2,6,10-Tris(dialkylamino)trioxatriangulenium Ions. Synthesis, Structure, and Properties of Exceptionally Stable Carbenium Ions

Abstract

A general synthetic route to a novel type of triamino-substituted planar carbenium ions (5) is reported. The synthetic method is based on a facile and selective nucleophilic aromatic substitution on the tris(2,4,6-trimethoxyphenyl)carbenium ion (1) with amines and gives access to a wide variety of more complex aminosubstituted carbenium ions. X-ray crystallography shows that the 2,6,10-tris(N-pyrrolidinyl)-4,8,12-trioxatriangulenium ion (5b) is planar and forms segregated stacks of cations and PF 6 anions in the solid phase. The stability of the 2,6,10-tris(diethylamino)-4,8,12-trioxatriangulenium ion 5a is expressed as the pK R+ value, which is determined in strongly basic nonaqueous solution on the basis of a new acidity function C_. The pK R+ value of 5a is measured to be 19.7, which is 10 orders of magnitude higher than the values found for the most stable carbenium ions previously reported. Electrochemical reduction of compound 5a leads to rapid dimerization. Two consecutive one-electron oxidations are identified by cyclic voltammetry.

Enhanced fluorescence emission of Me-ADOTA+ by self-assembled silver nanoparticles on a gold film

“…The triangulenes are highly fluorescent, electron rich cationic dyes, capable of photo electron transfer to most donors and they are excellent DNA intercalators [19,23,24]. Peripheral substitution of hydrogen with nitrogen leads to a different class of triangulenium dyes; amino-trioxatriangulene(A-TOTA + ) and amino-azadioxatriangulene(A-ADOTA + ) which effectively are blueshifted symmetric versions of rhodamine and aminoacridine respectively [25,26,27]. …”

Azadioxatriangulenium: a long fluorescence lifetime fluorophore for large biomolecule binding assay

“…The procedure follows classical triangulenium dye synthesis. 12, 18, 19 The carboxylic acid group was introduced in the triangulenium skeleton using methyl 4-amino-butanoate as nucleophile in a substitution reaction on the readily available tris(dimethoxyphenyl)methylium ion ( 1 ). 12, 20 The resulting acridinium salt ( 2 ) was isolated in 73–91 % yield.…”

Benzhydrylium and tritylium ions: complementary probes for examining ambident nucleophiles

“…It should also be mentioned that aromatic nucleophilic substitution of alkoxy groups in ortho-or para-positions of tritylium ions by amines, alcohols, hydroxide ions or malononitrile anions cannot be treated by eq. (1) [30][31][32][33]. However, the E values of the tritylium ions were found to be useful for determining the N and s N values of further 20 n-nucleophiles (primary amines, hydrazines, methanol, alkoxide and thiolate anions, CN -), for which kinetic data had previously been reported by Ritchie [27][28][29].…”