Dithienyl benzothiadiazole derivatives: a new type of stationary phases for capillary gas chromatography

Dithienyl benzothiadiazole (TBT) derivatives are characteristic of specific molecular structures and excellent thermal stability, offering the great potential for their use as stationary phases for capillary gas chromatography (GC). However, no related publications are available to date. Here we first report the exploration of two TBT derivatives, namely, 4,7-bis(5-dodecylthiophen-2-yl) benzothiadiazole (TBT-C12, a new derivative), and 4,7-di(thiophen-2-yl) benzothiadiazole (TBT), for the purpose. First, TBT-C12 and TBT were synthesized and statically coated onto capillary columns. Both of the as-prepared columns were characterized as nonpolar nature by the determined McReynolds constants. The results showed that both TBT-C12 and TBT columns achieved excellent separations for n-alkanes, esters and polycyclic aromatic hydrocarbons (PAHs), and the TBT-C12 column exhibited better thermal stability (up to 280°C) than the TBT column. Moreover, a comparative study between the TBT-type columns and a commercial column was also made, suggesting the better selectivity of the TBT-type stationary phases toward n-alkanes and PAHs than that of the commercial one. Additionally, thermodynamic parameters suggested that the retention behaviors of n-alkanes and PAHs on the TBT-C12 column was mainly controlled by entropy change (ΔS). In conclusion, this work demonstrates the excellent chromatographic performance of TBT derivatives as a new type of GC stationary phases and their potential in separation science.