Supramolecular Assembly of a Macrocyclic Rhodium(I) Isocyanide Complex with Long-Lived Near-Infrared Luminescence 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.

Macrocyclic Rh(I) complexes stack into tetramers and unlock red absorption and NIR luminescence

Alex Bukvic and Mathis Brändlin in @jacs.acspublications.org

pubs.acs.org/doi/10.1021/...

Homomolecular Photon Upconversion in a Perylene-Decorated Iron(III) Complex Classical upconversion employs sensitizers and annihilators as two distinct molecular species and is, therefore, classified as heteromolecular. Homomolecular upconversion, the unification of both role...

A molecular dyad of an iron complex covalently bound to an annihilator exhibits three photoactive excited states — singlet, doublet, and triplet — enabling homomolecular upconversion

Florian Doettinger, Jonathan Sagaya, Giacomo Morselli in @jacs.acspublications.org

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Ultrafast Dissipation via Interligand Electron Transfer in {Ru(tpy)(bpy)} Chromophores 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′...

Our study about dissipative ILET in {Ru(tpy)(bpy)} chromophores upon light absorption is out in Inorg. Chem. @acs.org ! it outcompetes diffusional reactivity = significant losses. Collab @solarfau.bsky.social @fau.de 🤝 Pedro Abate, Daiana Cabrosi and Luis Baraldo at UBA
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Captivating bimolecular photoredox dynamics of a ligand-to-metal charge transfer complex 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 ...

Super excited to see our work monitoring dynamics of the charge separated pair in a photocycle driven by a 2LMCT exited state now out in @chemicalscience.rsc.org ! ⚡️

Thanks for the great team efforts🌟

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Spin-State and Reorganization Energy Considerations for Metal-Centered Photoredox Catalysis Transition-metal complexes featuring metal-centered excited states have recently emerged as mechanistically distinct platforms for selective photochemistry, including photoredox catalysis. Among these...

Exploring metal-centered photoredox reactivity? 🚀Don’t forget to look at the spin-state landscape and the role of reorganisation energy, they can make a difference 😉

Huge thanks to Bekah for leading the experiments and shaping the story🥳 a true collaborative effort!😃

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Molecular Design Principles for Achieving High-Efficiency Light-Induced Charge Separation at the Nanometer Scale 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...

Molecular Design Principles for Achieving High-Efficiency Light-Induced Charge Separation at the Nanometer Scale

Mathis Brändlin and Felix Himmelreich in jacsau.bsky.social

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Chemists develop molecule for important step toward artificial photosynthesis 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...

Artificial photosynthesis could be the key to environmentally friendly fuels. A research team led by @wengeroliver.bsky.social has developed a special molecule that can store four charges simultaneously under light irradiation. Wenger calls this molecule "an important piece of the puzzle."

Rethinking the Excited-State Redox Properties of Iron(III) Complexes for LMCT Photoredox Catalysis 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...

Rethinking Iron Photoredox Catalysis

For Fe(III) complexes, excited-state redox potentials don’t follow the usual rules - standard estimation methods fall short

Joël Wellauer with Paul Francis & colleagues at Deakin University in @jacs.acspublications.org

pubs.acs.org/doi/10.1021/...

Pushing the Thermodynamic and Kinetic Limits of Near-Infrared Emissive CrIII Complexes in Photocatalysis 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...

Cr(III) complexes with enhanced metal–ligand covalency enable tunable NIR luminescence and red-light photoreduction.

@giacomo-morselli94.bsky.social & team find signs of doublet–doublet annihilation, or excited-state disproportionation.

In @jacs.acspublications.org

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Structural Control of Metal-Centered Excited States in Cobalt(III) Complexes via Bite Angle and π–π Interactions 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...

Bite angle optimization weakens ligand fields in cobalt(III) complexes, yet lifetimes can increase due to rigidification

pi-donor (instead of pi-acceptor) ligand properties are key

now in @jacs.acspublications.org

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Breaking Kasha’s Rule to Enable Higher Reactivity in Photoredox Catalysis 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...

We show how photoredox catalysis can bypass Kasha’s rule, enabling reactions from higher excited states.

This work, led by the exceptional @bjoernpfund.bsky.social, offers new insights into photochemical reactivity.

Published in JACS @jacs.acspublications.org

bit.ly/3IysmjX

Thrilled to share our new JACS paper on anti-Kasha photoreactivity!
We show that higher-lying excited states can drive electron transfer — opening new doors for photoredox catalysis.
Huge thanks to @wengeroliver.bsky.social for the incredible mentorship!

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