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Subphthalocyanine-type dye with enhanced electron affinity: Effect of combined azasubstitution and peripheral chlorination
Dyes and Pigments ( IF 4.1 ) Pub Date : 2020-10-17 , DOI: 10.1016/j.dyepig.2020.108944
Ivan A. Skvortsov , Ulyana P. Kovkova , Yuriy A. Zhabanov , Ilya A. Khodov , Nikolay V. Somov , Georgy L. Pakhomov , Pavel A. Stuzhin

Novel subphthalocyanine-type dye with enhanced electron-affinity was prepared by trimerization of 5,6-dichloropyrazine-2,3-dicarbonitrile in the presence of BCl3 in p-xylene. The obtained perchlorinated pyrazine fused subporphyrazine [Cl6Pyz3sPA] was characterized by mass-spectrometry, 13C and 11B NMR, IR and UV-VIS spectroscopy, cyclovoltammetry. Its molecular structure was confirmed by single crystal X-ray diffraction. To elucidate the combined effect of hexaazasubstitution and peripheral chlorination in subphthalocyanines on their electronic structure and spectral features, DFT and TD DFT calculations (B3LYP/pcseg-2 basis set) were used. Fusion of the pyrazine fragments instead of benzene rings strongly enhances the electron affinity of the macrocycle due to stabilization of the LUMO. Thus, the first reduction potential is observed at −0.20 V vs Ag/AgCl, that is macrocycle in [Cl6Pyz3sPA] is 0.5 V more easily reduced than in the peripherally hexachlorinated subphthalocyanine [Cl6sPc], the most popular subphthalocyanine-type acceptor for organic photovoltaics. The HOMO-LUMO gap is increased, so that the maximum of the Q band corresponding to the lowest ππ* transition 2a2→1e* shifts hypsochromically by 36 nm and appears at 535 nm. A distinct feature of the peripherally chlorinated macrocycles is appearance of two bands in the UV-region (B1 at ~300 nm and B2 at ~340 nm) corresponding to the electronic transitions 1a1→1e* and 2a1→1e*, respectively. Azasubstitution decreases fluorescence quantum yield, ΦF = 0.20 for [Cl6Pyz3sPA] and 0.37 for [Cl6sPc] in CH2Cl2. Spectrophotometric titrations indicate that unlike [Cl6sPc], that undergoes consecutive protonation of three meso-nitrogens in CH2Cl2-CF3COOH-H2SO4 medium, the presence of pyrazine rings in [Cl6Pyz3sPA] and their involvement in the acid-base interaction decrease the basicity of nitrogens in the meso-positions. The obtained data along with the photoelectric tests on the sublimed thin films point out at the prospects of [Cl6Pyz3sPA] for the photovoltaic applications.



中文翻译:

电子亲和力增强的亚酞菁型染料:氮杂取代和外围氯化反应的联合作用

二甲苯中存在BCl 3的情况下,通过5,6-二氯吡嗪-2,3-二碳腈的三聚制备了具有增强的电子亲和力的新型亚酞菁型染料。通过质谱,13 C和11对所得的高氯吡嗪稠合的亚卟啉[Cl 6 Pyz 3 s PA]进行表征。NMR,IR和UV-VIS光谱,循环伏安法。通过单晶X射线衍射确认了其分子结构。为了阐明亚酞菁中六氮杂取代和外围氯化反应对其电子结构和光谱特征的综合影响,使用了DFT和TD DFT计算(B3LYP / pcseg-2基集)。由于LUMO的稳定化,吡嗪片段而不是苯环的融合强烈地增强了大环的电子亲和力。因此,在-0.20 V相对于Ag / AgCl处观察到第一还原电位,即在[Cl 6 Pyz 3 s PA]中的大环比在外围六氯化亚酞菁[Cl 6 s ]中更容易还原0.5 VPC],最流行的有机光伏亚酞菁型受体。的HOMO-LUMO能隙的增加,从而使对应的最大的Q带的最低ππ*跃迁2一个2 →1 Ë *移位hypsochromically由36纳米和出现在535nm处。外围氯化大环化合物的一个显着特征是在UV区出现了两个谱带(〜300 nm处的B 1和〜340 nm处的B 2),分别对应于电子跃迁1 a 1 →1 e *和2 a 1 → 1 e *。Azasubstitution降低荧光量子产率,Φ ˚F  = 0.20 [氯6CH 2 Cl 2中的[Cl 6 sPc]为Pyz 3 sPA]和0.37 。分光光度滴定表明,与[Cl 6 sPc]不同,CH 2 Cl 2 -CF 3 COOH-H 2 SO 4介质中的三个内消旋氮连续质子化,[Cl 6 Pyz 3 sPA]和它们参与酸碱相互作用降低了位氮的碱性。所获得的数据以及对升华薄膜的光电测试指出了[Cl 6]的前景。Pyz 3 sPA]用于光伏应用。

更新日期:2020-11-22
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