Enhancement of orientation of rigid polymer blocks by incorporating rod–coil block copolymer chains into metal–organic frameworks

Spectroscopic and Time-Dependent DFT Study of the Photophysical Properties of Substituted 1,4-Distyrylbenzenes

In this contribution, we examine the photophysical properties of 15 totally trans-trans 1,4-distyrylbenzene derivatives (DSBs) functionalized with different electron-donating (ED) and electron-withdrawing (EW) groups by experimental and computational methodologies. We use UV-vis and fluorescence spectroscopies to determine the experimental optical properties such as the maximum absorption (λ_abs^exp) and emission (λ_em^exp) wavelengths, the highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO-LUMO) energy gaps (ΔE_abs^exp), the molar extinction coefficients (ε), the fluorescence quantum yields (Φ_f), and the fluorescence lifetimes (τ). We also calculate the experimental spontaneous emission decay rate (k_r^exp) and correlate all of these magnitudes to the corresponding calculated properties, maximum absorption (λ_abs^cal) and emission (λ_em^cal) wavelengths, vertical transition energies (ΔE_abs^cal), oscillator strength (F_osc), and spontaneous emission decay rate (k_r^cal), obtained by the time-dependent density functional theory method. We analyze the effect of the electronic nature of the substituents on the properties of the DSBs, finding that the ED and EW groups lead to bathochromic shifts. This is consistent with the decrease of ΔE values as the strength of ED and EW substituents increases. We find excellent correlations between calculated and experimental values for λ_abs, λ_em, and ΔE_abs (r ∼ 0.99-0.95). Additionally, the correlations between the relative ε with F_osc values and the k_r values are in good agreement (r ∼ 0.88-0.72) with the experimental properties. Overall, we find that for substituted 1,4-DSBs, computational chemistry is an excellent tool to predict structure-property relationships, which can be useful to forecast the properties of their polymeric analogues, which are usually difficult to determine experimentally.