Affiliation:
1. Departamento de Química Universidad Autónoma de Madrid C/Francisco Tomás y Valiente 7 28049 Madrid Spain
2. Department of Chemistry Case Western Reserve University 44106 Cleveland OH USA
Abstract
AbstractIt is intriguing how a mixture of organic molecules survived the prebiotic UV fluxes and evolved into the actual genetic building blocks. Scientists are trying to shed light on this issue by synthesizing nucleic acid monomers and their analogues under prebiotic Era‐like conditions and by exploring their excited state dynamics. To further add to this important body of knowledge, this study discloses new insights into the photophysical properties of protonated isoguanine, an isomorph of guanine, using steady‐state and femtosecond broadband transient absorption spectroscopies, and quantum mechanical calculations. Protonated isoguanine decays in ultrafast time scales following 292 nm excitation, consistently with the barrierless paths connecting the bright S1 (ππ*) state with different internal conversion funnels. Complementary calculations for neutral isoguanine predict similar photophysical properties. These results demonstrate that protonated isoguanine can be considered photostable in contrast to protonated guanine, which exhibits 40‐fold longer excited state lifetimes.
Funder
National Science Foundation
Ministerio de Ciencia, Innovación y Universidades
Ministerio de Ciencia e Innovación
Comunidad de Madrid
Subject
General Chemistry,Catalysis,Organic Chemistry