Aromatic Pathways in Porphyrinoids by Magnetically Induced Ring Currents

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Coupled-cluster calculations of the lowest 0-0 bands of the electronic excitation spectrum of naphthalene

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The influence of heteroatoms on the aromatic character and the current pathways of B2N2-dibenzo[a,e]pentalenes

Four polycyclic molecules have been investigated at the DFT B3LYP/def2-TZVP level of theory using calculated magnetically induced current densities as an indicator of their (anti)aromaticity. Complicated current pathways were found in dibenzo[a,e]pentalene and its three heterocyclic analogues each containing two boron and two nitrogen atoms. The antiaromatic character of the pentalene moiety is weaker in the hydrocarbon molecule and in 5,11-dihydrobenzo[d]benzo[4,5][1,2,3]azadiborolo[3,2-b][1,2,3]azadiborole as compared to the pentalene molecule. The antiaromatic character of the pentalene moiety is completely absent in the other two heterocyclic structures. In 6,12-dihydrobenzo[d]benzo[4,5][1,2,3]diazaborolo[2,1-a][1,2,3]diazaborole all four molecular rings are aromatic according to the ring-current criterion, and in 6,12-dihydrobenzo[d]benzo[3,4][1,2,5]azadiborolo[1,2-a][1,3,2]diazaborole, the diazaborole ring is aromatic, while the azadiborole ring is antiaromatic. In all four molecules the six-membered rings are aromatic sustaining a weaker ring current than benzene does.Peer reviewe

Relation Between Ring Currents and Hydrogenation Enthalpies for Assessing the Degree of Aromaticity

Magnetically induced ring-current strength susceptibilities and nucleus independent chemical shifts (NICS) have been studied for 15 single-ring aromatic, antiaromatic, and nonaromatic molecules. The current densities have been calculated at the density functional theory (DFT), Hartree-Fock (HF) theory, and second-order Moller-Plesset perturbation theory (MP2) levels using the gauge-including magnetically induced current method (GIMIC). The ring-current strength susceptibilities have been obtained by numerical integration of the current density flowing around the molecular ring. The calculated ring-current strength susceptibilities are almost independent of the level of theory. The relative degree of aromaticity deduced from the magnetic properties has been compared with the ones deduced from hydrogenation enthalpies that are considered to be proportional to aromatic stabilization energies (ASE). For the studied single-ring molecules, GIMIC, NICS, and ASE calculations yield similar trends. The study shows that there is a linear correlation between the magnetic and energetic criteria of aromaticity. The largest uncertainty originates from the accuracy of the energy data, because they are much more dependent on the employed computational level than the calculated magnetic properties. Thus, ring-current strength susceptibilities can be used for assessing the degree of aromaticity.Peer reviewe

Closed-shell paramagnetic porphyrinoids

Magnetizabilities and magnetically induced ring-current strength susceptibilities have been calculated at the Hartree-Fock, density functional theory and second order Moller-Plesset levels for a number of antiaromatic closed-shell carbaporphyrins, carbathia-porphyrins and isophlorins. The calculations yield a linear relation between magnetizabilities and ring-current strength susceptibilities. The calculations show that the porphyrinoids with the largest ring-current strength susceptibility are closed-shell paramagnetic molecules with positive magnetizabilities. The closed-shell paramagnetism is due to the large paramagnetic contribution to the magnetizability originating from the strong paratropic ring current in the antiaromatic porphyrinoids.Peer reviewe

Sports marketing

Tato bakalářská práce pojednává o problematice marketingové strategie plzeňského fotbalového klubu FC Viktoria Plzeň. V teoretické části práce je popsána obecná definice marketingu a sportovního marketingu, dále jsou zde vysvětleny pojmy jako marketingový mix a situační analýza. V následující praktické části je nedříve představen fotbalový klub FC Viktoria Plzeň. Dále je proveden marketingový mix spolu s konkrétním popisem a analýzou online marketingové komunikace zaměřenou na Instagram a Facebook. Analýza těchto sítí je provedena pomocí analytického nástroje ZoomSphere. Data získané díky této analýze jsou dále porovnány s konkurencí z horních příček nejvyšší české ligy. Posledním bodem je sestavená SWOT matice, z které jsou následně navržené možné doporučení pro zlepšení marketingové komunikace sledovaného týmu. Cíl této práce je vyhodnotit a zanalyzovat marketingovou komunikaci FC Viktorie Plzeň a ze získaných dat navrhnout doporučení pro zlepšení těchto aktivit klubu.ObhájenoThis bachelor thesis deals with the marketing strategy of FC Viktoria Plzeň. In the theoretical part of the thesis, the general definition of marketing and sports marketing is described, then concepts such as marketing mix and situational analysis are explained. In the following practical part, the football club FC Viktoria Plzeň is introduced. Furthermore, the marketing mix is presented along with a specific description and analysis of online marketing communication focusing on Instagram and Facebook. The analysis of these networks is performed using the ZoomSphere analytical tool. The data obtained through this analysis is further compared with the competition from the top ranks of the top czech league. Lastly, a SWOT matrix is compiled, from which possible recommendations for improving the marketing communication of the monitored team are then proposed. The aim of this thesis is to evaluate and analyze the marketing communication of FC Viktoria Plzeň and from the data obtained to propose recommendations for improving these activities of the club

Bicycloaromaticity and Baird-type bicycloaromaticity of dithienothiophene-bridged [34]octaphyrins

Aromatic properties of two recently synthesized dithienothiophene-bridged (DTT) [34]octaphyrins have been investigated by calculating magnetically induced current densities and vertical excitation energies. These intriguing molecules have been proposed to be the first synthesized neutral bicycloaromatic compounds. The triplet state of their dications was even suggested to be Baird-type bicycloaromatic rendering them very interesting as a new prototype of molecules possessing simultaneously the two rare types of aromaticity. Here, we investigate computationally the aromatic properties of the neutral as well as the singly and doubly charged DTT-bridged [34]octaphyrins. Our study provides unambiguous information about changes in the aromatic properties of the DTT-bridged [34]octaphyrins upon oxidation. The calculations identify two independent diatropic ring currents in the neutral DTT-bridged [34]octaphyrins, showing that they are indeed bicycloaromatic. The current-density flow of the two independent ring currents of the bicycloaromatic compounds are visualized and individual aromatic pathways are quantified by performing numerical integration. The calculations show that two independent diatropic ring currents can indeed be sustained by molecules consisting of two aromatic rings that share a common set of π electrons. The current density calculations on the singly charged DTT-bridged [34]octaphyrins show that they are weakly antiaromatic, which does not agree with the suggested aromatic character deduced from spectroscopical studies. The triplet state of the two DTT-bridged [34]octaphyrin cations with very similar molecular structures have unexpectedly different aromatic character. One of them is Baird-type bicycloaromatic, whereas the triplet state of the other dication has one aromatic and one nonaromatic ring, which could not be resolved from available spectroscopical data. Calculations of excitation energies reveal that a simple model cannot be employed for interpreting the electronic excitation spectra of the present molecules, because more than 20 excited states contribute to the spectra above 2.5 eV (500 nm) showing the importance of computations. The present work illustrates how detailed information about molecular aromaticity can nowadays be obtained by scrutinizing calculated current densities.Peer reviewe

Optical and magnetic properties of antiaromatic porphyrinoids

Magnetic and spectroscopic properties of a number of formally antiaromatic carbaporphyrins, carbathiaporphyrins and isophlorins with 4n pi electrons have been investigated at density functional theory and ab initio levels of theory. The calculations show that the paratropic contribution to the magnetically induced ring-current strength susceptibility and the magnetic dipole-transition moment between the ground and the lowest excited state are related. The vertical excitation energy (VEE) of the first excited state decreases with increasing ring-current strength susceptibility, whereas the VEE of the studied higher-lying excited states are almost independent of the size of the ring-current strength susceptibility. Strong antiaromatic porphyrinoids, based on the magnitude of the paratropic ring-current strength susceptibility, have small energy gaps between the highest occupied and lowest unoccupied molecular orbitals and a small VEE of the first excited state. The calculations show that only the lowest S-0 -> S-1 transition contributes signficantly to the magnetically induced ring-current strength susceptibility of the antiaromatic porphyrinoids. The decreasing optical gap combined with a large angular momentum contribution to the magnetic transition moment from the first excited state explains why molecules III-VII are antiaromatic with very strong paratropic ring-current strength susceptibilities. The S-0 -> S-1 transition is a magnetic dipole-allowed electronic transition that is typical for antiaromatic porphyrinoids with 4n pi electrons.Peer reviewe

Predicting the degree of aromaticity of novel carbaporphyrinoids

Magnetically induced current densities have been calculated for dioxaporphyrin, dithiaporphyrin, true carbaporphyrins, and N-confused porphyrins using the gauge-including magnetically induced current (GIMIC) method. The current-strength susceptibilities (current strengths) have been obtained by numerically integrating the current flow passing selected chemical bonds. The current strength calculations yield very detailed information about the electron delocalization pathways of the molecules. The strength of the ring-current that circles around the porphyrinoid macroring is used to estimate the degree of molecular aromaticity. The studied porphyrinoid structures have been obtained by replacing the NH and N groups of porphin with formally isoelectronic moieties such as O, S, CH and CH2. Replacing an NH moiety of trans-porphin with isoelectronic O and S does not significantly change the current strengths and pathways, whereas substitution of N with an isoelectronic CH group leads to significant changes in the current pathway and current strengths. CH2 groups cut the flow of diatropic currents, whereas in strongly antiaromatic molecules a significant fraction of the paratropic ring-current is able to pass the sp(3) hybridized inner carbons. N-confused porphyrinoids sustain a ring current whose strength is about half the ring-current strength of porphin with the dominating current flow along the outer pathway via the NH moiety. When no hydrogen is attached to the inner carbon of the inverted pyrrolic ring, the current prefers the inner route at that ring.Peer reviewe