publications

2026

1. Simultaneous Selective Recognition of Two Different Anions within a Hydrogen/Halogen-Bonding Cage

   Bailee R. Smith, Rosemary J. Goodwin, and Nicholas G. White

   Journal of the American Chemical Society, Nov 2026

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   The search for selective anion receptors that can function in water is a longstanding challenge in supramolecular chemistry, motivated by anions’ fundamental roles (and potential applications) in biological, environmental, and industrial processes. Here, we incorporate halogen and hydrogen bond donors into an easy-to-prepare organic cage molecule and demonstrate that this can bind anions at either or both of a halogen-bonding pocket and hydrogen-bonding pockets depending on the nature of the anions and the solvent. The halogen-bonding pocket comprising six bromopyridinium donors is a potent host for iodide anions and can selectively bind this guest in water as strongly as biological iodide binders (Ka = 43,000 M–1 measured by 1H NMR spectroscopy) with the exclusion of other halide anions. In DMSO/water mixtures, the hydrogen-bonding pockets are able to recognize chloride anions, resulting in the formation of mixed anion iodide/chloride complexes with an iodide bound in the center of the cage and chlorides in the peripheral binding sites. This demonstrates the exquisite selectivity afforded by halogen-bonding systems and reveals a general route to a range of supramolecular anion hosts that bind multiple guests in different locations.

2. Relative Influence of Pd(II) and Pt(II) Metal Centers on the Strength of Interactions Between Planar Species

   Jess L. Algar, Rosemary J. Goodwin, and Dan Preston

   Chemistry – An Asian Journal, 2026

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   ABSTRACT Palladium(II) or platinum(II) are often incorporated into metallo-supramolecular architectures as their square-planar geometry and relative accessibility make them attractive targets. The square-planar cationic panels where palladium(II) or platinum(II) are bound within these species frequently participate in interactions which enable host–guest chemistry or controlled conformation. We here investigate whether there could be a difference between the strength of interactions established by Pd(II) or Pt(II)-containing species. Analogous Pd(II) and Pt(II) model complexes were synthesized, and their behavior compared against aromatic and platinate guests. Predominantly through 1H NMR techniques, we have established that Pt(II) can allow for π interactions with an aromatic guest roughly twice the strength of their Pd(II) counterparts, where binding is strong. Similarly, the interactions between the Pt(II) model complex with a platinate guest, were stronger than those of the Pd(II) model complex, although notably weak in both cases.

3. Selective Postsynthetic Reduction of Pyridinium Hydrazone Cages

   Logan A. V. Faulkner, Rosemary J. Goodwin, Katarina Trajković, and 3 more authors

   Organic Letters, May 2026

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   Postsynthetic modification of a series of hexacationic organic cages containing pyridinium and hydrazone groups gave a new family of neutral organic cages through a high-yielding single-step reduction reaction. The reaction selectively reduces all six pyridinium rings to 1,2,3,6-tetrahydropyridines but leaves the hydrazone CN bond untouched. The neutral cages display strong sulfate binding to give cage·(SO42–)2 complexes in DMSO.

4. A Low-Symmetry FeII Tetrahedron From a Flexible Tritopic Ligand

   Rosemary J. Goodwin, Nina R. Lawson, Michael G. Gardiner, and 3 more authors

   Chemistry – A European Journal, 2026

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   ABSTRACT Most high yielding low symmetry cages formed by metal–ligand coordination are assembled through strictly defined ligand and/or metal ion geometries which have been manipulated to form systems with complex architectures. In this work, we report the near-quantitative synthesis of a new S4-symmetry meso achiral [Fe4L4]8+ homoleptic face-capped tetrahedron from a symmetric and flexible tris-bidentate tritopic ligand. The symmetry of the tetrahedron is solvent mediated, with the meso cage forming near-quantitatively in acetonitrile, while nitromethane causes the partial isomerisation to the racemic homochiral tetrahedron. The formation of this low symmetry tetrahedron is driven by ligand flexibility, which we attribute to the meso isomer effectively minimising its solvent shell and the ligand strongly favouring negative stereochemical coupling between metal centres, compared to the homochiral cage, thus being the dominant cage when in acetonitrile.

5. Dual Proton/Anion Binding Through Reciprocal Allostery in Platinum(II) Lantern-Shaped Cages

   Zack T. Avery, Elizabeth C. Elphick, Michael G. Gardiner, and 4 more authors

   Angewandte Chemie International Edition, 2026

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   Abstract Reciprocal allosteric regulation, where binding events influence each other simultaneously, is a key target for supramolecular chemists designing biomimetic systems. Platinum(II) lantern-shaped cages, formed from a series of ligands bearing central protonatable sites of varied basicity through rational tuning of the backbone, featured nuanced dual action host-guest chemistry. This reveals the first example of reciprocal allostery in a supramolecular system, between protonation and anion binding. Switching studies were conducted using acid/base and silver/chloride stimuli, with single and multi-anion systems.

2025

1. Coordination-Driven Orthogonal Ligand Pairings through Dual Hydrogen-Bonding/π-π Interaction Complementarity

   Jordan N. Smith, Yolanda Yau, Nina R. Lawson, and 2 more authors

   Chemistry – A European Journal, 2025

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   Abstract Multi-layered and orthogonal recognition is an excellent route to controlled molecular complexity. Here we report a series of heteroleptic complexes where two ligands pair together at a palladium(II) metal centre in complementary fashion and with orthogonality to others pairs. This complementarity is driven in part through hydrogen-bonding acceptor or donor sites proximal to the coordination domain (either DD:AA or AD:DA). These interactions alone are insufficient to control ligand pairing identity and/or orientation—secondary π-π interactions between electron-rich and electron-poor aromatic groups in the recognition domain combine with the hydrogen bonding to give high levels of complementarity. Importantly, the different heteroleptic complexes can be combined without significant scrambling or mismatching.

2. Low Symmetry Cage Complexes Formed by Metalation of Symmetric Hexa-Cationic Organic Cages

   Rosemary J. Goodwin, Annie L. Colebatch, and Nicholas G. White

   Angewandte Chemie International Edition, 2025

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   Abstract Most metal organic cages are assembled through metal–ligand coordination, resulting in cages where the metal ions are part of the cage architecture, and thus have limited reactivity. There are only a handful of metal organic cages produced by metalation of a pre-synthesised organic cage. In this work, we show that hexa-cationic hydrazone cages coordinate a range of transition metal ions upon deprotonation to give cage complexes with metal ions oriented towards the cage cavity. Remarkably, a cage with ethyl solubilising groups gives the expected three-fold symmetric metallocage, cages with alkoxy solubilising groups give low-symmetry zinc metallocages, and a cage without a solubilising group switches between high and low symmetry conformations depending on solvent. These low symmetry arrangements persist on the NMR timescale at temperatures as high as 360 K and in the presence of a wide range of anions.

3. Near-Quantitative Removal of Oxalate and Terephthalate from Water by Precipitation with a Rigid Bis-Amidinium Compound

   Rosemary J. Goodwin, Phonlakrit Muang-Non, Nikki A. Tzioumis, and 2 more authors

   Chemistry – A European Journal, 2025

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   Abstract A simple, readily-prepared precipitant (1⋅Cl2) precipitates oxalate or terephthalate from water with very high efficacy, removing these anions at sub-millimolar concentrations using only one equivalent of precipitant. A simple aqueous base/acid cycle can be used to regenerate 1⋅Cl2 after use. The resulting precipitates, 1⋅oxalate and 1⋅terephthalate, are anhydrous and closely-packed, with each anion receiving eight charge-assisted hydrogen bonds from amidinium N−H donors. Precipitation of oxalate and terephthalate occurs at much lower concentrations than other dicarboxylates, and direct competition experiments with the biologically/environmentally relevant divalent anions CO32−, HPO42− and SO42− reveal very high selectivity for oxalate or terephthalate over these competitors.

2024

1. Expedient Decagram-Scale Synthesis of Robust Organic Cages That Bind Sulfate Strongly and Selectively in Water

   Émer M. Foyle, Rosemary J. Goodwin, Cameron J. T. Cox, and 3 more authors

   Journal of the American Chemical Society, Oct 2024

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   Selective anion recognition remains a key challenge in supramolecular chemistry: only a very small number of systems that can function in water are known, and these nearly always preferentially bind hydrophobic anions. In this work, we report three robust hexa-cationic cages that can be prepared on scales up to 14 g in two simple and high-yielding steps from commercially available materials. One of these cages displays unusually strong sulfate binding in water (Ka = 12,000 M–1), and demonstrates high selectivity for this anion over H2PO4–/HPO42– in DMSO/buffer mixtures. These results demonstrate that relatively large, three-dimensional supramolecular hosts can be prepared in high yields and on large scales, and can be highly potent receptors.

2. A Cationic Catechol Derivative Binds Anions in Competitive Aqueous Media

   Rosemary J. Goodwin and Nicholas G. White

   Chemistry – An Asian Journal, 2024

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   Abstract A simple dihydroxy isoquinolinium molecule (3+) was prepared by a modification of a literature procedure. Interestingly, during optimisation of the synthesis a small amount of the natural product pseudopalmatine was isolated, and characterised for the first time by X-ray crystallography. Compound 3+ contains a catechol motif and positive charge on the same scaffold and was found to be a potent anion receptor, binding sulfate strongly in 8 : 2 d6-acetone:D2O and 7 : 3 d6-acetone:D2O (Ka>104 and 2,100 M−1, respectively). Unsurprisingly, chloride binding was much weaker, even in the less polar solvent mixture 9 : 1 d6-acetone:D2O. The sulfate binding is remarkably strong for such a simple molecule, however anion binding studies were complicated by the tendency of the molecule to react with BPh4− or BF4− species during anion metathesis reactions. This gave two unusual zwitterions containing tetrahedral boronate centres, which were both characterised by X-ray crystallography.

2023

1. Supramolecular chemistry of two new bis(1,2,3-triazolyl)pyridine macrocycles: metal complexation, self-assembly and anion binding

   Arthur H. G. David, Rosemary J. Goodwin, and Nicholas G. White

   Dalton Transactions, Feb 2023

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   Two new macrocycles containing the bis(1,2,3-triazolyl)pyridine (btp) motif were prepared in high yields from a btp diazide precursor (1). Solution 1H NMR studies show that this diazide undergoes self-assembly with divalent transition metal ions to form ML2 complexes with pendant azide groups, apparently suitable for conversion into metal-templated catenanes; however attempts to form these catenanes were unsuccessful. Instead a new macrocycle containing two btp motifs was prepared, which forms a nanotube structure in the solid state. Reduction of the azide groups to amines followed by amide bond formation was used to convert 1 into macrocycle 8 containing btp and isophthalamide functionalities. This macrocycle binds halide and oxalate anions in acetonitrile solely through the isophthalamide motif, and binds aromatic dicarboxylates very strongly through both the isophthalamide amide donors and the btp triazole donors. The macrocycle was complexed with Pd(ii) and the resulting complexes were shown to bind strongly to halide anions. The solid state structures of [Pd·8·X]BF4 (X = Cl−, Br−, I−) were investigated by X-ray crystallography, which showed that [Pd·8·Br] forms an unusual “chain of dimers” structure assembled by metal complexation, N–H⋯Br− hydrogen bonding and short Pd⋯Pd contacts.

2022

1. Hydroxy Groups Enhance [2]Rotaxane Anion Binding Selectivity

   Rosemary J. Goodwin, Andrew Docker, Hugo I. MacDermott-Opeskin, and 4 more authors

   Chemistry – A European Journal, 2022

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   Abstract We report the synthesis of two [2]rotaxanes containing an interlocked three dimensional binding cavity formed from a pyridinium bis(amide) axle component containing two phenol donors, and an isophthalamide based macrocycle. In the competitive solvent mixture 1 : 1 CDCl3 : CD3OD, one of the receptors exhibits a much higher selectivity preference for chloride than an analogous rotaxane without the hydroxy groups. X-ray crystal structures reveal the chloride anion guest encapsulated within the interlocked binding cavity, though not all of the hydrogen bond donors are utilised. Computational semi-empirical simulations indicate that secondary intermolecular interactions occur between the axle hydroxy hydrogen bond donors and the [2]rotaxane macrocycle components, contributing to a more preorganised binding pocket, which may be responsible for the observed enhanced selectivity.

2021

1. Simple acyclic molecules containing a single charge-assisted O–H group can recognize anions in acetonitrile : water mixtures

   Rosemary J. Goodwin, Mitchell T. Blyth, Alfred K. K. Fung, and 5 more authors

   Organic & Biomolecular Chemistry, Mar 2021

   Abs DOI

   Hydroxypyridinium and hydroxyquinolinium compounds containing acidic O–H groups attached to a cationic aromatic scaffold were synthesized, i.e. N-methyl-3-hydroxypyridinium (1+) and N-methyl-8-hydroxyquinolinium (2+). These very simple compounds are capable of binding to chloride very strongly in CD3CN and with moderate strength in 9 : 1 CD3CN : D2O. Comparison with known association constants reveals that 1+ and 2+ bind chloride in CD3CN or CD3CN : D2O with comparable affinities to receptors containing significantly more hydrogen bond donors and/or higher positive charges. Crystal structures of both compounds with coordinating anions were obtained, and feature short O–H⋯anion hydrogen bonds. A receptor containing two hydroxyquinolinium groups was also prepared. While the low solubility of this compound caused difficulties, we were able to demonstrate chloride binding in a competitive 1 : 1 CD3CN : CD3OD solvent mixture. Addition of sulfate to this compound results in the formation of a crystallographically-characterised solid state anion coordination polymer.