
  "abstract": "A series of 2,5-di(aryleneethynyl) pyrazine derivatives has been synthesised in 23-41% yields by two-fold reaction of 2,5-dibromo-3,6-dimethylpyrazine 3 with ethynylarenes (arene=phenyl, 2-pyridyl, 4-ethylphenyl, 4-chlorophenyl, 4-biphenyl) under standard Sonogashira conditions [CuI, Pd(PPh3)(2)C(l)2, NEt3, THF]. Compound 3 has been converted into 2,5-diethynyl-3,6-dimethylpyrazine, which reacts with 2-iodothiophene to yield 2,5-bis(thien-2-ylethynyl)-3,6-dimethylpyrazine. In the X-ray crystal structure of 2,5-di(phenylethynyl)-3,6-dimethylpyrazine 4 the two phenyl rings are parallel and the pyrazine ring is inclined to their planes by 14.2degrees. Quantum chemical calculations establish that the HOMO-LUMO gap for 4 (3.56 eV) is lower than that of di(phenylethynyl) benzene 12 (3.72 eV). The nitrogen atoms of 4 serve to localise the HOMO on the central ring's carbon atoms, resulting in a quinoidal-type population, in contrast to 12. Cyclic voltammetric studies establish that 4 undergoes a reduction to the radical anion at ca. -1.9 V (vs. Ag/Ag+ in MeCN), which is almost reversible at high scan rates (500 mV s(-1)). The UV-vis absorption and photoluminescence profiles of 4 in cyclohexane are similar to those of 12; the emission for 4 (lambda(max) 379 and 395 nm) is red-shifted compared to 12. Single-layer OLEDs using MEH-PPV as the emissive polymer show significantly enhanced external quantum efficiencies (up to 0.07%) when 20% by weight of 2,5-di(biphenyl-4-ethynyl)-3,6-dimethylpyrazine 8 is added as a dopant: this is ascribed to the enhanced electron-transporting properties of the pyrazine system.", 
  "author": [
    {
      "family": "Zhao", 
      "given": " L"
    }, 
    {
      "family": "Perepichka", 
      "given": " IF"
    }, 
    {
      "family": "Turksoy", 
      "given": " F"
    }, 
    {
      "family": "Batsanov", 
      "given": " AS"
    }, 
    {
      "family": "Beeby", 
      "given": " A"
    }, 
    {
      "family": "Findlay", 
      "given": " KS"
    }, 
    {
      "family": "Bryce", 
      "given": " MR"
    }
  ], 
  "container_title": "NEW JOURNAL OF CHEMISTRY", 
  "id": "94797", 
  "issue": "8", 
  "issued": {
    "date-parts": [
      [
        2004, 
        1, 
        1
      ]
    ]
  }, 
  "page": "912-918", 
  "title": "2,5-di(aryleneethynyl)pyrazine derivatives: synthesis, structural and optoelectronic properties, and light-emitting device", 
  "type": "article-journal", 
  "volume": "28"
}