Periodic Reporting for period 1 - LUMIFIELD (Chiral Metal-Based Luminophores for Multi-Field Responsive Bistable Switches)
Reporting period: 2022-04-01 to 2024-09-30
The project concerns the search for novel smart materials that will be suitable for the construction of new generations of efficient and miniaturized electronic, magnetic, optical, and energy conversion devices, in particular, high-performance data storage systems. To address the challenge of organizing people’s lives in a more efficient and less energy-consuming way, there is a strong necessity to have better and better devices relying on small portable energy sources. Technological progress in this matter needs novel materials fulfilling as many requirements as possible from the set of extreme miniaturization, high efficiency in demonstrating desired physical properties, low cost of production, low energy consumption level, and an environmentally friendly character. Recent years proved that constructing such new-era materials can be effectively realized by processing well-known or novel functional materials into the nanoscale. In this approach, nanomaterials bearing specific functions can be combined to get a high-performance multi-component system with an overall small, even nanometric, size. Aiming at smart devices, multifunctional nanomaterials, revealing a few different physical properties, can also be obtained using this strategy; however, the incorporated functionalities originate from separate materials that are further processed. This project is aimed at realizing the idea of multifunctional materials not at the nanoscale but at the molecular level by constructing single-phase materials based on molecules providing many desired properties. Such materials are expected to be alternatives to the currently explored nanodevices based on separate functional components as a single component of a device might then provide, e.g. both magnetic and optical memory effects. In this context, the project is aimed at crossing the current limits of single-phase multifunctional materials. To achieve this, the project is focused on searching for proper molecular precursors based on metal complexes that serve as chiral luminophores (CLs), i.e. the molecules linking the photoluminescence (PL) with chirality as then an advanced circularly polarized luminescence (CPL) will be observed. Moreover, it is planned that such CLs will be functionalized toward magnetic, ferroelectric, and photoswitching abilities to produce luminescence-based multi-field molecular switches where the PL and CPL optical effects will be sensitive to the magnetic field, electric field, and light, thus they will be great candidates for memory devices. The ultimate goal is to synthesize multifunctional materials based on CLs that will combine magnetic, ferroelectric, and photoswitching functionalities to use them as the single component for the nanometric multi-state memory device.
Within the reporting period (first 24 months of the project), the main efforts were devoted to the design, synthesis, and physicochemical characterization of proper molecular precursors, based on metal ions surrounded by organic and inorganic ligands, which will ensure the combination of chirality and photoluminescence. In this regard, the main achievement is the successful synthesis of chiral luminescent Ir(III) complexes bearing organic pinene-containing ligands and inorganic cyanido ligands. This unique molecular precursor was further fruitfully tested as a starting point for the synthesis of advanced molecular materials that might be potential magnetic chiral luminophores or ferroelectric chiral luminophores, thus the material’s candidates for expected switching of luminescent properties by magnetic or electric fields, respectively. The other alternative chiral molecular luminophores based on such metal centers as Pt(II), Pd(II), and Re(V), were also prepared. As mentioned above for the case of Ir(III) complexes, the next part of efforts in the project was devoted to the application of obtained chiral luminescent metal complexes as the molecular building blocks for the construction of objective materials, including magnetic chiral luminophores (MCLs), ferroelectric chiral luminophores (FCLs), and photoswitchable chiral luminophores (PhCLs), or even the combined cases (e.g. MFCLs). The first promising examples from each of these groups were prepared, in some cases (MCLs, PhCLs) the employment of the second, different metal complex, such as Mn(II) or lanthanide(III) ions was necessary, in others (FCLs) the polar organic cations were employed, or both the second metal ion and the organic molecular component. These materials candidates are planned to be examined thoroughly from the viewpoint of desired combinations of physical properties at the next stages of the project. Simultaneously, alternative synthetic strategies toward chiral metal-based luminophores were also established which was done based on the thorough and critical analyses of the current advances in the related research fields. Therefore, the families of chiral luminescent Mn(II)- and lanthanide(III)-based complexes were prepared, and their application for MCLs, FCLs, and PhCLs was performed providing other classes of candidates for advanced physical studies at the next stages of the project.
Within the reporting period, the most prominent result of a most important impact is the formulation of the efficient synthetic strategy for the preparation of chiral and strongly photoluminescent anionic Ir(III) complexes equipped with a chiral pinene-containing ligand and cyanido ligands. Such intrinsically chiral luminescent cyanido transition metal complex was not yet presented in the literature. More importantly, it has a great potential to become a convenient molecular precursor to achieve families of unique materials serving as variously functionalized chiral luminophores. There are a few reasons why this molecular precursor might be of great potential in its further exploration in coordination chemistry and materials science. It combines a chiral structure with strong photoluminescence in the visible range, i.e. under UV light irradiation, it emits green light. Therefore, a diversity of materials that can be built using this molecular precursor will also bear the mentioned properties. Moreover, it was obtained as a molecular anion, thus it is a great prerequisite for the construction of various materials with metal ions or polar organic cations, which was already tested in the project. The next stages of the project will be focused on checking how efficient the functionalization by such a cationic molecular component can be achieved as the mentioned Ir(III) complex can be then applicable for magnetic chiral luminophores as well as ferroelectric chiral luminophores, or even their combinations. After obtaining this Ir(III) complex, the other, analogously working, molecular precursors based on, e.g. Re(V) centers were also obtained, however more research on their ability to construct further multifunctional chiral luminescent materials is needed. It is also worth noting that the chemical applicability of the above-mentioned unique Ir(III)-based molecular precursors was already done within the project realization; however, the resulting multifunctional chiral luminophores (magnetic and/or ferroelectric) were not yet tested as the source of multi-state memory effects induced by a few different physical stimuli. This research is planned at the following stages of the project.