The spatio-temporal distribution of aromatase cytochrome in ovary throughout the canine oestrous cycle.

Context: New animal welfare legislation and ethical guidelines encourage alternative approaches for canine contraception, instead of surgical gonadectomy which is considered invasive and unjustified in healthy dogs.

Aims: Reversible contraception might be achieved by inhibition of aromatase (CYP19), an enzyme catalysing the conversion of androgens to oestrogens. This study provides insights into the spatio-temporal expression and distribution of aromatase in canine ovarian tissue.

Tailoring the Photophysical Properties of a Homoleptic Iron(II) Tetra -Heterocyclic Carbene Complex by Attaching an Imidazolium Group to the (CNC) Pincer Ligand─A Comparative Study.

We here report the synthesis of the homoleptic iron(II) -heterocyclic carbene (NHC) complex [Fe(miHpbmi)](PF) (miHpbmi = 4-((3-methyl-1-imidazolium-1-yl)pyridine-2,6-diyl)bis(3-methylimidazol-2-ylidene)) and its electrochemical and photophysical properties. The introduction of the π-electron-withdrawing 3-methyl-1-imidazol-3-ium-1-yl group into the NHC ligand framework resulted in stabilization of the metal-to-ligand charge transfer (MLCT) state and destabilization of the metal-centered (MC) states. This resulted in an improved excited-state lifetime of 16 ps compared to the 9 ps for the unsubstituted parent compound [Fe(pbmi)](PF) (pbmi = (pyridine-2,6-diyl)bis(3-methylimidazol-2-ylidene)) as well as a stronger MLCT absorption band extending more toward the red spectral region.

Multifaceted Deactivation Dynamics of Fe(II) -Heterocyclic Carbene Photosensitizers.

Excited state dynamics of three iron(II) carbene complexes that serve as prototype Earth-abundant photosensitizers were investigated by ultrafast optical spectroscopy. Significant differences in the dynamics between the investigated complexes down to femtosecond time scales are used to characterize fundamental differences in the depopulation of triplet metal-to-ligand charge-transfer (MLCT) excited states in the presence of energetically accessible triplet metal-centered (MC) states. Novel insights into the full deactivation cascades of the investigated complexes include evidence of the need to revise the deactivation model for a prominent iron carbene prototype complex, a refined understanding of complex MC dynamics, and a quantitative discrimination between activated and barrierless deactivation steps along the MLCT → MC → GS path.

Competing dynamics of intramolecular deactivation and bimolecular charge transfer processes in luminescent Fe(iii) N-heterocyclic carbene complexes.

Steady state and ultrafast spectroscopy on [Fe(phtmeimb)]PF (phtmeimb = phenyl(tris(3-methylimidazol-2-ylidene))borate) was performed over a broad range of temperatures. The intramolecular deactivation dynamics of the luminescent doublet ligand-to-metal charge-transfer (LMCT) state was established based on Arrhenius analysis, indicating the direct deactivation of the LMCT state to the doublet ground state as a key limitation to the lifetime. In selected solvent environments photoinduced disproportionation generating short-lived Fe(iv) and Fe(ii) complex pairs that subsequently undergo bimolecular recombination was observed.