Novel multifunctional organic semiconductor materials based on 4,8-substituted 1,5-naphthyridine: synthesis, single crystal structures, opto-electrical properties and quantum chemistry calculation
作者:Kun-Yan Wang、Chen Chen、Jin-Fang Liu、Qin Wang、Jin Chang、Hong-Jun Zhu、Chong Li
DOI:10.1039/c2ob25926e
日期:——
A series of 4,8-substituted 1,5-naphthyridines (1a–1h) have been successfully synthesised by a Suzuki cross-coupling between 4,8-dibromo-1,5-naphthyridine (4) and the corresponding boronic acids (2a–2h) in the presence of catalytic palladium acetate in yields of 41.4–75.8% and have ben well characterized. They are thermally robust with high phase transition temperatures (above 186 °C). Compounds 1b, 1e and 1f crystallized in the monoclinic crystal system with the space groups P21/c, P21/c and P21/n, respectively. All of them show the lowest energy absorption bands (λmaxAbs: 294–320 nm), revealing low optical band gaps (2.77–3.79 eV). These materials emit blue fluorescence with λmaxEm ranging from 434–521 nm in dilute solution in dichloromethane and 400–501 nm in the solid state. 4,8-Substituted 1,5-naphthyridines 1a–1h have estimated electron affinities (EA) of (2.38–2.72 eV) suitable for electron-transport materials and ionization potentials (IP) of 4.85–5.04 eV facilitate excellent hole-injecting/hole-transport materials properties. Quantum chemical calculations using DFT B3LYP/6-31G* showed nearly identical the lowest unoccupied molecular orbitals (LUMO) of −2.39 to −2.19 eV and the highest occupied molecular orbitals (HOMO) of −5.33 to −6.84 eV. These results demonstrate the 4,8-substituted 1,5-naphthyridines 1a–1h with a simple architecture might be promising blue-emitting (or blue-green-emitting) materials, electron-transport materials and hole-injecting/hole-transport materials for applications for developing high-efficiency OLEDs.
一系列4,8取代的1,5-萘啶(1a–1h)已成功合成,通过4,8-二溴-1,5-萘啶(4)与相应的硼酸(2a–2h)在催化性醋酸钯的存在下进行铃木交叉偶联反应,收率为41.4%–75.8%,并得到良好表征。它们在热稳定性方面表现优异,具有高相变温度(高于186°C)。化合物1b、1e和1f分别在单斜晶系中结晶,空间群为P21/c、P21/c和P21/n。所有化合物表现出最低能量吸收带(λmaxAbs: 294–320 nm),揭示了较低的光学带隙(2.77–3.79 eV)。这些材料在二氯甲烷稀溶液中发出蓝色荧光,λmaxEm范围为434–521 nm,在固态中为400–501 nm。4,8取代的1,5-萘啶1a–1h的估计电子亲合能(EA)为2.38–2.72 eV,适合用作电子传输材料,而离子化势(IP)为4.85–5.04 eV,促进了优良的孔注入/孔传输材料特性。使用DFT B3LYP/6-31G*进行的量子化学计算显示,最低未占分子轨道(LUMO)几乎相同,范围为−2.39至−2.19 eV,最高占分子轨道(HOMO)范围为−5.33至−6.84 eV。这些结果表明,具有简单结构的4,8取代1,5-萘啶1a–1h可能是开发高效OLED的有希望的蓝色发射(或蓝绿色发射)材料、电子传输材料以及孔注入/孔传输材料。