Periodic Reporting for period 2 - PHOTOMECH (Photoresponsive Multi-Addressable Smart Materials and Mechanical Synthesis by Molecular Machines)
Okres sprawozdawczy: 2023-01-01 do 2024-06-30
In this research program it is envisioned to make a leap in the creation of light-responsive intelligent matter, designing it from the bottom up. Introducing light-responsiveness to materials at the molecular scale allows to implement remote control of functions, properties, and capabilities with utmost precision. This will enable multi-level tailoring of properties and to adapt, repair, or repurpose materials at their constitutional level. Molecular machines go further beyond that and offer unique prospects for true mastery of a materials creation. Here we envision them for establishing a novel type of chemical synthesis, in which generation of structure is accomplished in a mechanical fashion under energy consumption akin to macroscopic weaving and sewing processes.
At present, it is not well explored how external control can step beyond simple ON/OFF behavior and how complex programming, energizing, or operation can be implemented and applied at the nanoscale. This project therefore targets the current frontiers and limits of photoswitching, molecular machines, chemical synthesis, and precision engineering of multi-responsive materials. It encompasses the creation of novel visible-light responsive photoswitches with general applicability across the natural sciences and the elucidation of new bond-rotation or isomerization photoreactions in the first stage. Building on these findings, molecular precision engineering of functional multi-state and multi-responsive materials are explored in the second stage. In the last two parts of the proposal molecular machines and a completely new type of chemical synthesis will be developed, which is termed “mechanical molecular construction”. The latter is exploiting the unique properties of molecular motors and can be regarded as first step into the uncharted territory of “molecular weaving”. This will open up an entire realm of untapped chemical and material structures for future explorations.
Knowledge and methods created in these projects will be of utmost importance for any scientist – academic or industrial – concerned with applying light as central means for manipulating matter at smallest scales with highest spatio- temporal control - and thus for a large part of the present natural science community.
At present, it is not well explored how external control can step beyond simple ON/OFF behavior and how complex programming, energizing, or operation can be implemented and applied at the nanoscale. This project therefore targets the current frontiers and limits of photoswitching, molecular machines, chemical synthesis, and precision engineering of multi-responsive materials. It encompasses the creation of novel visible-light responsive photoswitches with general applicability across the natural sciences and the elucidation of new bond-rotation or isomerization photoreactions in the first stage. Building on these findings, molecular precision engineering of functional multi-state and multi-responsive materials are explored in the second stage. In the last two parts of the proposal molecular machines and a completely new type of chemical synthesis will be developed, which is termed “mechanical molecular construction”. The latter is exploiting the unique properties of molecular motors and can be regarded as first step into the uncharted territory of “molecular weaving”. This will open up an entire realm of untapped chemical and material structures for future explorations.
Knowledge and methods created in these projects will be of utmost importance for any scientist – academic or industrial – concerned with applying light as central means for manipulating matter at smallest scales with highest spatio- temporal control - and thus for a large part of the present natural science community.
Since the beginning of the project, a range of novel molecular photoswitches have been developed, which are derived from the class of indigo-like chromophores. The novel photoswitches deliver a suite of advantageous properties, which are in high demand in all chemistry-related areas of research, especially in the material sciences, catalysis, biology, pharmaceutical sciences and medicine. Three major successes were achieved already in this regard. First, extremely low-energy red light and near infrared light responsiveness could be realized, which is a long sought-after and key property for virtually any application of a photoswitch. Second, multi-state photoswitches were developed, which can accommodate up to eight different switching states within only a small molecular entity and can be addressed individually and in different sequences by light and heat stimuli. Additionally, the types of stimuli were extended to include chemical triggers such as acid and base additions widening the applicability of switching in the signaling realm. Third, a number of so-far unknown light-induced molecular motions were discovered, which include unknown coupled bond rotations and structural rearrangements. With this progress the range of nanoscale motions accessible by photontrol has been enlarged significantly. Further, we have demonstrated a very new concept for recycling of molecular photoswitches and their functions, which allows multiple uses and repurposing of photoswitch components. In the next step, our advanced photoswitches were used for applications in photochromic polymers, for acid-base induced state pumping, and for molecular information processing with multi-stimuli to demonstrate their potential for light controlled and adaptable matter. In the realm of molecular machines we developed a range of integrated molecular motors enabling elucidation of directional molecular motions and complex control over multiple directional motions within a larger nanoscale machine setup. Finally, the first motor driven molecular threading process was achieved, in which the unidirectional rotation of a motor component forces the threading of a molecular string through a macrocyclic ring structure. This concept is the door-opener for further elaboration of a molecular sewing machine able to construct nanostructures in a fully mechanical fashion.
The progress made so far in PHOTOMECH has gone beyond the state of the art multiple times. With all-red light photoswitching it is possible for the first time to use exclusively very low energy light to affect large molecular changes. This performance pushes the limits of photoswitching and will open up applicability of photochromes much further. We expect a suite of benefiting developments for uses especially in materials and condensed phases, for multi-signaling and advanced information processing with light, combinatorial multi-responsive systems, and not least for molecular machine building. With eight-states of a photoswitch successfully manipulated, we realized an unprecedented density of switching states within a molecular framework. Further progress will determine how far this density can be pushed and what new types of molecular motions are waiting to be discovered. Transfer to materials will result in a leap of their complexity that can be managed and used for remote control of their properties and behavior. Our concept for recycling and the synthetic method for establishing simultaneous gain of function along with photochromism will change the way we think about generating, use, and dispose of photoswitches. We will explore the impact of this idea when transfering it to photochromic materials and different light-responsive molecular tools. With acid-induced switching we opened up another realm of application for indigo-derived chromophores enabling future endeavours into chemical pumping, sensing, or energy transduction. The molecular threading machine represents the first entry into an uncharted territory of active molecular weaving or sewing. It will be used for a new type of chemical synthesis, giving access to unprecedented topologically entangled molecules that cannot be made by classical chemistry. This synthesis proceeds in a mechanised fashion using the energy powered directional motions of molecular motors to control the manufacturing of other molecules. With such progress we will get closer to realizing the full potential of molecular machines for precision control of material production.