Proposals for systems embodying condensed matter spin qubits cover a very wide range of length scales, from atomic defects in semiconductors all the way to micron-sized lithographically defined structures. Intermediate scale molecular components exhibit advantages of both limits: like atomic defects, large numbers of identical components can be fabricated; as for lithographically defined structures, each component can be tailored to optimise properties such as quantum coherence. Here we demonstrate what is perhaps the most potent advantage of molecular spin qubits, the scalability of quantum information processing structures using bottom-up chemical self-assembly. Using Cr₇Ni spin qubit building blocks, we have constructed several families of two-qubit molecular structures with a range of linking strategies. For each family, long coherence times are preserved, and we demonstrate control over the inter-qubit quantum interactions that can be used to mediate two-qubit quantum gates.

Large macrocycles containing imine and borasiloxane links are obtained in polycondensation reactions of 4-formylbenzeneboronic acid, t-Bu₂Si(OH)₂, and diamines. The multicomponent reactions can be performed in solution or – advantageously – by mechanochemical syntheses in a ball mill.

Boronic acid-capped clathrochelates were used to build rigid, linear bipyridyl ligands with adjustable lengths between 1.5 and 5.4 nm. The syntheses can be accomplished in one or two steps from simple starting materials. The potential of these ligands as building blocks for metallasupramolecular chemistry is unveiled through the preparation of a discrete metallamacrocyclic structure and a heterometallic coordination polymer.

The realization of CO releasing molecules triggered by light (photoCORMs) within the phototherapeutic window (λ > 600 nm) constitutes an important goal for potential therapeutic applications of the molecules. The activation of photoCORMs with red/NIR light would enable exploiting the higher depth of penetration of this radiation with respect to higher energy photons. In this article we report a family of carbonyl Mn(I) complexes capable of releasing CO when triggered with red light (≥625 nm). Such complexes are based on 2,2′-azopyridine ligands modified by the introduction of electron-donating or electron-withdrawing substituents. Our results indicate that electron deficient ligands induce a gradual decrease of the HOMO−1/LUMO gap of the species (i.e. of the orbitals involved in the lowest energy transition), thus enabling a fine tuning of their visible absorption maxima between 630 and 693 nm. The synthesis of the complexes and their photodecomposition behaviour towards CO release are described. We suggest that this approach could be generalized for further development of low-energy activated photoCORMs.