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N-Heterocyclic carbene-carbodiimide (NHC-CDI) adducts are versatile compounds that can be used as ligands and (pre)catalysts, but their systematic structure–property relationships are underexplored. Herein, we investigated how structural electronic variations on both the NHC and CDI affect the inherent kinetic and thermodynamic properties of the adducts. Using in situ carbene trapping and variable-temperature NMR spectroscopy, we measured the rates of dissociation and the equilibrium constants and then used Eyring and van’t Hoff analyses to calculate ΔG‡ and ΔG, respectively. Linear free-energy relationships indicate that changing the para position of the CDI substituents yields a similar effect to changing the NHC core. These CDI structural modifications affected the adducts’ thermodynamics (ΔG) more than the kinetics (ΔG‡) and were found to be influenced more by inductive, rather than resonance, factors. Preliminary results suggest a steric threshold beyond which steric effects dominate electronic effects in governing the strength of the adduct bond. This systematic investigation provides valuable insight into the design of NHC-CDIs for current and future applications. 

Realistic quantum systems are affected by environmental loss, which is often seen as detrimental for applications in quantum technologies. Alternatively, weak coupling to an environment can aid in stabilizing highly entangled and mixed states, but determining optimal system-environment parameters can be challenging. Here, we describe a technique to optimize parameters for generating desired nonequilibrium steady states (NESSs) in driven-dissipative quantum systems governed by the Lindblad equation. We apply this approach to predict highly entangled and mixed NESSs in Ising, Kitaev, and Dicke models in several quantum phases. Published by the American Physical Society2025 

We report the experimental resonance enhanced multiphoton ionization spectrum of isoquinoline between 315 and 310 nm, along with correlated electronic structure calculations on the ground and excited states of this species. This spectral region spans the origin transitions to a π–π* excited state, which previous work has suggested to be vibronically coupled with a lower lying singlet n–π* state. Our computational results corroborate previous density functional theory calculations that predict the vertical excitation energy for the n–π* state to be higher than the π–π* state; however, we find an increase in the C–N–C angle brings the n–π* state below the energy of the π–π* state. The calculations find two out-of-plane vibrational modes of the n–π* state, which may be brought into near resonance with the π–π* state as the C–N–C bond angle increases. Therefore, the C–N–C bond angle may be important in activating vibronic coupling between the states. We fit the experimental rotational contour with a genetic algorithm to determine the excited state rotational constants and orientation of the transition dipole moment. The fits show a mostly in-plane polarized transition, and the projection of the transition dipole moment in the a-b plane is about 84° away from the a axis. These results are consistent with the prediction of our electronic structure calculations for the transition dipole moment of the π–π* excited state.