Acid‐mediated condensation of a 2,3‐dialkyl‐1,4‐benzoquinone with 1,4‐naphthoquinone produces a series of alkane‐soluble π‐extended tetraoxa[8]circulenes; these structures (shown here) were successfully incorporated in organic light‐emitting diodes.

We describe herein the first synthesis of a new class of anti-aromatic planar cyclooctatetraenes: the azatrioxa[8]circulenes. This was achieved by treating a suitably functionalised 3,6-dihydroxycarbazole with 1,4-benzoquinones or a 1,4-naphthoquinone. We fully characterised the azatrioxa[8]circulenes by using optical, electrochemical and computational techniques as well as by single-crystal X-ray crystallography. The results of a computational study (NICS) suggest that the central planar cyclooctatetraene is anti-aromatic when the molecules are in neutral or oxidised states (2+), and that the corresponding dianions are aromatic. We discuss the aromatic/anti-aromatic nature of the planar cyclooctatetraenes and compare them with the isoelectronic tetraoxa[8]circulenes.

We describe the first example of the synthesis of a tetraoxa[8]circulene with only four substituents by means of BF 3 ·OEt 2 mediated tetramerisation of tert-butyl-1,4-benzoquinone. Two of the four regioisomers of tetra-tert-butyltetraoxa[8]circulene have been isolated and characterised by

We present the synthesis of a peptide-based bicyclic carbohydrate receptor capable of carbohydrate recognition in 10 % deuterated acetic acid in water. The binding constants were estimated by using NMR spectroscopy, and furthermore, aThe most abundant class of organic molecules on earth is that of the carbohydrates. They serve as structural materials in the form of cellulose or chitin, for example, and as energy storage to provide the fuels for biochemical processes. The class of carbohydrates covers protein and cell membranes, and carbohydrates act as signalling molecules that by interaction with receptors and lectins determine the fate of these. Carbohydrates are implicated in cell differentiation, in cancer immunology as well as in host defence against viruses, bacteria and parasites. By interaction with numerous receptors in membranes or with secondary receptor sites on functional macromolecules, carbohydrates determine the distribution and architecture of functional macromolecular assemblies and bring together growth hormones, receptors, proteases and so on. [1] This important set of functionalities renders carbohydrate recognition an attractive target for artificial receptors. Selective artificial carbohydrate receptors could be used either diagnostically to determine the location and concentration of a particular carbohydrate structure, for example, the concentration of glucose in blood, or as a drug targeting compound functioning as an artificial antibody. In some instances an artificial receptor could even be a drug in itself by blockage of carbohydrate-mediated viral entry or bacterial adhesion.Diabetes will, according to WHO, affect more than 360 million people in the world by 2030 (http://www.who.int/ mediacentre/factsheets/fs312/en/index.html), and therefore [a]

Alkynyl substituents can be used to tune the acceptor properties of benzoquinones due to their slight electron‐withdrawing abilities. Applications of new acceptors rely on efficient and practical synthetic procedures. Herein we describe a general and convenient approach for the synthesis of 2,3‐dialkynyl‐1,4‐benzoquinones using a combination of regiospecific aromatic substitution, Sonogashira cross‐couplings and mild CAN oxidation chemistry. The regiochemical outcome of the synthetic protocol was verified by X‐ray crystallography of two compounds. Cyclic voltammetry, UV/Vis and DFT calculations on three derivatives show that the symmetrical dialkynyl‐substituted benzoquinones are attractive acceptors.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)