Síntesis de hidrazidas e hidrazonas, estudio fotoquímico y aplicación a sistemas dendriméricos

Resumen

In this doctoral thesis I present the results of the influence of the structural modifications of some acyl hydrazones in their photophysical and photochemical properties. We present in this work the synthesis of different structures with differents aromatics rings as pyridine, pyrrole or benzene. Also, differents kinds of acyl hydrazones where structural modifications affect to the photoactive core have been synthesized. In the same way were prepared hydrazones with different capacity of coordination with metallic cations, incorporating in their structures 2 or 3 coordination sites. The photophysical properties of the hydrazones have been evaluated, showing that every acyl hydrazones but 15 (possessing a pyrrole ring) have the ability of coordinating with metallic cations, especially with magnesium. The emission intensity of these acyl hydrazones is increased by the presence of magnesium in the medium with the exception of 16 and 17 that are not affected by the presence of magnesium. The acyl hydrazone 11 undergoes E/Z isomerization via photochemical activation. The E configuration is locked by the presence of magnesium cation. Compound 11 (Z) is stable, in both solid and in solution, without thermal back conversion to E isomer. The E isomer is observed when compound 11 (Z) is irradiated in basic media. Once studied the properties of these hydrazones, we considered the construction of supramolecular structures in which this functional group is included. A molecule with two acyl hydrazones in their structure have been prepared (compound 28), capable of binding with organic molecules like barbituric acid through hydrogen bonds. Additionally, a ruthenium complex in which have been included the acyl hydrazone previously prepared have been synthesized (compound 29). The photophysical and photochemical properties of compound 28 have been studied. Also, the possibility of energy/electron transfer between ruthenium complex and organic molecules with substituents that can be photoactive or electroactive, as fullerene, have been evaluated. A dendrimeric core (compound 65), that possesses an acyl hydrazone have been prepared. In this way, the spatial configuration of the dendrimer via E/Z photoisomerization can be controlled. Also, the dendrimeric core can act as host for cations and other organic molecules, that can be retained or released upon irradiation.