Final Report Summary - SCIIPT (Shaping Conical Intersections for Intramolecular Proton Transfer)
Project context and objectives
The objective of the project was to analyse the role of conical intersection (CI) seams in photochemical processes. As we have already highlighted in the mid-term report, we decided to postpone the study of intramolecular proton transfer because it is now known that there are three states involved in the mechanism (and hence a three-state conical intersection). Instead, we decided to focus on a problem in which there are just two states involved, but multiple coordinates, to test and experiment with a new code developed by our group to analyse conical intersection seams at the second order (F. Sicilia et al., J Chem Theory Comput., 2008, 4, 257). Such a problem is, indeed, very important in industry for chemical synthesis: photocycloadditions, specifically ethene+ethene and benzene+ethene, and to investigate substituent effects.
Project tasks
During the project, first we have analysed the ethene+ethane model system as a benchmark and for training on how to use the new code (now published in J.J. Serrano-Perez, DOI: 10.1080/00268976.2012.698757).In addition, the use of valence-bond (VB) theory helped us to understand the origin of the crossing seam that promotes decay of the excited state in this system. This knowledge proved invaluable for addressing the more complex benzene+ethene system, in which not only the seam proved to be important, but also the connections among multiple structures in both the excited and ground states. Specifically, we were forced to use non-standard techniques in order to obtain a picture of the photochemical panorama of this transformation (paper accepted by J. Org. Chem.) and to understand the origin of the products obtained experimentally. Finally, a study on the photocycloaddition of benzene with substituted alkenes is ongoing.
Project results and outcomes
These photochemical studies have enlightened the role of CI seams in photochemical mechanisms. Interaction of light with tissues or, in general, living or non-living entities, is a complex phenomenon which lies on the borders of physics, chemistry and biology and leads to many developments: understanding the effects of electromagnetic radiation on living tissues (DNA alteration, phototherapy, etc.), designing light-harvesting systems for clean and sustainable energy generation, photocatalysis and the design of efficient light-driven molecular devices for data storage and processing, and photoactive materials with particular chemical, biological, energy or information storage properties. Analysing spectroscopic phenomena at the molecular level provides information that may well be the source of interesting advances in the future. By learning how to design molecules that interact with light predictably, work of this type provides essential knowledge for the development of chemical engineering, nanotechnology, materials science and/or photobiology.
Following the grant application, the fellow has been involved in additional research projects, teaching duties, courses to develop the skills needed to become a senior researcher in the future, and supervision of visiting students.
The objective of the project was to analyse the role of conical intersection (CI) seams in photochemical processes. As we have already highlighted in the mid-term report, we decided to postpone the study of intramolecular proton transfer because it is now known that there are three states involved in the mechanism (and hence a three-state conical intersection). Instead, we decided to focus on a problem in which there are just two states involved, but multiple coordinates, to test and experiment with a new code developed by our group to analyse conical intersection seams at the second order (F. Sicilia et al., J Chem Theory Comput., 2008, 4, 257). Such a problem is, indeed, very important in industry for chemical synthesis: photocycloadditions, specifically ethene+ethene and benzene+ethene, and to investigate substituent effects.
Project tasks
During the project, first we have analysed the ethene+ethane model system as a benchmark and for training on how to use the new code (now published in J.J. Serrano-Perez, DOI: 10.1080/00268976.2012.698757).In addition, the use of valence-bond (VB) theory helped us to understand the origin of the crossing seam that promotes decay of the excited state in this system. This knowledge proved invaluable for addressing the more complex benzene+ethene system, in which not only the seam proved to be important, but also the connections among multiple structures in both the excited and ground states. Specifically, we were forced to use non-standard techniques in order to obtain a picture of the photochemical panorama of this transformation (paper accepted by J. Org. Chem.) and to understand the origin of the products obtained experimentally. Finally, a study on the photocycloaddition of benzene with substituted alkenes is ongoing.
Project results and outcomes
These photochemical studies have enlightened the role of CI seams in photochemical mechanisms. Interaction of light with tissues or, in general, living or non-living entities, is a complex phenomenon which lies on the borders of physics, chemistry and biology and leads to many developments: understanding the effects of electromagnetic radiation on living tissues (DNA alteration, phototherapy, etc.), designing light-harvesting systems for clean and sustainable energy generation, photocatalysis and the design of efficient light-driven molecular devices for data storage and processing, and photoactive materials with particular chemical, biological, energy or information storage properties. Analysing spectroscopic phenomena at the molecular level provides information that may well be the source of interesting advances in the future. By learning how to design molecules that interact with light predictably, work of this type provides essential knowledge for the development of chemical engineering, nanotechnology, materials science and/or photobiology.
Following the grant application, the fellow has been involved in additional research projects, teaching duties, courses to develop the skills needed to become a senior researcher in the future, and supervision of visiting students.
