Novel Metal–Organic Framework Based on Cubic and Trisoctahedral Supermolecular Building Blocks: Topological Analysis and Photoluminescent Property

A novel supermolecular building blocks (SBBs) based metal–organic
framework (MOF), with formula [Zn7(TMBHB)2·2NO3·5DMF·4CH3CH2OH·6H2O]n (SDU-1), was
constructed from C3-symmetric trimethyl
substituted 3,3′,3″,5,5′,5″-benzene-1,3,5-triylhexabenzoic
acid (H6TMBHB). Notably, the SDU-1 consists
of two kinds of rare secondary building units (SBUs), [Zn2(COO)3] and [Zn2(COO)4], which are
linked by TMBHB to form cubic and trisoctahedral SBBs, respectively.
TOPOS software analysis of SDU-1 indicates that two alternative
simplifications based on different SBBs can produce (3,24)-connected rht or (4,12)-connected ftw topologies. Compared
with a recently reported Zn-BHB (H6BHB = 3,3′,3″,5,5′,5″-benzene-1,3,5-triylhexabenzoic
acid) MOF, the structural dissimilarity between them was caused by
the steric hindrance of three methyl groups, which makes three isophthalate
units on TMBHB nearly perpendicular to the central phenyl ring, giving
TMBHB a nonplanar conformation. The photoluminescence behavior of SDU-1 was also discussed.