Helicenes are very attractive chiral non-planar polycyclic aromatic hydrocarbons possessing strong chiroptical properties. However, most of the helicenes absorb light mainly in the ultraviolet region, with only a small segment in the blue part of the visible spectrum. Furthermore, carbo[n]helicenes exhibit only weak luminescence that limits their utilization. Herein, we demonstrate that peripheral decoration of the helicene backbone with an aryl-carbonyl group shifts the absorption to the visible region and simultaneously improves their fluorescence quantum yields. We thus show that the carbonyl group, commonly considered as detrimental to emission, has the capability of improving optical and photophysical properties. Two different families, aceno[n]helicenones and fluoreno[n]helicenes, are presented with comprehensive spectrochemical characterization. TD-DFT calculations were implemented to clarify their electronic profiles. We show that increasing the helical length in aceno[n]helicenes increases absorption onset, g_abs and g_lum. Extension of the peripheral aromatic part in fluoreno[n]helicenes leads to a blue shift in both absorption and emission.

中文翻译：

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并苯[n]螺酮和芴[n]螺烯中羰基介导的荧光


螺旋烯是非常有吸引力的手性非平面多环芳烃，具有很强的手性光学性质。然而，大多数螺旋烯主要吸收紫外区域的光，只有一小部分吸收可见光谱的蓝色部分。此外，碳[n]螺烯仅表现出微弱的发光，这限制了它们的利用。在此，我们证明了用芳基羰基对螺旋烯主链进行外围装饰可将吸收转移到可见光区域，同时提高其荧光量子产率。因此，我们表明，通常被认为对发射有害的羰基具有改善光学和光物理性质的能力。两个不同的家族，并苯[n]螺烯酮和芴[n]螺烯，均进行了全面的光谱化学表征。进行 TD-DFT 计算是为了阐明它们的电子特征。我们表明，增加并苯[n]螺旋烯中的螺旋长度会增加吸收起始 g _abs 和 g _lum 。芴[n]螺烯中外围芳香族部分的延伸导致吸收和发射的蓝移。