Liam Wrigley, Doyk Hwang, Sebastian V. Pios, Cody W. Schlenker
{"title":"Optically Gated Dissociation of a Heptazinyl Radical Liberates H• through a Reactive πσ* State","authors":"Liam Wrigley, Doyk Hwang, Sebastian V. Pios, Cody W. Schlenker","doi":"10.1021/acsphyschemau.4c00030","DOIUrl":null,"url":null,"abstract":"Using trianisole heptazine (TAHz) as a monomeric analogue for carbon nitride, we performed ultrafast pump–photolysis–probe transient absorption (TA) spectroscopy on the intermediate TAHzH<sup>•</sup> heptazinyl radical produced from an excited state PCET reaction with 4-methoxyphenol (MeOPhOH). Our results demonstrate an optically gated photolysis that releases H<sup>•</sup> and regenerates ground state TAHz. The TAHzH<sup>•</sup> radical signature at 520 nm had a lifetime of 7.0 ps, and its photodissociation by the photolysis pulse is clearly demonstrated by the ground state bleach recovery of the closed-shell neutral TAHz. This behavior has been previously predicted as evidence of a dissociative πσ* state. For the first time, we experimentally demonstrate photolysis of the TAHzH<sup>•</sup> heptazinyl radical through a repulsive πσ* state. This is a critical feature of the proposed reaction mechanisms involving water oxidation and CO<sub>2</sub> reduction.","PeriodicalId":29796,"journal":{"name":"ACS Physical Chemistry Au","volume":"25 1","pages":""},"PeriodicalIF":3.7000,"publicationDate":"2024-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"ACS Physical Chemistry Au","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.1021/acsphyschemau.4c00030","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"CHEMISTRY, PHYSICAL","Score":null,"Total":0}
引用次数: 0
Abstract
Using trianisole heptazine (TAHz) as a monomeric analogue for carbon nitride, we performed ultrafast pump–photolysis–probe transient absorption (TA) spectroscopy on the intermediate TAHzH• heptazinyl radical produced from an excited state PCET reaction with 4-methoxyphenol (MeOPhOH). Our results demonstrate an optically gated photolysis that releases H• and regenerates ground state TAHz. The TAHzH• radical signature at 520 nm had a lifetime of 7.0 ps, and its photodissociation by the photolysis pulse is clearly demonstrated by the ground state bleach recovery of the closed-shell neutral TAHz. This behavior has been previously predicted as evidence of a dissociative πσ* state. For the first time, we experimentally demonstrate photolysis of the TAHzH• heptazinyl radical through a repulsive πσ* state. This is a critical feature of the proposed reaction mechanisms involving water oxidation and CO2 reduction.
期刊介绍:
ACS Physical Chemistry Au is an open access journal which publishes original fundamental and applied research on all aspects of physical chemistry. The journal publishes new and original experimental computational and theoretical research of interest to physical chemists biophysical chemists chemical physicists physicists material scientists and engineers. An essential criterion for acceptance is that the manuscript provides new physical insight or develops new tools and methods of general interest. Some major topical areas include:Molecules Clusters and Aerosols; Biophysics Biomaterials Liquids and Soft Matter; Energy Materials and Catalysis