Modelling solvent effects on the absorption and emission spectra of constrained cyanines with both implicit and explicit QM/EFP models

[Display omitted] •Continuum models allow to accurately estimate solvatochromic shifts of cyanines.•Going beyond the LR-PCM approach is mandatory for emission.•Explicit solvent models also proved efficient for the investigated dyes. In this contribution, we have combined Time-Dependent Density Functional Theory with both implicit solvation using variations of the well-known Polarisable Continuum Model (Linear-Response, corrected Linear-Response and State-Specific schemes) and explicit solvation approaches, to investigate the solvatochromic shifts undergone by three recently synthesised dyes. These dyes, an aza-BODIPY, a BODIPY and a so-called NBO fluorophore all present excited-states developing a significant cyanine-like character, that is known to be challenging for density-based theories. Our investigation reveals dramatic influence of the selected environmental model on both the predicted sign and amplitude of the solvent shifts. The impact of solvation on the 0–0 energies and vibronic band shapes is also discussed and comparisons with experimental data are performed.