Base-assisted one-pot synthesis of N,N',N" - triaryltriazatriangulenium dyes: enhanced fluorescence efficiency by steric constraints

TY - JOUR

T1 - Base-assisted one-pot synthesis of N,N',N" - triaryltriazatriangulenium dyes

T2 - enhanced fluorescence efficiency by steric constraints

AU - Hammershøj, Peter

AU - Sørensen, Thomas Just

AU - Han, Bao-Hang

AU - Laursen, Bo Wegge

PY - 2012/7/6

Y1 - 2012/7/6

N2 - In this paper we report the first synthesis of cationic N,N′,N″-triaryltriazatriangulenium dyes (Ar 3-TATA +). Previously, only alkyl-substituted triazatriangulenium derivatives (R 3-TATA +) were known, a consequence of the low reactivity of anilines in the aromatic nucleophilic substitution reaction leading to the formation of the TATA + core. The synthesis of Ar 3-TATA + was achieved by heating the tris(2,6- dimethoxyphenyl)methylium ion (DMP 3C +) in various anilines in the presence of NaH. In the solvent-free reaction all three aryl substituents could be introduced despite the low reactivity of the anilines. The symmetric Ar 3-TATA + derivatives with Ar = phenyl (2), 4-methoxyphenyl (3), and 4-bromophenyl (4) were synthesized. Single crystal structures of 2 and 4 were obtained as BF 4 - salts, where torsional angles larger than 80° were observed between the TATA + chromophore and the aryl substituents. The photophysical properties were studied in solution and in thin films. The results show that the Ar 3- TATA + dyes have a surprising 3-fold increase in fluorescence quantum yields when compared to the parent alkyl-substituted R 3-TATA + salts. With a high quantum yield (>50%) and emission in the red ( fl = 560 nm) the Ar 3-TATA + dyes represent a promising new addition to the family of superstable cationic triangulenium dyes. Additionally, the synthesized tribromo derivative 4 is shown to be a potential triagonal synthon for polymers and other macromolecules.

AB - In this paper we report the first synthesis of cationic N,N′,N″-triaryltriazatriangulenium dyes (Ar 3-TATA +). Previously, only alkyl-substituted triazatriangulenium derivatives (R 3-TATA +) were known, a consequence of the low reactivity of anilines in the aromatic nucleophilic substitution reaction leading to the formation of the TATA + core. The synthesis of Ar 3-TATA + was achieved by heating the tris(2,6- dimethoxyphenyl)methylium ion (DMP 3C +) in various anilines in the presence of NaH. In the solvent-free reaction all three aryl substituents could be introduced despite the low reactivity of the anilines. The symmetric Ar 3-TATA + derivatives with Ar = phenyl (2), 4-methoxyphenyl (3), and 4-bromophenyl (4) were synthesized. Single crystal structures of 2 and 4 were obtained as BF 4 - salts, where torsional angles larger than 80° were observed between the TATA + chromophore and the aryl substituents. The photophysical properties were studied in solution and in thin films. The results show that the Ar 3- TATA + dyes have a surprising 3-fold increase in fluorescence quantum yields when compared to the parent alkyl-substituted R 3-TATA + salts. With a high quantum yield (>50%) and emission in the red ( fl = 560 nm) the Ar 3-TATA + dyes represent a promising new addition to the family of superstable cationic triangulenium dyes. Additionally, the synthesized tribromo derivative 4 is shown to be a potential triagonal synthon for polymers and other macromolecules.

U2 - 10.1021/jo3007732

DO - 10.1021/jo3007732

M3 - Journal article

C2 - 22616844

SN - 0022-3263

VL - 77

SP - 5606

EP - 5612

JO - Journal of Organic Chemistry

JF - Journal of Organic Chemistry

IS - 13

ER -