Trigonal Prismatic Cu₆L₃ Coordination Cage: Encapsulation of Aromatic Molecules and Tuned Photoluminescence

Abstract

A trigonal prismatic Cu6L3 coordination cage has been assembled from Cu(I) and semi‐rigid bipyrazolyl ligand. The X‐ray crystallography demonstrates that the cage has a cavity and can encapsulate the toluene as a guest, exhibiting thermochromism phenomenon. Empty cage can be obtained by expulsion of the guest through single crystal to single crystal transformation. After removed the guest, the empty cage shows a blue‐shifted emission (580 nm), in comparison to its parent cage (615 nm). The empty cage could further serve as a host to encapsulate other aromatic molecules (e. g. mesitylene), which shows new emission band. The trigonal prismatic Cu6L3 coordination cage provides a platform to make advanced luminescent materials.

Coinage-Metal-Based Cyclic Trinuclear Complexes with Metal–Metal Interactions: Theories to Experiments and Structures to Functions

“…In 2019, Li's group constructed a very similar trigonal prismatic Cu 6 L 3 (L = 2,5-bis(4′-methylene-3′,5′-dimethylpyrazolate)thiophene) coordination cage. 50 Interestingly, this Cu 6 L 3 cage can act as a host to encapsulate one toluene molecule, resulting in the guest-induced luminescencethermochromic phenomenon. Because of the poor solubility of this cage, the encapsulation of other guests failed.…”

“…Li's group constructed a hexanuclear Cu(I) trigonal coordination prism, which displayed emission maxima shifts as large as 35 nm after the inclusion of toluene molecules. 50 Later, a hexanuclear Cu(I) trigonal coordination prism with a nanocavity was prepared, which accommodates a series of aromatic guests (Figure 72). 52 These resulting host−guest inclusion complexes show guest-dependent phosphorescence behaviors.…”

“…The formation of hexanuclear Au­(I)/Ag­(I)/Cu­(I) CTU-based coordination prism or antiprism cages by the direct reactions of metal sources with semirigid bis-pyrazole ligands (Figure ) was reported. − The synthetic method for CTCs was also adopted for CTU-based coordination cages. The first Cu­(I)/Ag­(I)/Au­(I) CTU-based cages were reported in 2011 by Thiel’s group .…”

“…A series of hexanuclear Ag­(I) and Cu­(I) prism cages with semirigid bis-pyrazole ligands (Figure ) was obtained under hydro­(solvo)­thermal conditions. − The one-pot hydro­(solvo)­thermal reaction could give rise to the corresponding X-ray quality crystals of these cages as the final products.…”

“…The unique affinity and/or luminescence properties of CTCs have inspired researchers to move forward to construct a series of CTU-based coordination cages − and polymers. − Since the introduction of the hydro­(solvo)­thermal method into the construction of the CTC family in 2006, CTU-based coordination cages, polymers, and supramolecular aggregates have been feasibly prepared. , Over the past 10 years, exciting progresses have been demonstrated, including a dual-emitting Cu 6 –Cu 2 –Cu 6 cluster as a self-calibrated and wide-range luminescent molecular thermometer, an exceptionally water-stable metal–organic framework (MOF) with hydrophobic nanospaces for extracting trace aromatic pollutants from water, flexible MOFs for aborting several unsaturated hydrocarbons in a single-crystal-to-single-crystal manner, and a luminescent sensor toward various organic compounds …”