Quantum Materials from an Inorganic Chemistry Perspective

T his Special Issue on "Quantum Materials from anInorganic Chemistry Perspective" presents some of the latest research in the field of quantum materials, highlighting how this area is being explored and advanced from the viewpoint of inorganic chemists.Quantum materials feature interactions and/or correlations between electrons, orbitals, charge, or phonons that yield complex behavior that cannot be explained by classical physics.This intriguing class of compounds includes superconductors, where electrons are paired (either by interactions with phonons or by an unconventional mechanism such as involvement of heavy fermions) and move through the lattice with zero resistance.Topological materials have arisen in recent years; these compounds are insulating in the bulk but exhibit conducting behavior in robust surface states which are formed by interactions between electronic bands and spin-orbit coupling.A variety of complex magnetic behaviors�spin liquids, spin ices, skyrmions�fall under the umbrella of quantum materials, induced by interactions between electrons, spins, and lattice symmetry which lead to magnetic fluctuations or frustrated magnetic coupling interactions.The future of quantum computing will rely on development of quantum bits, which can access a superposition of states rather than the binary 0/1 states currently available from classical bits.Molecular complexes of paramagnetic transition metal or lanthanide ions are potential qubits, particularly if the coordinating ligands are designed with suitable geometry, nuclear composition, and charge distribution to interact with the unpaired electrons on the metal ion to enable a magnetically anisotropic state and long-lived spin coherence.Quantum materials lie at the intersection of chemistry, physics, and materials engineering.Inorganic chemists have many strengths that are needed to address the challenges in this field.While new quantum materials are not quite at the point of application yet, their discovery and optimization of their behavior could lead to incredible advancements in the fields of computing, sensors, energy storage and transmission, and some fields that are hard to envision at this time�as John Corbett once stated, "It is always difficult to predict the unimaginable." 1 In the meantime, the work that goes into designing, discovering, and optimizing quantum materials will lead to formation of new compounds.In this Special Issue, we present recent research that explores the boundaries of quantum materials, using the periodic table as a palette.The materials range from ordered extended solids containing nets of paramagnetic ions exhibiting complex magnetic coupling, to compounds tailored by deliberate substitution or defect engineering to manipulate electronic properties, to molecular complexes of paramagnetic ions with coordination geometry designed to target qubit or single-molecule magnet behavior.