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This review summarizes recent advances in the chemistry of curved aromatic molecules. By focusing on the key accomplishments of the last decade, we provide a general overview of synthetic methods capable of efficient induction of internal strain in π‐conjugated frameworks. The review is structured according to the topology change involved in the strain‐inducing reaction step (cyclizations, eliminations, ring expansions and contractions), and highlights the striking diversity of structures achievable with modern synthetic methodology. Straining for effect: Synthetic and methodological advances in the chemistry of curved aromatic molecules, made during the last decade, are discussed. Various methods of building strained aromatic frameworks are presented and classified according to the topological features of the underlying reactivity. The practical implementation of these methods is illustrated for diverse cylindrical, spherical, and hyperbolic aromatics, with wide‐ranging curvature and strain levels. [ABSTRACT FROM AUTHOR]

A non-catalytic condensation of NiII β-aminonorcorrole with aryl aldehydes is shown to produce a family of pyrromethane dimers that undergo deaminative cyclization to yield pyridine-fused bis(norcorrole)s comprising two antiaromatic macrocycles communicating by an aromatic moiety. The new compounds were characterized by spectroscopic, structural, and electrochemical methods supported by DFT calculations, all of which revealed unexpected antiaromaticity enhancement in the fused system. [ABSTRACT FROM AUTHOR]

Octulene, the higher homologue of kekulene and septulene, was synthesized using the fold-in method. This new hydrocarbon macrocycle contains a large 24-membered inner circuit, which is peripherally fused to 24 benzene rings. Such an arrangement produces considerable hyperbolic distortion of the π-conjugated surface. The consequences of distortion in octulene were explored using photophysical methods, which revealed a reduced electronic band gap and greater flexibility of the π system. Octulene contains a functional cavity with a diameter larger than 5.5 Å that is capable of efficiently binding the chloride anion in a nonpolar solvent ( Ka= 2.2(4)×104 m−1, 1 % dichloromethane (DCM) in benzene). The octulene-chloride interaction is stabilized by eight weak C(sp2)H⋅⋅⋅Cl bonds, providing the first example of a hydrocarbon-based anion receptor. [ABSTRACT FROM AUTHOR]

Copyright of Chemistry - A European Journal is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Journal of Chemistry is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In a series of thiaaceneporphyrinoids, their conformers exhibit macro-cyclic π-conjugation pathways controlled by a dihedral angle between the porphyrin framework and acene planes. Conformational equilibria significantly affect the photophysical properties of these macrocycles. [ABSTRACT FROM AUTHOR]

A 3-phosphonated N-confused phlorin 3 was synthesized by the reaction of N-confused porphyrin 1 and trimethyl or triethyl phosphite 2 in the presence of acetic acid in good yield. The presence of hydrogen and aryl substituents in one of the meso positions (C5) generates a stereogenic center, resulting in configurationally stable enantiomers. The enantiomers were separated by HPLC and characterized by the circular dichroism method for the first time in the case of phlorin. Further oxidation of 3 by DDQ (2,3-dichloro-5,6-dicyano-1,4-benzoquinone) afforded the achiral 3-phosphonated N-confused porphyrin 4. Chiral chlorozinc 4--Zn and chlorocadmium 4--Cd, as well as achiral nickel(II) complexes 4--Ni were also characterized. For 4--Cd in the solid state, formation of a dimer consisting of heterochiral subunits joined by two H-bonds was established by a single crystal X-ray analysis. For 4--Cd, separation of enantiomers was achieved. Slow racemization of 4--Cd in solution prevented the absolute configuration determination by the X-ray method indicating the labile character of the complex. The relationship between circular dichroism and absolute configuration of 3a and 4--Cd was established on the basis of TD-DFT calculations. [ABSTRACT FROM AUTHOR]