@article{ee3f757ba2994afaaffe09c5c127c416,
title = "Tuning the UV spectrum of PAHs by means of different N-doping types taking pyrene as paradigmatic example: categorizationviavalence bond theory and high-level computational approaches: Categorization: Via valence bond theory and high-level computational approaches",
abstract = "Tuning of the electronic spectra of carbon dots by means of inserting heteroatoms into the π-conjugated polycyclic aromatic hydrocarbon (PAH) system is a popular tool to achieve a broad range of absorption and emission frequencies. Especially nitrogen atoms have been used successfully for that purpose. Despite the significant progress achieved with these procedures, the prediction of specific shifts in the UV-vis spectra and the understanding of the electronic transitions is still a challenging task. In this work, high-level quantum chemical methods based on multireference (MR) and single-reference (SR) methods have been used to predict the effect of different nitrogen doping patterns inserted into the prototypical PAH pyrene on its absorption spectrum. Furthermore, a simple classification scheme based on valence bond (VB) theory and the Clar sextet rule in combination with the harmonic oscillator measure of aromaticity (HOMA) index was applied to arrange the different doping structures into groups and rationalize their electronic properties. The results show a wide variety of mostly redshifts in the spectra as compared to the pristine pyrene case. The most interesting doping structures with the largest red shifts leading to absorption energies below one eV could be readily explained by the occurrence of diradical VB structures in combination with Clar sextets. Moreover, analysis of the electronic transitions computed with MR methods showed that several of the low-lying excited states possess double-excitation character, which cannot be realized by the popular SR methods and, thus, are simply absent in the calculated spectra.",
author = "Xin Shao and Michal Otyepka and Dana Nachtigallova and Hans Lischka and Aquino, {Adelia J.A.}",
note = "Funding Information: We are grateful for support from the School of Pharmaceutical Science and Technology (SPST), Tianjin University, Tianjin, China, including computer time on the SPST computer cluster Arran. This work was supported by the Center for Integrated Nanotechnologies (Project No. 2019BC0064), an Office of Science User Facility operated for the U.S. Department of Energy Office of Science by Los Alamos National Laboratory (Contract No. 89233218CNA000001) and Sandia National Laboratories (Contract No. DE-NA-0003525). D. N. acknowledges the support of the Czech Science Foundation (GA18-09914S). This work was also a part of the research project RVO (61388963) of the IOCB of the Czech Academy of Sciences. M. O. acknowledges support from the Ministry of Education, Youth and Sports of the Czech Republic (project CZ.02.1.01/0.0/ 0.0/16_019/0000754). Funding Information: We are grateful for support from the School of Pharmaceutical Science and Technology (SPST), Tianjin University, Tianjin, China, including computer time on the SPST computer cluster Arran. This work was supported by the Center for Integrated Nanotechnologies (Project No. 2019BC0064), an Office of Science User Facility operated for the U.S. Department of Energy Office of Science by Los Alamos National Laboratory (Contract No. 89233218CNA000001) and Sandia National Laboratories (Contract No. DE-NA-0003525). D. N. acknowledges the support of the Czech Science Foundation (GA18-09914S). This work was also a part of the research project RVO (61388963) of the IOCB of the Czech Academy of Sciences. M. O. acknowledges support from the Ministry of Education, Youth and Sports of the Czech Republic (project CZ.02.1.01/0.0/0.0/16_019/0000754). Publisher Copyright: {\textcopyright} the Owner Societies.",
year = "2020",
month = oct,
day = "14",
doi = "10.1039/d0cp02688c",
language = "English",
volume = "22",
pages = "22003--22015",
journal = "Physical Chemistry Chemical Physics",
issn = "1463-9076",
publisher = "Royal Society of Chemistry",
number = "38",
}