Strategic ligand engineering is essential for the development of new photoactive transition metal complexes. One such application is the control of supramolecular, one-dimensional stacking of square-planar d8-organometallic systems. Here, we report the synthesis of a macrocyclic, tetradentate isocyanide ligand, CN4, and facile coordination to rhodium(I) yielding [Rh(CN4)][BArF4]. Single-crystal X-ray diffraction upon acetone-solution grown crystals reveals formation of a tetrameric RhI stack, constructed of two dimeric forms of monomers. UV–visible absorption spectroscopy shows two prominent absorption bands, assigned to dimer (525 nm) and tetramer (840 nm), confirming stacked species. These assignments are further supported by DOSY measurements. Solvent control over this equilibrium is achieved first with acetonitrile, favoring only tetrameric aggregation, and also with dichloromethane, disabling aggregation completely. Upon excitation, the monomeric form returns to its electronic ground state in less than 10 ns. The near-infrared-absorbing tetramer exhibits an excited state with a lifetime of 150 ns in deaerated acetonitrile and NIR-II emission at 1040 nm. This discovery provides new opportunities for innovation in photophysics and photochemistry through polynuclear architectures that exhibit emergent properties compared to traditional mononuclear transition metal complexes.

Classical upconversion employs sensitizers and annihilators as two distinct molecular species and is, therefore, classified as heteromolecular. Homomolecular upconversion, the unification of both role...

With the aim of studying interligand electron transfer (ILET) with different driving forces, [Ru(tpy)(R-bpy)(CN)]+ complexes with R-bpy = 4,4′-dimethylamino-2,2′-bipyridine (dMAb), 4,4′-dimethoxy-2,2′...

Transition metal complexes featuring ligand-to-metal charge transfer (LMCT) excited states have been identified as promising candidates for driving electron transfer processes. To obtain an efficient ...

Transition-metal complexes featuring metal-centered excited states have recently emerged as mechanistically distinct platforms for selective photochemistry, including photoredox catalysis. Among these...

The light-induced separation of charges, fundamental to natural photosynthesis, is key to converting solar energy into chemical energy in artificial systems. One challenge is that charges tend to spon...

A research team from the University of Basel has developed a new molecule modeled on plant photosynthesis: under the influence of light, it stores two positive and two negative charges at the same tim...

The reduction potentials of electronically excited states are crucial input values for photoredox reaction design. Since they are not directly measurable, they are typically estimated from the corresp...

Photoactive CrIII complexes are typically based on polypyridine coordination environments, exhibit red luminescence, and are good photo-oxidants but have modest photoreducing properties. We report new...

CoIII complexes have recently become an important focus in photophysics and photoredox catalysis due to metal-centered excited states with strong oxidizing properties. Optimizing chelate ligand bite a...

Nearly all photochemical transformations known to date follow Kasha’s rule, implying that reactions occur only from the lowest electronically excited state of a given spin multiplicity due to the fast...