Understanding the extension of π-conjugation in 2-dimensions is useful for controlling the optical, photophysical and electronic properties of 2D-π-conjugated materials. Slanted H-mers, wherein two strands are connected via rungs, have previously been studied to shed light on π-conjugation in 2-dimensions. However, for the synthesis of larger oligomers or polymers, non-slanted H-mers having mirror plane symmetry are ideal. In this poster, I will discuss the synthesis of three non-slanted H-mers and the impact of rung twists and the rung electronic nature on the optical and photophysical properties of H-mers. In H-shaped molecules the strands were connected using benzimidazole linkages, which are relatively easy to synthesize. H-mer-1 contained 1H-benzimidazole linkages, H-mer-2 had N-methylated benzimidazole and H-mer-3 had N-methylated benzimidazole linkages with a tetrafluoro substituted phenyl rung. UV-Vis absorption and emission spectra of the three H-mers were recorded in neutral, basic and acidic environments. The different chemical environments did not significantly affect the UV-Vis absorption spectra of the H-mers, however H-mer-3 showed a larger stokes shift in comparison to the other H-mers. The fluorescence lifetimes of all three H-mers were also recorded and showed that H-mer-3 with donor and acceptor moieties exhibited an excited state lifetime that was at least 5 times higher than that of the other two H-mers. Interesting optical and photophysical properties of H-mer-3 is attributed to the twist along with the electron deficient rung in H-mer-3.

Synthesis and study of non-slanted H-mers to understand π-conjugation in 2-dimensions

ACS Spring Meeting 2021

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