Germanium- and tin-bridged diazulenylmethyl cations: effects of group 14 elements on the structure and properties of π-extended cations.

Diazulenylmethyl cations bridged with a germanium and tin moiety were synthesized. In these cations, the nature of these elements has impacts on the chemical stability and photophysical properties. Upon aggregation, these cations exhibit absorption bands in the near-infrared region, which are slightly blue-shifted compared to those of silicon-bridged congeners.