This critical review describes some developments on the chemistry of fluorescent and colorimetric molecular probes or chemosensors, based on polyamines and associated compounds having oxygen and/or sulfur as donor atoms. The reported systems are essentially based on some selected published work in this field in the last five years, and in the work developed by the authors from 2000 onwards. Some interesting properties beyond sensing molecules, ions or/and cations by fluorescence, colorimetry as well as by MALDI-TOF MS spectrometry can arise from these systems. A short brief on different examples activated by PET (photoinduced electron transfer), ICT (internal charge transfer) and EET (electronic energy transfer) phenomena will be provided. Finally the introduction of bio-inspired compounds derived from emissive amino acid or short peptide systems and nanoparticle devices to detect metal ions will be reviewed (202 references).

Pyridine-functionalized β-diketone ligands of the type 1-(2-pyridyl)-3-(4-n-alkyloxyphenyl)propane-1,3-dione [HL^R(n)py] (R = C₆H₄OC_nH_{2n  + 1}, n = 12 (1), 14 (2)) were carried to react with the BF₂ fragment giving rise to the corresponding adducts [BF₂(L^R(n)py)] (n = 12 (5), 14 (6)) which were characterized and their luminescent and thermal behaviour studied. All the ligands and boron derivatives are photoluminescent both in the solid state and in solution. The related compounds 2-[3-(4-n-alkyloxyphenyl)propane-1,3-dion-1-yl]pyridinium chloride [HL^R(n)pyH]Cl (n = 12 (3), 14 (4)) were also proved to have luminescent properties. On the other hand the organometallic compounds [Pd(η³-C₃H₅)(HL^R(14)py)][PF₆] (7) and [Pd(η³-C₃H₅)(L^R(14)pyH)][PF₆] (8), based on the coordination of the [Pd(η³-C₃H₅)]⁺ fragment to the above neutral 2 or ionic 4β-diketone derivatives, respectively, were also established to be luminescent materials, compound 8 exhibiting liquid crystalline properties. The luminescent behaviour of all compounds was also investigated as a function of the metal addition of Zn²⁺ and Cu²⁺ ions. As a result it is proven that the free β-diketone pyridine ligands [HL^R(n)py], the related chloride salts [HL^R(n)pyH]Cl and their palladium(II) complexes behave as fluorescence chemosensors for Zn²⁺ and Cu²⁺. The luminescent behaviour of the allyl-palladium complex 8, which exhibits enantiotropic liquid crystalline properties, was also studied as a function of the temperature. As a consequence it is established that the liquid crystal state does not quench the fluorescence emission.