The introduction of unconventional elements into π‐conjugated systems has been studied to manipulate the electronic states and properties of compounds. Herein, boron‐ and germanium‐containing hybrid macrocycles, as a new class of element‐hybrid conjugated systems, have been synthesized. The palladium‐catalyzed Stille cross coupling of bis(bromothienyl)borane and bis(trimethylstannylthienyl)‐ or bis(trimethylstannylphenyl)‐substituted dithienogermoles as the boron‐ and germanium‐containing building blocks, respectively, produced a mixture of several macrocyclic compounds. Single‐crystal X‐ray analysis of the 2:2 coupling product revealed a planar structure with a cavity inside the macrocycle. The optical properties of the macrocyclic products indicated rather small electronic interactions between the building units. However, intramolecular photoenergy transfer from the dithienogermole unit to the boron unit was clearly observed with respect to the fluorescence spectra.

The photophysical properties and DSSC performances of dithienosilole (DTS) and dithienogermole (DTG) containing photosensitizing dyes were directly compared.

New conjugated macrocycles consisting of tricoordinate boron units and dithienogermole (DTG) were prepared by Stille cross‐coupling reactions. The element‐hybrid macrocycles exhibited energy transfer from the DTG units to the macrocyclic backbone in the fluorescence spectra. In the fluoride titration experiments, clear turn‐on and turn‐off fluorescence responses were observed for different conjugated linkers. For more information, see the Full Paper by F. Jäkle and J. Ohshita et al. on page 3306.

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