Table 2. Calculated Molecular Parameters for the Series of BODIPYs Studied: B–N Bond Length (r_B–N); B–N Symmetric Stretch Frequency (ν_B–N); Ionicity, Calculated as the Difference between B and N NPA Atomic Charges; Energy Necessary to Elongate the B–N Bond by 0.2 Å (ΔE_B–N); Bond-Length Alternation Parameter (BLA) in the BODIPY Core; Substituent Mesomeric Parameters (M); Gibbs-Free Energy of the Hydrogen-Bond Formation between BODIPY and TFA in Chloroform (ΔG_{BODIPY···TFA})^a.

^aΔE_B–N is calculated at CISD/aug-cc-pVDZ level in vacuum. All other parameters are calculated at B3LYP/6-31+G(d,p) level in chloroform.