| Popis: |
The natural RNA and DNA nucleobases absorb ultraviolet radiation, in such quantities to fragment or dissociate typical organic chemical bonds, nevertheless, the capacity to dissipate this excess electronic energy efficiently to the ground state renders them highly photostable. Understanding how deliberate structural modifications on the pyrimidine and purine chromophores, affect their photochemical properties is critical for gaining better insight on the chemical evolution of life as well as advancement in biological applications and medicinal therapeutics. The ubiquitous presence of the purine chromophore and its canonical substituents, make it an exceptional candidate to investigate why nature settled upon five RNA/DNA building blocks to encode genetic material and life. Likewise, it can give insights on how to conceivably expand the genetic code for advancements in biotechnology. Notwithstanding, when aiming to expand the genetic alphabet, mitigating adverse effects is of paramount concern. This includes its participation in unintended photochemistry. Fundamental investigations using time-resolved spectroscopic techniques, complemented with quantum chemical calculations, will be presented within this dissertation work, with emphasis on the influence of the16imidazole ring, in combination with the C2 and C6 positions that govern the photophysical and photochemical properties of purine derivatives. The ambition of this research is to ultimately create a set of design guidelines that allow molecules to be synthesized for a specific application where following absorption of light ultrafast nonradiative decay, high fluorescence, or population of long-lived excited states may be tuned on-demand. |
