## 3 Results and Discussion
### Fluorescence Spectra Behaviour of Cimnamaldehyde (CAD) in SDS-Ethanol Media  
Cimnamaldehyde (CAD + ethanol + SDS) exhibits the maximum fluorescence emission at 310 nm. The maximum emission was shown between 300-400 nm for SDS in ethanol + CAD. The study was further inferred by utilizing specified sets of parameters, such as to investigate the fluorescence intensities in a region before and after micellization [30]. The pre-micellar region of SDS with varying concentration in CAD + ethanol was inferred as depicted in Figure 4. In addition, it was observed that after a certain point i.e., 0.012 m concentration of SDS with CAD in ethanol, a linear decrease in fluorescence intensity with decreasing concentrations was attained. The observed results are believed to be due to the presence of more SDS monomers in the surfactant micellar system which further modifies monomer interactions in aggregates, thereby alter the fluorescence intensities in the premicellar and postmicellar region. In premicellar region, CAD molecules possibly interact onto the surface of SDS via hydrogen bonding between the head group of SDS and substitute (H-C=O) groups of CAD molecules resulting in aggregates rather than micelles. In other words, with an increase in the concentration of SDS molecules to CAD in an ethanol solution, more aggregates are possibly formed leading to increase in fluorescence intensities up to a concentration i.e., critical micellar concentrations (CMC). In addition, at the micellar region a sudden jump was observed in fluorescence intensity, leading to a constant decrease in fluorescence intensities, with an increase in the concentration of SDS with CAD in ethanol media. However, in the post-micellar concentration another rearrangement occurs between the SDS monomers and drug molecules in ethanol media. The maximum fluorescence intensity was observed at 0.019 m concentration in the post-micellar region as depicted in Figure 5. Micellar systems consisting of a surfactant and an additive such as an organic compound usually self-organize as a series of worm-like micelles that ultimately form a micellar network. The nature of the additive influences micellar structure and properties such as aggregate lifetime. CAD molecules show \(\pi\)-\(\pi\) stacking interaction that somewhat segregates into SDS micelle at higher micellar concentrations [29; 30]. It is believed that at higher micellar concentrations, the hydrogen bonding forces onto the surface between CAD and SDS monomers become more favorable and organize as micelle assemblies in comparison to the sole structural forces of the solvent i.e., ethanol molecules. In addition, the hydrophilic counterpart of the CAD molecules does not intervene in the micellar growth. Therefore, the fluorescence quenching of SDS with the cinnaldehyde is mainly achieved by photo-excited electron transfer between the micelles of SDS and cinnamaldehyde molecules, and the process is thermodynamically feasible with a \(\Delta G\) value of \(-4.30\)\(\times\)\(10^{4}\) kcal mol\({}^{-1}\). The maximum fluorescence intensity of SDS is quenched gradually with the cinnamaldehyde in ethanol and the quenching efficiency of CAD can be finely fitted with the Stern-Volmer equation. Fluorescence measurement offers the information about the binding process during the self-aggregation process of SDS in the CAD-ethanol system. The fluorescence spectra of the observed pre- and post-micellar regions are shown in Figures 4 and 5 at maximum fluorescence excitation (\(\Lambda_{\text{ex}}\) 295 nm). The fluorescence intensities increase in the pre-micellar region whereas with the increase of SDS concentration the intensities decrease steeply resulting in the fluorescence quenching. Quenching can appear as a result of micellization depicting the role of hydrophobic interaction in the binding of molecules with the micelles. Fluorescence quenching is the decrease of the quantum yield of fluorescence from a fluorophore induced by a variety of molecular interactions with quencher molecules [31].