Targeted Construction of Light-Harvesting Metal–Organic Frameworks Featuring Efficient Host–Guest Energy Transfer

Metal–organic
frameworks (MOFs) have emerged as promising light-harvesting platforms
for energy-transfer materials. However, the targeted construction
of MOFs with desirable photophysical properties and pore structures
is still a challenge. Herein, 1,1,2,2-tetrakis­(4-(pyridin-4-yl)­phenyl)­ethene
(tppe) is selected as the ligand for the construction of light-harvesting
MOFs due to its highly emissive and rigid backbone, which could benefit
the light-harvesting performance of the MOFs. Three MOFs (MOFs 1–3) were obtained on the basis of different
metal centers (Zn2+ and Cd2+) and carboxylate
building blocks. The complete structure characterization of the MOFs
helps the illustration of the principles for structure tuning of this
system. All three MOFs exhibit strong tppe-originated photoluminescence
emission, with quantum yields as high as 47.6%. The fluorescence quantum
yield and time-resolved fluorescence studies reveal that a remarkable
energy-transfer efficiency (up to 96%) was achieved in this system.
These results clearly indicate tppe-MOFs could be promising light-harvesting
materials.