Design and photophysical investigation of dipyrromethenates coordinated with the boron(III), zinc(II) and cadmium(II) as optical elements

Stability of Dibromo-Dipyrromethene Complexes Coordinated with B, Zn, and Cd in Solutions of Various Acidities

“…The mechanism of losing emission intensity is simpler for the BF 2 -based compounds, which exhibit very efficiency fluorescence, but halogenation, particularly with Br, quenches the process due to increasing nonradiative intersystem spin crossing from the lowest excited photoactive singlet to the triplet system [29]. The calculated longwave absorptions for all the compounds in the neutral solvent are blueshifted about ∆λ abs = 40 nm relative to the measured spectra (Table 1), which is an acceptable accuracy in comparison with the previous TD-DFT results, as previously discussed [24,29].…”

“…A high accuracy of the calculated spectral-luminescence properties of the isolated halogen-dpm compounds coordinated with BF 2 , Zn, and Cd was achieved in our previous theoretical description and the explanation of the observed photo-induced processes [24,29]. The same TD-DFT settings for optimization in both the ground and fluorescence states, as well as for calculating the long wavelength regions of absorption and emission spectra of the brominated compounds in neutral and HCl acidified forms in the ethanol solvent model were used in the present research (Table 2).…”

“…In order to reveal the spectral-luminescent features of the dpm complexes and their acidified forms, electronic structures were optimized in both the ground and fluorescence states, and the photophysical properties were calculated in the continuum of the solvation model using the electron density (SMD) [42] of the ethanol solvent by means of the hybrid B3LYP [43,44] exchange-correlation function implemented in Gaussian 16 [45] of the TD-DFT method, in combination with the composite def2-SVP[H, B, C, N, F]/def2-TZVP[Br, Zn]/def2-TZVPP_ECP[Cd] basis sets for different elements of the compounds, as successfully used in a recent study [24,29].…”

“…Despite the large number of works describing the synthesis, there is a lack of published studies devoted to a detailed analysis of the influence of electronic, structural, and solvation factors on the stability and photo-induced properties of dpm and their metal complexes. The manifested properties have only recently begun to be analyzed [22][23][24]. The practical use of Molecules 2022, 27, 8815 2 of 12 complex organic molecules-in particular, dpm compounds-requires deep study and an understanding of their inherit physical and chemical properties exhibited under different conditions; therefore, this is the most important step in designing such optical devices.…”