The Impact of the Interplay between Steric and Electronic Effects on the Synthesis and Optical Properties of Diketopyrrolopyrroles Bearing Pyridine Moieties was written by Vakuliuk, Olena;Purc, Anna;Clermont, Guillaume;Blanchard-Desce, Mireille;Gryko, Daniel T.. And the article was included in ChemPhotoChem in 2017.Reference of 1620-76-4 This article mentions the following:
The influence of a combination of steric and electronic factors on both the preparation and the optical properties of diketopyrrolopyrroles was investigated. The attachment of a cyano group to the electron-deficient pyridine ring overcame the neg. influence of the flanking Me group on the efficiency of the synthesis of diketopyrrolopyrroles. Diketopyrrolopyrroles possessing pyridine-N-oxide moieties were studied for the first time. We have also shown that reactions of cyanopyridines possessing an addnl. dialkylamino group were very capricious and depending on the relative position of all substituents, can lead to low yields of diketopyrrolopyrroles. The interplay between the dihedral angle between the diketopyrrolopyrrole core and the pyridyl substituents as well as the presence and position of electron-donating moieties made it possible to modulate the photophys. properties of N,N’-dialkyldiketopyrrolopyrroles. In particular, it was found that pyridine-N-oxides as the aryl moieties had a strong influence on the optical properties of diketopyrrolopyrroles, shifting both absorption and emission bands bathochromically. Two-photon absorption cross-sections had low values except for those dyes possessing a clear quadrupolar centrosym. nature. In the experiment, the researchers used many compounds, for example, 4-Methylpicolinonitrile (cas: 1620-76-4Reference of 1620-76-4).
4-Methylpicolinonitrile (cas: 1620-76-4) belongs to pyridine derivatives. Pyridine has a conjugated system of six 锜?electrons that are delocalized over the ring. The molecule is planar and, thus, follows the H鐪塩kel criteria for aromatic systems. Pyridine derivatives are also useful as small-molecule 浼?helix mimetics that inhibit protein-protein interactions, as well as functionally selective GABA ligands.Reference of 1620-76-4