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.

高度连通且边传递的网络在晶体化学中极具重要性，被视为合理设计与构建金属有机框架（metal–organic frameworks, MOFs）的理想蓝图。我们报道了基于仅有的两种以双六元环（double six-membered-ring, d6R）为顶点构型的边传递网络进行网状构筑的高度连通MOFs的设计与合成，这两种网络分别是（4,12）配位的shp网络（方形与六方棱柱型）以及（6,12）配位的alb网络（二硼化铝型，涵盖六方棱柱与三方棱柱构型）。确切而言，结合我们近期分离得到的12配位（12-c）稀土（RE）九核[RE9(μ3-OH)12(μ3-O)2(O2C–)12]羧酸基簇——其延伸位点与六方棱柱型d6R的12个顶点相匹配——与4配位（4-c）方形卟啉型四羧酸配体，成功得到了目标稀土基shp型MOF（RE-shp-MOF）。这是首次基于12配位分子构筑单元（molecular building blocks, MBBs）与d6R构筑单元的稀土基MOFs被精准靶向设计并成功分离，为期待已久的具有alb拓扑结构的（6,12）配位MOF铺平了研究道路。诚然，通过定制设计的六羧酸配体与稀土盐结合，我们得到了首例相关的alb型MOF（RE-alb-MOF）。直观而言，我们成功将alb拓扑结构移植到另一化学体系中，以三核[In3(μ3-O)(O2C–)6]作为所需的6配位三方棱柱型构筑单元，并特意合成了十二羧酸配体作为适配的12配位分子构筑单元，构建了首例铟基alb型MOF（In-alb-MOF）。尤为突出的是，我们利用铜桨轮型[Cu2(O2C–)4]作为互补的方形构筑单元，结合该十二羧酸配体将shp拓扑结构移植到铜基MOFs中，得到了首例Cu-shp-MOF。我们的研究表明，诸如shp与alb这类高度连通的边传递网络，非常适合用于拓扑移植，并基于最简边传递网络精准构建相关MOFs。