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New polymeric macroporous materials based on poly 2-hydroxyethyl methacrylate (pHEMA) were synthesized and tested to adsorb CO2. To this purpose, bio and affordable amine-based molecules such as lysine (LYS) and histidine (HIS) were selected as CO2active sites and used to functionalize HEMA monomer before its crosslinking polymerization. The as-prepared monomers and polymers were characterized by using Nuclear Magnetic Resonance (NMR), Fourier Infrared Spectroscopy (FT-IR), Thermal gravimetric analysis (TGA), and Scanning Electron Microscopy (SEM) equipped with Energy Dispersive X-ray (EDX). Compared to materials reported in the recent literature, all produced ones provide exceptional adsorption capacity in the 162–193 ppm range. In particular, H-HEMA-LYS exhibits the best adsorption grade, well-fitting the Linear Driving Force (LFD) model. H-HEMA-LYS reusability was also tested for up to 5 cycles without significant loss in capture performance. Finally, to get insight into the role of morphology in CO2adsorption, two diverse macroporous structures were synthesized (hydrogels and cryogels) for both HIS and LYS-based materials. As it turns out, hydrogel formulations of an average area ranging from 15.5 to 230 μm2adsorb 12% more than cryogels with higher values (266–605 μm2).

Artificial molecular machines capable of converting chemical, photochemical and electrochemical energy into mechanical motion represent a high-impact, fast-growing field of interdisciplinary research. These molecular-scale systems utilize a “bottom-up” technology centered upon the design and manipulation of molecular assemblies and are potentially capable of delivering efficient actuation at length scales dramatically smaller than traditional microscale actuators. Much of the inspiration to construct molecular devices and machines comes from the outstanding progress in molecular biology that has begun to reveal the secrets of the natural nanodevices that constitute the material base of life. Mechanically interlocked molecules, such as rotaxanes are one of the most suitable candidates for molecular machines because (i) the mechanical bond allows a large variety of mutual arrangements of the molecular components, while conferring stability on the system; (ii) the interlocked architecture limits the amplitude of the intercomponent motion in the three dimensions; (iii) the stability of a specific arrangement is determined by the strength of the intercomponent interactions; and (iv) such interactions can be modulated by external stimulation. These systems, initially gained interest due to their interesting topology and associated synthetic challenge, but recent efforts have showed that they, by virtue of their electrical properties and bi- or multistable behaviour, are also attractive as nanoscale switches for molecular electronics and nanoelectromechanical systems. This reivew will focused on the recent progress occurred in the development of new and more functional molecular shuttles based on rotaxane chemistry.

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