Using high-resolution ion mobility-mass spectrometry (IM-MS), we demonstrate the resolution and characterisation of heterobimetallic [M4L6]8+ coordination cages, enabling the identification and interrogation of individual mixed metal assemblies from complex mixtures. IM-MS guided synthesis represents a paradigm shift in the development of supramolecular sensors and catalysts that embrace complexity rather than exclusively pure materials.

Metallosupramolecular cages are widely studied for their unique host–guest properties in solution yet translating these functionalities to the solid state remains challenging due to cavity inaccessibility and dense packing. Here, we demonstrate a hierarchical approach that employs halogen bonding to control the spatial arrangement of tetrahedral [Fe 4 L 6 ] 8+ cages in the solid state. By incorporating perfluorinated halogen bond donors of varying geometry, we demonstrate selective modulation of cage packing motifs without disrupting the cage architecture. Structural analysis reveals that incorporation of 1,3,5‐triiodotrifluorobenzene disrupts the robust honeycomb arrangement, producing a distorted cubic lattice with significantly reduced cage density and potentially enhanced cavity accessibility. This approach offers a pathway to design tunable porous molecular solids, ultimately enabling the transfer of solution‐phase properties to the solid state for applications in catalysis, separations, and molecular recognition.

Metallosupramolecular cages are widely studied for their unique host-guest properties in solution yet translating these functionalities to the solid state remains challenging due to cavity inaccessibility and dense packing. Here, we demonstrate a hierarchical approach that employs halogen bonding to control the spatial arrangement of tetrahedral [Fe4L6]8+ cages in the solid state. By incorporating perfluorinated halogen bond donors of varying geometry, we demonstrate selective modulation of cage packing motifs without disrupting the cage architecture. Structural analysis reveals that incorporation of 1,3,5-triiodotrifluorobenzene disrupts the robust honeycomb arrangement, producing a distorted cubic lattice with significantly reduced cage density and potentially enhanced cavity accessibility. This approach offers a pathway to design tunable porous molecular solids, ultimately enabling the transfer of solution-phase properties to the solid state for applications in catalysis, separations, and molecular recognition.

Flexible crystals are finding increased applications in optoelectronics. The mechanism of elastic and plastic bending and thermal expansion in 9, 10-dibromoanthracene (DBrA) crystals is determined. In addition, the X-ray radiation luminescence performance of DBrA elastoplastic crystals is investigated and successfully prepare a flexible composite film (DBrA-PMMA) for X-ray radiation imaging by dispersing the crystal in polymethyl methacrylate (PMMA). This work provides new insights for the applications of elastoplastic crystals in the field of flexible optoelectronics.

As one of the key representatives of carbon-nitrogen-based materials, melem (2,5,8-triamino-s-heptazine) holds significant potential for applications in luminescence and catalysis. In previous studies, acid treatment has been frequently used to modify the optical and catalytic properties of melem and its family materials. However, the underlying mechanism of this process has been barely studied and remains poorly understood. In this study, we reveal that acidification results in the formation of new supramolecular structures via protonation of melem with different protonation states after reacting with strong acids. In this regard, we identified the micromechanism of the evolved optical absorption by protonation through density functional theory (DFT) calculations. Notably, when these crystals were transferred back to water, the protonated melem molecules underwent deprotonation, causing hydrogen bonds to break and the protons released to water instantly. This rapid proton release can be easily visualized by the color change of a pH indicator as the crystals are immersed in water. Interestingly, the deprotonated melem molecules recrystallized into purified melem crystals with well-defined morphologies, which varied depending on the specific acid used. The reversible structural transition between melem and protonated melem crystals can be cycled multiple times, making melem a perfect solid proton carrier and may find applications in catalysis and fuel cells.

Elasticity is ubiquitous and produces a spontaneously reversible response to applied stress1. Despite the utility and importance of this property in regard to scientific and engineering applications, the atomic-scale location of the force that returns an object to its original shape remains elusive in molecular crystals. Here we use a series of density functional theory calculations to locate precisely where the energy is stored when single crystals of three molecular materials are placed under elastic stress. We show for each material that different intermolecular interactions are responsible for the restoring force under both expansive and compressive strain. These findings provide insight into the elastic behaviour of crystalline materials that is needed for more efficient design of flexible technologies and future smart devices.

Mechanically flexible single crystals are emerging as a useful class of materials due to their unique combination of crystallinity and molecular-scale responses to applied mechanical stress.

There is growing focus on metal-free molecules and polymers owing to their potential applications in various energy and catalysis-related applications. Melem (2,5,8-triamino-s-heptazine, C6H6N10) has emerged as a metal-free material for solar-to-fuel conversion. However, its reactivity with metal ions or organic molecules has never been reported although it possesses multiple supramolecular interaction sites. In this work, we report on the synthesis of a novel metal-organic coordination framework (melem-Ag) by simply introducing Ag+ into the aqueous suspension of aggregated melem particles. Notably, as the reaction progresses, the melem disappears, and the morphology of the newly formed complex spontaneously evolves from nanofibers to single-crystalline blocks, which possess the same chemical structure, indicating that the morphology evolution is driven by Ostwald ripening. The structure of melem-Ag displays infinite nanocages of triangular pyramids consisting of melem molecules and Ag+, linked via Ag-N coordinate bonding and Ag-Ag argentophilic interactions. It is noteworthy that Ag+ is the only transition-metal cation that reacts with melem suspensions, even in the presence of other transition-metal cations (Co2+, Ni2+, Cu2+, and Zn2+). The coordination of Ag+ to melem results in metal-to-ligand charge transfer (MLCT), resulting in a quenched photoluminescence and enhanced light absorption. Exposing the melem-Ag crystals to UV light for varying time intervals results in the formation of colorful powders, which may be used for Ag-decorated photocatalysts.

Unequivocally establishing chemical connectivity and ultimately chemical identity is of central importance to all branches of science and particularly chemistry. Accordingly, the determination of a crystal structure is often considered the "gold standard" as this technique can unambiguously establish both the connectivity and identity of a compound. Crystal structure data, however, are prone to misinterpretation, and the increasing development of automatic data processing and verification has the potential to result in an epidemic of incorrectly modeled crystal structures. Here, we present a series of case studies where structures were modeled to current publication standards with the incorrect chemical composition. It is essential that researchers, referees, editors, and the scientific community be vigilant in upholding the scientific method.

The impact that the anion and alkyl group has on the electronic structures and magnetic properties of four mononuclear Mn(III) complexes is explored in [Mn(salEen-Br)2]Y (salEen-Br = 2-{[2-(ethylamino)ethylimino]methyl}-4-Br-phenol; Y = ClO4- 1 and BF4-·1/3CH2Cl2 2) and [Mn(salBzen-Br)2]Y (salBzen-Br = 2-{[2-(benzylamino)ethylimino]methyl}-4-Br-phenol; Y = ClO4- 3 and BF4- 4). X-ray structures of [Mn(salEen-Br)2]ClO4·0.45C6H14 1-hexane, [Mn(salEen-Br)2]BF4·0.33CH2Cl2·0.15C6H14 2-dcm-hexane, and 3-4 reveal that they crystallize in ambient conditions in the monoclinic P21/c space group. Lowering the temperature, 2-dcm-hexane uniquely exhibits a structural phase transition toward a monoclinic P21/n crystal structure determined at 100 K with the unit cell trebling in size. Remarkably, at room temperature, the axially elongated Jahn-Teller axis in 2-dcm-hexane is poorly defined but becomes clearer at low temperature after the phase transition. Magnetic susceptibility measurements of 1-4 reveal that only 3 and 4 show slow relaxation of magnetization with Δeff/kB = 27.9 and 20.7 K, implying that the benzyl group is important for observing single-molecule magnet (SMM) properties. Theoretical calculations demonstrate that the alkyl group subtly influences the orbital levels and therefore very likely the observed SMM properties.

In this work, competition between different supramolecular interactions is investigated based on a fibrous crystal composed of hydrogen-bonded cyanuric acid (CA) and amidinothiourea (ADT). Melamine (M) is found to prevail over ADT and bond to CA due to its stronger triple H-bonding affiliation, forming hollow microtubes assembled by oriented CAM crystalline arrays, as guided by the directionality of peripheral hydrogen bonds. Furthermore, competitive interaction between hydrogen bonding and ionic/covalent bonding is demonstrated by mixing Ag+ ions with the CA-ADT fibers, where sulfur atoms are abstracted from ADT molecules to produce Ag2S ligaments. The in situ-formed Ag2S serves as a binding glue to generate CA-ADT/Ag2S composites with significantly enhanced mechanical strength compared to the pristine CA-ADT fiber pellet. [GRAPHICS] .

Coordination complex of a copper cyanurate (Cu(II)-CA) was transformed into coordination polymers upon the stimulus of extra Cu(II) through “directed Ostwald ripening”. By increasing the molar ratio of Cu(II) to CA, we obtained two coordination polymers with selective coordination sites: Cu(II)-κN(HCA)κN-Cu(II) and Cu(II)-κN(HCA)κO-Cu(II), which display disparate magnetic interactions.

Protein function results from the precise folding of polypeptides into bespoke architectures. Taking inspiration from nature, the field of single-chain nanoparticles (SCNPs), intramolecularly crosslinked synthetic polymers, emerged. In contrast to nature, the function of SCNPs is generally defined by the parent polymer or the applied crosslinker, rather than by the crosslinking process itself. This work explores the cyanopyridine-aminothiol click reaction to crosslink peptide-decorated polymers intra-macromolecularly to endow the resulting SCNPs with emerging functionality, resulting from the conversion of N-terminal cysteine units into pyridine-thiazolines. Dimethylacrylamide based polymers with different cysteine-terminated amino acid sequences tethered to their sidechains are investigated (P1 (C), P2 (GDHC), P3 (GDSC)) and intramolecularly crosslinked into SCNPs. Since the deprotection of the parent polymers yields disulfide-based SCNPs, a direct comparison between disulfide and pyridine-thiazolines crosslinked SCNPs is possible. This comparison revealed two emerging properties of the pyridine-thiazoline crosslinked SCNPs: 1) The formation of pyridine-thiazolines gave rise to metal binding sites within the SCNP, which complexed iron. 2) Depending on the peptide sequence in the precursor polymer, the hydrolytic activity of the peptide sequences is either increased (GDHC) or decreased (GDSC) upon pyridine-thiazoline formation compared to identical SCNPs based on disulfide crosslinks.

In order to bind guest molecules with exquisite selectivity, biological host molecules often employ low symmetry binding pockets. The majority of metallosupramolecular assemblies, however, rely on symmetrical ligands to form high-symmetry assemblies that enclosing similarly symmetrical cavities. Here we employ an unsymmetrical quaterpyridine ligand in combination with cobalt(ii) to form a mixture of low-symmetry [M2L3] helicates and [M4L6] tetrahedra and their subsequent oxidation to Co(iii)-containing assemblies.

Organic materials are promising candidates for the development of efficient sensors for many medicinal and materials science applications. Single crystals of a small molecule, 4-trifluoromethyl phenyl isothiocyanate (4CFNCS), exhibit plastic deformation when bent, twisted, or coiled. Synchrotron micro-focus X-ray diffraction mapping of the bent region of the crystal confirms the mechanism of deformation. The crystals are incorporated into a flexible piezoresistive sensor using a composite constituting PEDOT: PSS/4CFNCS, which shows an impressive performance at high-pressure ranges (sensitivity 0.08 kPa-1 above 44 kPa).

Molecular crystals displaying elastic flexibility have important applications in the fields of optoelectronics and nanophotonic technologies. Understanding the mechanisms by which these materials bend is critical to the design of future materials incorporating these properties. Based on the known elastic properties of bis(acetylacetonato)copper(II), a series of 14 aliphatic derivatives are synthesized and crystallized. All those which grew in a needle morphology display noticeable elasticity, with 1D chains of π-stacked molecules parallel to the long metric length of the crystal a consistent crystallographic feature. Crystallographic mapping is used to measure the mechanism of elasticity at an atomic-scale. Symmetric derivatives with ethyl and propyl side chains are found to have different mechanisms of elasticity, which are further distinguished from the previously reported mechanism of bis(acetylacetonato)copper(II). While crystals of bis(acetylacetonato)copper(II) are known to bend elastically via a molecular rotation mechanism, the elasticity of the compounds presented is facilitated by expansion of their π-stacking interactions.

Coordination polymers exhibiting mechanical flexibility including elastic or plastic bending are rare. Here, we report an example of a mechanically flexible one-dimensional coordination polymer that shows elastic bending. Quantitative insights on the inter and intra-chain bonding as well as structural flexibility from a combination of techniques including variable temperature single crystal X-ray diffraction (XRD), highpressure crystallography (ambient-15 GPa), synchrotron micro-XRD mapping of the bent crystal, and high-resolution synchrotron X-ray charge density analysis show that the helical coordination polymer behaves like a spring when subjected to external stimuli. Changes that occur with the variation of temperature, pressure, or bending, however, result in very different mechanistic changes. The exceptional coordination sphere flexibility rendered by the presence of Jahn-Teller distorted coordination bonds leads to the flexibility of the polymer.

We report a new supramolecular structure of cyanuric acid–melamine–zinc (CA–M–Zn) demonstrating unique molecular rotation induced negative thermal expansion along the c axis, accompanied by a significant decrease of β angle (−3.8%).

Coordination cages can be used for enantio- and regioselective catalysis and for the selective sensing and separation of isomeric guest molecules. Here, stereoisomers of a family of coordination cages are resolved using ultra-high-resolution cyclic ion-mobility mass spectrometry (cIM-MS). The observed ratio of diastereomers is dependent on both the metal ion and counter ion. Moreover, the point groups can be assigned through complementary NMR experiments. This method enables the identification and interrogation of the individual isomers in complex mixtures of cages which cannot be performed in solution. Furthermore, these techniques allow the stability of individual isomers within the mixture to be probed, with the T-symmetric isomers in this case shown to be more robust than the C3 and S4 analogues.