Our research is devoted towards establishing new synthetic avenues, structural understanding, and applications for inorganic, organometallic and organomimetic chemistry. We focus on the development of an extensive and versatile synthetic toolbox, allowing for the functionalization of various 3D cluster motifs including polyhedral boranes and carboranes. We are currently working on new ligand platforms with unique electronic and steric features, stable inorganic radicals, solid-state materials, new reagents for synthetic organic and bioconjugation chemistry and atomically precise nanosized molecules used to selectively bind biomolecules. These research efforts will reveal novel and potentially useful solutions to important problems across several fields, including: synthesis, catalysis, energy conversion and storage and biomolecular recognition, imaging and labeling.
Boron Cluster Building Blocks: A significant component of our research program focuses on the chemistry of inorganic clusters and integrates concepts spanning fundamental and applied chemistry. Synthetic chemistry has long sought to develop versatile molecular platforms and transformations that expand the available chemical toolbox and enable new solutions to scientific and societal challenges. In this context, our work aims to move beyond the traditional boundaries of organic, inorganic, and organometallic chemistry by exploring alternative molecular architectures that can be described as “organomimetic.” These efforts center on boron-rich cluster molecules whose three dimensional structures impart chemical properties that are fundamentally distinct from those of classical molecular systems. In particular, we have been interested in perfunctionalized dodecaborate clusters, a class of boron based molecules that exhibit unusual multi electron redox behavior and exceptional chemical stability. Our research has focused on developing synthetic approaches to these clusters, understanding their redox chemistry, and translating these fundamental properties into functional chemical systems. For example, we have demonstrated that perfunctionalized B12(OR)12 clusters exhibit remarkable stability during high concentration electrochemical cycling, maintaining their integrity over extended operation with negligible decomposition of the active species. These observations highlight the potential of boron cluster frameworks as robust redox active molecular platforms for electrochemical applications. Another major direction of this work has involved integrating redox active boron clusters into extended solid state architectures to generate new classes of hybrid materials. We have shown that these molecular clusters can function as structural building blocks within metal oxide networks, where they serve as molecular cross linkers that fundamentally alter the photophysical and electronic properties of the resulting materials. In such systems, boron cluster units act as thermally stable molecular connectors that link metal oxide frameworks into interconnected networks, enabling enhanced charge transport through three dimensional electron delocalization. These materials exhibit significantly improved electronic transport properties relative to conventional metal oxide systems, illustrating the potential of boron cluster chemistry as a design element for energy storage and electronic materials.
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The unique electronic structure of boron clusters has also enabled their use as functional dopants in hybrid electronic materials. Incorporation of redox active cluster dopants into conducting polymer systems has been shown to dramatically increase electrical conductivity by effectively shielding the electrostatic interactions between dopant counterions and the host material. This design strategy enables the formation of fully mobile charge carriers and opens new opportunities for engineering hybrid materials in which charge transport is governed primarily by intrinsic electronic structure rather than dopant interactions. Beyond electronic materials, the distinctive electronic properties of boron clusters have also enabled new approaches in magnetic resonance signal amplification. In particular, cluster derived radicals can serve as stable three dimensional aromatic species capable of mediating magnetization transfer through dynamic nuclear polarization, thereby enhancing nuclear magnetic resonance signals of nearby molecules. These findings establish a new class of molecular systems for signal amplification and sensing based on the unique electronic characteristics of boron cluster frameworks. More recently, we have explored how these clusters can be incorporated into solid state electrochemical systems. For example, perfunctionalized dodecaborate clusters have been shown to undergo reversible electrochemical cycling in the solid state, illustrating their potential as redox active components in next generation energy storage materials. Collectively, these studies highlight a broader conceptual theme emerging from this work: boron cluster frameworks provide a versatile molecular platform for designing photoredox active species with tunable weakly coordinating anion behavior. By modifying the substituents on perfunctionalized cluster cores, the strength of interaction between the cluster and surrounding cations can be systematically tuned in both solution and solid state environments, enabling new strategies for controlling charge transport, reactivity, and materials properties.
Boron Cluster Reagents: We discovered a new mode of reactivity in which boron clusters serve as reagents for nucleophilic borylation of organic and main group electrophiles. Formation of boron-carbon bonds is a central transformation in synthetic chemistry, yet most established methods rely on electron-deficient boron reagents that function as Lewis acids. In contrast, we found that small, air-stable boron clusters can react with benzyl and alkyl halides under mild conditions to form B–C bonds through a fundamentally different pathway. Electrochemical studies revealed that, unlike the highly robust dodecaborate clusters, these smaller clusters undergo irreversible one-electron oxidation that triggers selective cage deconstruction.Building on this concept, we developed a strategy in which a polynuclear B10-based cluster acts as a non-classical electrophilic reagent for arene borylation. In this process, the cluster framework undergoes controlled cage deconstruction, selectively cleaving B–B bonds while preserving exopolyhedral B–C bonds to generate well-defined mononuclear boron-containing molecules. The key intermediate is a highly reactive cluster borenium species, which enables a straightforward open-flask two-step sequence for arene C–H borylation with unusual selectivity relative to previously known systems. These studies demonstrate that the controlled redox instability of boron clusters can be harnessed to generate mononuclear boron compounds through programmed cage deconstruction. More broadly, this work establishes a conceptual link between the chemistry of polyhedral boron clusters and single-site boron reagents used in organic synthesis, highlighting a new paradigm in which cluster frameworks can serve as reagents for preparing cluster-free boron-containing organic molecules.
Biomaterials and Bioconjugation Chemistry: We have been developing strategies to functionalize polyhedral boron clusters through precise covalent attachment chemistry, enabling the construction of atomically defined nanomolecular architectures. By expanding cluster core size and installing functional groups at each vertex, these systems provide rigid, densely functionalized scaffolds that differ fundamentally from traditional three dimensional platforms such as dendrimers, oligomers, or coordination assemblies. Using this approach, we created nanomolecules in which peptides, carbohydrates, or polymers are densely arranged around a boron cluster core, producing fully covalent assemblies that mimic the surface organization of thiol capped gold nanoparticles while maintaining high stability under biological conditions. This chemistry was initially enabled by perfluoroaryl functionalized clusters that undergo efficient nucleophilic aromatic substitution with thiols to generate robust carbon-sulfur linkages. To improve reaction speed and compatibility with biological systems, we later developed a class of gold(III) aryl reagents capable of rapidly and selectively modifying cysteine residues in unprotected peptides and proteins across a wide range of solvent and pH conditions. This chemistry proceeds with kinetics comparable to the fastest click reactions and enables the rapid assembly of densely functionalized nanoclusters with well defined surfaces. These platforms combine the structural precision of inorganic clusters with the modularity typically associated with nanoparticle functionalization. The resulting hybrid nanomaterials have shown promise as multivalent biological agents. For example, glycosylated clusters display strong binding to lectin receptors through multivalent interactions and can be engineered to target receptors involved in viral entry pathways. More broadly, these studies demonstrate that organometallic chemistry can provide robust and selective tools for modifying biomolecules under aqueous conditions, challenging the long standing assumption that reactive organometallic species are incompatible with complex biological environments. Current efforts are expanding this concept to polymer conjugation, radiochemical labeling, and direct installation of boron cluster units onto biomolecules, establishing a versatile platform for constructing densely functionalized nanoscale architectures.
Other research areas: Beyond fundamental studies, we have worked to translate our boron cluster technologies broadly to the community. Several cluster reagents developed in our laboratory are now commercially available, and related systems have been the subject of intellectual property and translational collaborations aimed at developing next generation boron neutron capture therapy agents. Our group has also expanded these platforms into biomedical and materials applications, industry collaborations on peptide macrocyclization and bioconjugation technologies, and partnerships focused on UV resistant coatings and chromophores for aerospace applications. In parallel, we continue to develop boron cluster based systems for sensing and molecular recognition, including probes for physiological ion detection, host guest assemblies with supramolecular receptors, and emerging electron microscopy imaging agents based on boron cluster carriers.
An additional area of interest involves the development of boron cluster systems for boron neutron capture therapy (BNCT) and related theranostic applications. BNCT relies on the selective delivery of boron-containing agents to diseased tissue followed by neutron irradiation, which generates high-energy particles capable of inducing localized cell death. Because polyhedral boron clusters possess exceptionally high boron content and tunable chemical properties, they represent promising platforms for next generation BNCT agents. Our work in this area focuses on developing functionalized cluster scaffolds that enable targeted delivery, improved biological compatibility, and integration with diagnostic and delivery modalities, thereby advancing molecular systems that combine therapeutic and imaging capabilities.
An additional area of interest involves the development of boron cluster systems for boron neutron capture therapy (BNCT) and related theranostic applications. BNCT relies on the selective delivery of boron-containing agents to diseased tissue followed by neutron irradiation, which generates high-energy particles capable of inducing localized cell death. Because polyhedral boron clusters possess exceptionally high boron content and tunable chemical properties, they represent promising platforms for next generation BNCT agents. Our work in this area focuses on developing functionalized cluster scaffolds that enable targeted delivery, improved biological compatibility, and integration with diagnostic and delivery modalities, thereby advancing molecular systems that combine therapeutic and imaging capabilities.
Spokoyny Group, October 2022.
We thank our generous sponsors for supporting our research over the years:
