Substituent effects in the so-called cation⋯π interaction of benzene and its boron–nitrogen doped analogues: overlooked role of σ-skeleton

2019 ◽  
Vol 21 (12) ◽  
pp. 6453-6466 ◽  
Author(s):  
Sirous Yourdkhani ◽  
Michał Chojecki ◽  
Tatiana Korona
Keyword(s):  
Substituent Effect ◽  
Substituent Effects ◽  
Interaction Energies ◽  
Nitrogen Doped ◽  
Π Interactions ◽  
Atom Interaction ◽  
Classical Effect ◽  
Boron Nitrogen

By decomposing IQA atom–atom interaction energies to σ and π contributions, we have shown that the substituent effect in cation⋯π interactions is a nonlocal classical effect in which σ-polarization plays an important role.

Substituent effects in arosemibullvalene photochemistry: the methylcyclopropane rearrangement of 1,8-dimethylbenzosemibullvalene

1982 ◽  
Vol 60 (15) ◽  
pp. 1942-1952 ◽  
Author(s):  
Christopher Owen Bender ◽  
Donald Laverne Bengtson ◽  
Douglas Dolman ◽  
Carolyn Elaine L. Herle ◽  
Seamus Francis O'Shea
Keyword(s):  
Gas Phase ◽  
Excited States ◽  
Substituent Effects ◽  
Interaction Energies ◽  
Direct Irradiation ◽  
Atom Interaction ◽  
Ci Calculations

1,6- and 1,8-Dimethylbenzotricyclo[3.3.0.02,8]octa-3,6-diene (16 and 14) are the major semibullvalene products formed from acetophenone sensitized irradiations of the barrelenes 2,6- and 2,3-dimethyl-1,4-dihydro-1,4-ethenonaphthalene (37 and 22), respectively (Φ37→16 = 0.65; Φ22→14=0.57). The direct (Φ14 = 0.017) or chlorobenzene sensitized (Φ14 = 0.12) irradiation of 14 yields 2,3-benzo-5-methyl-6-methylenebicyclo[3.3.0]octa-2,7-diene (17), a transformation typical of methylcyclopropanes. Gas phase thermolysis (420 °C/6 Torr) of 14 gives 6,7-dimethylbenzocyclooctatetraene (15). The direct irradiation (Φ39 = 0.003) or the gas phase thermolysis (395 °C/6 Torr) of 16 gives 6,9-dimethylbenzocyclooctatetraene (39). The rearrangement 14 → 17 is in accord with predictions based upon CNDO-CI calculations of changes in atom–atom interaction energies on excitation to the S1 or T1 excited states of 14.

Electronic properties and nonlinear optical responses of boron/nitrogen-doped zigzag graphene nanoribbons

2016 ◽  
Vol 94 (7) ◽  
pp. 620-625 ◽  
Author(s):  
Yang-Yang Hu ◽  
Wei-Qi Li ◽  
Li Yang ◽  
Ji-Kang Feng ◽  
Wei Quan Tian
Keyword(s):  
Electronic Properties ◽  
Nonlinear Optical ◽  
Graphene Nanoribbons ◽  
Second Order ◽  
Zigzag Edge ◽  
Nitrogen Doped ◽  
Optical Responses ◽  
Nlo Response ◽  
Boron Nitrogen

The electronic properties and second-order nonlinear optical (NLO) responses of B/N-doped zigzag graphene nanoribbon (ZGNR) have been investigated using quantum chemistry methods. The electron-deficient B atoms prefer to form π-conjugation with the C atoms nearby along the B-doped zigzag edge. On the other hand, the electron-rich N atoms with radical characteristics weaken the conjugated bonding effects in the N-doped ZGNR. The NLO response of the ZGNR is enhanced by doping only one zigzag edge with B or N atoms. The conjugated B-doped zigzag edge takes the role of electron donor, while the N-doped zigzag edge serves as electron acceptor, giving rise to the discordant impact on the second-order NLO response of the BN-doped ZGNR.

Boron-Nitrogen Doped Dihydroindeno[1,2-b]fluorene Derivatives as Acceptors in Organic Solar Cells

2019 ◽  
Author(s):  
Matthew Morgan ◽  
Maryam Nazari ◽  
Thomas Pickl ◽  
J. Mikko Rautiainen ◽  
Heikki M. Tuononen ◽  
...  
Keyword(s):  
Solar Cells ◽  
Solar Cell ◽  
Organic Solar Cells ◽  
Organic Solar Cell ◽  
Broad Absorption ◽  
Nitrogen Doped ◽  
Large Depth ◽  
End Products ◽  
Boron Nitrogen ◽  
The Way

The electrophilic borylation of 2,5-diarylpyrazines results in the formation of boron-nitrogen doped dihydroindeno[1,2-<i>b</i>]fluorene which can be synthesized via mildly air-sensitive techniques and the end products handled readily under atmosphereic conditions. Through transmetallation via diarylzinc reagents a series of derivatives were sythesized which show broad absorption profiles that highlight the versatility of this backbone to be used in organic solar cell devices. These compounds can be synthesized in large yields, in alow number of steps and functionalized at many stages along the way providing a large depth of possibilities. Exploratory device paramaters were studied and show PCE of 2%.

Kinetic Study of Hydrolysis of Benzoates. Part XXVI. Variation of the Substituent Effect with Solvent in Alkaline Hydrolysis of Substituted Alkyl Benzoates

2006 ◽  
Vol 71 (11-12) ◽  
pp. 1557-1570 ◽  
Author(s):  
Vilve Nummert ◽  
Mare Piirsalu ◽  
Ilmar A. Koppel
Keyword(s):  
Kinetic Study ◽  
Alkaline Hydrolysis ◽  
Rate Constants ◽  
Substituent Effect ◽  
Substituent Effects ◽  
Alkyl Substituent ◽  
Solvent Parameters ◽  
Substituent Constants ◽  
Hydrolysis Of ◽  
Main Factor

The second-order rate constants k2 (dm3 mol-1 s-1) for the alkaline hydrolysis of substituted alkyl benzoates C6H5CO2R have been measured spectrophotometrically in aqueous 0.5 M Bu4NBr at 50 and 25 °C (R = CH3, CH2Cl, CH2CN, CH2C≡CH, CH2C6H5, CH2CH2Cl, CH2CH2OCH3, CH2CH3) and in aqueous 5.3 M NaClO4 at 25 °C (R = CH3, CH2Cl, CH2CN, CH2C≡CH). The dependence of the alkyl substituent effects on different solvent parameters was studied using the following equations:      ∆ log k = c0 + c1σI + c2EsB + c3∆E + c4∆Y + c5∆P + c6∆EσI + c7∆YσI + c8∆PσI     ∆ log k = c0 + c1σ* + c2EsB + c3∆E + c4∆Y + c5∆P + c6∆Eσ* + c7∆Yσ* + c8∆Pσ* .  ∆ log k = log kR - log kCH3. σI and σ* are the Taft inductive and polar substituent constants. E, Y and P are the solvent electrophilicity, polarity and polarizability parameters, respectively. In the data treatment ∆E = ES - EH2O , ∆Y = YS - YH2O , ∆P = PS - PH2O were used. The solvent electrophilicity, E, was found to be the main factor responsible for changes in alkyl substituent effects with medium. When σI constants were used, variation of the polar term of alkyl substituents with the solvent electrophilicity E was found to be similar to that observed earlier for meta and para substituents, but twice less when σ* constants were used. The steric term for alkyl substituents was approximately independent of the solvent parameters.

Substituent Effect on Emission of Flavonolate-Boron Difluoride Complexes: The Role of π-system for Dual-state (Solution and Solid) Emission

2020 ◽  
pp. 109081
Author(s):  
Keiji Ohno ◽  
Fuka Narita ◽  
Hidehisa Yokobori ◽  
Nanami Iiduka ◽  
Tomoaki Sugaya ◽  
...  
Keyword(s):  
Substituent Effect ◽  
State Solution ◽  
Boron Difluoride

scholarly journals Deciphering the Role of π-Interactions in Polyelectrolyte Complexes Using Rationally Designed Peptides

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2074
Author(s):  
Sara Tabandeh ◽  
Cristina Elisabeth Lemus ◽  
Lorraine Leon
Keyword(s):  
Hydrogen Bonding ◽  
Phase Separation ◽  
Liquid Phase ◽  
Charge Density ◽  
Secondary Structures ◽  
Liquid Phase Separation ◽  
Polyelectrolyte Complexes ◽  
Π Interactions ◽  
Liquid Liquid Phase Separation

Electrostatic interactions, and specifically π-interactions play a significant role in the liquid-liquid phase separation of proteins and formation of membraneless organelles/or biological condensates. Sequence patterning of peptides allows creating protein-like structures and controlling the chemistry and interactions of the mimetic molecules. A library of oppositely charged polypeptides was designed and synthesized to investigate the role of π-interactions on phase separation and secondary structures of polyelectrolyte complexes. Phenylalanine was chosen as the π-containing residue and was used together with lysine or glutamic acid in the design of positively or negatively charged sequences. The effect of charge density and also the substitution of fluorine on the phenylalanine ring, known to disrupt π-interactions, were investigated. Characterization analysis using MALDI-TOF mass spectroscopy, H NMR, and circular dichroism (CD) confirmed the molecular structure and chiral pattern of peptide sequences. Despite an alternating sequence of chirality previously shown to promote liquid-liquid phase separation, complexes appeared as solid precipitates, suggesting strong interactions between the sequence pairs. The secondary structures of sequence pairs showed the formation of hydrogen-bonded structures with a β-sheet signal in FTIR spectroscopy. The presence of fluorine decreased hydrogen bonding due to its inhibitory effect on π-interactions. π-interactions resulted in enhanced stability of complexes against salt, and higher critical salt concentrations for complexes with more π-containing amino acids. Furthermore, UV-vis spectroscopy showed that sequences containing π-interactions and increased charge density encapsulated a small charged molecule with π-bonds with high efficiency. These findings highlight the interplay between ionic, hydrophobic, hydrogen bonding, and π-interactions in polyelectrolyte complex formation and enhance our understanding of phase separation phenomena in protein-like structures.

scholarly journals Specificity of the HIV-1 Protease on Substrates Representing the Cleavage Site in the Proximal Zinc-Finger of HIV-1 Nucleocapsid Protein

Viruses ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 1092
Author(s):  
János András Mótyán ◽  
Márió Miczi ◽  
Stephen Oroszlan ◽  
József Tőzsér
Keyword(s):  
Amino Acid ◽  
Zinc Finger ◽  
Cleavage Site ◽  
Potential Role ◽  
Binding Mode ◽  
Interaction Energies ◽  
Vitro Assay ◽  
Hiv 1

To explore the sequence context-dependent nature of the human immunodeficiency virus type 1 (HIV-1) protease’s specificity and to provide a rationale for viral mutagenesis to study the potential role of the nucleocapsid (NC) processing in HIV-1 replication, synthetic oligopeptide substrates representing the wild-type and modified versions of the proximal cleavage site of HIV-1 NC were assayed as substrates of the HIV-1 protease (PR). The S1′ substrate binding site of HIV-1 PR was studied by an in vitro assay using KIVKCF↓NCGK decapeptides having amino acid substitutions of N17 residue of the cleavage site of the first zinc-finger domain, and in silico calculations were also performed to investigate amino acid preferences of S1′ site. Second site substitutions have also been designed to produce “revertant” substrates and convert a non-hydrolysable sequence (having glycine in place of N17) to a substrate. The specificity constants obtained for peptides containing non-charged P1′ substitutions correlated well with the residue volume, while the correlation with the calculated interaction energies showed the importance of hydrophobicity: interaction energies with polar residues were related to substantially lower specificity constants. Cleavable “revertants” showed one residue shift of cleavage position due to an alternative productive binding mode, and surprisingly, a double cleavage of a substrate was also observed. The results revealed the importance of alternative binding possibilities of substrates into the HIV-1 PR. The introduction of the “revertant” mutations into infectious virus clones may provide further insights into the potential role of NC processing in the early phase of the viral life-cycle.

Role of non-covalent interactions in the supramolecular architectures of mercury(ii) diphenyldithiophosphates: An experimental and theoretical investigation

2021 ◽  
Vol 45 (4) ◽  
pp. 2249-2263
Author(s):  
Pretam Kumar ◽  
Snehasis Banerjee ◽  
Anu Radha ◽  
Tahira Firdoos ◽  
Subash Chandra Sahoo ◽  
...  
Keyword(s):  
Theoretical Investigation ◽  
Supramolecular Organization ◽  
Π Interactions ◽  
Supramolecular Architectures ◽  
Non Covalent Interactions ◽  
Covalent Interactions

The H-bond, spodium bond and CH⋯π interactions playing an important role in the supramolecular organization of two mercury(ii) diphenyldithiophosphate complexes have been discussed.

Sign in / Sign up

Export Citation Format

Share Document