In chemistry, function and behaviour flow directly from structure. As chemists seek to develop highly complex functional molecules, we need to harness routes to complex structures. In metallosupramolecular self-assembly, this...
Conformational control is a key prerequisite for much molecular function. As chemists seek to create complex molecules that have applications beyond the academic laboratory, correct spatial positioning is critical. This is particularly true of flexible systems. Conformationally flexible molecules show potential because they resemble in many cases naturally occurring analogues such as the secondary structures found in proteins and peptides such as α-helices and β-sheets. One of the ways in which conformation can be controlled in these molecules is through interaction with or coordination to metal ions. This review explores how secondary structure (i.e., controlled local conformation) in foldamers and other conformationally flexible systems can be enforced or modified through coordination to metal ions. We hope to provide examples that illustrate the power of metal ions to influence this structure toward multiple different outcomes.
Self‐assembly makes metallo‐interlocked architectures attractive targets, but being in equilibrium with smaller species means that they can suffer from dilution effects. We show that a junctioned system gives rise to a [Pd4(L)2]8+ trefoil entangled tetrahedron irrespective of concentration. Heating the sample reversibly shifts the equilibrium from the knot to an isomeric non‐interlocked dual metallo‐cycle, demonstrating that thermodynamic equilibria can still be exploited for switching even in the absence of concentration effects.
Drug checking is a harm reduction measure which provides people with the opportunity to confirm the identity and purity of substances before consumption. The CanTEST Health and Drug Checking Service is Australia’s first fixed-site drug checking service, where clients can learn about the contents of the samples they provide whilst receiving tailored harm reduction and health advice. Three samples were recently presented to the service with the expectation of 4-fluoromethylphenidate (4F-MPH) 1, methoxetamine (MXE) 2 and 3-methylmethcathinone (3-MMC) 3. The identity of all three samples did not meet these expectations and remained unknown on-site as no high confidence identifications were obtained. However, further analysis by nuclear magnetic resonance (NMR) spectroscopy, high resolution gas chromatography-electron ionisation-mass spectrometry (GC-EI-MS) and liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS) at the Australian National University (ANU) allowed for the structure elucidation of the three samples as 4-fluoro-α-pyrrolidinoisohexanophenone (4F-α-PiHP) 4, 1-(4-fluorobenzyl)-4-methylpiperazine (4F-MBZP) 5 and N-propyl-1,2-diphenylethylamine (propylphenidine) 6 respectively. Given all three samples were not of the expected identity and have not yet been described in the literature, this study presents a full characterisation of each substance. As exemplified by this rapid identification of three unexpected new psychoactive substances, drug checking can be used as an effective method to monitor the unregulated drug market.
Self-assembly makes metallo-interlocked architectures attractive targets, but being in equilibrium with smaller species means that they can suffer from dilution effects. We show that a junctioned system gives rise to a [Pd 4 (L) 2 ] 8 + trefoil entangled tetrahedron irrespective of concentration. Heating the sample reversibly shifts the equilibrium from the knot to an isomeric non-interlocked dual metallo-cycle, demonstrating that thermodynamic equilibria can still be exploited for switching even in the absence of concentration effects.
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