scholarly journals Fluorine-Containing Dibenzoanthracene and Benzoperylene-Type Polycyclic Aromatic Hydrocarbons: Synthesis, Structure, and Basic Chemical Properties

Molecules ◽  
2018 ◽  
Vol 23 (12) ◽  
pp. 3337 ◽  
Author(s):  
Otohiro Gotsu ◽  
Tomomi Shiota ◽  
Hiroki Fukumoto ◽  
Tomoko Kawasaki-Takasuka ◽  
Takashi Yamazaki ◽  
...  
Keyword(s):  
Density Functional ◽  
Dft Calculation ◽  
Chemical Properties ◽  
Crystallographic Analysis ◽  
Functional Theory ◽  
X Ray ◽  
Td Dft ◽  
Polycyclic Aromatic ◽  
Stilbene Derivatives ◽  
Hydrocarbons Synthesis

Intramolecular photocyclization of stilbene derivatives (Mallory reaction) is one of the efficient methods for building polycyclic aromatic hydrocarbon (PAH) frameworks, and is also expected to be applicable to synthesis of fluorine-containing PAHs (F-PAHs). In this study, dibenzoanthracene-type (4a) and benzoperylene-type (4b) F-PAHs were synthesized using the Mallory reaction of the 1,4-distyrylbenzene-type π-conjugated molecule (3a), which was prepared by addition-defluorination of available octafluorocyclopentene (OFCP) and aryllithium in three steps. The structure of 4a originating from π–π interaction was characterized by X-ray crystallographic analysis. The absorption maxima of UV-Vis spectra and emission maxima of photoluminescence spectra of the PAHs were positioned at a longer wavelength compared to those of the corresponding unsubstituted PAHs, presumably due to the electron-withdrawing nature of perfluorocyclopentene (PFCP) units. The effect of PFCP units in F-PAHs was also studied by time-dependent density functional theory (TD-DFT) calculation.

The Nature of S-N Bonding in Sulfonamides and Related Compounds: Insights into π-Bonding Contributions from Sulfur K-Edge XAS

2020 ◽  
Author(s):  
Tulin Okbinoglu ◽  
Pierre Kennepohl
Keyword(s):  
Density Functional ◽  
Chemical Properties ◽  
Functional Theory ◽  
Rotational Barriers ◽  
Td Dft ◽  
Nitrogen Bonds ◽  
X Ray Absorption ◽  
Related Compounds ◽  
And Chemical Properties

Molecules containing sulfur-nitrogen bonds, like sulfonamides, have long been of interest due to their many uses and chemical properties. Understanding the factors that cause sulfonamide reactivity is important, yet their continues to be controversy regarding the relevance of S-N π bonding in describing these species. In this paper, we use sulfur K-edge x-ray absorption spectroscopy (XAS) in conjunction with density functional theory (DFT) to explore the role of S<sub>3p</sub> contributions to π-bonding in sulfonamides, sulfinamides and sulfenamides. We explore the nature of electron distribution of the sulfur atom and its nearest neighbors and extend the scope to explore the effects on rotational barriers along the sulfur-nitrogen axis. The experimental XAS data together with TD-DFT calculations confirm that sulfonamides, and the other sulfinated amides in this series, have essentially no S-N π bonding involving S<sub>3p</sub> contributions and that electron repulsion and is the dominant force that affect rotational barriers.

scholarly journals Six-fold C–H borylation of hexa-peri-hexabenzocoronene

2020 ◽  
Vol 16 ◽  
pp. 391-397 ◽  
Author(s):  
Mai Nagase ◽  
Kenta Kato ◽  
Akiko Yagi ◽  
Yasutomo Segawa ◽  
Kenichiro Itami
Keyword(s):  
Density Functional ◽  
Bathochromic Shift ◽  
Density Functional Theory Calculations ◽  
Absorption Bands ◽  
Functional Theory ◽  
X Ray ◽  
X Ray Crystallography ◽  
Polycyclic Aromatic ◽  
Direct Functionalization ◽  
Poorly Soluble

Hexa-peri-hexabenzocoronene (HBC) is known to be a poorly soluble polycyclic aromatic hydrocarbon for which direct functionalization methods have been very limited. Herein, the synthesis of hexaborylated HBC from unsubstituted HBC is described. Iridium-catalyzed six-fold C–H borylation of HBC was successfully achieved by screening solvents. The crystal structure of hexaborylated HBC was confirmed via X-ray crystallography. Optoelectronic properties of the thus-obtained hexaborylated HBC were analyzed with the support of density functional theory calculations. The spectra revealed a bathochromic shift of absorption bands compared with unsubstituted HBC under the effect of the σ-donation of boryl groups.

scholarly journals DFT and TD-DFT Study of Structure and Properties of Semiconductive Hybrid Networks Formed by Bismuth Halides and Different Polycyclic Aromatic Ligands

2011 ◽  
Vol 8 (s1) ◽  
pp. S195-S202
Author(s):  
Y. Belhocine ◽  
M. Bencharif
Keyword(s):  
Density Functional Theory ◽  
Band Gap ◽  
Density Functional ◽  
Relativistic Effects ◽  
Spectroscopic Properties ◽  
Basis Set ◽  
Dft Methods ◽  
Functional Theory ◽  
Td Dft ◽  
Polycyclic Aromatic

The structure and spectroscopic properties of polycyclic aromatic ligands of 2,3,6,7,10,11-hexakis (alkylthio) triphenylene (alkyl: methyl, ethyl, and isopropyl; corresponding to the abbreviations of the molecules: HMTT, HETT and HiPTT) were studied using density functional theory (DFT) and time dependent density functional theory (TD-DFT) methods with triple-zeta valence polarization (TZVP) basis set. It was shown that the type of functional theory used, Becke-Perdew (BP) and Leeuwen-Baerends (LB94) implemented in Amsterdam Density functional (ADF) program package, does not have essential influence on the geometry of studied compounds in both ground and excited states. However, significant differences were obtained for the band gap values with relativistic effects of the zero order regular approximation scalar corrections (ZORA) and LB94 functional seems to reproduce better the experimental optical band gap of these systems.

DFT Study on Two Plausible Mechanistic Routes to Pyrazolo[3,4-d]pyrimidine-4- Amines from Pyrazoloformimidate

2020 ◽  
Vol 24 (2) ◽  
pp. 216-229
Author(s):  
Amal Al-Azmi
Keyword(s):  
Density Functional ◽  
Room Temperature ◽  
Dft Calculation ◽  
Reaction Pathways ◽  
Nucleophilic Attack ◽  
X Ray Diffraction ◽  
Dimroth Rearrangement ◽  
Functional Theory ◽  
X Ray ◽  
Moderate Yield

Pyrazolo[3,4-d]pyrimidine-4-amine was prepared at room temperature in a catalyst- free medium with moderate yield and characterized by spectroscopic and X-ray diffraction techniques. Two possible mechanistic routes were suggested for its formation. Route 1 entails attack by the N of the amine on the imidate carbon followed by Dimroth rearrangement after cyclization. Route 2 is the nucleophilic attack by the amine on the CN function followed by cyclization to pyrazolo[3,4-d]pyrimidine-4-amine. Density functional theory (DFT) calculation studies of the two proposed reaction pathways illustrated that the Route 2 reaction was more likely than that of Route 1.

scholarly journals Synthesis, Characterization, Absorption Properties, and Electronic Structures of Paddlewheel-Type Dirhodium(II) Tetra-μ-(n-naphthoate) Complexes: An Experimental and Theoretical Study

Molecules ◽  
2019 ◽  
Vol 24 (3) ◽  
pp. 447 ◽  
Author(s):  
Yusuke Kataoka ◽  
Raiki Fukumoto ◽  
Natsumi Yano ◽  
Daiki Atarashi ◽  
Hidekazu Tanaka ◽  
...  
Keyword(s):  
Electronic Structures ◽  
Density Functional ◽  
Dft Calculation ◽  
X Ray Diffraction ◽  
Absorption Properties ◽  
Thermal Stabilities ◽  
Functional Theory ◽  
X Ray ◽  
Light Region ◽  
Ligand Charge Transfer

The reactions of [Rh2(O2CCH3)4(OH2)2] with n-naphthalenecarboxylic acids (n = 1: 1-HNC, n = 2: 2-HNC) afford the dirhodium tetra-μ-(n-naphthoate) complexes [Rh2(1-NC)4] (1) and [Rh2(2-NC)4] (2), respectively. Single crystal X-ray diffraction analyses of [1(OCMe2)2] and [2(OCMe2)2], which were obtained by recrystallization from acetone (OCMe2) solutions of 1 and 2, reveal that the dirhodium cores are coordinated by four equatorially bridging naphthoate ligands and two axial OCMe2 ligands. Density functional theory (DFT) calculation confirmed that (i) the single Rh–Rh bond is formed between the two Rh ions and (ii) the electronic structures between two Rh ions in [1(OCMe2)2] and [2(OCMe2)2] are best described as π4δ2σ2δ*2π*4 and δ2π4σ2δ*2π*4, respectively. Time-dependent DFT (TDDFT) calculations clarify the absorption band characters of [1(OCMe2)2] and [2(OCMe2)2]; the former shows the bands due to d–d and metal–to–metal-ligand charge transfer (MMLCT) excitations in the visible light region, whereas the latter shows the bands due to only d–d excitations in the same region. The electrochemical properties and thermal stabilities of [1(OCMe2)2] and [2(OCMe2)2] were also investigated in this study.

scholarly journals Optoelectronic Properties of Polycyclic Aromatic Hydrocarbons of Various Sizes and Shapes: A DFT Study

2020 ◽  
Author(s):  
Ramachandran Rakhi ◽  
Cherumuttathu H Suresh
Keyword(s):  
Polycyclic Aromatic Hydrocarbons ◽  
Aromatic Hydrocarbons ◽  
Density Functional ◽  
Optoelectronic Properties ◽  
Frontier Molecular Orbital ◽  
Functional Theory ◽  
Practical Applications ◽  
Td Dft ◽  
Polycyclic Aromatic ◽  
Electron Withdrawing Group

Polycyclic aromatic hydrocarbons (PAHs) can be considered as graphene nanoflakes in which the edges are hydrogenated. Zigzag and armchair-edged PAHs possessing circular, parallelogram, rectangular and triangular shapes have been studied using M06L/6-31+G(d) level of density functional theory (DFT). Molecular electrostatic potential (MESP) analysis of the PAHs is done to characterize their electron distribution while the time-dependent DFT (TD-DFT) analysis was used for the absorption spectral analysis. MESP analysis clearly showed Clar’s sextet like electronic arrangement in armchair-edged systems whereas zigzag-edged ones showed significant electron localization towards the edges. TD-DFT analysis casts light upon the absorption features of these systems, which followed a linear trends in absorption maximum (lmax) for most of the armchair-edged systems with respect to the number of π-electrons. MESP analysis on the electron rich and electron deficient features of PAH systems led to the design of donor-spacer-acceptor type PAH-π-PAH systems (D-π-A systems) wherein a conjugated diene moiety functions as the π-spacer. Though these systems behaved weakly as D-π-A systems, with the introduction of electron donating functional group NMe2 on one PAH and electron withdrawing group COOH on the other led to the formation of strong D-π-A systems.  The MESP features, frontier molecular orbital (FMO) distribution, and absorption spectral features supported their strong D-π-A character. Among the different shapes studied, the rectangular PAH moiety showed the most efficient tuning of HOMO-LUMO gap. The optical and electronic data of PAH, PAH-π-PAH and functionalized PAH-π-PAH systems shed light upon possible tuning of their optoelectronic properties for practical applications.

scholarly journals On the Relationship Between Hydrogen-Bonding Motifs and the 1b1 Splitting in the X-ray Emission Spectrum of Liquid Water

2020 ◽  
Author(s):  
Vinicius Cruzeiro ◽  
Andrew Wildman ◽  
Xiasong Li ◽  
Francesco Paesani
Keyword(s):  
Hydrogen Bonding ◽  
Liquid Water ◽  
Density Functional ◽  
Potential Energy Function ◽  
Ambient Conditions ◽  
Functional Theory ◽  
Systematic Analysis ◽  
X Ray ◽  
Td Dft ◽  
The Relationship

The split of the 1<i>b</i><sub>1</sub> peak observed in the X-ray emission (XE) spectrum of liquid water has been the focus of intense research over the last two decades. Although several hypotheses have been proposed to explain the origin of the 1<i>b</i><sub>1</sub> splitting, a general consensus has not yet been reached. In this study, we introduce a novel theoretical/computational approach which, combining path-integral molecular dynamics (PIMD) simulations carried out with the MB-pol potential energy function and time-dependent density functional theory (TD-DFT) calculations, correctly predicts the split of the 1<i>b</i><sub>1</sub> peak in liquid water and not in crystalline ice. A systematic analysis in terms of the underlying local structure of liquid water at ambient conditions indicates that several different hydrogen-bonding motifs contribute to the overall XE lineshape in the energy range corresponding to emissions from the 1<i>b</i><sub>1</sub> orbitals, which suggests that it is not possible to unambiguously attribute the split of the 1<i>b</i><sub>1</sub> peak to only two specific structural arrangements of the underlying hydrogen-bonding network.

Bowl-to-bowl inversion of sumanene derivatives

2012 ◽  
Vol 84 (4) ◽  
pp. 1089-1100 ◽  
Author(s):  
Toru Amaya ◽  
Toshikazu Hirao
Keyword(s):  
Density Functional Theory ◽  
Polycyclic Aromatic Hydrocarbons ◽  
Aromatic Hydrocarbons ◽  
Density Functional ◽  
Dft Calculation ◽  
Functional Theory ◽  
Ongoing Research ◽  
Benzene Rings ◽  
Polycyclic Aromatic ◽  
Anion Species

Bowl-to-bowl inversion is one of the characteristic behaviors for some flexible open-end molecular bowls consisting of polycyclic aromatic hydrocarbons with benzene rings fused by imbedded five-membered rings (π bowls). This intriguing dynamics was studied with sumanene, which is the smallest C3v symmetric fragment of fullerenes. In this article, our ongoing research on the bowl-to-bowl inversion of sumanene, its benzylic anion species, hexasubstituted derivatives, mononaphthosumanene, and [CpRu(η6-sumenene)]+ complex is summarized. Estimation based on density functional theory (DFT) calculation is also described.

The Nature of S-N Bonding in Sulfonamides and Related Compounds: Insights into π-Bonding Contributions from Sulfur K-Edge XAS

2020 ◽  
Author(s):  
Tulin Okbinoglu ◽  
Pierre Kennepohl
Keyword(s):  
Density Functional ◽  
Chemical Properties ◽  
Functional Theory ◽  
Rotational Barriers ◽  
Td Dft ◽  
Nitrogen Bonds ◽  
X Ray Absorption ◽  
Related Compounds ◽  
And Chemical Properties

Molecules containing sulfur-nitrogen bonds, like sulfonamides, have long been of interest due to their many uses and chemical properties. Understanding the factors that cause sulfonamide reactivity is important, yet their continues to be controversy regarding the relevance of S-N π bonding in describing these species. In this paper, we use sulfur K-edge x-ray absorption spectroscopy (XAS) in conjunction with density functional theory (DFT) to explore the role of S<sub>3p</sub> contributions to π-bonding in sulfonamides, sulfinamides and sulfenamides. We explore the nature of electron distribution of the sulfur atom and its nearest neighbors and extend the scope to explore the effects on rotational barriers along the sulfur-nitrogen axis. The experimental XAS data together with TD-DFT calculations confirm that sulfonamides, and the other sulfinated amides in this series, have essentially no S-N π bonding involving S<sub>3p</sub> contributions and that electron repulsion and is the dominant force that affect rotational barriers.

scholarly journals Synthesis, physical properties, and chemistry of donor–acceptor-substituted pentacenes

2017 ◽  
Vol 95 (3) ◽  
pp. 303-314 ◽  
Author(s):  
Dan Lehnherr ◽  
Matthias Adam ◽  
Adrian H. Murray ◽  
Robert McDonald ◽  
Frank Hampel ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Density Functional Theory ◽  
Density Functional ◽  
Cycloaddition Reaction ◽  
Chemical Properties ◽  
Functional Theory ◽  
X Ray ◽  
Donor Acceptor ◽  
Insight Into ◽  
And Chemical Properties

Pentacenes bearing electron-donating and (or) -withdrawing groups, namely methoxy-, dialkylamino-, and nitroaryl moieties, are synthesized to afford polarized pentacenes. The optical, electrochemical, and chemical properties of these derivatives are explored. The cycloaddition reaction of selected derivatives with tetracyanoethylene (TCNE) is explored, and the experimental results are rationalized on the basis calculations using density functional theory (DFT). X-ray crystallographic data provides insight into the molecular structure and intermolecular interactions present in the solid state.

Sign in / Sign up

Export Citation Format

Share Document