One step Pd(0)-catalyzed synthesis, X-ray analysis, and photophysical properties of cyclopent[hi]aceanthrylene: fullerene-like properties in a nonalternant cyclopentafused aromatic hydrocarbon

Bisindeno Fusion on the Zigzag Edge of Bis(benzooxa)-2,6-anthraquinodimethane: Effect on Diradical Character, Photostability, and Redox Properties

We report the synthesis of the bis(benzooxa)-2,6-anthraquinodimethane (BAQ) derivative and its bisindeno fused analogue BIBAQ. We found bisindeno fusion on the quinoidal zigzag edge of BAQ results in decreased diradical character and corresponding increased photostability. Furthermore, BAQ could only be oxidized into its cationic species, while BIBAQ showed balanced redox properties.

Post-Formation of Fused Pentagonal Structure on Fjord Region of Polyaromatic Hydrocarbons under Hydrothermal Conditions

This study explores the synthesis of cyclopenta-fused polyaromatic hydrocarbons (CP-PAHs) via Pt-catalyzed cyclization in water, focusing on the formation of fused pentagonal rings within heavily fused PAH frameworks. Utilizing platinum catalysts at lower temperatures (200-260 °C) in water, led to the successful synthesis of singly cyclized CP-PAHs. The reaction conditions facilitated the mono-cyclization of substrates such as dibenzo[g,p]chrysene and its isomers, yielding the desired products while suppressing the formation of bis-cyclized compounds. The use of Fe2O3 as an additive in conjunction with PtO2 was effective to suppress hydrogenation of the substrates and products. The products exhibited a redshift in UV-visible absorption and photoluminescence bands due to a decrease in the HOMO-LUMO energy gap. These findings highlight the potential of Pt-catalyzed cyclization for the controlled synthesis of CP-PAHs, with implications for various applications in materials science.

Buckybowl and its chiral hybrids featuring eight-membered rings and helicene units

Here we report the synthesis of a novel buckybowl (7) with a high bowl-to-bowl inversion barrier (ΔG‡ = 38 kcal mol-1), which renders the rate of inversion slow enough at room temperature to establish two chiral polycyclic aromatic hydrocarbons (PAHs). By strategic fusion of eight-membered rings to the rim of 7, the chiral hybrids 8 and 9 are synthesized and display helicity and positive and negative curvature, allowing the enantiomers to be configurationally stable and their chiroptical properties are thoroughly examined. Computational and experimental studies reveal the enantiomerization mechanisms for the chiral hybrids and demonstrate that the eight-membered ring strongly affects the conformational stability. Because of its static and doubly curved conformation, 9 shows a high binding affinity towards C60. The OFET performance of 7-9 could be tuned and the hybrids show ambipolar characteristics. Notably, the 9·C60 cocrystal exhibits well-balanced ambipolar performance with electron and hole mobilities of up to 0.19 and 0.11 cm2 V-1 s-1, respectively. This is the first demonstration of a chiral curved PAH and its complex with C60 for organic devices. Our work presents new insight into buckybowl-based design of PAHs with configurational stability and intriguing optoelectronic properties.

Highly Substituted Acephenanthrylenes and Their π-Extended Derivatives: Syntheses, Structural Analyses, and Properties

This investigation demonstrates that a series of (highly) substituted acephenanthrylenes (APs) 2, benzo[l]acephenanthrylene 3, and dicyclopenta[cd,mn]pyrene 4 are easily prepared by palladium-catalyzed cycloaromatization of 2,3-diethynylbiphenyls 1. The first nonpyrolysis synthesis of 4 by two-fold cycloaromatization was achieved in a high yield. This synthetic protocol has two crucial advantages: facile introduction of various substituents and efficient extension of the AP backbone.

π-Expanded triple [5]helicenes bearing dibenzocoronene monoimide subunits

Two novel π-expanded triple [5]helicenes containing three dibenzocoronene monoimide subunits have been synthesized and characterized. The helicenes exhibit low-energy conformational interconversions, as supported by NMR spectra. The single-crystal X-ray analysis reveals a C₁ conformation in the solid state. Furthermore, the helicenes exhibit ambipolar transport characteristics in thin film transistors.

Benzodithiophene-Fused Cyclopentannulated Aromatics via a Palladium-Catalyzed Cyclopentannulation and Scholl Cyclodehydrogenation Strategy

We report the synthesis of a new class of cyclopenta-fused polyaromatic hydrocarbon (CP-PAH) incorporating fused benzodithiophene subunits. These CP-PAHs were prepared utilizing a two-step process involving a palladium catalyzed cyclopentannulation followed by a Scholl cyclodehydrogenation. This work broadens the scope of annulation chemistry by employing 1,2-bis(5-hexylthiophen-3-yl)ethyne and dibromoaryl derivatives based on anthracene, pyrene, and perylene to give 4,4',4'',4'''-(cyclopenta[hi]aceanthrylene-1,2,6,7-tetrayl)tetrakis(2-hexylthiophene), 4,4',4'',4'''-(dicyclopenta[cd,jk]pyrene-1,2,6,7-tetrayl)tetrakis(2-hexylthiophene), and 1,2,7,8-tetrakis(5-hexylthiophen-3-yl)-1,2,7,8-tetrahydrodicyclopenta[cd,lm]perylene. Scholl cyclodehydrogenation of the pendant thiophene units provided access to the π-extended polyaromatic systems 2,5,11,14-tetrahexylrubiceno[5,4-b:6,7-b':12,11-b'':13,14-b''']tetrathiophene, 2,5,11,14-tetrahexyldithieno-[4,5:6,7]indeno[1,2,3-cd]dithieno[4,5:6,7]indeno-[1,2,3-jk]pyrenes, and 2,9,12,19-tetrahexyldithieno[4,5:6,7]indaceno[1,2,3-cd]dithieno[4,5:6,7]indaceno[1,2,3-lm]perylene that possess helicene-like fragments. The anthracene-based CP-PAH was contorted owing to [5]helicene-like arrangements, while the pyrene- and perylene-based systems were essentially planar. The fully conjugated small molecules give low optical gaps (1.7-2.1 eV) with broad light absorption. The HOMO and LUMO energies of the CP-PAHs were found to be in the range of -5.48 to -5.05 eV and -3.48 to -3.14 eV, respectively. Finally, the anthracene-based CP-PAH was found to be a p-type semiconductor when tested in an organic field effect transistor.

A Tetraindeno-Fused Bis(anthraoxa)quinodimethane with Nine Consecutively Fused Six-Membered Rings

A tetraindeno-fused bis(anthraoxa)quinodimethane RBR with nine consecutively fused six-membered rings in a row was synthesized. Its structure was confirmed by X-ray crystallographic analysis and NMR measurement. Compared with an unfused analogue ABA, the indeno fusion onto the zigzag edges not only enhanced the photostability but also dramatically tuned the electronic properties. Due to the existence of two rubicene units, RBR can also be readily reduced to form a radical anion and dianion.

One-pot synthesis of dicyclopenta-fused peropyrene via a fourfold alkyne annulation

A novel dicyclopenta-fused peropyrene derivative 1 was synthesized via a palladium-catalyzed four-fold alkyne annulation of 1,3,6,8-tetrabromo-2,7-diphenylpyrene (5) with diphenylacetylene. The annulative π-extension reaction toward 1 involved a twofold [3 + 2] cyclopentannulation and subsequent twofold [4 + 2] benzannulation. The structure of 1 is unambiguously confirmed by X-ray crystallography; 1 adopted a twisted geometry due to the steric hindrance of the phenyl rings and the hydrogen substituents at the bay regions. Notably, compound 1 exhibits a narrow energy gap (1.78 eV) and a lower LUMO energy level than the parent peropyrene without the fusion of the five-membered rings. In addition, the effects of the peri-fused pentagons on the aromaticity and molecular orbitals of 1 were evaluated by theoretical calculations. This work presents an efficient method to develop π-extended aromatic hydrocarbons with cyclopenta moieties.

Quadrupolar Cyclopenta[hi]aceanthrylene-Based Electron Donor-Acceptor-Donor Conjugates: Charge Transfer versus Charge Separation

Cyclopenta[hi]aceanthrylenes (CPAs) have been functionalized at two of the peripheral positions with electronically inert trimethylsilylethynyl (1), as well as with electron-donating 4-ethynyl-N,N-dimethylaniline (2), ethynyl Zn^II phthalocyanine (3), and ethynyl Zn^II porphyrin (4) units. Consistent with X-ray crystal structures of 2 and 4, analyses of absorption and fluorescence of 2-4 point to strong electronic communication between the CPA and the peripheral units, affording quadrupolar electron donor-acceptor-donor charge-transfer conjugates. By virtue of their quadrupolar/dipolar charge-transfer characters in the excited state, 2-4 exhibit fluoro-solvatochromism. Transient absorption spectroscopy confirmed delocalized quadrupolar ground states and formation of weakly solvent stabilized quadrupolar singlet excited states. The latter transform into strongly stabilized dipolar excited states before deactivating to the ground state in 2 and give rise to a fully charge separated state in 3 and 4.

Self-assembly of a redox-active bolaamphiphile into supramolecular vesicles

Self-assembly of a redox-active bolaamphiphile leads to the formation of narrow-bandgap supramolecular vesicles.

Prolonged Charge Separated States in Twisted Stacks of All-Carbon Donor and Acceptor Chromophores

Twisted donor-on-donor and acceptor-on-acceptor bicontinuous assembly in all-carbon pyren-1-ylaceanthrylene (PA) dyad extends the survival time of the photoinduced radical ion-pair intermediates. Aceanthrylene, a functional analog of C₇₀, acts as a versatile electron acceptor owing to its high electron affinity and visible light absorption. Antithetical trajectories of the excitons in the nonparallel π-ways led to persistent radical ion-pair intermediates in aggregated (τ_cr^A ∼ 1.28 ns) vs monomeric (τ_cr^M ≤ 110 fs) PA dyad as observed using femtosecond transient absorption spectroscopy. Marcus theory of charge transfer rates predicts an ambipolar transport characteristic in crystalline PA, thereby endorsing PA as an all-carbon DA hybrid for nonfullerene photovoltaic applications.

Dicyclopenta[cd,jk]pyrene based acceptors in conjugated polymers

Reduced band gap materials via cyclopenta-fused polycyclic aromatic hydrocarbon inclusion in donor–acceptor copolymers.

Vibrational spectroscopic studies and molecular docking of 10,10-Dimethylanthrone

FT-IR and FT-Raman spectra of 10,10-Dimethylanthrone were recorded and analyzed. The vibrational wavenumbers were computed using DFT quantum chemical calculations. The data obtained from wavenumber calculations are used to assign vibrational bands obtained experimentally. In its most stable form, the title compound maintains C2v symmetry as determined by XRD results, where both methyl groups are staggered with respect to the corresponding C23-C24 and C23-C28 bonds. The geometrical parameters (B3LYP/6-311++G(d,p)(5D,7F)) of the title compound are in agreement with the XRD results. The calculated HOMO and LUMO energies allow the calculations of atomic and molecular properties and they also showed that charge transfer occurs in the molecule. A detailed molecular picture of the title compound and its interactions were obtained from NBO analysis. As seen from the MEP map, negative potential regions are localized over the carbonyl group and are possible sites for electrophilic attack. The title compound, 10,10-Dimethylanthrone forms a stable complex with human topoisomerase-II as is evident from the ligand-receptor interactions and show appreciable antineoplastic activity.

Anthanthrene as a large PAH building block for the synthesis of conjugated polymers

New anthanthrene-based conjugated polymers exhibiting promising optical and electronic properties for organic electronics applications were prepared from low-cost vat orange 3.

Diindeno[1,2-g:1′,2′-s]rubicene: all-carbon non-fullerene electron acceptor for efficient bulk-heterojunction organic solar cells with high open-circuit voltage

An all carbon non-fullerene electron acceptor material based on diindeno[1,2-g:1′,2′-s]rubicene (DIR) was readily synthesized and processed for bulk-heterojunction organic solar cells.

Metal-catalyzed annulation reactions for π-conjugated polycycles

The progress of the metal-catalyzed annulation reactions toward construction of various π-conjugated polycyclic cores with high conjugation extension is described. This article gives a brief overview of various annulation reactions promoted by metal catalysts including C-H bond functionalization, [2+2+2] cycloaddition, cascade processes, ring closing metathesis, electrophilic aromatization, and various cross-coupling reactions. A variety of conjugated polycycles with planar, bowl-shaped, and helical structures have been constructed in high efficiency and selectivity.

Vibrational spectroscopic (FT-IR, FT-Raman, SERS) and quantum chemical calculations of 3-(10,10-dimethyl-anthracen-9-ylidene)-N,N,N-trimethylpropanaminiium chloride (Melitracenium chloride)

FT-IR, FT-Raman spectra of Melitracenium chloride were recorded and analyzed. SERS spectrum was recorded in silver colloid. The vibrational wavenumbers were computed using DFT quantum chemical calculations. The data obtained from wavenumber calculations are used to assign vibrational bands obtained in infrared and Raman spectra as well as in SERS of the studied molecule. Potential energy distribution was done using GAR2PED program. The geometrical parameters (SDD) of the title compound are in agreement with the XRD results. The presence anthracene ring modes in the SERS spectrum suggest a tilted orientation with respect to the metal surface. The methyl groups in the title molecule are also close to the metal surface. The first hyperpolarizability, NBO analysis and molecular electrostatic potential results are also reported.

Electron acceptors based on functionalizable cyclopenta[hi]aceanthrylenes and dicyclopenta[de,mn]tetracenes

We report the synthesis and selective functionalization of two externally fused cyclopenta-fused polycyclic aromatic hydrocarbons (CP-PAHs) and demonstrate their electron accepting behavior. 2,7-Bis(trimethylsilyl)cyclopenta[hi]aceanthrylene (1) and 2,8-bis(trimethylsilyl)dicyclopenta[de,mn]tetracene (4) were prepared in a one-pot, palladium-catalyzed cross-coupling of (trimethylsilyl)acetylene and either 9,10-dibromoanthracene or 5,11-dibromotetracene, respectively. The trimethylsilyl groups were selectively converted into bromides via substitution with N-bromosuccinimide to create universal partners (2 and 6) for metal-catalyzed cross-coupling reactions. To demonstrate the utility of the halogenated CP-PAHs, we successfully employed a Sonogashira cross-coupling between the CP-PAHs and a phenylacetylene derivative. The resulting compounds (3 and 7) were found to be highly conjugated between the CP-PAH core and the substituents, as demonstrated by large bathochromic shifts in the absorption spectra as well as density functional theory calculations. Ethynylated CP-PAHs 3 and 7 were found to possess low optical bandgaps (1.52 and 1.51 eV, respectively) and displayed two reversible reductions. We further demonstrated the fullerene-like electron-accepting behavior of 3 through solution-phase fluorescence quenching of the prototypical electron donor, poly(3-hexylthiophene).

FT-IR, FT-Raman spectroscopy and computational study of (E)-4-((anthracen-9-ylmethylene)amino)-N-carbamimidoylbenzene sulfonamide

The infrared and Raman spectra of (E)-4-((anthracen-9-ylmethylene)amino)-N-carbamimidoylbenzene sulfonamide have been recorded and analysed. Geometry and harmonic vibrational wavenumbers were calculated theoretically using Gaussian03 set of quantum chemistry codes. The data obtained from vibrational wavenumber calculations are used to assign vibrational bands found in infrared and Raman spectra of the studied molecule. The red-shift of the NH stretching band in the infrared spectrum from the computed wavenumber indicates the weakening of the NH bond. The NH stretching band has split into a doublet in the IR spectrum owing to the Davydov coupling between neighbouring units. The geometrical parameters of the title compound are in agreement with the reported similar derivatives. The calculated first hyperpolarizability is comparable with the reported value of similar structures and may be an attractive object for further studies on non-linear optics. The important thermodynamical parameters are also reported.

4-(9-Anthryl)-2-methylbutyn-2-ol

There are two mol­ecules in the asymmetric unit of the title compound, C₁₉H₁₆O. Neighbouring mol­ecules are linked through O—H⋯O hydrogen bonds into an R₄⁴(8) ring motif. There are also C—H⋯π hydrogen and π–π inter­actions. The mol­ecules are either parallel to each other or are inclined at an angle of 12.5 (1)°.