The synthesis of new phthalocyanine iron(ii) (FePc) based coordination complexes , their structural characterization by multinuclear NMR ((1)H, (13)C, (15)N, (31)P, (57)Fe), and their use as improved sensitive and cheap optical NO(2) sensors is described. delta((15)N) and delta((57)Fe) values obtained via HMQC NMR methods show an interesting trend, the larger the chemical shift value the more the selectivity towards NO(2). Among all the sensing films prepared, the novel mixed ligand phosphite-amine [FePc(benzylamine)(P(OEt)(3)] () immobilized into AP200/19 showed the best sensitivity, reversibility (LOD and LOQ of 1.2 ppb and 4.0 ppb, respectively), and thermostability in the range of 4 to 25 degrees C.