## 3 Results
### UV-Vis Absorption and Fluorescence Properties
We can conclude that, to achieve maximum emission intensity, a high fraction of water (\(f_{\rm w}\) = 80-90%) is required. The addition of a water fraction (0-90%) to THF solution strongly influences the emission properties of these compounds with respect to peak position and peak intensities (Figure 3D). From fluorescence emission, it can be clearly seen that steady increment of the fluorescent intensity was observed up to 90% water content, with red-shifted peak intensity. However, with a further increase of the water fraction >98%, a decrease in intensity was observed, which is due to the larger aggregates and precipitation of self-assembled structures from the solution, as resulting in only a small amount of AIGs being involved in emission. The comparative investigation of emission properties in THF/water clearly suggested that the compound structures **TPE-Se**, **TPE-Az**, **TPE-Su** and **TPE-Pi** are dramatically affected in \(f_{\rm w}\) = 90%. These results clearly demonstrate that the phenyl ring of TPE around the alkyl chains is restricted in the aggregated state due to the restricted intramolecular rotation (RIR), the mechanism model for the aggregation-induced emission (AIE) phenomenon. The bulky TPE moieties impair the intermolecular \(\pi\)-\(\pi\) stacking. Thus, the increased FL intensity upon aggregation in higher water content compared to in the dilute THF solutions is because the mechanism for consuming the excitation energy is switched out, similar to earlier report by [PERSON] group [10]. Figure 2: The UV-Vis absorption spectra of **TPE-Se**, **TPE-Az**, **TPE-Su** and **TPE-Pi** (10 \(\upmu\)M). In order to elucidate the aggregation behaviour of **TPE-Se**, **TPE-Az**, **TPE-Su** and **TPE-Pi** in THF/water, as well as the effect of the number of carbons in the alkyl chains on assembly, SEM studies in the presence of various fractions of water/THF were undertaken to observe the morphology of aggregates produced from **TPE-Se**, **TPE-Az**, **TPE-Su** and **TPE-Pi**, and images are shown in Figure 4 and Figure S2. Figure 4A shows the morphology produced from **TPE-Pi** aggregation in a THF/water mixture with the water fraction at 80%. It can be clearly seen that, under these conditions, the **TPE-Pi** (with an odd number of carbons in the alkyl chain of 7) assembled into well-defined nanospheres, with diameters in the range of 200-1000 nm. A further increase in the water fraction (\(f_{\rm w}=90\%\)) led to the collapse of the nanospheres into nanobeads, as shown in ESI Figure S3A. When the odd alkyl chains in the TPE compound was increased to 9 (**TPE-Az**), the morphology of the aggregates in the THF/H\({}_{2}\)O are remained as spheres, ranging in diameter from 50-500 nm with \(f_{\rm w}=80\%\) (Figure 4B) and nanobeads with \(f_{\rm w}=90\%\) (ESI Figure S3B). Interestingly, when the number of carbons in the alkyl chains of the compound are even (**TPE-Su** with 8 alkyl carbons and **TPE-Se** with 10 carbons), different morphologies were observed. With the alkyl chain of 8 carbons, microbelts with a width of 5 \(\upmu\)m and a length of a hundred \(\upmu\)m were obtained when the **TPE-Su** was assembled at \(f_{\rm w}=80\%\) (Figure 4C). However, similar to **TPE-Az** and **TPE-Pi**, only **TPE-Su** nanobeads were observed upon further addition of water (\(f_{\rm w}=90\%\)) (ESI Figure S3C). With an alkyl chain of 10 carbons, we recently reported the morphologies of dumbbell shaped **TPE-Se** in THF/water at different water fractions [34]. Herein, at \(f_{\rm w}=80\%\), self-assembly of **TPE-Se** led to flower-like aggregates several micrometers in diameter (Figure 4D). These microflowers were composed of several fractal nanostructures grown from the centre of the flower.