Two Principles of Reticular Chemistry Uncovered in a Metal–Organic Framework of Heterotritopic Linkers and Infinite Secondary Building Units

Structural diversity of metal–organic
frameworks (MOFs)
has been largely limited to linkers with at most two different types
of coordinating groups. MOFs constructed from linkers with three or
more nonidentical coordinating groups have not been explored. Here,
we report a robust and porous crystalline MOF, Zn3(PBSP)2 or MOF-910, constructed from a novel linker PBSP (phenylyne-1-benzoate,
3-benzosemiquinonate, 5-oxidopyridine) bearing three distinct types
of coordinative functionality. The MOF adopts a complex and previously
unreported topology termed tto. Our study suggests that
simple, symmetric linkers are not a necessity for formation of crystalline
extended structures and that new, more complex topologies are attainable
with irregular, heterotopic linkers. This work illustrates two principles
of reticular chemistry: first, selectivity for helical over straight
rod secondary building units (SBUs) is achievable with polyheterotopic
linkers, and second, the pitch of the resulting helical SBUs may be
fine-tuned based on the metrics of the polyheterotopic linker.