We also found a linear relationship between vertical energy of these charge transfer transitions and the electron donating power of an aniline fragment and electron accepting power of the BODIPY core depending on the number and position of methyl groups. At the same time, the presence of aniline fragments leads to the appearance of new S0 → S2 transitions of the charge transfer character in electronic spectra of BODIPYs. 500 nm as well as absorption bands in the region of 300-400 nm. These transitions in experimental spectra form the most long-wave absorption bands at ca. Methyl substituents in the BODIPY frame and the aniline fragment at the meso position disturb energy of local excitations S0 → S1, S0 → S 3, and S0 → S4 weakly in comparison with the fully unsubstituted BODIPY molecule. The S0 → Si, i = 1-5 electronic transitions of four 8-(4-aniline)-BODIPY and four 8-(N,N-dimethyl)-BODIPY dyes, differ by number and position of methyl substituents in the BODIPY frame, were investigated theoretically using ab initio the coupled cluster doubles (CC2) and TD- CAM-B 3 LYP methods. All rights reserved.Įffect of methyl substituents on the electronic transitions in simple meso-aniline-BODIPY based dyes: RI-CC2 and TD- CAM-B 3 LYP computational investigation This phenomenon and the synthesized test molecules can be used to benchmark theoretical methods as well as to help the development of new functionals intended for spectroscopical studies. CAM-B 3 LYP allows sufficient spatial overlap between the nitro group and distant parts of the molecule, which is necessary for the accurate description of excited states especially for charge transfer states. Fragment population analysis revealed that the nitro groups form highly localized molecule orbitals but the exact composition depends on the functional. It was found that the range separated CAM-B 3 LYP gives better predictions than B 3 LYP for all test molecules. Spectra were computed by B 3 LYP and CAM-B 3 LYP functionals with 6-311++G(2d,2p) basis set. A test set of molecules of known stereochemistry were synthesized to study this phenomenon in detail.
Komjáti, Balázs Urai, Ãkos Hosztafi, Sándor Kökösi, József Kováts, Benjámin Nagy, József Horváth, Péterī 3 LYP is one of the most widely used functional for the prediction of electronic circular dichroism spectra, however if the studied molecule contains aromatic nitro group computations may fail to produce reliable results. Systematic study on the TD-DFT calculated electronic circular dichroism spectra of chiral aromatic nitro compounds: A comparison of B 3 LYP and CAM-B 3 LYP.