"On the Dot"-The Timing of Self-Assembled Growth to the Quantum Scale

Sanjiv Sonkaria; Sung-Hoon Ahn; Caroline S Lee; Varsha Khare

doi:10.1002/chem.201604994

"On the Dot"-The Timing of Self-Assembled Growth to the Quantum Scale

Chemistry. 2017 Jun 16;23(34):8104-8117. doi: 10.1002/chem.201604994. Epub 2017 Mar 15.

Authors

Sanjiv Sonkaria¹, Sung-Hoon Ahn^{1

2}, Caroline S Lee³, Varsha Khare¹

Affiliations

¹ Institute of Advanced Machinery and Design, Seoul National University, Gwanak Ro1, Seoul, Republic of Korea.
² Department of Mechanical and Aerospace Engineering, Seoul National University, Gwanak Ro1, Seoul, Republic of Korea.
³ Department of Materials Engineering, Hanyang University, Gyeongi, Ansan, 426-791, Republic of Korea.

PMID: 28032925
DOI: 10.1002/chem.201604994

Abstract

Understanding the complex world of material growth and tunability has mystified the minds of material scientists and has been met with increasing efforts to close the gap between controllability and applicability. The reality of this journey is frustratingly tortuous but is being eased through better conceptual appreciation of metal crystalline frameworks that originate from shape and size dependent solvent responsive growth patterns. The quantum confinement of TiO₂ in the range of 0.8-2 nm has been synthetically challenging to achieve but lessons from biomineralization processes have enabled alternative routes to be explored via self-induced pre-nucleation events. In driving this concept, we have incorporated many of these key features integrating aspects of low temperature annealing at the interface of complex heterogeneous nucleation between hard and soft materials to arrest the biomimetic amorphous phase of TiO₂ to a tunable crystalline quantumized state. The stabilization of metastable states of quantum sized TiO₂ driven by kinetic and thermodynamic processes show hallmarks of biomineralized controlled events that suggest the inter-play between new pathways and interfacial energies that preferentially favor low dimensionality at the quantum scale. This provides the potential to re-direct synthetic assemblies under tightly controlled parameters to generate a host of new materials with size, shape and anisotropic properties as smart stimuli responsive materials. These new stabilities leading to the growth arrest of TiO₂ are discussed in terms of molecular interactions and structural frameworks that were previously inaccessible via conventional routes. There exists an undiscovered parallel between synthetic and biomineralized routes enabling unprecedented access to the availability and tunability of novel quantum confined materials. The parametrics of complex material design at the crossroads of synthetically and biologically driven processes is only now surfacing.

Keywords: TiO2 quantum dots; anisotropy; biomimetics; polystyrene; tetraphenylporphyrin.