Search results for "Aromaticity"
showing 8 items of 138 documents
Rearrangements of 1,2,4-Oxadiazole: “One Ring to Rule Them All”
2017
[Figure not available: see fulltext.] 1,2,4-Oxadiazoles are heterocycles characterized by low aromaticity and the presence of a weak OâN bond and are widely studied due to their tendency to rearrange into more stable heterocyclic compounds. This review covers literature from the last fifteen years, highlighting the general features of 1,2,4-oxadiazoles and their applications. Regarding the reactivity, the development of classical reactions (thermal and photochemical rearrangements) is presented in terms of synthetic utility and mechanistic insight. Among the relevant rearrangement reactions, the BoultonâKatritzky Rearrangement (BKR), Migration â Nucleophilic Attack â Cyclization (MN…
Crystal structure and Hirshfeld surface analysis of (2E)-3-(3-bromo-4-fluorophenyl)-1-(3,4-dimethoxyphenyl)prop-2-en-1-one
2018
The title compound is constructed from two aromatic rings (3-bromo-4-fluorophenyl and 3,4-dimethoxyphenyl), which are linked by a C=C—C(=O)—C enone bridge and form a dihedral angle of 17.91 (17)°. In the crystal, molecules are linked by C—H⋯O hydrogen bonds enclosing rings of (14) graph-set motif to form layers parallel to (10).
Self-assembly mechanism based on charge density topological interaction energies
2017
The packing interactions have been evaluated in the context of the self-assembly mechanism of crystal growth and also for its impacts on the aromaticity of the trimesate anion. The structure of ethylammonium trimesate hydrate (1) measured at 100 K and a charge density model, derived in part from theoretical structures, is reported. Theoretical structure factors were obtained from the geometry-optimized periodic wave function. The trimesic acid portion of 1 is fully deprotonated and participates in a variety hydrogen bonding motifs. Topological analysis of the charge density model reveals the most significant packing interactions and is then compared to a complementary analysis performed by …
Dicyclopentaannelated Hexa-peri-hexabenzocoronenes with a Singlet Biradical Ground State
2021
Abstract Synthesis of two dicyclopentaannelated hexa‐peri‐hexabenzocoronene (PHBC) regioisomers was carried out, using nonplanar oligoaryl precursors with fluorenyl groups: mPHBC 8 with two pentagons in the “meta”‐configuration was obtained as a stable molecule, while its structural isomer with the “para”‐configuration, pPHBC 16, could be generated and characterized only in situ due to its high chemical reactivity. Both PHBCs exhibit low energy gaps, as reflected by UV‐vis‐NIR absorption and electrochemical measurements. They also show open‐shell singlet ground states according to electron paramagnetic resonance (EPR) measurements and density functional theory (DFT) calculations. The use of…
3,5-Dimethoxy-4'-methylbiphenyl
2013
The title compound, C15H16O2, crystallizes with three independent molecules in the asymmetric unit. The intramolecular torsion angle between the aromatic rings of each molecule are −36.4 (3), 41.3 (3) and −37.8 (3)°. In the crystal, the complicated packing of the molecules forms wave-like layers along the b and c axes. The molecules are connected via extensive methoxy–phenyl C—H…π interactions. A weak C—H…O hydrogen-bonding network also exists between methoxy O atoms and aromatic or methoxy H atoms.
3,4-Dimethoxy-4'-methylbiphenyl
2013
In the title compound, C15H16O2, the dihedral angle between the planes of the aromatic rings is 30.5 (2). In the crystal, molecules are linked via C—HO hydrogen bonds and C— H interactions, forming a two-dimensional network lying parallel to (100). peerReviewed
Crystal Structures and Density Functional Theory Calculations of o-and p-Nitroaniline Derivatives: Combined Effect of Hydrogen Bonding and aromatic i…
2013
The interplay of strong and weak hydrogen bonds, dipole–dipole interactions, and aromatic interactions of o- and p-nitroaniline derivatives was studied by combining crystal structure analysis and density functional theory (DFT) calculations. Crystal structures of four 2-nitroaniline derivatives, 2-((2-nitrophenyl)amino)ethyl methanesulfonate (1A), 2-((2-nitrophenyl)amino)ethyl 4-methylbenzenesulfonate (2A), N,N′-((1,3-phenylenebis(oxy))bis(ethane-2,1-diyl))bis(2-nitroaniline) (3A), and N-(2-chloroethyl)-2-nitroaniline (4A), and crystal structures of three 4-nitroaniline derivatives, 2-((4-nitrophenyl)amino)ethyl methanesulfonate (1B), 2-((4-nitrophenyl)amino)ethyl 4-methylbenzenesulfonate (…
Właściwości strukturalne i aromatyczność ftalocyjaniny cynku
2017
Metaloftalocyjaniny są grupą związków, które otworzyły nowy rozdział w wielu dziedzinach przemysłu i nauki. Dzięki czterem pierścieniom izoindolowym połączonym ze sobą za pomocą mostków azometinowych, powstaje szesnastoatomowy układ sprzężonych wiązań podwójnych składających się na makrocykl, który zawiera 18 zdelokalizowanych elektronów π spełniając regułę aromatyczności Hückla (4 n + 2, n = 4).Pojęcie aromatyczności jest jednym z najpopularniejszych terminów używanych w analizie związków π-elektronowych. Jej definicja jest niejednoznaczna. Cechami układów aromatycznych są podwyższona trwałość, zmiana długości wiązań oraz szczególne właściwości magnetyczne. Możliwe jest jednak odkształceni…