Effect of octabromination of a tetrakis(4-carboxyphenyl)porphine derivative bound to silica gels on HPLC retention behaviors of polyaromatic hydrocarbons

The effect of bromination of Cu-porphyrin-derivative-immobilized silica gels (Cu-TCPPD) was examined by comparing the retention behaviors of polyaromatic hydrocarbons (PAHs) on Cu-TCPPD and Cu-octabromotetrakis(4-carboxyphenyl)porphine-derivative-immobilized silica gels (Cu-OBTCPPD) columns. It was revealed that bromination affects strongly the π–π electron interactions caused from hydration energy in a polar eluent (80% methanol) possibly as a result of a destruction of planar structure of porphine-ring by bromination. It was also revealed that bromination enhances π–d interactions as well as the π–π electron interactions in a broad sense (e.g., dispersion forces) in a non-polar eluent (n-hexane). However, the bromination did not exert much influence on electrostatic interactions caused from polarization of mono-halogenated benzenes.