Designing solid materials from their solute state: a shift in paradigms towards a holistic approach in functional materials chemistry.

"Non-classical" notions consider formation pathways of crystalline materials where larger species than monomeric chemical constituents, i.e., ions or single molecules, play crucial roles, which are not covered by the classical theories dating back to the 1870s and 1920s. Providing an outline of "non-classical" nucleation, we demonstrate that pre-nucleation clusters (PNCs) can lie on alternative pathways to phase separation, where the very event of demixing is not primarily based on the sizes of the species forming, as in the classical view, but their dynamics. Rationalizing, on the other hand, that precursors that can be analytically detected in pre-nucleation stages and that play a role in phase separation must be considered PNCs and cannot be explained by classical notions, we outline a variety of systems where PNCs are important. Indeed, in recent years, with the advent of "non-classical" theories, a primary focus of research concentrated on the fundamental understanding of oligomer-ic/polymeric and particulate species involved in nucleation and crystallization processes, respectively. At the same time, the near-to unfathomable potential of "non-classical" routes for the synthesis of inorganic functional materials slowly unfolds. An overview over recent developments in the fundamental and mechanistical understanding of "non-classical" nucleation and crystallization in this perspective then allows us mapping out the potential of cluster/particle-driven mineralization pathways to intrinsically tailor the properties of inorganic functional (hybrid) materials via structuration from the nano- to the mesoscale. This is of utter importance for the functionality and performance of materials as it may even confer emergent properties such as self-healing. Biominerals - often formed via particle accretion mechanisms- demonstrate this impres-sively and thus can serve as further source of inspiration how to exploit nonclassical crystallization routes for syntheses of structured and functional materials. These new avenues to synthetic approaches may finally provide a holistic material con-cept, in which fundamental chemistry and materials science synergistically alloy.