Oxidative aromatic coupling occupies a fundamental place in the modern chemistry of aromatic compounds. It is a method of choice for the assembly of large and bewildering architectures. Considerable effort was also devoted to applications of the Scholl reaction for the synthesis of chiral biphenols and natural products. The ability to form biaryl linkages without any prefunctionalization provides an efficient pathway to many complex structures. Although the chemistry of this process is only now becoming fully understood, this reaction continues to both fascinate and challenge researchers. This is especially true for heterocoupling, that is, oxidative aromatic coupling with the chemoselective formation of a C-C bond between two different arenes. Analysis of the progress achieved in this field since 2013 reveals that many groups have contributed by pushing the boundary of structural possibilities, expanding into surface-assisted (cyclo)dehydrogenation, and developing new reagents.

Synthetic Applications of Oxidative Aromatic Coupling – from Biphenols to Nanographenes

We present the one-dimensional optical-waveguiding crystal dithieno[3,2-a:2',3'-c]phenazine with a high aspect ratio, high mechanical flexibility, and selective self-absorbance of the blue part of its fluorescence (FL). While macrocrystals exhibit elasticity, microcrystals deposited at a glass surface behave more like plastic crystals due to significant surface adherence, making them suitable for constructing photonic circuits via micromechanical operation with an atomic-force-microscopy cantilever tip. The flexible crystalline waveguides display optical-path-dependent FL signals at the output termini in both straight and bent configurations, making them appropriate for wavelength-division multiplexing technologies. A reconfigurable 2×2-directional coupler fabricated via micromanipulation by combining two arc-shaped crystals splits the optical signal via evanescent coupling and delivers the signals at two output terminals with different splitting ratios. The presented mechanical micromanipulation technique could also be effectively extended to other flexible crystals.

Mechanophotonics: Flexible Single-Crystal Organic Waveguides and Circuits.

Next-Generation Organic Photonics: The Emergence of Flexible Crystal Optical Waveguides

Asymmetric zinc phthalocyanines with alkyl chain substituents formed highly efficient light-harvesting layers on a TiO2 surface. Dye-sensitized solar cells using PcS20 exhibited a record efficiency of 6.4% under one-sun irradiation.

Molecular Engineering of Zinc Phthalocyanine Sensitizers for Efficient Dye-Sensitized Solar Cell

Open-shell singlet diradicaloids display unique electronic, nonlinear optical, and magnetic activity and could become novel molecular materials for organic electronics, photonics, and spintronics. However, design and synthesis of diradicaloids with a significant polyradical character is a challenging task for chemists. In this Article, we report our efforts toward a tetraradicaloid system. A series of potential tetraradicaloids by fusion of two p-quinodimethane (p-QDM) units with naphthalene or benzene rings in different modes were synthesized. Their model compounds containing one p-QDM moiety were also prepared and compared. Their ground-state structures, physical properties, and chemical reactivity were systematically investigated by various experimental methods such as steady-state and transient absorption, two-photon absorption, X-ray crystallographic analysis, electron spin resonance, superconducting quantum interference device, and electrochemistry, assisted by density functional theory calculations. It was found that their diradical and tetraradical characters show a clear dependence on the fusion mode. Upon the introduction of more five-membered rings, the diradical characters greatly decrease. This difference can be explained by the pro-aromaticity/antiaromaticity of the molecules as well as the intramolecular charge transfer. Our comprehensive studies provide a guideline for the design and synthesis of stable open-shell singlet polycyclic hydrocarbons with significant polyradical characters.

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Toward Tetraradicaloid: The Effect of Fusion Mode on Radical Character and Chemical Reactivity

With their electron-rich skeletons, acenes have traditionally been used as hole transporting materials in organic electronic applications. However, prudent structural modifications and revision of the structure of devices can yield good electron mobilities from acene-based organic semiconductors (OSCs). The majority of OSCs predominantly exhibit hole transporting behaviour and there is a scarcity of efficient and operationally stable n-type materials. Organic field effect transistors (OFETs) have been proved to be commercially viable alternatives to their inorganic counterparts, and there is increased need for efficient electron transporting materials in n-channel OFETs to build complementary circuit elements. This has boosted thorough investigation into acene-based n-type materials. In this review, various strategies are discussed for chemical modification of acenes for n-channel OFETs.

Modification of acenes for n-channel OFET materials

Bisindeno-annulated pentacenes with exceptionally high photo-stability and ordered molecular packing: simple synthesis by a regio-selective Scholl reaction

Arun Naibi Lakshminarayana

Papers

Modification of acenes for n-channel OFET materials

Bisindeno-annulated pentacenes with exceptionally high photo-stability and ordered molecular packing: simple synthesis by a regio-selective Scholl reaction

N‐Containing Polycyclic Heteroarenes