In this contribution, we present a computational protocol to predict anti-Kasha photoluminescence. The herein developed protocol is based on state-of-the-art quantum chemical calculations and excited-state decay rate theories (i.e., thermal vibration correlation function formalism), along with appropriate kinetic models which include all relevant electronic states. This protocol is validated for a series of azulene derivatives. For this series, we have computed absorption and emission spectra for both their first and second excited states, their radiative and nonradiative rates, as well as fluorescence yields from the two different excited states. All the studied azulene derivatives are predicted to exclusively display anomalous anti-Kasha S2 emission. A quantitative agreement for the herein computed excited-state spectra, lifetimes, and fluorescence quantum yields is obtained with respect to the experimental values. Given the increasing interest in anti-Kasha emitters, we foresee that the herein developed computational protocol can be used to prescreen dyes with the desired aforementioned anomalous photoluminescence properties.

According to Kasha's rule, emission of a photon in a molecular system always comes from the lowest excited state. A corollary of this rule, i.e., the Kasha-Vavilov rule, states that the emission spectra are independent of the excitation wavelength. Although these rules apply for most of the molecular systems, violations of these rules are often reported for molecular systems. The prototypical case of a Kasha's rule violation is the fluorescence observed from S 2 in azulene.Thanks to the advances in both theoretical and experimental research, other types of anomalous fluorescence arising from higher-lying excited states (e.g., excitation energy transfer (EET)-based dual emissions, thermally-activated fluorescence etc.), and which mechanistically differ from the azulene-like anomalous fluorescence, are more recurrently reported in the literature. However, the underlying mechanisms leading to these anomalous emissions can be numerous and they are not yet well understood.

New easily functionalisable and highly fluorescent BOPAHY chromophores are synthesised via one pot two step reaction starting from commercially available pyrrole-2-carbaldehydes and respective acyl hydrazides in the presence of BF3·OEt2.

The adsorption of molecular deuterium (D 2 ) onto charged cobalt-fullerene-complexes Co n C 60 + (n = 1-8) is measured experimentally in a few-collision reaction cell. The reactivity is strongly size-dependent, hinting at clustering of the transition metal atoms on the fullerenes. Formation and desorption rate constants are obtained from the pressure-dependent deuterogenation curves. DFT calculations indeed find that this transition metal clustering is energetically more favorable than decorating the fullerene. For n = 1, D 2 is predicted to bind molecularly and for n = 2 dissociative and molecular configurations are quasi-isoenergetic. For n = 3-8, dissociation of D 2 is thermodynamically preferred. However, reaching the ground state configuration with dissociated deuterium on the timescale of the experiment may be hindered by dissociation barriers.[a] Dr.

The from-first-principles calculation of fluorescence quantum yields (FQYs) and lifetimes of organic dyes remains very challenging. In this manuscript we extensively test the static machinery to calculate FQYs. Specifically, we perform an extensive analysis on the parameters influencing the intersystem crossing (ISC), internal conversion (IC), and fluorescence rates calculations. The impact of i) the electronic structure (chosen exchange-correlation functional and spin-orbit Hamiltonian), ii) the vibronic parameters (coordinate system, broadening function, and dipole expansion), and iii) the excited-state kinetic models, are systematically assessed for a series of seven rigid aromatic molecules. Our studies provide more insights into the choice of parameters and the expected accuracy for the computational protocols aiming to deliver FQYs values. Some challenges are highlighted, such as, on the one hand, the difficulty to benchmark against the experimental non-radiative rates, for which the separation between the IC and ISC contributions is often not provided in the literature and, on the other hand, the need to go beyond the harmonic approximation for the calculation of the IC rates.