Highly Twisted Azobenzene Ligand Causes Crystals to Continuously Roll in Sunlight

Abstract

Direct conversion of solar energy to mechanical work promises higher efficiency than multistep processes, adding a key tool to the arsenal of energy solutions necessary for our global future. The ideal photomechanical material would convert sunlight into mechanical motion rapidly, without attrition, and proportionally to the stimulus. We describe crystals of a tetrahedral isocyanoazobenzene−copper complex that roll continuously when irradiated with broad spectrum white light, including sunlight. The rolling results from bending and straightening of the crystal due to blue light-driven isomerization of a highly twisted azobenzene ligand. These findings introduce geometrically constrained crystal packing as a strategy for manipulating the electronic properties of chromophores. Furthermore, the continuous, solar-driven motion of the crystals demonstrates direct conversion of solar energy to continuous physical motion using easily accessed molecular systems.

Self-Sustained Euler Buckling of an Optically Responsive Rod with Different Boundary Constraints

“…To investigate the dynamic Euler buckling of the LCE rod, its number fraction of cis -isomers in Equation (4) should be calculated. The experimental results show that the trans -to- cis isomerization of LCE could be induced by UV or laser with wavelength less than 400 nm [ 63 ] and by blue light with wavelength 465 nm [ 64 ]. It is noted that the temperature increase caused by irradiation can also induce deformation because the nematic order monotonically decreases with temperature.…”

Iron complexes of bridging azo ligands in aqueous solution: changes in the thermal switching mechanism on coordination and oxidation state of metal centres

“…2 The complementary back cis-to-trans thermal isomerisation reaction has also been thoroughly studied, given the importance of the process involved in photoswitching materials. 3,4 The thermal process has been found dependent on a wealth of factors that, ultimately, relate to structural characteristics that favour rotation (charge-separated) or inversion (non-chargeseparated) transition states. 5,6 These characteristics have been mostly tuned by push-pull functionalisation of the diazenecontaining molecule in order to achieve a desired switching response time.…”

Novel 3D Cubic Topology in Hybrid Lead Halides with a Symmetric Aromatic Triammonium Exhibiting Water Stability

“…The 3D hybrid halide perovskite structure can be dimensionally reduced to layers of two-dimensional (2D) structure, ,,− chains of one-dimensional (1D) structure, − or zero-dimensional (0D) clusters of [MX 6 ] 4– octahedra − through the incorporation of diverse organic cations. These organic cations are larger than the aforementioned A-site cations, permitting a vast compositional space of structural tunability for the synthesis of new hybrid halide materials for optoelectronic and technological applications. ,,− Despite the expandable phase space, the reported bulk, hybrid metal halide perovskite-related frameworks mainly feature aliphatic or aromatic organic cations that are not optically active and do not contribute to the luminescent properties of the hybrid material, ,,,,,− whereas the incorporation of organic luminophores is comparatively a much more narrow phase space with insufficient structural design principles to guide the rational synthetic design of functional hybrid materials. ,,− In order to establish greater structural complexity in luminsecent hybrid metal halides while significantly enhancing the moisture stability of the resultant compounds, it is desirable to template sophisticated hybrid halide compounds with optically active organic cations. ,,,− Thus far, only a handful of low-dimensional water-stable hybrid halide perovskites have been reported such as (1,8-octyldiammonium)­Sn 2 I 6 that is water stable for at least 15 h, [Pb 2 Cl 2 ] 2+ [ − O 2 C­(CH 2 ) 4 CO 2 – ] that is water stable for 24 h, [ N -methyldabconium]­PbI 3 that is water stable for 1 month, and (4,4′-ethylenedipyridinium)­Pb 2...…”