Next Generation Multifunctional Nano-Science of Advanced Metal Complexes with Quantum Effect and Nonlinearity

<jats:title>Abstract</jats:title><jats:p>My research target can be described as “Next Generation Multifunctional Nano-Science of Advanced Metal Complexes with Quantum Effect and Nonlinearity”. My work encompasses four important key areas: (1) inorganic-organic hybrid systems, (2) nano-size and nano-space, (3) bottom-up and self-assembly, and (4) nonlinearity and quantum effect. Among them, nonlinearity and quantum effect are the most important for nano-science of advanced metal complexes. I have been working on these two topics (nonlinearity and quantum effect) simultaneously for more than 40 years. As for quantum effect, I have focused on Haldane gap systems, single-chain magnets (SCMs), single-molecule magnets (SMMs), Kondo resonance on SMMs, photo-switchable SMMs, metallic conducting SMMs, SMMs encapsulated into single-walled carbon nanotube (SWCNT), and metal-organic framework (MOF)-spintronics for spin qubits, for pursuing high-density memory devices and quantum computing. As for nonlinearity, I have focused on quasi-one-dimensional halogen-bridged metal complexes (MX-Chains; M = Pt, Pd, and Ni; X = Cl, Br, and I) with nonlinear excitons such as solitons and polarons, strongly electron-correlated Ni(III) complexes with gigantic third-order optical nonlinearity, and phase transitions and charge fluctuations between Pd(III) averaged states (= Mott insulator) and Pd(II)-Pd(IV) mixed-valence states (= charge density wave states), for pursuing optical communication, optical switching, and optical computing. In this review article, I will describe the above main topics (quantum effect and nonlinearity) according to my research history of more than 40 years, respectively. Finally, I will propose future perspectives for the two topics.</jats:p>