Covalent organic frameworks (COFs) define a versatile structural paradigm combining attractive properties such as crystallinity, porosity, and chemical and structural modularity which are valuable for various applications. For the incorporation...

The investigation of the mechanisms of mechanochromic luminescence is of fundamental importance for the development of materials for photonic sensors, data storage, and luminescence switches. The structural origin of this phenomenon in phosphorescent molecular systems is rarely known and thus the formulation of structure-property relationships remains challenging. Changes in the M-M interactions have been proposed as the main mechanism with d coinage metal compounds. Herein, we describe a new mechanism-a mechanically induced reversible formation of a cation-anion exciplex based on Cu-F interactions-that leads to highly efficient mechanochromic phosphorescence and unusual large emission shifts from UV-blue to yellow for Cu complexes. The low-energy luminescence is thermo- and vaporesponsive, thus allowing the generation of white light as well as for recovering the original UV-blue emission.

Herein, two new quadrupolar acceptor-p-donor-pacceptor (A-p-D-p-A) chromophores have been prepared featuring as trongly electron-donating diborene core and strongly electron-accepting dimesitylboryl (BMes 2 )a nd bis(2,4,6-tris(trifluoromethyl)phenyl)boryl (B F Mes 2 )e nd groups.A nalysis of the compounds by NMR spectroscopy, X-ray crystallography,c yclic voltammetry,a nd UV/Vis-NIR absorption and emission spectroscopyi ndicated that the compounds have extended conjugated p-systems spanning their B 4 C 8 cores.T he combination of exceptionally potent pdonor (diborene) and p-acceptor (diarylboryl) groups,b oth based on trigonal boron, leads to very small HOMO-LUMO gaps,resulting in strong absorption in the near-IR region with maxima in THF at 840 and 1092 nm and very high extinction coefficients of ca. 120 000 m À1 cm À1 .B oth molecules also displayw eak near-IR fluorescence with small Stokes shifts.

The first application of electroluminescence detected electron spin resonance technique on electroluminescent thermally activated delayed fluorescence (TADF) devices is shown. It indubitably proves the involvement of spins in the emergence of TADF electroluminescence and reveals the temperature dependency of such spin‐dependent processes on bilayer devices that consist of two different material systems.