Stimuli‐Responsive Cyclopenta[ef]heptalenes: Synthesis and Optical Properties

Abstract

We report the one-pot synthesis, 1D and 2D NMR characterization, and UV/Vis study of a series of cyclopenta [ef]heptalenes 4a-c that exhibit strong stimuli-responsive behavior, with a tunable energy gap as a result of perturbation of HOMO, LUMO, and LUMO+1 energies upon doping/dedoping with TFA/Et 3 N. The approach employed allows for the extension of conjugation at C-4 of the cyclopenta[ef]heptalene skeleton from X = H (4a) to X = CN (4b) and X = 2-thiophenyl (4c), resulting in longer absorption maxima and

Biazulene diimides: a new building block for organic electronic materials

“… 3 On the other hand, azulene and its derivatives have attracted more and more attention in materials science due to their unique optical and electronic properties. 4 For example, azulene derivatives have been used for developing advanced organic materials, including liquid crystals, 5 molecular switches, 6 anion receptors/sensors, 7 nonlinear optical materials, 8 organic/polymeric conductors, 9 and near-infrared resonance materials. 10 In recent years, azulene derivatives have attracted ever increasing attention due to their successful applications in organic electronic and photovoltaic devices, such as organic field-effect transistors (OFETs), 11 organic photovoltaics (OPVs), 12 and perovskite solar cells.…”

Gold(III) Meets Azulene: A Class of [(tBuC∧N∧C)AuIII(azulenyl)] Pincer Complexes

“…Despite the long history of azulene, − this molecule is still in the focus of chemists and especially in the past decade high interest in the development of efficient and modular azulene syntheses has arisen, which can be rationalized by its extraordinary properties and the potential for material science, − bioimaging, − medicinal chemistry, − and stimuli-response materials. − Azulenes are bicyclic aromatics, which contain an electron-rich five-membered ring and an electron-deficient seven-membered ring. This delocalization in the molecular architecture of azulene induces a dipole moment of 1.08 D. This unique dipolar structure, paired with the optical properties, makes azulenes promising candidates for second-order nonlinear optical (NLO) materials, Organic field-effect transistors (OFETs), solar cells, and molecular devices. − ,− …”

Two Isomeric Azulene-Decorated Naphthodithiophene Diimide-based Triads: Molecular Orbital Distribution Controls Polarity Change of OFETs Through Connection Position

“…Azulene is a resonance-stabilized nonalternant aromatic hydrocarbon with a large dipole moment (1.08 D) that arises from the electron drift from its electron-deficient seven-membered ring to its electron-rich five-membered ring (Figure a) . Density functional theory (DFT) calculations on azulene reveal that the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) are not “mirror-related” in molecular orbital (MO) geometry, and their charge distributions are nonuniform (Figure b). − Owing to their unique electronic structure and unusual photophysical properties, azulene and its derivatives have been widely used in various applications, including nonlinear optical materials, − conducting polymers, , fluorescence switchings, − electrochromic materials, − near-infrared (IR) absorption materials, − organic solar cells, − and so forth. In recent years, azulene has also been studied as the building block for the development of π-functional materials used in organic field-effect transistors (OFETs). − BAzSQ1, as the first example of azulene-based OFET materials (Figure c), exhibits an ambipolar transport characteristic with electron mobilities of ∼10 –4 cm 2 V –1 s –1 and hole mobilities of ∼10 –3 cm 2 V –1 s –1 .…”