Resumen de Macrocyclic chemistry. From anion recognition to the reactivity of their copper complexes
Macrocyclic ligands have been used in a wide variety of fields such as anion recognition or coordinated to metal ions as biomimetic systems. In this context, the behaviour of different polyazamacrocyclic compounds in different conditions is reported in this thesis, paying special attention on how small variations of the ligand lead to different behaviour of the compound.
On one hand, it is reported the host-guest interaction of the hexaazamacrocyclic ligand L9 towards three different aromatic dicarboxylic acids, varying in the relative disposition of the acid groups: terephthalic acid (te), isophthalic acid (is) and phthalic acid (ph). The interaction between the receptor and the substrates has been studied by means of potentiometric titrations, HRMN studies and computational calculations. It has been observed that the strength of the L-S interaction increases with the order L9:is > L9:ph > L9:te. This is in contrast with the behaviour of the similar ligand L12 with these substrates, as it is presented in the literature. Indeed, the methylation of the central amines of the ligand lead to a decrease and to a change of the order of the selectivity for the substrates, being the most stable the complex of the L12 receptor, the complex with the terephthalic acid L12:te.
On the other hand, it has been synthesised a new family of imine macrocyclic ligands with pyridyl pendant arms, through a 2+2 condensation of an aromatic dialdehyde and a pendant arm triamine.
The ligands of the family differ in the geometry of the aromatic spacer (meta or para) as well as in the length of the aliphatic spacers (two or three methylenes).
Within this family, the macrocyclic ligand with meta geometry and spacer of 2 methylenic units (bsm2py) undergoes a ring expansion when complexed with Cu(I) in acetonitrile solution, obtaining the trinuclear complex of the 3+3 ligand, in contrast with the other three pendant arm imine macrocyclic ligands of the family (bsp3py, bsm3py and bsp2py), which do not perform any ligand expansion in presence of Cu(I). In order to study this backbone rearrangement, two analogous ligands to bsm2py but with different pendant arms have been synthesised, one bearing a phenol group (bsm2phOH) and another bearing an ethyl group (bsm2Et), all of them undergo ring expansion when complexed with Cu(I) in acetonitrile, as shown by mass studies and X-ray structures of the obtained complexes. The ligand rearrangement of these ligands with pendant arms (bsm2py, bsm2phOH and bsm2Et) is in sharp contrast with the analogous imine macrocyclic ligand without pendant arms bsM2 described in the literature, which does not undergo any ligand rearrangement when complexed with Cu(I).
The dinuclear Cu(I) complexes with the ligands bsp3py, bsm3py and bsp2py have been synthesized and fully characterized, and their nuclease activity has been studied by means of Electrophoresis Mobility in Agarose Gel, Circular Dichroism spectroscopy and Atomic Force Microscopy. All complexes interact with DNA and produce nicking in presence of H2O2, clearly being the complex with the ligand bsp2py the one with less activity. The interaction mode of the complexes with DNA is non intercalative in all three cases as evidenced by CD spectroscopy. In absence of H2O2 the order of the complexes interaction with DNA is [Cu2(bsp3py)]2+ > [Cu2(bsm3py)]2+ > [Cu2(bsp2py)]2+, while with H2O2, the nuclease activity of the complexes follows the order [Cu2(bsm3py)]2+ > [Cu2(bsp3py)]2+ > [Cu2(bsp2py)]2+. The difference in reactivity among the complexes can be associated with the properties of the products, both electronic and geometric
