Deuteration effects on the vibronic structure of the fluorescence spectra and the internal conversion rates of triangular [4]phenylene

Dosche, Carsten; Kumke, Michael U.; Löhmannsröben, Hans‐Gerd; Ariese, Freek; Bader, Arjen N.; Gooijer, C.; Miljanić, Ognjen Š.; Iwamoto, M.; Vollhardt, K. Peter C.; Puchta, Ralph; Hommes, Nicolaas J. R. van Eikema

doi:10.1039/b414545c

Cited by 12 publications

(7 citation statements)

References 53 publications

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“…Mixed isomers that contain linear and angular structural units are also known. , These [ N ]phenylenes have been prepared by Vollhardt and co-workers via a convenient [2 + 2 + 2] cycloaddition reaction using CpCo(CO) 2 as the catalyst. The geometry, aromaticity, and properties of [ N ]phenylenes have been reported based on both experimental ,,− and theoretical approaches. − These studies have revealed that the aromaticity and E Gap of [ N ]phenylenes are influenced by the number and position of annulated benzocyclobutadieno moieties on the central 6MRs. For instance, the anti-aromatic character of four-membered rings in [ N ]phenylenes decreases in the following order: linear [3]phenylene, angular [3]phenylene, and branched [4]phenylene, leading to overall E Gap enlargement …”

Section: Introductionmentioning

confidence: 99%

Theoretical Study on the Geometry, Aromaticity, and Electronic Properties of Benzo[3,4]cyclobutathiophenes and Their Homologues

Hashimoto

Tahara

2019

J. Org. Chem.

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The geometry, aromaticity, and electronic properties of benzo[3,4]cyclobutathiophenes (BCTs) and their homologues have been examined theoretically using density functional theory calculations. The harmonic oscillator measure of aromaticity and nucleus-independent chemical shift analyses revealed the aromaticity characteristics of the two regioisomers benzo[3,4]cyclobuta[1,2-b]thiophene and benzo[3,4]cyclobuta[1,2-c]thiophene. When the aromaticity of one of the six-π-electron rings increases, it concomitantly decreases in the other ring. The anti-aromaticity of the four-membered ring varies depending on the π-electron density of the shared bond with the thiophene ring. This leads to a large difference of the highest occupied molecular orbital–lowest unoccupied molecular orbital gap between the isomers. Linear BCT homologues show medium diradical characters and the smallest E Gap values. In the angular and branched homologues, the π-electrons of central benzene rings are localized avoiding the shared bonds, which results in a nonaromatic character. These data were compared to those of the parent hydrocarbons. Because of the diene character of the thiophene ring, the number and position of annulated thiophenocyclobutadieno moieties significantly influence the aromaticity and E Gap values of BCT homologues. The present study does not only provide insight into the aromaticity and the properties of organic compounds containing four-membered rings but also affords helpful design guidelines of novel organic semiconductors.

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Section: Introductionmentioning

confidence: 99%

Theoretical Study on the Geometry, Aromaticity, and Electronic Properties of Benzo[3,4]cyclobutathiophenes and Their Homologues

Hashimoto

Tahara

2019

J. Org. Chem.

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“…Conjugated ladder polymers have attracted intense attention because of their intriguing properties, which are distinct from those of conventional conjugated polymers. − As a result of their fully conjugated and rigid polymer backbones, conjugated ladder polymers possess some intriguing properties, − including high charge carrier mobilities, , long exciton diffusion lengths, and low energy gaps. ,, Ladder phenylenes (LPs) represent a unique family of conjugated ladder polymers, comprising one-dimensional ladder chains of linearly alternating fused benzene and cyclobutadiene rings. , Because of the unusual combination of aromatic and antiaromatic moieties, LPs are expected to possess unique optical and electronic properties and are considered promising materials for applications in optoelectronic devices. − Ever since the pioneering synthesis of biphenylene by Hosaeus, many efforts have been made to synthesize LP chains. ,,− To date, the longest prepared LPs have contained five benzene units, , and the synthesis of longer, polymeric LPs remains a great challenge. Moreover, experimental investigation of the properties of existing LPs has been limited to collecting the average signals of ensembles of LP molecules. ,− Thus, the synthesis and characterization of individual LPs have not been achieved, which severely hampered the exploration of the properties of these unusual conjugated ladder polymers.…”

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confidence: 99%

Ladder Phenylenes Synthesized on Au(111) Surface via Selective [2+2] Cycloaddition

Qiu

et al. 2021

J. Am. Chem. Soc.

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Ladder phenylenes (LPs) composed of alternating fused benzene and cyclobutadiene rings have been synthesized in solution with a maximum length no longer than five units. Longer polymeric LPs have not been obtained so far because of their poor stability and insolubility. Here, we report the synthesis of linear LP chains on the Au(111) surface via dehalogenative [2+2] cycloaddition, in which the steric hindrance of the methyl groups in the 1,2,4,5-tetrabromo-3,6-dimethylbenzene precursor improves the chemoselectivity as well as the orientation orderliness. By combining scanning tunneling microscopy and noncontact atomic force microscopy, we determined the atomic structure and the electronic properties of the LP chains on the metallic substrate and NaCl/Au(111). The tunneling spectroscopy measurements revealed the charged state of chains on the NaCl layer, and this finding is supported by density functional theory calculations, which predict an indirect bandgap and antiferromagnetism in the polymeric LP chains.

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“…All frequencies are unscaled. DFT, in particular B3LYP, has shown to provide accurate geometries and good harmonic vibrational frequencies for a broad range of molecules and ions [48][49][50]. As shown recently, the level of theory selected is well suited for nuclear magnetic resonance [51,52] and NICS calculations [53][54][55][56].…”

Section: Methodsmentioning

confidence: 99%

Aplicyanins – brominated natural marine products with superbasic character

Kostić

Divac

Alzoubi³

et al. 2016

Zeitschrift Für Naturforschung B

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By using quantum chemical methods (B3LYP/6-311+G(2df,p)//B3LYP/6-31G(d)), we investigated the structures of aplicyanin A, aplicyanin B, aplicyanin C, aplicyanin D, aplicyanin E, and aplicyanin F along with their protonated structures. The calculated gas phase proton affinities of aplicyanin A, aplicyanin C, and aplicyanin E are around -250 kcal mol −1 and therefore more than 10 kcal mol −1 higher as in typical proton sponges such as 1,8-bis(dimethylamino)naphthalene. The compounds aplicyanin B, aplicyanin D, and aplicyanin F show reduced proton affinities of approximately -240 kcal mol −1 because of the acetyl group being conjugated with the imine N = C moiety. Nucleus-independent chemical shift (NICS) calculations on the same level of theory do not show any peculiarities, and a reasonable correlation between the toxicity of aplicyanins and the gas phase proton affinity is not observed.

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Deuteration effects on the vibronic structure of the fluorescence spectra and the internal conversion rates of triangular [4]phenylene

Abstract: Deuteration effects on the vibronic structure of the fluorescence spectra and the internal conversion rates of triangular [4]Phenylene U n i v e r s i t ä t P o t s d a m

Cited by 12 publications

References 53 publications

Theoretical Study on the Geometry, Aromaticity, and Electronic Properties of Benzo[3,4]cyclobutathiophenes and Their Homologues

Theoretical Study on the Geometry, Aromaticity, and Electronic Properties of Benzo[3,4]cyclobutathiophenes and Their Homologues

Ladder Phenylenes Synthesized on Au(111) Surface via Selective [2+2] Cycloaddition

Aplicyanins – brominated natural marine products with superbasic character

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