A Self-Sustaining Supramolecular (Auto)Photocatalysis via the Synthesis of N-Vinylacetamides

Efforts to enhance photocatalysts prioritize improving their accessibility and practicality in photocatalytic applications. Supramolecular (auto)photocatalysis, which exploits transient self-assembled complexes, facilitates visible light-driven reactions, with autocatalytic systems promoting sustainable and atom-economical processes. In this study, the photocatalyst Mes-Acr-MeClO4, typically active under blue light, formed a dark red charge-transfer (CT) complex with N-bromoacetamide (NBA) in the presence of K2CO3 in DCE, enabling green-light photocatalysis. This self-assembled CT complex initiated an auto-photocatalytic process via two-photon absorption, generating an N-centered radical that drove anti-Markovnikov, syn-periplanar addition to phenylacetylene, achieving exclusive Z-selective formation of (Z)-N-(2-bromo-2-phenylvinyl)acetamide. Interestingly, the product itself functioned as a potent green-LED photocatalyst (λem = 518 nm, τ = 10 ns), driving its own synthesis with added terminal alkynes. With 100% atom economy, this work highlights a system chemistry approach, showcasing a highly efficient, self-sustaining catalytic process that advances green and sustainable synthetic strategies. This protocol emphasizes sustainability with an outstanding E-factor of 11.15, reflecting minimal waste production (11.15 kg per 1 kg of product) and demonstrating a strong commitment to green chemistry principles.

Exploring the emergence of complexity using synthetic replicators

A significant number of synthetic systems capable of replicating themselves or entities that are complementary to themselves have appeared in the last 30 years. Building on an understanding of the operation of synthetic replicators in isolation, this field has progressed to examples where catalytic relationships between replicators within the same network and the extant reaction conditions play a role in driving phenomena at the level of the whole system. Systems chemistry has played a pivotal role in the attempts to understand the origin of biological complexity by exploiting the power of synthetic chemistry, in conjunction with the molecular recognition toolkit pioneered by the field of supramolecular chemistry, thereby permitting the bottom-up engineering of increasingly complex reaction networks from simple building blocks. This review describes the advances facilitated by the systems chemistry approach in relating the expression of complex and emergent behaviour in networks of replicators with the connectivity and catalytic relationships inherent within them. These systems, examined within well-stirred batch reactors, represent conceptual and practical frameworks that can then be translated to conditions that permit replicating systems to overcome the fundamental limits imposed on selection processes in networks operating under closed conditions. This shift away from traditional spatially homogeneous reactors towards dynamic and non-equilibrium conditions, such as those provided by reaction-diffusion reaction formats, constitutes a key change that mimics environments within cellular systems, which possess obvious compartmentalisation and inhomogeneity.

Emergent Behaviors in Kinetically Controlled Dynamic Self-Assembly of Synthetic Molecular Systems

Living systems are categorically a kinetic state of matter that exhibits complex functions and emergent behaviors. By contrast, synthetic systems are relatively simple and are typically controlled by the thermodynamic parameters. To understand this inherent difference between the biological and synthetic systems, novel approaches are of vital importance. In this regard, we have designed a three-component molecular system (a triad) by conjugating an amino acid with two functional molecules (naphthalenediimide and pyrene), which facilitates kinetically controlled self-assemblies. Herein, we describe three different molecular aggregation states of triads (entitled State I, State II, and State III) and also the dynamic pathway complexities associated with their transformations from one state to another. By meticulously employing the triads of different molecular aggregation states and the stereochemical information of the amino acid, we report emergent behaviors termed "supramolecular speciation" and "supramolecular regulation". Further, we present a hitherto unknown emergent property in a self-assembled state under the majority-rules experiment, which has been termed "super-nonlinearity". This work provides novel insights into complex synthetic systems having unprecedented functions and properties. Such emergent behaviors of synthetic triads that involve an interplay among complex interactions may find relevance in the context of prebiotic chemical evolution.

Using dispersion-corrected density functional theory to understand supramolecular binding thermodynamics

A recently published theoretical approach employing a nondynamic structure model using dispersion-corrected density functional theory (DFT-D3) to calculate equilibrium free energies of association (Chem. – Eur. J., 2012, 18, 9955–9964) is illustrated by its application to eight supramolecular complexes.