## 4 Synthesis/Applications of Organo-Fluorine Molecules
The article entitled: _Computational Study on the Acid Catalyzed Reactions of Fluorine-Containing 2,4-Dialkoxy-3,4-dihydro-2H-pyrans with Aromatic Compounds_ by [PERSON] [17] and coworkers illustrated that the predicted product outcomes from DFT calculations were consistent with the experimental data and mechanistic pathways to products when fluorinated dihydropyrans were reacted with aromatics. Fluorine-18, widely used in clinical positron emission tomography (PET) imaging in biomedical science because its optimal physical decay properties (**t**1/2 = 110 min, **E\({}_{\text{\#+, max}}\)** = 0.6 MeV) facilitates multistep syntheses and PET images of high quality. [PERSON] and coworkers [18] in their review _Silicon-[18]F Fluorine Radiochemistry: Basics, Applications and Challenges_ describe the radiochemical science surrounding Si-\({}^{18}\)F bond synthesis, the application of Si-\({}^{18}\)F tracers for PET imaging and some of the remaining challenges regarding the optimization/balance of the _in vivo_ physic-chemical properties of these radiochemicals in relation to their stability and biodistribution. The increased application of \({}^{18}\)F Fluoro-click-bioconjugation to the variety of bio-scaffolds employed, promises to be an effective strategy able to counter balance the high lipophilicity-hydrophilicity nature of the radiochemical carriers, thereby enhancing target visualization via PET with only minute retention of radioactivity in other tissues and organs. One of the most significant classes of synthetic antibacterial are fluoro-quinolone antibiotics. The article: _A Study of Fluorinated \(\beta\)-Nitrostyrenes as Antimicrobial Agents_ by [PERSON] _et al_. [19] examined the effect of the presence of fluorine functionalities in \(\beta\)-methyl-\(\beta\)-nitrostyrenes on their antimicrobial activity. The MIC values confirmed that fluorinated \(\beta\)-methyl-\(\beta\)-nitrostyrenes had the highest antimicrobial activity against Gram negative, Gram positive bacteria and the fungus _C. albicans_. However the correlations between MIC and K\({}_{\text{D}}\) [logP] values were not straightforward. Similarly it was also difficult to correlate the position of fluorine substitution on the benzene ring or the effect of multiple fluorine substituents with antibacterial activity and logP values. Can aromatic ring fluorine/hydrogen exchange influence membrane permeability? Generally, aromatic F/H substitution tends to increase compound lipophilicity, in direct contrast to what was observed. Alternatively, the reason for the effectiveness of fluorine substitution on the aromatic ring may be connected with the high electronegativity of fluorine, although size factors could also be important. Perhaps the electronegativity of fluorine could affect binding affinity to the binding site of the bacteria, thus causing inhibition of the enzyme. Further investigations with other fluorine-substitutedcompounds to determine the structural features required for the optimal anti-bacterial activity of \(\beta\)-methyl-\(\beta\)-nitrostyrene compounds, and where the activity occurs, are currently being carried out.