Non‐Porous Iron(II)‐Based Sensor: Crystallographic Insights into a Cycle of Colorful Guest‐Induced Topotactic Transformations

Abstract

Materials capable of sensing volatile guests at room temperature by an easily monitored set of outputs are of great appeal for development as chemical sensors of small volatile organics and toxic gases. Herein the dinuclear iron(II) complex, [Fe (L) (CH CN) ](BF ) ⋅2 CH CN (1) [L=4-(4-methylphenyl)-3-(3-pyridazinyl)-5-pyridyl-4H-1,2,4-triazole], is shown to undergo reversible single-crystal-to-single-crystal (SCSC) transformations upon exposure to vapors of different guests: 1 (MeCN)⇌2 (EtOH)→3 (H O)⇌1 (MeCN). Whilst 1 and 2 remain dimetallic, SCSC to 3 involves conversion to a 1D polymeric chain (due to a change in L bridging mode), which, remarkably, can undergo SCSC de-polymerization, reforming dimetallic 1. Additionally, SC-XRD studies of two ordered transient forms, 1TF3 and 2TF3, confirm that guest exchange occurs by diffusion of the new guests into the non-porous lattices as the old guests leave. These reversible SCSC events also induce color and magnetic responses. Indeed dark red 1 is spin crossover active (T ↓ 356 K; T ↑ 369 K), whilst orange 2 and yellow 3 remain high spin.

Blockable Zn10L15 Ion Channels through Subcomponent Self‐Assembly

“…[6] Artificial anion channels adopt these principles,incorporating functionalities able to interact non-covalently with anions during transport, thus energetically compensating for the dehydration penalty.Asynthetic ion channel must also span the membrane.A lthough large synthetic molecules can span ab ilayer to mediate ion transport, [7] self-assembly has emerged as an attractive strategy to construct complex membrane-spanning structures from smaller, more accessible building blocks.S mall organic molecules have been shown to associate in the bilayer environment to form membrane-spanning ion channels, [8] while DNAa nd peptides have also served to build transmembrane channels. [12] Certain complex multi-metallic architectures [13] can self-assemble biomimetically, [14] and others have been shown to function as self-assembling anion channels, [15] with the assembly and disassembly of metal-organic channels having been shown to function as agating mechanism. [12] Certain complex multi-metallic architectures [13] can self-assemble biomimetically, [14] and others have been shown to function as self-assembling anion channels, [15] with the assembly and disassembly of metal-organic channels having been shown to function as agating mechanism.…”

Two Consecutive Magneto-Structural Gas-Solid Transformations with Single-Crystal Retention in Non-Porous Molecular Materials

“…In addition, nonporous crystalline materials permit overcoming the challenges to combine magnetic exchange and gas sorption, but this usually results in the loose of single crystallinity, thus hindering the understanding of the magnetostructural changes caused by the vapor. With the exception of some exchangeable solvents directly coordinated to the metal centres, which can be cycled for several species, [19] all the reported examples of single-crystal-to-single-crystal transformations in molecular (non-porous) solids occur in a single step, [12] To the best of our knowledge, this is the first report of multiple transformations with rearrangement of molecules in the solid state while preserving the single crystals at the end of the transformations.…”

Overcoming the Inertness of Iridium(III) in a Facile Single‐Crystal to Single‐Crystal Reaction of Iodine Vapor with a Cyclometalated Chloride Monomer

“…Single‐crystal to single‐crystal (SCSC) reactions, in combination with X‐ray diffraction analysis, are a very powerful tool to obtain comprehensive structural data on chemical species involved in the reactions, and to give insights into the dynamics of their mutual transformations . Still, for discrete molecular organometallic complexes, SCSC reactions involving ligand exchange are rare, because the formation or cleavage of metal‐ligand bonds is usually accompanied by the loss of crystallinity …”