Antifouling Properties of N,N′-Dialkylated Tetraazamacrocyclic Polyamines and Their Metal Complexes

The prevention of biofouling (biological fouling) became a major economic and environmental issue. In the present study, we designed a series of four cyclam and cyclen derivatives with a modulation of their lipophilicity by introducing either two benzyl (Bn) groups or two tetradecyl (C₁₄) chains in the structure to produce (Cyclam(Bn)₂, Cyclam(C₁₄)₂, Cyclen(Bn)₂ and Cyclen(C₁₄)₂). Additionally, copper (Cu) and zinc (Zn) complexes of each compound were prepared and evaluated as potential antifouling candidates against two models of <i>Vibrio</i> species (<i>V. natriegens</i> and <i>V. aestuarianus</i>). The results highlight that no significant antifouling activity was measured for the metal free polyazamacrocyclic derivatives. However, for the metal complexes, the nature of the cation (Cu²⁺ or Zn²⁺) modulates both the growth and adhesion capacities of the two bacteria. Overall, in most cases, Zn complexes showed better activity than the Cu complexes, revealing the importance of the metal cation. Moreover, in the cyclam series, the anti-adhesion properties could be linked to a biocidal effect while a full anti-adhesion activity was observed in the cyclen series.