Synthesis and Characterization of Some Aza[5]helicenes

Abstract

A systematic study on the synthesis and properties of aza- [5]helicenes bearing one or two nitrogen atoms in selected ring positions is reported for the first time. This photochemical approach can be conveniently applied to the preparation of either mono- or diaza[5]helicenes. The aza[5]helicenes were characterized by NMR spectroscopy, X-ray crystallography, emission spectroscopy, and luminescence lifetime. The extremely long triplet lifetime observed (in the range of seconds) makes these molecules promising candidates for practical applications in photo- and optoelectronics

Highly Selective Recognition of α‐Chiral Primary Organoammonium Ions by C3‐Symmetric Peptide Receptors

“…The reduction of the aldehyde group with sodium borohydride gave the corresponding alcohol 12 in good yield. [28] The best way to transform the alcohol 12 into the bromide turned out to be the use of hydrogen bromide in acetic acid. After 2 h of refluxing in acetic acid and the addition of ether, we obtained the hydrobromide of 4-(bromomethyl)isoquinoline (13) in a good yield.…”

Synthesis and Characterization of Novel Chiral Conjugated Materials

“…[13]helicene from hexahelicene-2-carboxylic acid) [49]. The oxidative photocycliza tion of stilbenes is still the method of choice for the preparation of selected [n]helicenes and their heteroatom analogs [50][51][52][53][54][55][56][57][58].…”

Determination of acid–base dissociation constants of azahelicenes by capillary zone electrophoresis

“…Although a renewed interest in azahelicenes can recently be seen, and various approaches to their synthesis have emerged [4][5][6], their physico-chemical properties have not systematically been studied. There are only few papers reporting on basicities [7], self-assembly [8], and emission spectroscopy [9] of pyridohelicenes (azahelicenes comprising a pyridine unit embedded in all-ortho fused benzene rings). However, utilizations of azahelicenes, in particular pyridohelicenes, in various branches of chemistry and material science might be envisaged.…”