scholarly journals Triplet state (anti)aromaticity of some monoheterocyclic analogues of benzene, naphthalene and anthracene

2021 ◽  
Vol 45 (11) ◽  
pp. 5060-5074
Author(s):  
Marija Baranac-Stojanović ◽  
Milovan Stojanović ◽  
Jovana Aleksić
Keyword(s):  
Dft Calculations ◽  
Triplet State ◽  
Heteroatom Substitution

By employing DFT calculations, we show the influence of heteroatom substitution on the triplet state (anti)aromaticity of benzene, naphthalene and anthracene.

DFT Calculations on Group 5 Mixed Metal Tetramers: TaxNbyVz (x + y + z = 4)

2004 ◽  
Vol 57 (12) ◽  
pp. 1197 ◽  
Author(s):  
Magdalene A. Addicoat ◽  
Mark A. Buntine ◽  
Gregory F. Metha
Keyword(s):  
Density Functional Theory ◽  
Dft Calculations ◽  
Triplet State ◽  
Density Functional ◽  
Metal Cluster ◽  
Functional Theory ◽  
Mixed Metal ◽  
Mixed Metal Cluster ◽  
Group 5

We report Density Functional Theory (DFT) calculations on mixed-metal tetramers comprised of the Group 5 (Vb) elements V, Nb, and Ta. Our results show that the lowest energy structures for Nb4 and Ta4 are regular tetrahedra with Td symmetry and singlet multiplicity whereas V4 is a triplet state with C2v symmetry. The monosubstituted isomers, A3B, all have C3v symmetry but several higher energy Cs structures have been found that are approximately 100 kJ mol−1 higher in energy. The disubstituted isomers all posses arachno-butterfly structures; the A2B2 types with C2v symmetry and the A2BC types with Cs symmetry. However, the relative openness of the arachno structures is found to be specific to the composition of the mixed-metal cluster.

Similarity and Specificity of Chlorophyll b Triplet State in Comparison to Chlorophyll a as Revealed by EPR/ENDOR and DFT Calculations

2019 ◽  
Vol 123 (39) ◽  
pp. 8232-8239 ◽  
Author(s):  
Alessandro Agostini ◽  
Maria Giulia Dal Farra ◽  
Harald Paulsen ◽  
Antonino Polimeno ◽  
Laura Orian ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Triplet State ◽  
Chlorophyll A ◽  
Chlorophyll B

A stable triplet-state γ-cyclodextrin bicapped C60 dianion and molecular clusters in water: ESR spectroscopy and DFT calculations

2003 ◽  
Vol 137 (1-3) ◽  
pp. 1315-1316 ◽  
Author(s):  
N. Mori ◽  
K. Fukui ◽  
S. Nakazawa ◽  
S. Takekuma ◽  
H. Takekuma ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Triplet State ◽  
Esr Spectroscopy ◽  
Molecular Clusters

Synthesis, photophysicochemical properties and TD-DFT calculations of tetrakis(2-benzoyl-4-chlorophenoxy) phthalocyanines

2014 ◽  
Vol 18 (04) ◽  
pp. 326-335 ◽  
Author(s):  
Yusuf Yılmaz ◽  
John Mack ◽  
M. Kasım Şener ◽  
Mehmet Sönmez ◽  
Tebello Nyokong
Keyword(s):  
Quantum Yield ◽  
Dft Calculations ◽  
Triplet State ◽  
Singlet Oxygen ◽  
Quantum Yields ◽  
Visible Absorption ◽  
H Nmr ◽  
Wide Range ◽  
Td Dft ◽  
The Impact

The synthesis of metal free, magnesium and zinc tetrakis(2-benzoyl-4-chlorophenoxy) phthalocyanine derivatives (2–4) is described along with their characterization by elemental analysis, IR, UV-visible absorption, and 1 H NMR spectroscopy and mass spectrometry. Trends observed in the fluorescence, triplet state, singlet oxygen and photodegradation quantum yields and the triplet state lifetimes are also analyzed. The compounds exhibit high solubility in a wide range of organic solvents and no evidence of aggregation was observed over a wide concentration range. The Zn ( II ) complex (4) was found to have a very high singlet oxygen quantum yield (ΦΔ = 0.78) in dimethylsulfoxide (DMSO) and a reasonably large triplet state quantum yield (ΦT = 0.82). The photophysical and photochemical properties clearly demonstrate that these compounds could prove useful in singlet oxygen applications such as photodynamic therapy (PDT). DFT and TD-DFT calculations were used to assess the impact of the positional isomerism of the 2-benzoyl-4-chlorophenoxy substituents on the electronic structures and optical spectroscopy.

scholarly journals Singlet/Triplet State Anti/Aromaticity of CyclopentadienylCation: Sensitivity to Substituent Effect

Chemistry ◽  
2021 ◽  
Vol 3 (3) ◽  
pp. 765-782
Author(s):  
Milovan Stojanović ◽  
Jovana Aleksić ◽  
Marija Baranac-Stojanović
Keyword(s):  
Density Functional Theory ◽  
Dft Calculations ◽  
Triplet State ◽  
Substituent Effect ◽  
Density Functional ◽  
Singlet State ◽  
Substituent Effects ◽  
Functional Theory

It is well known that singlet state aromaticity is quite insensitive to substituent effects, in the case of monosubstitution. In this work, we use density functional theory (DFT) calculations to examine the sensitivity of triplet state aromaticity to substituent effects. For this purpose, we chose the singlet state antiaromatic cyclopentadienyl cation, antiaromaticity of which reverses to triplet state aromaticity, conforming to Baird’s rule. The extent of (anti)aromaticity was evaluated by using structural (HOMA), magnetic (NICS), energetic (ISE), and electronic (EDDBp) criteria. We find that the extent of triplet state aromaticity of monosubstituted cyclopentadienyl cations is weaker than the singlet state aromaticity of benzene and is, thus, slightly more sensitive to substituent effects. As an addition to the existing literature data, we also discuss substituent effects on singlet state antiaromaticity of cyclopentadienyl cation.

scholarly journals Pump–probe XAS investigation of the triplet state of an Ir photosensitizer with chromenopyridinone ligands

2018 ◽  
Vol 17 (7) ◽  
pp. 896-902 ◽  
Author(s):  
Grigory Smolentsev ◽  
Kaj M. van Vliet ◽  
Nicolo Azzaroli ◽  
Jeroen A. van Bokhoven ◽  
Albert M. Brouwer ◽  
...  
Keyword(s):  
Excited State ◽  
Dft Calculations ◽  
Triplet State ◽  
Absorption Spectroscopy ◽  
Triplet Excited State ◽  
Pump Probe ◽  
X Ray ◽  
X Ray Absorption

The triplet excited state of a new Ir-based photosensitizer with two chromenopyridinone and one bipyridine-based ligands has been studied by pump–probe X-ray absorption spectroscopy (XANES) coupled with DFT calculations.

scholarly journals Phenalenyls as tunable excellent molecular conductors and switchable spin filters

2021 ◽  
Author(s):  
Manuel Smeu ◽  
Oliver L.A. Monti ◽  
Dominic V. McGrath
Keyword(s):  
Density Functional Theory ◽  
Dft Calculations ◽  
Electronic Properties ◽  
Density Functional ◽  
Molecular Conductors ◽  
Functional Theory ◽  
Heteroatom Substitution ◽  
Spin Filters ◽  
Stable Radicals ◽  
Non Equilibrium Green’S Function

Phenalenyl-based radicals are stable radicals whose electronic properties can be tuned readily by heteroatom substitution. We employ density functional theory-based non-equilibrium Green’s function (NEGF-DFT) calculations to show that this class...

The Aryl Cation – the Trapping and Characterisation of a Hyper-Reactive Species

2003 ◽  
Vol 28 (1) ◽  
pp. 11-34 ◽  
Author(s):  
Terence J. Kemp
Keyword(s):  
Dft Calculations ◽  
Triplet State ◽  
Ab Initio ◽  
Picosecond Laser ◽  
Reactive Species ◽  
Laser Photolysis ◽  
Theoretical Understanding ◽  
Spectroscopic Characterisation ◽  
Ab Initio And Dft ◽  
Picosecond Laser Photolysis

The article traces the development of the epr and optical spectroscopic characterisation and progressive theoretical understanding of the aryl cation, starting from the initial cryogenic epr study of 2,5-dialkoxyl-4-morpholinophenyl cation, which defined unambiguously its triplet state character, through simple MO, ab initio and DFT calculations on substituted aryl cations, to picosecond laser photolysis studies in fluorinated solvents, noting especially the early and vital contribution of Martyn Symons.

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