IMX Talks - Design, properties, and applications of metal-containing soft materials: a brief survey in the realm of intermolecular interactions

Soft biomaterials, which include liquids, colloids, polymers, foams, gels and liquid crystals, are able to interact with biological systems, due to the similarity of their properties, with demonstrated applications in various medical devices, implants, drug delivery systems, tissue engineering, and regenerative medicine. Liquid crystals represent the most attractive soft matter systems, being outstanding examples of spontaneous self-assembly of soft building blocks though intermolecular interactions, with the generation of a fragile balance between entropic and enthalpic contributions to the free energy. The first part of this talk will be devoted to the significant progresses made in the field of liquid crystals based on metal complexes (metallomesogens), modulating factors such as nano-segregation, molecular motifs functional to specific intermolecular interactions and molecular shapes. Transition metal complexes can organize themselves generating mesophases (liquid crystalline phases) closely related to the shape of the single molecules and to the supramolecular organization governed by many different types of intermolecular interactions (hydrophilic/hydrophobic/metallophilic interactions, π-π stackings, hydrogen-bonds….). A short library of unconventionally shaped metal complexes with ordered supramolecular organization in mesophases will be illustrated, showing that the design and the modulation of the molecular shape (by changing the metal ions and the organic ligands) and non-covalent interactions (by changing substituents on the molecular organic fragments) are the key for the generation of different properties. Along the second part of the talk, the modification of the molecular shape of metal complexes and the organic ligands surrounding the central metal ions, previously seen at work in the modulation of liquid crystalline properties, will be exposed for their biological properties and their interactions with biopolymers when used as active ingredients in the preparation of coating materials. In particular, the formation of biopolymer thin films incorporating metal-based additives can be a versatile tool to prepare new active packaging materials. Conjugation and/or embedding of metal complexes, without chemical modifications of the natural biopolymers, can be modulated by varying the chemical and structural features of the metal-based additives in relation to the chosen biopolymer.
Crispini, A., Aiello, I.; Godbert, N.; Ghedini, M.; La Deda, M., Liquid Crystals: Role of Transition Metal Ions in the Design of Metallomesogens. In Comprehensive Coordination Chemistry III; Constable, E. C., Parkin, G., Que Jr, L., Eds., Vol. 7, Elsevier, 2021; pp 241–313; https://dx.doi.org/10.1016/B978-0-08-102688-5.00122-7; ISBN: 9780081026885
Policastro, D., Giorno, E., Scarpelli, F., Godbert, N., Ricciardi, L., Crispini, A., Candreva, A., Marchetti, F., Xhafa, S., De Rose, R., Nucera, A., Barberi, R. C., Castriota, M., De Bartolo, L., & Aiello, I. (2022). New Zinc-Based Active Chitosan Films: Physicochemical Characterization, Antioxidant, and Antimicrobial Properties. Frontiers in Chemistry, 10, 1–16. https://doi.org/10.3389/fchem.2022.884059
Bio: Prof. Alessandra Crispini is full Professor of General and Inorganic Chemistry at the Department of Chemistry and Chemical Technologies at the University of Calabria. Head of the Department of Chemistry and Chemical Technologies of the University of Calabria from November 2015 until October 2021. Responsible of Inorganic Molecular Materials Research Laboratory based in the Department of Chemistry and Chemical Technologies of the University of Calabria. The research activity of Prof. Alessandra Crispini started with the molecular structure determination using X-ray diffraction techniques of inorganic and coordination compounds. Nowadays the crystallography background is finalized on the knowledge of the molecular structures and supramolecular organization in inorganic and metalorganic materials in the definition of the structure/property’s relationships. In this field the research work has been devoted towards the studies of the intermolecular interaction within both the crystalline solid state and liquid crystalline aggregation of pro-mesogenic molecular materials. From this point of view, the engineering and the synthesis of new metal containing materials has been supported by the deep analysis of the supramolecular organization of the pro-mesogenic molecules starting from their aggregation at room temperature in their crystalline solid state. The structural characterization has been performed by the use of X ray diffraction analysis using both conventional Diffraction apparatus and by the use of synchrotron source (European Synchrotron Radiation Facility, Grenoble, France (ESRF) BM 16 CRG beamline).  All the subsequent characterization within the soft aggregation state (mono e bi-dimensional architectures) has been conducted by the use of X ray powder diffraction technique at variable temperature.