Molecular spectroscopic determination of nitroaromatic and peroxide type energetic subtances with carbon dots

The most well–known of the nitroaromatic energetics are undoubtedly 2,4,6–trinitrotoluene (TNT) and 2,4,6-trinitrophenol (TNP). The most popular member of peroxide–based energetics is triacetone triperoxide (TATP), but both peroxide–based energetics and nitroaromatic energetics are potential environmental pollutants due to their contamination of soil, surface and groundwater after explosions. Thus, selective determination of trace amounts of these substances has become important. In this context, determination of nitroaromatic energetics TNT and TNP, and peroxide–based energetic TATP by carbon quantum dot based fluorescence nanoprobes was carried out within the scope of the thesis. In the first part of the thesis, surface nitrogen–doped carbon quantum dots (A–KKN) were used as fluorescence nanoprobes in the determination of nitroaromatic energetic TNT. The fluorescence emission of A–KKN was quenched by the dominant dynamic quenching mechanism supported by charge–transfer interaction only in the presence of TNT among different energetics. The detection limit of the highly sensitive method was calculated as 30 nmol L-1. In the second part of the thesis, surface heteroatom–doped carbon quantum dots (HA–KKN) were developed for the simultaneous fluorometric and colorimetric determination of another nitroaromatic energetic, TNP. The blue fluorescence of HA–KKN was quenched in the presence of TNP by the inner filter effect (IFE) mechanism and hydrogen–bonding interaction, and fluorometric signals were obtained. In addition, HA–KKN and TNP formed an orange complex, different from the characteristic yellow color of TNP, by hydrogen–bonding and charge–transfer interactions, and this allowed the production of colorimetric signals simultaneously with the fluorometric signals. In the selective determination method, the limits of determination for fluorometric and colorimetric parts were found to be 12.5 picomol L-1 and 0.9 nmol L-1, respectively. In the third and last part of the thesis, the simultaneous fluorometric and colorimetric determination of the peroxide–based explosive TATP was carried out via the Fenton–type reaction in the presence of oxygen– and nitrogen–doped carbon quantum dots (OA–KKN). Analytical determinations were carried out on the products formed as a result of the Fenton–type reaction in the method where all reagents were in the same environment. The detection limit of the method, which utilizes the catalytic activity of OA–KKN as well as the fluorescence nanoprobe, is 3 nmol L-1 for fluorometric part and 0.01 µmol L-1 for colorimetric part.