Charlotte Stern

• Crystallographer at Northwestern University

Rare earth (RE) elements are critical materials that underpin many modern technologies, particularly in the clean energy industry. Despite their importance, these vital resources are difficult to obtain due to the presence of numerous metals and radioactive contaminants, such as thorium, that are present in RE ores. Current processing methods, whic...

Mechanical bonds arise between molecules that contain interlocked subunits, such as one macrocycle threaded through another. Within polymers, these linkages will confer distinctive mechanical properties and other emergent behaviors, but polymerizations that form mechanical bonds efficiently and use simple monomeric building blocks are rare. In this...

We report a systematic tuning of chelation ring strain on the hemilability of the platinum-based coordination complexes made from the weak link approach.

Mimicking the superstructures and properties of spherical biological encapsulants such as viral capsids¹ and ferritin² offers viable pathways to understand their chiral assemblies and functional roles in living systems. However, stereospecific assembly of artificial polyhedra with mechanical properties and guest-binding attributes akin to biologica...

Electrostatic interactions between oppositely charged entities play a key role in pre‐organizing substrates and stabilizing transition states of reactions in enzymes. The use of electrostatic interactions to pre‐organize ions in nanoconfined pores, however, has not been investigated to its full potential. Herein, we describe how carboxylate anions...

Electrostatic interactions between oppositely charged entities play a key role in pre‐organizing substrates and stabilizing transition states of reactions in enzymes. The use of electrostatic interactions to pre‐organize ions in nanoconfined pores, however, has not been investigated to its full potential. Herein, we describe how carboxylate anions...

The storage of hydrogen is key to its applications. Developing adsorbent materials with high volumetric and gravimetric storage capacities, both of which are essential for the efficient use of hydrogen as a fuel, is challenging. Here we report a controlled catenation strategy in hydrogen-bonded organic frameworks (RP-H100 and RP-H101) that depends...

For over a century, naturally occurring cyclodextrins (CDs) have been investigated intensively and extensively. CDs possess inherently stable chiralities, which render them versatile players in diverse arenas of technology. Although naturally occurring CDs can be mass-produced by the enzymatic modification of amylose, their mirror-images have, howe...

The sequence-controlled assembly of nucleic acids and amino acids into well-defined superstructures constitutes one of the most revolutionary technologies in modern science. The elaboration of such superstructures from carbohydrates, however, remains elusive and largely unexplored on account of their intrinsic constitutional and configurational com...

Organic trisradicals featuring threefold symmetry have attracted significant interest because of their unique magnetic properties associated with spin frustration. Herein, we describe the synthesis and characterization of a triangular prism-shaped organic cage for which we have coined the name PrismCage6+ and its trisradical trication─TR3(•+). Pris...

Energy transfer and exciplex emission are not only crucial photophysical processes in many living organisms but also important for the development of smart photonic materials. We report, herein, the rationally designed synthesis and characterization of two highly charged bischromophoric homo[2]catenanes and one cyclophane incorporating a combinatio...

Molecular electronic spin qubits have great potential for use in quantum information science applications because their structure can be rationally tuned using synthetic chemistry. Their integration into a new class of materials, ion-paired frameworks, allows for the formation of ordered arrays of these molecular spin qubits. Three ion-paired frame...

The alkynylation of 4-siloxyquinolinium triflates has been achieved under the influence of copper bis(oxazoline) catalysis. The identification of the optimal bis(oxazoline) ligand was informed through a computational approach that enabled the dihydroquinoline products to be produced with up to 96% enantiomeric excess. The conversions of the dihydro...

Near-infrared (NIR) light is known to have outstanding optical penetration in biological tissues and to be non-invasive to cells compared with visible light. These characteristics make NIR-specific light optimal for numerous biological applications, such as the sensing of biomolecules or in theranostics. Over the years, significant progress has bee...

Developing an eco-friendly, efficient, and highly selective gold-recovery technology is urgently needed in order to maintain sustainable environments and improve the utilization of resources. Here we report an additive-induced gold recovery paradigm based on precisely controlling the reciprocal transformation and instantaneous assembly of the secon...

Cocrystal engineering, involving the assembly of two or more components into a highly ordered solid-state superstructure, has emerged as a popular strategy for tuning the photophysical properties of crystalline materials. The reversible co-assembly and disassembly of multicomponent cocrystals and their reciprocal transformation in the solid state r...

Macroscopic electric motors continue to have a large impact on almost every aspect of modern society. Consequently, the effort towards developing molecular motors1–3 that can be driven by electricity could not be more timely. Here we describe an electric molecular motor based on a [3]catenane4,5, in which two cyclobis(paraquat-p-phenylene)6 (CBPQT4...

Addressing pertinent and perplexing questions regarding why nonfullerene acceptors (NFAs) promote higher power conversion efficiencies (PCEs) than traditional fullerenes and how photoactive bulk heterojunction (BHJ) film morphology, charge photogeneration, and...

This work discloses a newly-discovered Cu 8- x Ge(S, Te) 6 argyrodite stabilizing in a high-symmetry cubic phase in the entire low-to-mid temperature region (250 K – 700 K). Partially substituting the sulfur with...

Group 5 and 6 metal chlorides, MCl x (M = Ta, Nb, Mo, W) are easily and controllably reduced, in a stepwise fashion, by stoichiometric PhMe 2 SiH, yielding only PhMe 2 SiCl, a useful...

Molecular recognition, based on noncovalent bonding interactions, plays a central role in directing supramolecular phenomena in both chemical and biological environments. The identification and investigation of weakly associated recognition motifs, however, remains a major challenge, especially when the motifs are interlinked with and obscured by o...

Polar and polarizable π-conjugated organic molecules containing push-pull chromophores have been investigated extensively in the past. Identifying unique backbones and building blocks for fluorescent dyes is a timely exercise. Here, we report the synthesis and characterization of a series of fluorescent dyes containing quadrupolar A-D-A constitutio...

Here, we report an approach to the synthesis of highly charged enantiopure cyclophanes by the insertion of axially chiral enantiomeric binaphthyl fluorophores into the constitutions of pyridinium‐based macrocycles. Remarkably, these fluorescent tetracationic cyclophanes exhibit a significant AIE compared to their neutral optically active binaphthyl...

Supramolecular chemistry has the potential to be used to impart dynamic molecular elements into coordination polymers so that sophisticated, multifunctional materials can be prepared. Indeed, the Weak-Link Approach (WLA) to supramolecular chemistry is a coordination chemistry-based platform that can be used for the design of stimuli-responsive and...

Here, we report an approach to the synthesis of highly charged enantiopure cyclophanes by the insertion of axially chiral enantiomeric binaphthyl fluorophores into the constitutions of pyridinium‐based macrocycles. Remarkably, these fluorescent tetracationic cyclophanes exhibit a significant AIE compared to their neutral optically active binaphthyl...

Triplet excited-state organic chromophores present countless opportunities for applications in photocatalysis. Here we describe an approach to the engineering of the triplet excited states of aromatic chromophores, which involves incorporating pyrene into pyridinium-containing mechanically interlocked molecules (MIMs). The π-extended nature of the...

Three achiral polycyclic aromatic fluorophores─namely, 1-pyrenecarboxylic acid, 9-anthracenecarboxylic acid, and perylene-3,9-dicarboxylic acid─were chosen based on their desired properties before being incorporated into the construction of a K+-carrying gamma-cyclodextrin (γ-CD)-based metal-organic framework (CD-MOF-1) and γ-CD-containing hybrid f...

The bis(diethyl ether) and 1,2-dimethoxyethane (dme) adducts of molybdenum(IV) chloride and tungsten(IV) chloride are valuable starting materials for a variety of synthetic inorganic and organometallic reactions. Despite the broad utility and extensive use of these 6-coordinate complexes, their syntheses remain unoptimized, and their characterizati...

Molecular recognition1–4 and supramolecular assembly5–8 cover a broad spectrum9–11 of non-covalently orchestrated phenomena between molecules. Catalysis12 of such processes, however, unlike that for the formation of covalent bonds, is limited to approaches13–16 that rely on sophisticated catalyst design. Here we establish a simple and versatile str...

Die selektive Erkennung von zwei gestapelten Viologen‐Radikalkationen in Lösung unter Verwendung eines größenangepassten radikalischen Wirts wird von J. Fraser Stoddart et al. in ihrer Zuschrift beschrieben (DOI: 10.1002/ange.202109647). Durch die Verwendung von 2,6‐Bismethylennaphthalin als Linker ist der bisradikalische dikationische Wirt in der...

Selective recognition of two stacked viologen radical cations in solution using a size‐matched radical host is reported by J. Fraser Stoddart et al. in their Communication (DOI: 10.1002/anie.202109647). By employing 2,6‐bismethylenenaphthalene as the linker, the bisradical dicationic host is able to accommodate two methyl viologen radical cation gu...

Complexation between a viologen radical cation (V.+) and cyclobis(paraquat‐p‐phenylene) diradical dication (CBPQT2(.+)) has been investigated and utilized extensively in the construction of mechanically interlocked molecules (MIMs) and artificial molecular machines (AMMs). The selective recognition of a pair of V.+ using radical‐pairing interaction...

Nanographenes have kindled considerable interest in the fields 11 of materials science and supramolecular chemistry as a result of their 12 unique self-assembling and optoelectronic properties. Encapsulating the 13 contorted nanographenes inside artificial receptors, however, remains 14 challenging. Herein, we report the design and synthesis of a t...

Complexation between a viologen radical cation ( V •+ ) and cyclobis(paraquat‐ p ‐phenylene) diradical dication ( CBPQT 2(•+) ) has been investigated and utilized extensively in the construction of mechanically interlocked molecules (MIMs) and artificial molecular machines (AMMs). The selective recognition of two V •+ using radical‐pairing interact...

The recognition and separation of anions attracts attention from chemists, materials scientists, and engineers. Employing exo‐binding of artificial macrocycles to selectively recognize anions remains a challenge in supramolecular chemistry. We report the instantaneous co‐crystallization and concomitant co‐precipitation between [PtCl6]²⁻ dianions an...

A instantaneous co-crystallization protocol relying on the selective recognition of the [PtCl6]²⁻ dianions by the exo-binding of cucurbit[6]uril has been demonstrated. This protocol could be exploited to recover platinum from spent vehicular three-way catalytic converters and other platinum-bearing metal scrap in a fast, efficient, and highly selec...

The end-capping group (EG) is the essential electron-withdrawing component of nonfullerene acceptors (NFAs) in bulk heterojunction (BHJ) organic solar cells (OSCs). To systematically probe the impact of two frequent EG functionalization strategies, π-extension and halogenation, in A-DAD-A type NFAs, we synthesized and characterized four such NFAs:...

We studied a series of dynamic weak-link approach (WLA) complexes that can be shuttled between two immiscible solvents and switched between two structural states via ion exchange. Here, we established that hydrophobic anions transfer cationic, amphiphilic complexes from the aqueous phase to the organic phase, while a chloride source reverses the pr...

Electron donor-acceptor cocrystals are receiving increasing interest because of their many useful optoelectronic properties. While the steady-state properties of many different cocrystals have been characterized, very few studies have addressed...

We report the molecular recognition of the Au(CN)2– anion, a crucial intermediate in today’s gold mining industry, by α-cyclodextrin. Three X-ray single-crystal superstructures—KAu(CN)2⊂α-cyclodextrin, KAu(CN)2⊂(α-cyclodextrin)2, and KAg(CN)2⊂(α-cyclodextrin)2—demonstrate that the binding cavity of α-cyclodextrin is a good fit for metal-coordinatio...

The solid-state properties of organic radicals depend on radical–radical interactions that are influenced by the superstructure of the crystalline phase. Here, we report the synthesis and characterization of a substituted tetracationic cyclophane, cyclobis(paraquat-p-1,4-dimethoxyphenylene), which associates in its bisradical dicationic redox state...

Mechanically interlocked molecules (MIMs), which undergo controllable motions between their component parts in more than one dimension, are of interest in controlling nanoconfinement in a three-dimensional space. Cyclic [n]daisy chains ([cn]DCs) are a class of garland-like rotaxanes composed of self-complementary monomers with cross-threaded archit...

Suitanes are a class of mechanically interlocked molecules (MIMs) that consist of two components: a body with limbs protruding outward and a suit that fits appropriately around it, so that there is no easy way for the suit to be removed from the body. Herein, we report the synthesis and characterization of a suit[3]ane, which contains a benzotrithi...

Designing new materials for effective detoxification of chemical warfare agents (CWAs) is of current interest given the recent use of CWAs. Although halogenated boron-dipyrromethene derivatives (4,4-difluoro-4-bora-3a,4a-diaza-s-indacene or BDP or BODIPY) at the 2 and 6 positions have been extensively explored as efficient photosensitizers for gene...

Two-photon excited near-infrared fluorescence materials have garnered considerable attention because of their superior optical penetration, higher spatial resolution, and lower optical scattering compared with other optical materials. Herein, a convenient and efficient supramolecular approach is used to synthesize a two-photon excited near-infrared...

One ring threaded by two other rings to form a non-intertwined ternary ring-in-rings motif is a challenging task in noncovalent synthesis. Constructing multicolor photoluminescence systems with tunable properties is also a fundamental research goal, which can lead to applications in multidimensional biological imaging, visual displays, and encrypti...

Emerging non-fullerene acceptors (NFAs) with crystalline domains enable high-performance bulk heterojunction (BHJ) solar cells. Thermal annealing is known to enhance BHJ photoactive layer morphology and performance. However, the microscopic mechanism of annealing-induced performance enhancement is poorly understood in emerging NFAs, espe-cially reg...

Suitanes are two-component mechanically interlocked molecules in which one (torso) of the components, with several protruding limbs, is encompassed by another (suit) all-in-one component. This kind of molecular ship-in-a-bottle architecture remains a challenging one to make. Herein, we report a porphyrin-based suit[4]ane, which is composed of a por...

We report the encapsulation of free-base and zinc porphyrins by a tricyclic cyclophane receptor with subnanomolar binding affinities in water. The high affinities are sustained by the hydrophobic effect and multiple [CH···π] interactions covering large [π···π] stacking surfaces between the substrate porphyrins and the receptor. We discovered two co...

Collisional intermolecular interactions between excited states form short-lived dimers and complexes that lead to the emergence of excimer/exciplex emission of lower energy, a phenomenon which must be differentiated from the photoluminescence (PL) arising from the monomeric molecules. Although the utilization of noncovalent bonding interactions, le...

Two new highly charged [2]catenanes—namely, mHe[2]C•6PF6 and mHo[2]C•6PF6—were synthesized by exploiting radical host-guest templation between BIPY•+ derivatives and mCBPQT2(•+). In contrast to related [2]catenanes that have been isolated as air-stable monoradicals, both mHe[2]C•6PF6 and mHo[2]C•6PF6, exist as air-stable singlet bisradicals as evid...

Correction for ‘Tuning radical interactions in trisradical tricationic complexes by varying host-cavity sizes’ by Kang Cai et al. , Chem. Sci. , 2020, DOI: 10.1039/c9sc04860j.

The rational design of wholly synthetic receptors that bind active substrates with ultrahigh affinities is a challenging goal, especially in water. Here, we report the synthesis of a tricyclic octacationic cyclophane, which exhibits complementary stereoelectronic binding towards a widely used fluorescent dye, perylene diimide, with picomolar affini...

Although host-guest pairing interactions between bisradical dicationic cyclobis(paraquat-p-phenylene) (BB2(•+)) and the bipyridinium radical cation (BIPY•+) have been studied extensively, host molecules other than BB2(•+) are few and far between. Herein, four bisradical dicationic cyclophanes with tunable cavity sizes are investigated as new bisrad...

A series of donor-acceptor (D–A) naphthalene–viologen-based cyclophanes of different shapes, sizes and symmetries have been synthesized and characterized. Solution optical studies on these cyclophanes reveal the existence of photoinduced intramolecular charge transfer (CT) at 465 nm from naphthalene (D) to viologen (A) units, resulting in a conform...

Reported here is the synthesis, solid‐state characterization, and redox properties of new triangular, threefold symmetric, viologen‐containing macrocycles. Cyclotris(paraquat‐p‐phenylene) (CTPQT⁶⁺) and cyclotris(paraquat‐p‐1,4‐dimethoxyphenylene) (MCTPQT⁶⁺) were prepared and their X‐ray single‐crystal (super)structures reveal intricate three‐dimens...

Überstrukturen: Über die Synthese, Festkörpercharakterisierung und Redoxeigenschaften dreieckiger, dreifach-symmetrischer, viologenhaltiger Makrocyclen wird berichtet. Cyclotris(paraquat-p-phenylen) (CTPQT⁶⁺) und Cyclotris(paraquat-p-1,4-dimethoxyphenylen) (MCTPQT⁶⁺) bilden (Über-)Strukturen mit komplexer dreidimensionaler Packung. Abstract Report...

Herein we report a hydrogen-bonded three-dimensional porous supramolecular polyknot assembled from a rigid trigonal prismatic triptycene building block with six extended peripheral aryl-carboxyl groups. Within this superstructure, three arrays of undulated 2D rhombic subnets, which display an inclined polycatenation, are interconnected to give an u...

Hierarchical self-assembly is a ubiquitous process for building sophisticated supramolecular architectures in nature. Mimicking the process and unraveling the mechanisms involved in high-precision self-assembly, however, remain a formidable challenge. Here, we present a unique strategy for constructing a hierarchical diamondoid superstructure—namel...

A hexacationic triangular covalent organic cage AzaEx2Cage6+ has been synthesized by means of a tetrabutylammonium iodide-catalyzed SN2 reaction. The prismatic cage is composed of two triangular 2,4,6-triphenyl-1,3,5-triazine (TPT) platforms bridged...

Indacenodithienothiophene (IDTT)-based postfullerene electron acceptors, such as ITIC (2,2′-[[6,6,12,12-tetrakis(4-hexylphenyl)-6,12-dihydrodithieno[2,3-d:2′,3′-d′]-s-indaceno[1,2-b:5,6-b′]dithiophene-2,8-diyl]-bis[methylidyne(3-oxo-1H-indene-2,1(3H)-diylidene)]]bis[propanedinitrile]), have become synonymous with high power conversion efficiencies...

We describe an example of “interpenetration isomerism” in three‐dimensional hydrogen‐bonded organic frameworks. By exploiting the crystallization conditions for a peripherally extended triptycene H6PET, we can modulate the interpenetration of the assembled frameworks, yielding a two‐fold interpenetrated structure PETHOF‐1 and a five‐fold interpenet...

We describe an example of “interpenetration isomerism” in three‐dimensional (3D) hydrogen‐bonded organic frameworks (HOFs). By exploiting the crystallization conditions for a peripherally extended triptycene H6PET, we can modulate the interpenetration of the assembled frameworks, yielding a two‐fold interpenetrated structure PETHOF‐1 (acs‐2c topolo...

The host-guest recognition between two macrocycles to form hierarchical non-intertwined ring-in-ring assemblies remains an interesting and challenging target in noncovalent synthesis. Herein, we report the design and characterization of a box-in-box assembly on the basis of host-guest radical-pairing interactions between two rigid diradical dicatio...

Along with the advent of supramolecular chemistry, research on fullerene receptors based on noncovalent bonding interactions has attracted a lot of attention. Here, we present the design and synthesis of a cationic molecular cage – a cyclophane composed of two tetraphenylporphyrins, bridged face-to-face by four viologen units in a rhomboid prismati...

Layered perovskites with the formula (R-NH3)2PbI4 have excellent environmental stability but poor photovoltaic function due to the preferential orientation of the semiconducting layer parallel to the substrate and the typically insulating nature of the R-NH3+ cation. Here, we report a series of these n = 1 layered perovskites with the form (aromati...

The direct enantioselective chiral calcium(II)·phosphate complex (Ca[CPA]2)-catalyzed conjugate addition of unprotected alkyl amines to maleimides was developed. This mild catalytic system represents a significant advance towards the general convergent asymmetric amination of α,β-unsaturated electrophiles, providing medicinally relevant chiral amin...

Improved understanding of fundamental structure-property relationships, particularly the effects of molecular shape and intermolecular packing on film morphology and active layer charge transport characteristics, enables more rational synthesis of new p-type small molecules. Here we investigate a series of small molecules consisting of an acene-bas...

Although ibuprofen is one of the most widely used non-steroidal anti-inflammatory drugs (NSAIDs), it exhibits poor solubility in aqueous and physiological environments as a free acid. In order to improve its oral bioavailability and rate of uptake, extensive research into the development of new formulations of ibuprofen has been undertaken, includi...

Flexible organic materials possessing useful electrical properties, such as ferroelectricity, are of crucial importance in the engineering of electronic devices. Up until now, however, only ferroelectric polymers have intrinsically met this flexibility requirement, leaving small-molecule organic ferroelectrics with room for improvement. Since both...

Supplementary Figures 1-21, Supplementary Tables 1-17, Supplementary Notes 1-4, Supplementary Methods and Supplementary References