The new ligands (E)-4-[2-(4-(N-methyl-N-hexadecylaminophenyl)ethenyl]pyridine (L 1 ) and 4′-(C 6 H 4 -p-N(Me)(hexadecyl))-2,2′:6′,2″-terpyridine (L 2 ) were prepared along with their complexes [cis-Ir(CO) 2 ClL 1 ], [fac-Os(CO) 3 Cl 2 L 1 ], [ZnCl 2 L 2 ] and [IrCl 3 L 2 ]. Whereas these complexes show a large second-order nonlinear optical (NLO) response at the molecular level, similar to that of related organic alkylated salts as evidenced by the Electric Field Induced Second-Harmonic (EFISH) generation technique, their Langmuir–Blodgett (LB) film susceptibility is lower than that of the salts.