Constructing Full-Color Highly Emissive Organic Solids Based on an X‑Shaped Tetrasubstituted Benzene Skeleton

With
the aim of highlighting the potential talent of the unique
single-benzene skeleton versus the common large π-systems, we
propose a general strategy to construct single-benzene fluorophores 1–9, featuring fascinating emission properties in the
solid state, for example, high fluorescence quantum yields and wide
variety of emission colors. Our molecular design is X-shaped tetrasubstituted
benzene of which two electron-donating groups (EDGs) and two electron-withdrawing
groups are arranged in an X-shaped fashion. This molecular design
enables a very small single-benzene skeleton to show intense fluorescence
in the solid state because the π–π stacking and
dipole–dipole interaction are inherently avoided in the crystal.
More importantly, by simply changing the EDGs, the emission colors
in the solid state of these single-benzene fluorophores can be continuously
tuned from deep blue to red. In addition, the potential applications
of these single-benzene fluorophores as crystal lasing media have
been demonstrated by an amplified spontaneous emission measurement.