In Quest of a Systematic Framework for Unifying and Defining Nanoscience*

A \textit{central paradigm driven, Mendeleev-like nano-periodic system} has been cited as a critical missing link in the transformation of nanotechnology from an empirical to a highly predictive science. A systematic framework is proposed based on the same first principles underpinning ``central paradigms'' for chemistry/physics.\footnote{D.A. Tomalia, \textit{J. Nanopart. Res.} (2009), 11, 1251.} As such, a \textbf{Nanomaterials Classification Roadmap} considers \textit{structure controlled} nanoparticles defined by \textbf{Critical Nanoscale Design Parameters (CNDPs); }namely, \textbf{size, shape, surface chemistry, flexibility, architecture and elemental composition}. Classified as either \textbf{hard (H) (}inorganic) or \textbf{soft (S) (}organic)\textbf{ nano-element categories}$, $these nanoparticles (e.g., nano-clusters) generally manifest pervasive \textbf{atom mimicry }features.\footnote{S.N. Khanna, A.W. Castleman, et al., \textit{PNAS }(2006), 103 (49), 18405.} Many literature examples demonstrate chemical bonding/assembly of these nano-element categories to produce extensive libraries of \textbf{hard-hard [H}$_{n}$\textbf{:H}$_{n}$\textbf{], soft-soft [S}$_{n}$\textbf{-S}$_{n}$\textbf{]or hard-soft [H}$_{n}$\textbf{-S}$_{n}$\textbf{]} nano-element combinations, referred to as \textbf{nano-compounds}. Due to their quantized CNDP features, these nano-element/compounds exhibit many well-defined\textbf{ nano-periodic property patterns}. These property patterns are observed in their intrinsic physico-chemical properties (i.e., melting points, reactivity/self-assembly, sterics), as well as important functional/ performance properties (i.e., magnetic, photonic, and electronic behavior). The importance of these CNDP directed property patterns was recently demonstrated by publication of \textbf{first Mendeleev-like nano-periodic tables} by Percec, et al.\footnote{V. Percec, et al., \textit{J. Am. Chem. Soc}. (2009), 131, 17500.} Similarly, Mirkin, et al.\footnote{C.A. Mirkin, et al., \textit{Science }(2011), 334, 204.} recently reported six CNDP dependent nano-periodic rules for predicting hard-soft nano-element assemblies. These two independent reports appear to fulfill/validate this proposed nano-periodic concept. This lecture will overview this unifying \textbf{nano-periodic system }suitable for tuning optimal nanostructure/application properties, as well as predicting important risk/benefit/performance boundaries in the nanoscience field.