Smoothing the single-crystal to single-crystal conversions of a two-dimensional metal–organic framework via the hetero-metal doping of the linear trimetallic secondary building unit

Abstract

The two-dimensional (2D) metal-organic framework (MOF) [Cd2.25Co0.75(BTB)2(DEF)4]·2(DEF)0.5 (1a, BTB = benzene-1,3,5-tribenzolate; DEF = N,N'-diethylformamide) featuring linear trimetallic cluster secondary building units (SBUs) and replaceable DEF solvates reacts smoothly with dipyridyl ligands DPS, DPDS, and BIPY (DPS = 4,4'-dipyridyl sulfide; DPDS = 4,4'-dipyridyl disulfide; BIPY = 4,4'-bipyridine), yielding three-dimensional (3D) non-interpenetrated [Cd2.25Co0.75(BTB)2(DPS)2]·xSol (2) and [Cd2.25Co0.75(BTB)2(DPDS)2]·xSol (3), and interpenetrated [Cd2.25Co0.75(BTB)2(BIPY)(H2O)2]·xSol (4). The smooth conversion of 1a to 3 contrasts the drastic single-crystal to single-crystal (SCSC) conversion observed for the homometallic [Cd3(BTB)2(DEF)4]·2(DEF)0.5 (1b), presumably due to the presence of the relatively Lewis acidic Co2+ that lessens the propensity for binding by soft dipyridyl donors. Activated samples of 2-4 showed no obvious absorption of N2 at 77 K, but reversible type I uptake of CO2 at 195 K.

Connectivity Replication of Neutral Eu3+- and Tb3+-Based Metal–Organic Frameworks (MOFs) from Anionic Cd2+-Based MOF Crystallites

“…In these SBUs, each Eu 3+ or Tb 3+ ion was associated with two chelating carboxylates, a pair of chelating–bridging carboxylates in a complementary fashion, and two H 2 O solvates. It is also notable that this double-deckered structure resembles those found in {[Ln­(BTB)­(H 2 O) 2 ]·3DMF·2H 2 O} n (Ln = La, Nd, Sm, Er) and other 2D (6,3) networks sustained by linear trinuclear SBUs. − Looking along the c direction, one can observe 1D channels with hexagonal apertures (Figure b).…”

A Heterometallic Three-Dimensional Metal−Organic Framework Bearing an Unprecedented One-Dimensional Branched-Chain Secondary Building Unit

“…The motivation for introducing Ca 2+ into a Cd 2+ /H 3 BTB assembly originated from our quest to incorporate Ca 2+ into the linear Cd 3 -based two-dimensional (2D) MOF of [Cd 3 (BTB) 2 (DEF) 4 ]·2(DEF) 0.5 [ 62 , 63 ], as we and others have demonstrated that the heterometallic combinations of Cd/Zn, Cd/Co, and Zn/Co are readily tolerated in linear trimetallic cluster SBUs [ 26 , 66 ]. Our previous trial of the solvothermal reaction of Cd(NO 3 ) 2 ∙4H 2 O and H 3 BTB in a DEF/H 2 O/HNO 3 mixed solvent with CaSO 4 yielded a 3D anionic MOF of [Et 2 NH 2 ] 2 [Cd 5 (BTB) 4 (DEF) 2 ]∙4.75DEF featuring a zigzag-shaped Cd 5 cluster SBU [ 65 ].…”

“…The motivation for introducing Ca 2+ into a Cd 2+ /H 3 BTB assembly originated from our quest to incorporate Ca 2+ into the linear Cd 3 -based two-dimensional (2D) MOF of [Cd 3 (BTB) 2 (DEF) 4 ]•2(DEF) 0.5 [62,63], as we and others have demonstrated that the heterometallic combinations of Cd/Zn, Cd/Co, and Zn/Co are readily tolerated in linear trimetallic cluster SBUs [26,66] [65]. The [Et 2 NH 2 ] + cations likely arose from the acid-catalyzed hydrolysis of DEF [67][68][69][70], and subsequently served as a template for the framework formation.…”

“…Heterometallic metal−organic frameworks (MOFs) merge the traits of two or more different metal ions in one ordered array with synergistic advantages that can be applied to catalysis [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 ], gas adsorption [ 9 , 10 , 11 , 12 , 13 ], bioimaging [ 14 , 15 , 16 ], and other applications [ 17 , 18 , 19 , 20 , 21 ]. The heterometal can be introduced by the direct one-pot assembly of mixed metal sources and ligands [ 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 ], or from preformed secondary building units (SBUs) [ 17 , 18 , 30 , 31 , 32 , 33 , 34 , 35 , 36 ]. Post-synthetic metal coordination to the functionalized ligands [ 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 ] and transmetalation/incorporation of ions into the SBUs have also been reported [ 3 ,…”

Two-Dimensional Metal-Organic Framework Materials: Synthesis, Structures, Properties and Applications

“…Using this approach topologically identical, but functionally diverse MOFs can be obtained in the solid state. − There is no topological change or structural transformation expected during this process. In this context, metal ions or metal clusters in the 2D MOFs can be exchanged in an SCSC manner. − However, these metal ion exchange reactions are out of the scope of this review.…”