Synthesis and Photophysical Evaluation of Assembly of a New Donor-Spacer-Acceptor (Push-Pull) Molecule

By varying the donor and acceptor groups, which are connected by a π-spacer arm, we designed and synthesised a novel molecule with the donor-spacer-acceptor compound 2f as a multifunctional component of fluorescence emitters in solution and 93% of yield. The proposed study aims to compare and quantify a set of push-pull type molecules of new linear conjugated systems with a variation of the acceptor force and a distance π between the donor and the acceptor for biological (biomedical) applications and materials in the field of semiconductors and photocatalysis. The absorption spectrums of this molecule, as well as its fluorescence have been studied. Structure 2f was confirmed by means of single-crystal X-ray diffraction, 1H-NMR, 13C-NMR, 19F-NMR, and mass spectroscopy. A series of new compounds, similar to a D-π-A, were also designed and synthesised, which show a high propensity for aggregation and crystallization (2e, 2g, and 2h) and increased the charge mobility in thin films. These push-pull organic molecules are formed from the electron-withdrawing functional groups (diester, diketone, bis-cyano, and hexafluoro-diketone), which are based on useful properties to improve the donor/acceptor interface, the optical absorption in the solution state, and the quantum yield. The photochemical properties of these compounds were studied using UV-Visible spectroscopy and fluorescence. The best dyes with having a yield of 26% (2g), 67% (2e), and 93% for (2f) showed NIR emission in solution state with an emission quantum yield of 14.5% at 627 nm, 1% at 570 nm, and 1% at 621 nm, respectively.