Electron donor–acceptor (EDA) complexes provide a means to initiate radical reactions under visible light irradiation using substrates that do not absorb visible light individually. Catalytic approaches to complex formation are vital for advancing this synthetic strategy as it decouples the complexation and photogeneration of radicals from substrate functionalization, a limitation inherent to stoichiometric approaches that restricts structural diversity. This Synopsis highlights recent developments in EDA complex photochemistry in which either the donor or acceptor are employed catalytically.

The creation of ordered arrays of qubits that can be interfaced from the macroscopic world is an essential challenge for the development of quantum information science (QIS) currently being explored by chemists and physicists. Recently, porous metal–organic frameworks (MOFs) have arisen as a promising solution to this challenge as they allow for atomic-level spatial control of the molecular subunits that comprise their structures. To date, no organic qubit candidates have been installed in MOFs despite their structural variability and promise for creating systems with adjustable properties. With this in mind, we report the development of a pillared-paddlewheel-type MOF structure that contains 4,7-bis­(2-(4-pyridyl)-ethynyl) isoindoline N-oxide and 1,4-bis­(2-(4-pyridyl)-ethynyl)-benzene pillars that connect 2D sheets of 9,10-dicarboxytriptycene struts and Zn2(CO2)4 secondary binding units. The design allows for the formation of ordered arrays of reorienting isoindoline nitroxide spin centers with variable concentrations through the use of mixed crystals containing the secondary 1,4-phenylene pillar. While solvent removal causes decomposition of the MOF, magnetometry measurements of the MOF containing only N-oxide pillars demonstrated magnetic interactions with changes in magnetic moment as a function of temperature between 150 and 5 K. Variable-temperature electron paramagnetic resonance (EPR) experiments show that the nitroxides couple to one another at distances as long as 2 nm, but act independently at distances of 10 nm or more. We also use a specially designed resonance microwave cavity to measure the face-dependent EPR spectra of the crystal, demonstrating that it has anisotropic interactions with impingent electromagnetic radiation.

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The title compound, [Cu2(C19H23N7O)(C2H3O2)4] n , was obtained via reaction of copper(II) acetate with the coordinating ligand, 6-ethoxy-N 2,N 4-bis[2-(pyridin-2-yl)ethyl]-1,3,5-triazine-2,4-diamine. The crystallized product adopts the monoclinic P21/c space group. The metal core exhibits a paddle-wheel structure typical for dicopper tetraacetate units, with triazine and pyridyl nitrogen atoms from different ligands coordinating to the two axial positions of the paddle wheel in an asymmetric manner. This forms a coordination polymer with the segments of the polymer created by the c-glide of the P21/c setting of the space group. The resulting chains running along the c-axis direction are held together by intramolecular N—H...O hydrogen bonding. These chains are further packed by dispersion forces, producing an extended three-dimensional structure.