Outer Benzene Research Articles

Synthesis and Properties of Pyridofluoranthenes

AbstractA series of N‐doped Benzo[b]fluoranthenes was synthesized. Specifically varying the position of the Nitrogen atom in all four positions of the bottom ring. In the last reaction step the five‐membered ring of the unsubstituted core structure is formed by palladium catalyzed CH‐activation. This synthetic approach allows for the selective introduction of heteroatoms into the core structure and leads to four regioisomeric products. Subsequently the optical and electrochemical properties of these polyaromatic heterocycles were compared. DFT/TD‐DFT and NICS calculations were performed to further analyze, how the position of Nitrogen impacts the overall characteristics of the molecules. This composes a thorough study on the chemical behavior of N‐doped Benzo[b]fluoranthenes.

Successive Free-Radical C(sp 2 )–C(sp 2 ) Coupling Reactions to Form Graphene

Successive Free-Radical C(sp ² )–C(sp ² ) Coupling Reactions to Form Graphene

Layered Hexaphenylbenzene (HPB) derivatives with pseudo-2D structure for high-performance Li ion batteries

Herein, we have synthesized a series of hexaphenylbenzene (HPB) derivatives: HPB-H, HPB-COOCH3 and HPB-COOH that differs in functional groups attached to the periphery of the outer benzene rings. Among them, the HPB with carboxyl functional group (HPB-COOH) as LIB anode shows a superior capacity of 997.4 mAh g−1 and better rate performance than HPB and HPB-COOCH3. Such superior anode properties can be attributed to the fact that HPB-COOH has a layered morphology, a pseudo-2D structure, lower LUMO energy, and higher electron conductivity, compared with that of HPB-COOCH3 and HPB-H, respectively. Moreover, low energy packing with transport channels is beneficial for Li ions diffusion during the lithiation and extraction processes. Furthermore, HPB-COOH shows excellent cycling stability presumably due to its layered molecular packing structures. Our work paves the way for the design synthesis of novel organic molecules with suitable electrochemical redox-active groups and layered hierarchical structure to achieve high capacity, good rate performance, and high cyclic stability for next generation Li ion batteries (LIBs).

Biaxial ordering in the supercooled nematic phase of bent-core mesogens: effects of molecular symmetry and outer wing lateral groups

ABSTRACT In previous research, we have found that the incorporation of three lateral substituents on bent-core oxadiazole-based liquid crystals has allowed for the presence of a nematic phase that supercooled to room temperature. X-ray diffraction (XRD) studies of these derivatives have confirmed that the nematic phase consists of cybotactic clusters. Moreover, the wide-angle XRD pattern showed a splitting indicative of local biaxial ordering within this phase. In this paper, we report the phase behaviour of two series of compounds that contain up to four lateral methyl groups. In one series, the arrangement of the lateral groups is symmetrical, and in the other case, the groups are not symmetrically distributed. All of the non-symmetric derivatives supercool to room temperature in the nematic phase, while symmetric derivatives tend to crystallise well above room temperature. XRD analysis of all of these compounds indicates the presence of cybotactic order. However, a splitting of the wide-angle XRD pattern is observed only in derivatives with lateral groups on the outer benzene rings, regardless of their supercooling behaviour, indicating the crucial influence of these substituents on the molecular packing.

Crystal structures and Hirshfeld surface analyses of 4,4'-{[1,3-phenyl-enebis(methyl-ene)]bis-(-oxy)}bis-(3-meth-oxy-benzaldehyde) and 4,4'-{[(1,4-phenyl-ene-bis(methyl-ene)]bis-(-oxy)}bis-(3-meth-oxy-benzalde-hyde).

The title compounds, C24H22O6 (I) and C24H22O6 (II), each crystallize with half a mol-ecule in the asymmetric unit. The whole mol-ecule of compound (I) is generated by twofold rotation symmetry, the twofold axis bis-ecting the central benzene ring. The whole mol-ecule of compound (II) is generated by inversion symmetry, the central benzene ring being located on an inversion center. In (I), the outer benzene rings are inclined to each other by 59.96 (10)° and by 36.74 (9)° to the central benzene ring. The corresponding dihedral angles in (II) are 0.0 and 89.87 (12)°. In the crystal of (I), mol-ecules are linked by C-H⋯O hydrogen bonds and C-H⋯π inter-actions, forming ribbons propagating along the [10] direction. In the crystal of (II), mol-ecules are linked by C-H⋯O hydrogen bonds, forming a supra-molecular framework. The Hirshfeld surface analyses indicate that for both compounds the H⋯H contacts are the most significant, followed by O⋯H/H⋯O and C⋯H/H⋯C contacts.

Persistent Solid‐State Phosphorescence and Delayed Fluorescence at Room Temperature by a Twisted Hydrocarbon

AbstractThe dehydrating cyclotrimerization of 1‐tetralone in the presence of titanium tetrachloride at high temperatures leads to homotruxene, a nonplanar arene in which the twist angles between its three outer benzene rings and the central benzene are stabilized by ethylene bridges. This non‐planar configuration allows for pronounced spin–orbit coupling and a high triplet energy, leading to room‐temperature phosphorescence in air with a lifetime of 0.38 s and a quantum yield of 5.6 %, clearly visible to the human eye after switching off the excitation. Triplet–triplet annihilation is found to simultaneously lead to a substantial delayed fluorescence, unprecedented from a pure hydrocarbon at ambient conditions, with a lifetime of 0.11 s.

Persistent Solid‐State Phosphorescence and Delayed Fluorescence at Room Temperature by a Twisted Hydrocarbon

The dehydrating cyclotrimerization of 1-tetralone in the presence of titanium tetrachloride at high temperatures leads to homotruxene, a nonplanar arene in which the twist angles between its three outer benzene rings and the central benzene are stabilized by ethylene bridges. This non-planar configuration allows for pronounced spin-orbit coupling and a high triplet energy, leading to room-temperature phosphorescence in air with a lifetime of 0.38 s and a quantum yield of 5.6 %, clearly visible to the human eye after switching off the excitation. Triplet-triplet annihilation is found to simultaneously lead to a substantial delayed fluorescence, unprecedented from a pure hydrocarbon at ambient conditions, with a lifetime of 0.11 s.

Can Baird's and Clar's Rules Combined Explain Triplet State Energies of Polycyclic Conjugated Hydrocarbons with Fused 4nπ- and (4n + 2)π-Rings?

Compounds that can be labeled as "aromatic chameleons" are π-conjugated compounds that are able to adjust their π-electron distributions so as to comply with the different rules of aromaticity in different electronic states. We used quantum chemical calculations to explore how the fusion of benzene rings onto aromatic chameleonic units represented by biphenylene, dibenzocyclooctatetraene, and dibenzo[a,e]pentalene modifies the first triplet excited states (T1) of the compounds. Decreases in T1 energies are observed when going from isomers with linear connectivity of the fused benzene rings to those with cis- or trans-bent connectivities. The T1 energies decreased down to those of the parent (isolated) 4nπ-electron units. Simultaneously, we observe an increased influence of triplet state aromaticity of the central 4n ring as given by Baird's rule and evidenced by geometric, magnetic, and electron density based aromaticity indices (HOMA, NICS-XY, ACID, and FLU). Because of an influence of triplet state aromaticity in the central 4nπ-electron units, the most stabilized compounds retain the triplet excitation in Baird π-quartets or octets, enabling the outer benzene rings to adapt closed-shell singlet Clar π-sextet character. Interestingly, the T1 energies go down as the total number of aromatic cycles within a molecule in the T1 state increases.

2,2′-[(1E,1′E)-1,2-Phenylenebis(azanylylidene)bis(methanylylidene)]bis(4-bromophenol)

In the title compound, C20H14Br2N2O2, there are two intramolecular O—H...N hydrogen bonds forming S(6) ring motifs. The outer benzene rings are inclined to the central benzene ring by 39.09 (11) and 24.31 (11)°, and to one another by 37.12 (11)°. In the crystal, molecules are linked by a short Br...O contact [3.1307 (19) Å], forming zigzag chains propagating along the a-axis direction. The chains are linked by weak offset π–π interactions [intercentroid distance = 3.716 (1) Å], forming layers parallel to the ac plane.

2-(5-Bromothiophen-2-yl)-1-phenyl-1H-phenanthro[9,10-d]imidazole

In the title molecule, C25H15BrN2S, the phenanthrene system is slightly skewed, with a dihedral angle of 8.94 (16)° between the outer benzene rings. The imidazole ring makes dihedral angles of 15.18 (16), 2.94 (15) and 88.46 (16)°, respectively, with the thiophene ring, the central benzene ring of the phenanthrene unit and the phenyl ring attached to the latter unit. In the molecule, there are two C—H...π interactions present involving the phenyl ring. In the crystal, molecules are linked by C—H...N and C—H...Br hydrogen bonds, forming zigzag chains along the a axis. The chains are linked by C—H...π interactions, forming a three-dimensional supramolecular structure.

Crystal structure of N-{4-[(6-chloro-pyridin-3-yl)meth-oxy]phen-yl}-2,6-di-fluoro-benzamide.

In the title compound, C19H13ClF2N2O2, the conformation of the N-H bond in the amide segment is anti to the C=O bond. The mol-ecule is not planar, with dihedral angles between the central benzene ring and the outer benzene and pyridyl rings of 73.35 (7) and 81.26 (6)°, respectively. A weak intra-molecular C-H⋯O hydrogen bond occurs. In the crystal, N-H⋯N, C-H⋯O and C-H⋯F hydrogen bonds lead to the formation of dimers. The N-H⋯N inversion dimers are linked by π-π contacts between adjacent pyridine rings [centroid-centroid = 3.8541 (12) Å] and C-H⋯π inter-actions. These contacts combine to stack the mol-ecules along the a axis.

Indacenodibenzothiophenes: synthesis, optoelectronic properties and materials applications of molecules with strong antiaromatic character.

Indeno[1,2-b]fluorenes (IFs), while containing 4n π-electrons, are best described as two aromatic benzene rings fused to a weakly paratropic s-indacene core. In this study, we find that replacement of the outer benzene rings of an IF with benzothiophenes allows the antiaromaticity of the central s-indacene to strongly reassert itself. Herein we report a combined synthetic, computational, structural, and materials study of anti- and syn-indacenodibenzothiophenes (IDBTs). We have developed an efficient and scalable synthesis for preparation of a series of aryl- and ethynyl-substituted IDBTs. NICS-XY scans and ACID calculations reveal an increasingly antiaromatic core from [1,2-b]IF to anti-IDBT, with syn-IDBT being nearly as antiaromatic as the parent s-indacene. As an initial evaluation, the intermolecular electronic couplings and electronic band structure of a diethynyl anti-IDBT derivative reveal the potential for hole and / or electron transport. OFETs constructed using this molecule show the highest hole mobilities yet achieved for a fully conjugated IF derivative.

Donor–Acceptor-Type Semiconducting Polymers Consisting of Benzothiadiazole Derivatives as Electron-Acceptor Units for Organic Photovoltaic Cells

We synthesized two fused pentacyclic donor-acceptor structures, where the two different outer electron rich thiophene (DTPBT) and electron poor benzene (ICTh) moieties are covalently bonded to the central electron-deficient benzothiadiazole core by two nitrogen bridges. These new electron-acceptor DTPBT and ICTh building blocks were copolymerized with fluorene, as the electron donor group, via Suzuki coupling polymerization, to produce two new alternating copolymers, PFDTPBT and PFICTh, respectively. The average molecular weights of the synthesized polymers were determined by GPC. The number-average molecular weights of PFDTPBT and PFICTh were 19,000 (PDI = 2.5) and 20,000 (PDI = 4.0), respectively. The optical bandgap energies of the polymers were measured from their absorption onsets to be 2.15 and 2.55 eV, depending on the polymer structure. The HOMO energy levels of the polymers were determined, by measuring the oxidation onsets of the polymer films by cyclic voltammetry. The measured HOMO energy levels of PFDTPBT and PFICTh were -5.10 and -5.57 eV, respectively. When the polymers were blended with PC71BM, as the active layer for bulk-heterojunction photovoltaic devices, power conversion efficiencies were 2.08% and 0.34%, respectively, under AM 1.5 G (100 mW cm(-2)) conditions.

Crystal structure of (E)-1-[4-({4-[(4-meth-oxy-benzyl-idene)amino]-phen-yl}sulfan-yl)phen-yl]ethan-1-one.

The title Schiff base compound, C22H19NO2S, crystallized with two independent mol­ecules (A and B) in the asymmetric unit. Both mol­ecules have an E conformation about the C=N bond. The two mol­ecules differ in the orientation of the aromatic rings with respect to each other. The outer 4-meth­oxy­benzene ring is inclined to the central benzene ring and the outer 4-acetyl­benzene ring by 1.80 (19) and 63.73 (19)°, respectively, in mol­ecule A, and by 6.72 (18) and 68.53 (19)°, respectively, in mol­ecule B. The two outer benzene rings are inclined to one another by 63.77 (18) and 63.19 (18)° in mol­ecules A and B, respectively. In the crystal, the individual mol­ecules stack in columns along [010], and are linked by a number of C—H⋯π inter­actions, forming slabs lying parallel to (001).

A new thieno-isoindigo derivative-based D–A polymer with very low bandgap for high-performance ambipolar organic thin-film transistors

A new thieno-isoindigo derivative was synthesized by replacing the outer benzene ring of the isoindigo derivative (BIBDF) with thiophene.

Crystal structure of (Z)-1-(ferrocenylethyn-yl)-10-(phenyl-imino)-anthracen-9(10H)-one from synchrotron X-ray powder diffraction.

In the title compound, [Fe(C5H5)(C27H16NO)], designed and synthesized to explore a new electron-donor (D) and -acceptor (A) conjugated complex, the two cyclo-penta-dienyl rings adopt an eclipsed conformation. The anthracene tricycle is distorted towards a butterfly conformation and the mean planes of the outer benzene rings are inclined each to other at 22.7 (3)°. In the crystal, mol-ecules are paired into inversion dimers via π-π inter-actions. Weak inter-molecular C-H⋯π inter-actions link further these dimers into one-dimensional columns along the b axis, with the ferrocenylethynyl arms arranged between the stacks to fill the voids.

The Quantum Research on the Nucleophilic Reaction Activity of Polycyclic Aromatic Hydrocarbons

Using the Hartree Fock (RHF) method, we study the most reactive carbon atoms in the polycyclic aromatic hydrocarbons (PAHs). In order to identify the most reactive carbon atoms, the Mulliken charges and the Mayers bond orders were calculated as the criterion. The results demonstrate that the most reactive carbon atoms appear at the locations of the outer C in the inner benzene rings for cata-condensed PAHs, while for peri-condensed PAHs they are the outer C in the outer benzene rings。

Spontaneous formation of chiral macrostructures in achiral hockey-stick liquid crystals

We report the synthesis and properties of a homologous series of asymmetrically substituted 4-(5-(4-benzyloxyphenyl)-1,3,4-oxadiazol-2-yl)phenyl 2-X-4-dodecyloxybenzoates, which have pronounced hockey-stick molecular architectures. The structure was varied through the lateral substitution with various groups, X (H, Me, MeO, Cl, F) in the outer benzene ring. The effect of the lateral group on liquid crystal phase behaviour was investigated by thermal optical microscopy and differential scanning calorimetry. Nematic and dark conclomerate phases were observed with both displaying macroscopically chiral domains.

Dimethyl 2-[(acridin-9-yl)methylidene]malonate

In the title compound, C19H15NO4, the acridine system is essentially planar (r.m.s. deviation = 0.015 Å). The crystal packing exhibits π–π inter­actions between pairs of centrosymmetric mol­ecules, one of them between the central heterocyclic rings and others between the outer benzene rings of the acridine systems, with centroid–centroid distances of 3.692 (1) and 3.754 (1) Å, respectively. These pairs are further linked by additional π–π inter­actions along the a-axis direction through one of the two outer benzene ring of neighboring mol­ecules, with a centroid–centroid distance of 3.642 (2) Å.

7-Bromo-1-(3-fluorophenylsulfonyl)-2-methylnaphtho[2,1-b]furan

In the title compound, C19H12BrFO3S, the 3-fluoro­phenyl ring makes a dihedral angle of 80.85 (5)° with the mean plane [r.m.s. deviation = 0.009 (2)Å] of the naphtho­furan fragment. In the crystal, mol­ecules are linked by slipped π–π inter­actions between the furan and the outer benzene rings of neighbouring mol­ecules [centroid–centroid distance = 3.756 (3) Å and slippage of 1.189 (3) Å].