Azaisoquinolinones: N Positions Tell You Different Stories in Their Optical Properties

Abstract

Since isoquinolinones and their derivatives have been demonstrated to be powerful building blocks in constructing larger acenes and twistacenes, azaisoquinolinones and their analogues could also be important intermediates to approach larger N-heteroacenes. In this paper, we are interested in developing a concise method to synthesize novel azaisoquinolinones building blocks and studying their physical properties. Our results showed that the different N positions have a large effect on the optical and electrochemical properties of azaisoquinolinones. For example, protonation of 6- and 7-azaisoquinolinones shows different shifts of UV-vis and FL spectra. More interestingly, 6- and 7-azaisoquinolinones exhibited different interactions with metal ions in CH3CN solution. Upon the addition of 2 equiv of Fe(3+), 6-azaisoquinolinone displayed an absorption wavelength red-shifted from 470 to 540 nm (Δλ = 70 nm) with a color change from yellow to red, while the interaction between Fe(3+) and 7-azaisoquinolinone was very weak and there was no obvious color change (Δλ = 18 nm). Moreover, theoretical calculations confirmed the different optical properties with 6- and 7-azaisoquinolinones.

Linearly Fused Azaacenes: Novel Approaches and New Applications Beyond Field-Effect Transistors (FETs)

“…The resulting azapentacenes have been shown to be ambipolar organic semiconductors . To construct larger azaacenes, our group has prepared two new building blocks 25 and 26 for D–A reaction that contain N atoms at different positions (Scheme ) . Because the similar isoquinolinone ( 27 ) had been used by us as an effective building block to construct larger acenes or twistacenes, ,− it seemed logical that azaisoquinolinones ( 25 and 26 ) could be useful building blocks for preparing larger azaacenes.…”

‘Heteroaromatic Rings of the Future’: Exploration of Unconquered Chemical Space

“…The first synthesis of substituted azaisoquinolinones was reported in 2013 by Li and co-workers using a twosteps strategy (Scheme 28). 61 The [4+2] cycloaddition reaction between mesoionic pyrimidine 103 and 3,4-pyridyne intermediate generated in situ from 3-aminopyridine-4carboxylic acid (102) afforded a mixture of two separable isomers 104 and 105. Each of the two isomers 104 and 105 decomposed at high temperatures via a retro-Diels-Alder reaction to give 106 and 107, respectively.…”

Pyrene-fused Acenes and Azaacenes: Synthesis and Applications

“…Actually, the pyrene‐fused diazatetracene and diazapentacene with different functional groups, such as crown (ion sensor) and Ru(II) complexes (DNA intercalation), have been summarized by Mateo‐Alonso 31. Although N‐heterocycles, such as pyridine,34 pyridazine,35 and 1,2,4‐triazine36 have been inserted into the backbones of acenes to construct azaacenes, the pyrene‐fused azaacenes with N‐heterocycles beyond pyrazine rings are still rare. More recently, our group successfully prepared a series of new diazaacenes (from azanaphthalene to azapentacene) through D‐A reactions between in situ generated arynes as dienophiles and substituted 1,2,4,5‐tetrazines as dienes (Scheme ) 37.…”