https://www.pnas.org/content/pnas/90/5/1635.full.pdf

Supramolecular chemistry.

Aggregation-induced emission (AIE) describes a photophysical phenomenon in which molecular aggregates exhibit stronger emission than the single molecules. Over the course of the last 20 years, AIE research has made great strides in material development, mechanistic study and high-tech applications. The achievements of AIE research demonstrate that molecular aggregates show many properties and functions that are absent in molecular species. In this review, we summarize the advances in the field of AIE and its related areas. We specifically focus on the new properties of materials attained by molecular aggregates beyond the microscopic molecular level. We hope this review will inspire more research into molecular ensembles at and beyond the meso level and lead to the significant progress in material and biological science.

Aggregation-Induced Emission: New Vistas at the Aggregate Level

Chemistry welcomes a new bond: The mechanical bond has endowed molecules with component parts whose movements can be controlled and monitored. In his Nobel Lecture, J. F. Stoddart describes how being able to template the formation of mechanically interlocked molecules has led to the design and synthesis of shuttles, switches, and machines at the nanoscale.

Mechanically Interlocked Molecules (MIMs)-Molecular Shuttles, Switches, and Machines (Nobel Lecture).

Motor proteins are nature's solution for directing movement at the molecular level. The field of artificial molecular motors takes inspiration from these tiny but powerful machines. Although directional motion on the nanoscale performed by synthetic molecular machines is a relatively new development, significant advances have been made. In this review an overview is given of the principal designs of artificial molecular motors and their modes of operation. Although synthetic molecular motors have also found widespread application as (multistate) switches, we focus on the control of directional movement, both at the molecular scale and at larger magnitudes. We identify some key challenges remaining in the field.

/pdf/artificial-molecular-motors-1nvb4yi49g.pdf

Artificial molecular motors

TURBOMOLE is a collaborative, multi-national software development project aiming to provide highly efficient and stable computational tools for quantum chemical simulations of molecules, clusters, periodic systems, and solutions. The TURBOMOLE software suite is optimized for widely available, inexpensive, and resource-efficient hardware such as multi-core workstations and small computer clusters. TURBOMOLE specializes in electronic structure methods with outstanding accuracy-cost ratio, such as density functional theory including local hybrids and the random phase approximation (RPA), GW-Bethe-Salpeter methods, second-order Moller-Plesset theory, and explicitly correlated coupled-cluster methods. TURBOMOLE is based on Gaussian basis sets and has been pivotal for the development of many fast and low-scaling algorithms in the past three decades, such as integral-direct methods, fast multipole methods, the resolution-of-the-identity approximation, imaginary frequency integration, Laplace transform, and pair natural orbital methods. This review focuses on recent additions to TURBOMOLE's functionality, including excited-state methods, RPA and Green's function methods, relativistic approaches, high-order molecular properties, solvation effects, and periodic systems. A variety of illustrative applications along with accuracy and timing data are discussed. Moreover, available interfaces to users as well as other software are summarized. TURBOMOLE's current licensing, distribution, and support model are discussed, and an overview of TURBOMOLE's development workflow is provided. Challenges such as communication and outreach, software infrastructure, and funding are highlighted.

/pdf/turbomole-modular-program-suite-for-ab-initio-quantum-4pumrnnyz6.pdf

TURBOMOLE: Modular program suite for ab initio quantum-chemical and condensed-matter simulations

There is a growing interest in the photoregulation of biological functions, due to the high level of spatiotemporal precision achievable with light. Additionally, light is non-invasive and waste-free. In particular, the photoregulation of oligonucleotide structure and function is a rapidly developing study field with relevance to biological, physical and material sciences. Molecular photoswitches have been incorporated in oligonucleotides for 20 years, and the field has currently grown beyond fundamental studies on photochemistry of the switches and DNA duplex stability, and is moving towards applications in chemical biology, nanotechnology and material science. Moreover, the currently emerging field of photopharmacology indicates the relevance of photocontrol in future medicine. In recent years, a large number of publications has appeared on photoregulation of DNA and RNA structure and function. New strategies are evaluated and novel, exciting applications are shown. In this comprehensive review, the key strategies for photoswitch inclusion in oligonucleotides are presented and illustrated with recent examples. Additionally the applications that have emerged in recent years are discussed, including gene regulation, drug delivery and materials design. Finally, we identify the challenges that the field currently faces and look forward to future applications.

Recent developments in reversible photoregulation of oligonucleotide structure and function.

The field of dynamic functional molecular systems has progressed enormously over the past few decades. By coupling the mechanical properties of molecular switches and motors to chemical and biological processes, exceptional control of function has been attained. Overcrowded alkene-based light-driven molecular motors are very attractive in this respect owing to their unique multistate photochemically and thermally induced switching processes and their helical chirality inversion in each switching step. However, extending our control over properties from the molecular scale to larger length scales is still a fundamental challenge. In this Perspective, we discuss recent developments that address this challenge, ranging from the application of these motors in catalysis and synthetic materials to the control of biological properties. We may now be positioned at the dawn of a new era in which artificial molecular motors are able to perform programmed tasks and dynamic functions akin to the biological machines that are found in daily life. Light-driven artificial molecular switches and motors afford dynamic control of various molecular systems, ranging from catalytic to biological. This Perspective provides insight into the challenges that must be addressed to transition the field from the proof-of-concept stage to realization of its myriad applications.

Dynamic control of function by light-driven molecular motors

Reversible control over the functionality of biological systems via external triggers may be used in future medicine to reduce the need for invasive procedures. Additionally, externally regulated biomacromolecules are now considered as particularly attractive tools in nanoscience and the design of smart materials, due to their highly programmable nature and complex functionality. Incorporation of photoswitches into biomolecules, such as peptides, antibiotics, and nucleic acids, has generated exciting results in the past few years. Molecular motors offer the potential for new and more precise methods of photoregulation, due to their multistate switching cycle, unidirectionality of rotation, and helicity inversion during the rotational steps. Aided by computational studies, we designed and synthesized a photoswitchable DNA hairpin, in which a molecular motor serves as the bridgehead unit. After it was determined that motor function was not affected by the rigid arms of the linker, solid-phase synthesis was ...

/pdf/photoswitching-of-dna-hybridization-using-a-molecular-motor-179ktrbtea.pdf

Photoswitching of DNA Hybridization Using a Molecular Motor

The ability to induce and amplify motion at the molecular scale has seen tremendous progress ranging from simple molecular rotors to responsive materials. In the two decades since the discovery of light-driven rotary molecular motors, the development of these molecules has been extensive; moving from the realm of molecular chemistry to integration into dynamic molecular systems. They have been identified as actuators holding great potential to precisely control the dynamics of nanoscale devices, but integrating molecular motors effectively into evermore complex artificial molecular machinery is not trivial. Maximising efficiency without compromising function requires conscious and judicious selection of the structures used. In this perspective, we focus on the key aspects of motor design and discuss how to manipulate these properties without impeding motor integrity. Herein, we describe these principles in the context of molecular rotary motors featuring a central double bond axle and emphasise the strengths and weaknesses of each design, providing a comprehensive evaluation of all artificial light-driven rotary motor scaffolds currently present in the literature. Based on this discussion, we will explore the trajectory of research into the field of molecular motors in the coming years, including challenges to be addressed, potential applications, and future prospects.

/pdf/designing-light-driven-rotary-molecular-motors-3orsab66yc.pdf

Anouk S. Lubbe

Papers

Artificial molecular motors

Recent developments in reversible photoregulation of oligonucleotide structure and function.

Dynamic control of function by light-driven molecular motors

Photoswitching of DNA Hybridization Using a Molecular Motor

Designing light-driven rotary molecular motors