Applying the Power of Reticular Chemistry to Finding the Missing alb-MOF Platform Based on the (6,12)-Coordinated Edge-Transitive Net

Highly connected and edge-transitive
nets are of prime importance
in crystal chemistry and are regarded as ideal blueprints for the
rational design and construction of metal–organic frameworks
(MOFs). We report the design and synthesis of highly connected MOFs
based on reticulation of the sole two edge-transitive nets with a
vertex figure as double six-membered-ring (d6R) building unit, namely
the (4,12)-coordinated shp net (square and hexagonal-prism)
and the (6,12)-coordinated alb net (aluminum diboride,
hexagonal-prism and trigonal-prism). Decidedly, the combination of
our recently isolated 12-connected (12-c) rare-earth (RE) nona­nuclear
[RE9­(μ3-OH)12­(μ3-O)2­(O2C–)12] carboxylate-based cluster, points of extension matching the 12
vertices of hexagonal-prism d6R, with 4-connected (4-c) square porphyrinic
tetracarboxylate ligand led to the formation of the targeted RE-shp-MOF. This is the first time that RE-MOFs based on 12-c
molecular building blocks (MBBs), d6R building units, have been deliberately
targeted and successfully isolated, paving the way for the long-awaited
(6,12)-c MOF with alb topology. Indeed, combination of
a custom-designed hexa­carboxylate ligand with RE salts led to
the formation of the first related alb-MOF, RE-alb-MOF. Intuitively, we successfully transplanted the alb topology to another chemical system and constructed the
first indium-based alb-MOF, In-alb-MOF,
by employing trinuclear [In3­(μ3-O)­(O2C–)6] as the requisite 6-connected trigonal-prism
and purposely made a dodeca­carboxylate ligand as a compatible
12-c MBB. Prominently, the dodeca­carboxylate ligand was employed
to transplant shp topology into copper-based MOFs by
employing the copper paddle­wheel [Cu2­(O2C–)4] as the complementary square building
unit, affording the first Cu-shp-MOF. We revealed that
highly connected edge-transitive nets such shp and alb are ideal for topological transplantation and deliberate
construction of related MOFs based on minimal edge-transitive nets.