Considering that 5-nitrofurfual is potentially the antibacterial agent in nitrofurantoin and its above derivatives thereof, the other essential constituent of this associative heterodimer is mainly the InC fragment. To this end, it was deemed worthwhile to eliminate the problematic spacer from this series of prospective heterodimers in order to evaluate bioactivities of the two set of fragments, namely, 4 and 10, separately (Fig. ).