caa a22 4500 605511780 CHVBK 20210128100652.0 cr unu---uuuuu 210128e20151201xx s 000 0 eng 10.1007/s00894-015-2862-3 doi (NATIONALLICENCE)springer-10.1007/s00894-015-2862-3 Theoretical investigation of the aromaticity and electronic properties of protonated and unprotonated molecules in the series hexaphyrin(1.0.0.1.0.0) to hexaphyrin(1.1.1.1.1.1) [Elektronische Daten] [Gang Sun, Xi-Xin Duan, Chun-Hui Yu, Chun-Guang Liu] A series of hexaphyrins with different meso-carbon atoms and their protonated structures were investigated using density functional theory (DFT) and time-dependent DFT. Frontier molecular orbitals (FMOs), aromaticity, and electronic spectra were investigated systematically before and after protonation. The FMO energy gaps before and after protonation were different for the antiaromatic molecules, while they were only slightly different for the aromatic molecules. By analyzing the electronic spectra of the aromatic molecules, the absorption peaks in the Q-like and B-like bands were not significantly different before and after protonation. However, the absorption peaks of the antiaromatic molecules were clearly different before and after protonation in both the Q-like and B-like bands. [24]Hexaphyrin (1.0.1.0.1.0) has 24 π-electrons and is Hückel antiaromatic. However, the absorption spectrum of protonated [24]hexaphyrin (1.0.1.0.1.0) showed aromaticity. In addition, these conclusions were generally consistent with the FMOs, nucleus-independent chemical shifts, harmonic oscillator model of aromaticity, and absorption spectra. Although protonated [24]hexaphyrin (1.0.1.0.1.0) has 24 π-electrons and is Hückel antiaromatic, it has Möbius aromaticity because of the single-sided Möbius topological structure. This explains why [24]hexaphyrin (1.0.1.0.1.0) has diatropic ring currents in solvent. To the best of our knowledge, this system is the smallest Möbius aromatic molecule among the many uncoordinated extended porphyrins. Graphical abstract These conclusions are generally consistent with the FMOs, nucleus-independent chemical shifts, harmonic oscillator model of aromaticity, and absorption spectra. Although protonated [24]hexaphyrin (1.0.1.0.1.0) has 24 π-electrons and is Hückel antiaromatic, it has Möbius aromaticity because of the single-sided Möbius topological structure. The maximum absorption peak of molecule 3b at 728nm is more than 200nm away from the peak location of the antiaromaticity molecule 3a. Springer-Verlag Berlin Heidelberg, 2015 Hexaphyrin nationallicence Aromaticity nationallicence Time-dependent density functional theory nationallicence Electronic spectrum nationallicence Protonation nationallicence Möbius cyclacenes nationallicence Sun Gang Chemistry and Biology Academy, Beihua University, 132013, Jilin, China aut Duan Xi-Xin Chemistry and Biology Academy, Beihua University, 132013, Jilin, China aut Yu Chun-Hui Chemistry and Biology Academy, Beihua University, 132013, Jilin, China aut Liu Chun-Guang College of Chemical Engineering, Northeast Dianli University, 132012, Jilin, China aut Journal of Molecular Modeling Springer Berlin Heidelberg 21/12(2015-12-01), 1-8 1610-2940 21:12<1 2015 21 894 https://doi.org/10.1007/s00894-015-2862-3 text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s00894-015-2862-3 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Sun Gang Chemistry and Biology Academy, Beihua University, 132013, Jilin, China aut NATIONALLICENCE 700 1- Duan Xi-Xin Chemistry and Biology Academy, Beihua University, 132013, Jilin, China aut NATIONALLICENCE 700 1- Yu Chun-Hui Chemistry and Biology Academy, Beihua University, 132013, Jilin, China aut NATIONALLICENCE 700 1- Liu Chun-Guang College of Chemical Engineering, Northeast Dianli University, 132012, Jilin, China aut NATIONALLICENCE 773 0- Journal of Molecular Modeling Springer Berlin Heidelberg 21/12(2015-12-01), 1-8 1610-2940 21:12<1 2015 21 894