The second series of BUs investigated here consists of BU derivatives with para-functionalized benzyl substituents. Herein, BUs 7, 9, 10 and 12 have been previously reported as anion receptors. Moreover, BU 7 was also shown to be an effective anionophore. The -SCF3 group in BU 7 was replaced by -CF3 and -OCF3 groups to obtain BUs 6 and 8, respectively. It is anticipated that this alternation will result in a variation in lipophilicity and anion binding strength when compared to BU 7. BU 11 was synthesised for comparison to 10, with an additional oxygen atom placed in between the -SO2CF3 group and the benzyl substituent, resulting in a -OSO2CF3 group. This variation is predicted to lead to a reduction in anion binding strength according to the σp Hammett substituent parameter (Table ) and calculated electrostatic potential map (Figure ). BU 12 serves as a non-fluorinated analogue of 11.