Experimental and theoretical elucidation of SPAAC kinetics for strained alkyne-containing cycloparaphenylenes

Pinwheel-like Curved Aromatics from the Cyclotrimerization of Strained Alkyne Cycloparaphenylenes

Carbon nanomaterials composed of curved aromatics, such as carbon nanotubes, are difficult to selectively synthesize and modify precisely. Smaller molecular fragments of curved nanomaterials, such as cycloparaphenylenes, benefit from the precision of bottom-up synthesis, however, efforts to expand the curved molecular framework into even larger structures often rely on restrictive early stage synthetic strategies or difficult to control polymerizations. In this work we report a high yielding, strain-promoted, late-stage modification of a series of [n + 1]CPPs. We show that the conversion of these [n + 1]CPPs into soluble, pinwheel-like multipore carbon nanostructures is achievable via a straightforward and efficient metal-mediated alkyne cyclotrimerization reaction. We provide insight into suitable metals for this transformation, the photophysics of these trimeric molecules, as well as their strain profiles and crystal packing. We also demonstrate the strain-enhanced nature of the reaction under the optimized conditions, showing that strained internal-alkyne [n + 1]CPPs efficiently undergo complete conversion whereas unstrained diphenylacetylene remains completely unreacted. We anticipate that this work will have broader impacts on the study of reactivity in strained-alkyne-containing hydrocarbons, and that access to this new molecular architecture will inspire new research and applications in materials science and related fields.

Computational Organic Chemistry: The Frontier for Understanding and Designing Bioorthogonal Cycloadditions

Computational organic chemistry has become a valuable tool in the field of bioorthogonal chemistry, offering insights and aiding in the progression of this branch of chemistry. In this review, I present an overview of computational work in this field, including an exploration of both the primary computational analysis methods used and their application in the main areas of bioorthogonal chemistry: (3 + 2) and [4 + 2] cycloadditions. In the context of (3 + 2) cycloadditions, detailed studies of electronic effects have informed the evolution of cycloalkyne/1,3-dipole cycloadditions. Through computational techniques, researchers have found ways to adjust the electronic structure via hyperconjugation to enhance reactions without compromising stability. For [4 + 2] cycloadditions, methods such as distortion/interaction analysis and energy decomposition analysis have been beneficial, leading to the development of bioorthogonal reactants with improved reactivity and the creation of orthogonal reaction pairs. To conclude, I touch upon the emerging fields of cheminformatics and machine learning, which promise to play a role in future reaction discovery and optimization.

Clicking in harmony: exploring the bio-orthogonal overlap in click chemistry

In the quest to scrutinize and modify biological systems, the global research community has continued to explore bio-orthogonal click reactions, a set of reactions exclusively targeting non-native molecules within biological systems. These methodologies have brought about a paradigm shift, demonstrating the feasibility of artificial chemical reactions occurring on cellular surfaces, in the cell cytosol, or within the body - an accomplishment challenging to achieve with the majority of conventional chemical reactions. This review delves into the principles of bio-orthogonal click chemistry, contrasting metal-catalyzed and metal-free reactions of bio-orthogonal nature. It comprehensively explores mechanistic details and applications, highlighting the versatility and potential of this methodology in diverse scientific contexts, from cell labelling to biosensing and polymer synthesis. Researchers globally continue to advance this powerful tool for precise and selective manipulation of biomolecules in complex biological systems.