This thesis has been conducted within the field of study of supramolecular chemistry and is based on the synthesis of macrocyclic receptors with 1H-pyrazol units. The 1H-pyrazol units are able to form coordination bonds with metal cations and they can form also hydrogen bonds with anionic species. These receptors form stable complexes with metal cations and anionic complexes due the formation of intermolecular hydrogen bonds between the protonated amine groups and the anionic species. The objectives for the realization of this thesis are: - Synthesis and characterization of macrocyclic poliamines with 1H-pyrazole units L1-L7. - Study of the fluorescent receptor L1 and L2 as chromogenic and fluorogenic sensors of transition metal cations in aqueous solution. - Study of the interaction of receptor L3 with environmental pollutants anions and transition metals. - Study of complex formation of Cu (II) with the L4-L7 receptors. The receptors L1 and L2 are functionalized with two fluorescent groups, methylnaphthalene or dansyl, and two spacer units of 1H-pyrazole. Fluorescent groups allow the recognition of metal cations in solution. This is because the coordination of the receptor with the metal produce changes in the fluorescence emission of the fluorophores groups. With the receptor L1 we have studied the formation of metal complexes with different metals cations such as Cu(II), Zn(II) and Cd(II). Coordination with Zn(II) cations results in the formation of an intense intramolecular excimer between naphthalene units with a fluorescence emission band centred at 393 nm. The detection limit of Zn (II) in aqueous solution is 9 ppb. The fluorescence emission of receptor L2 decreases due to the coordination of metal cations. Has been studied the coordination with Cu(II) with which the fluorescence emission decreases by 50% by adding one equivalent of metal. The detection limit of Cu (II) in aqueous solution is 10 ppb. The receptor L3 is a cryptand type macrocycle containing 3 units of 1H-pyrazole. The formation of anionic complexes with environmental pollutants anions such as oxyanions, nitrate, phosphate, sulphate, perchlorate, chromate, arsenate and perrhenate, and halide anions, fluoride, chloride and bromide, have been studied. In all cases the anionic complexes are stabilized by the formation of hydrogen bonds between the protonated amines of the receptor and the anions. We also studied the coordination of metal cations such as Mn(II), Ni(II), Cu(II), Zn(II) and Pd(II). They were obtained crystal structures of mononuclear and binuclear complexes. It has also solved the structure of a dimeric hexanuclear complex and a helical polymer with Cu (II) at low pH. L4-L7 has been studied the complexation of Cu(II) and the formation of binuclear [2+1] and dimeric tetranuclear complex [4+2] at neutral and basic pH which depend on the concentration of the receptor. The [4+2] complexes have a metalocage structure. It has studied the formation at acidic pH values of trimeric hexanuclear complexes [6+3] which have a metalocage structure. We also studied the formation of coordination polymers at pH 1.5. Finally we have studied the encapsulation of different substrates, as solvents and anionic species, within metalocages [4+2] and [6+3] and their capability to adapt the macrocyclic cavity to the size and shape of the substrates.
2016-01-29
