Flores J Reyes, Castruita-De León Griselda, Turlakov Gleb, Arias Eduardo, Moggio Ivana, Montemayor Sagrario M, Torres Román, Ledezma Raquel, Ziolo Ronald F, González-Torres Julio
Centro de Investigación en Química Aplicada, Blvd. Enrique Reyna Hermosillo 140, 25294, Saltillo, Coahuila, Mexico.
CONACYT-Centro de Investigación en Química Aplicada, Blvd. Enrique Reyna Hermosillo 140, 25294, Saltillo, Coahuila, Mexico.
Chemistry. 2021 Feb 1;27(7):2493-2505. doi: 10.1002/chem.202004481. Epub 2020 Dec 22.
Two series of 2,5-di(butoxy)phenyleneethynylenes, one halogenated (nPEC4-X; n=2, 3, or 4) and the other boron-dipyrromethene (BODIPY) terminated (nPEC4-By; n=3, 4, or 5; By=BODIPY), were synthesized monodirectionally by the step-by-step approach and the molecular structure was corroborated by NMR spectroscopy ( H, C-DEPTQ-135, COSY, HSQC, HMBC, B, F) and MALDI-TOF mass spectrometry. The multiplicity and J-coupling constants of H, B, and F/ B NMR signals revealed, in the nPEC4-By series, that the phenyl in the meso position of BODIPY becomes electronically part of the conjugation of the phenyleneethynylene chain, whereas BODIPY is electronically isolated. The photophysical, electrochemical, and theoretical studies confirm this finding because the properties of nPEC4-By are comparable to those of the nPEC4-X oligomers and BODIPY, indicating negligible electron communication between BODIPY and the nPEC4 moieties. Nevertheless, energy transfer (ET) from nPEC4 to BODIPY was rationalized by spectroscopy and theoretical calculations. Its yield decreases with the nPEC4 conjugation length, according to the increase in distance between the two chromophores, resulting in dual emission for the longest oligomer in which ET is quenched.
通过逐步方法单向合成了两个系列的2,5-二（丁氧基）亚苯基乙炔，一个是卤代的（nPEC4-X；n = 2、3或4），另一个是硼二吡咯亚甲基（BODIPY）封端的（nPEC4-By；n = 3、4或5；By = BODIPY），并通过核磁共振光谱（氢谱、碳谱-DEPTQ-135、COSY、HSQC、HMBC、硼谱、氟谱）和基质辅助激光解吸电离飞行时间质谱对分子结构进行了确证。在nPEC4-By系列中，氢谱、硼谱和氟谱/硼谱核磁共振信号的多重性和J耦合常数表明，BODIPY中位的苯基在电子上成为亚苯基乙炔链共轭的一部分，而BODIPY在电子上是孤立的。光物理、电化学和理论研究证实了这一发现，因为nPEC4-By的性质与nPEC4-X低聚物和BODIPY的性质相当，表明BODIPY与nPEC4部分之间的电子通信可忽略不计。然而，通过光谱学和理论计算对从nPEC4到BODIPY的能量转移（ET）进行了合理分析。其产率随着nPEC4共轭长度的增加而降低，这是由于两个发色团之间距离的增加，导致最长低聚物出现双重发射，其中ET被淬灭。
