Conical-Intersection Topographies Suggest That Ribose Exhibits Enhanced UV Photostability.
Conical-Intersection Topographies Suggest That Ribose Exhibits Enhanced UV Photostability.
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DOI：
10.1021/acs.jpcb.6b09048
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发表时间：
2016-10
期刊：
影响因子：
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通讯作者：
D. Tuna;A. Sobolewski;W. Domcke
中科院分区：
文献类型：
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作者：
D. Tuna;A. Sobolewski;W. Domcke
碳水化合物是生命的重要组成部分，在地球上发现的所有生物体中承担多种生物功能。最近有报道称，在紫外线照射的星际冰类似物中发现了核糖，这表明它可以在彗星上找到，并且可能通过彗星的撞击被运送到地球。在这里，我们提出了用多构型从头算量子化学方法获得的计算结果，表明无辐射失活的各种光化学过程可用于光激发核糖。这些过程由 nσ* 态驱动，涉及 O-H- 或环内或环外 C-O-键伸长，从而与电子基态形成圆锥形交叉。这些圆锥形交叉点周围势能表面的局部形貌表明，这些交叉点介导有效的无辐射失活，并有利于最初光激发基态反应物的再生。这些发现表明，在星际空间中发现的核糖在紫外星光照射下预计具有高度的光稳定性，这可能在天体生物学领域具有重要意义。
Carbohydrates are essential building blocks of life that assume a multitude of biological functions in all living organisms found on Earth. It was recently reported that ribose was identified in UV-irradiated interstellar ice analogs, which suggests that it can be found on comets and that it may have been transported to Earth via the impact of comets. Herein, we present computational results obtained with multiconfigurational ab initio quantum-chemical methods showing that various photochemical processes for radiationless deactivation are available for photoexcited ribose. These processes are driven by nσ* states and involve either O-H- or endocyclic or exocyclic C-O-bond elongation whereby a conical intersection with the electronic ground state becomes accessible. The local topography of the potential-energy surfaces around these conical intersections suggests that these intersections mediate efficient radiationless deactivation and favor regeneration of the initially photoexcited ground-state reactant. These findings indicate that ribose found in interstellar space can be expected to be highly photostable upon irradiation with UV starlight, which could be of relevance in the field of astrobiology.