Periodic Reporting for period 3 - LifeLikeMat (Dissipative self-assembly in synthetic systems: Towards life-like materials)
Período documentado: 2022-01-01 hasta 2023-07-31
As the first such complex, we studied a combination of the metal–organic cage and phenylazopyrazole. We showed that each cage molecule can encapsulate two molecules of the phenylazopyrazole guest. Upon exposure to UV light, the trans guest undergoes photoisomerization to the bulkier cis form, which is too bulky to remain in the cage as a dimer. Hence, light-induced expulsion of the guest from the cage has been achieved. When the irradiation is ceased, back-isomerization proceeds and the expelled guest re-enters the cage (Beilstein J. Org. Chem. 2020). As another photoresponsive guest, dihydropyrene (DHP) was used. In this case, exposure to blue light induced an efficient photoswitching process without the guest being expelled from the cage; instead, we demonstrated that the cage can greatly improve the reversibility of the photoswitching process (J. Am. Chem. Soc 2020). More recently, we reported on 2:1 inclusion complexes of the metal–organic cage and fluorescent dyes (J. Am. Chem. Soc. 2020). These inclusion complexes are currently being incorporated as key elements of various dissipative self-assembly systems.
In addition, we studied the behavior of light-switchable compounds within a new type of medium: nanoporous networks of silicone filaments (Nano Letters 2019). More recently, various families of photoswitchable molecules that can be used to control self-assembly of nanoparticles using light, thus inducing dissipative self-assembly processes, have been reviewed (Adv. Mater. 2020). In another review, analogies and differences between light- and chemically fuelled dissipative self-assembly systems have been developed (Chem 2021).
At the same time, we have made significant progress on developing nanoparticle-based dissipative self-assembly. Three conceptually different approaches to dissipative self-assembly have been developed of which two will be communicated soon. The third one has recently been published (Nat. Chem. 2021) and it is based on electrostatic interactions between positively charged nanoparticles and negatively charged, highly energetic small molecules, such as ATP. In the presence of phosphatase enzymes, ATP is hydrolyzed into smaller ions, which do not support the aggregated state of the NPs. However, this hydrolysis reaction is slower than self-assembly; thus, in the presence of an enzyme, the nanoparticles only exist in the assembled state for as long as the ATP “fuel” is continuously supplied.