Two-dimensionally extended, polycyclic heteroaromatic molecules (heterocyclic nanographenes) are a highly versatile class of organic materials, applicable as functional chromophores and organic semiconductors. In this Review, we discuss the rich chemistry of large heteroaromatics, focusing on their synthesis, electronic properties, and applications in materials science. This Review summarizes the historical development and current state of the art in this rapidly expanding field of research, which has become one of the key exploration areas of modern heterocyclic chemistry.

Heterocyclic Nanographenes and Other Polycyclic Heteroaromatic Compounds: Synthetic Routes, Properties, and Applications

Low band gap (Eg < 1.5 eV) polycyclic hydrocarbons have become one of the most important types of materials for many applications, for example, as semiconductors in organic field effect transistors (OFETs), as light-harvesting dyes in organic solar cells and photodetectors, as near infrared (NIR) fluorescent probes in high resolution bio-imaging and bio-sensing, and as chromophores in non-linear optics. The benzenoid polycyclic hydrocarbons as nano-sized graphene fragments also serve as perfect model compounds to understand the fundamental structure–property relationship of graphene. The ground state of these molecules can be described as either a closed-shell or an open-shell structure on the basis of their molecular size and edge structure. In this review, a summary will be given on a series of low band gap polycyclic hydrocarbons about their synthesis, physical properties and material applications.

Low band gap polycyclic hydrocarbons: from closed-shell near infrared dyes and semiconductors to open-shell radicals

A photoconductive imaging member comprised of a substrate, a photogenerating layer, and thereover a charge transport layer comprised of a charge transport component or components, a polymer binder and metal oxide particles, wherein said metal oxide particles contain or are attached with or to a silane or a siloxane, or alternatively a polytetrafluoroethylene.

Photoconductive imaging members

https://kops.uni-konstanz.de/bitstream/handle/123456789/25243/Burke_252435.pdf;sequence=1

A novel blue dye for near-IR ‘dye-sensitised’ solar cell applications

Perylene diimides are among the most important chromophores in dyestuff chemistry. They do not only have excellent thermal, chemical and photochemical stability, high absorption coefficients and fluorescence quantum yields but also permit various chemical functionalizations. Over the last decades, academic and industrial interest in this class of chromophores has steadily increased due to their favourable properties and potential application in various research fields like organic electronics, biochemistry, photophysics and supramolecular chemistry. Higher rylene diimide dyes (e.g.2–6), however, are still in their infancy and must be further explored by combining more research efforts of chemists, physicists, biologists, and material scientists since these dyes possess unique optical, electrochemical, and electronic properties. One of the main obstacles in such rylene based dyes seems to be their synthetic challenges. Thus, in this feature article, we summarize the latest advances in the field of rylene diimide dyes focusing on synthetic strategies toward their preparation. The self-assembly behaviour and applications of larger rylene chromophores are discussed as well.

Beyond perylene diimides: synthesis, assembly and function of higher rylene chromophores

A process for the preparation of Type V hydroxygallium phthalocyanine which comprises the in situ formation of an alkoxy-bridged gallium phthalocyanine dimer, hydrolyzing said alkoxy-bridged gallium phthalocyanine dimer to hydroxygallium phthalocyanine, and subsequently converting the hydroxygallium phthalocyanine product obtained to Type V hydroxygallium phthalocyanine.

Processes for the preparation of hydroxygallium phthalocyanine

The proton and 13C NMR of azulene and dialkylaminohydroxyphenyl squaraines have been investigated. The four-membered ring carbon resonances occur in the 180–190 ppm range and are attributed to the ...

Conformational isomerism in squaraines: saturation transfer NMR studies on hydroxy squaraines

Disclosed are unsymmetrical squaraine compounds of the following formula ##STR1## wherein R1, R2, R3 and R4 are independently selected from the group consisting of alkyl, aryl heterocyclic, benzyl, and halobenzyl; and X1, X2 and X3 are independently selected from the group consisting of hydrogen, alkyl, halogen, carboxy, and hydroxy; and photoresponsive imaging members having incorporated therein the aforementioned squaraine compounds.

Photoconductive imaging members with unsymmetrical squaraine compounds containing an hydroxyl group

The usefulness of the Pariser–Parr–Pople molecular orbital method for the identification of near-infrared absorbing pigment candidates for photogenerator applications is outlined. Several pigments based on the well-known class of photogenerators N,N′-dialkyl-3,4,9,10-perylenetetracarboxylic diimides were investigated and pigments of the dibenzoperylene, bisanthene, and zethrene classes were identified as the most promising candidates of the series. On the basis of the predictions, 7,8,15,16-dibenzo[a, j]perylenetetracarboxylic diimide was prepared and the validity of the calculations was verified. Keywords: photoconductor, near-infrared, Pariser–Parr–Pople calculations, polycyclic aromatic hydrocarbon, aceanthrene green.

Design and synthesis of near-infrared absorbing pigments. I. Use of Pariser–Parr–Pople molecular orbital calculations for the identification of near-infrared absorbing pigment candidates

The reported structure of aceanthrene green, a pigment prepared by potassium hydroxide fusion of 1,9-anthracenedicarboxylic imide, was found to be incorrect. The structure of the pigment is reassig...

Richard A. Burt

Papers

Processes for the preparation of hydroxygallium phthalocyanine

Conformational isomerism in squaraines: saturation transfer NMR studies on hydroxy squaraines

Photoconductive imaging members with unsymmetrical squaraine compounds containing an hydroxyl group

Design and synthesis of near-infrared absorbing pigments. I. Use of Pariser–Parr–Pople molecular orbital calculations for the identification of near-infrared absorbing pigment candidates

Design and synthesis of near-infrared absorbing pigments. ii: structure determination of aceanthrene green and derivatives