3,6-Di-tert-butylcarbazole Chemical Properties

Melting point:

233-235℃

Boiling point:

424.2±14.0 °C(Predicted)

Density 

1.037

storage temp. 

Sealed in dry,Room Temperature

pka

17.70±0.30(Predicted)

form 

powder

color 

White to Almost white

InChI

InChI=1S/C20H25N/c1-19(2,3)13-7-9-17-15(11-13)16-12-14(20(4,5)6)8-10-18(16)21-17/h7-12,21H,1-6H3

InChIKey

OYFFSPILVQLRQA-UHFFFAOYSA-N

SMILES

N1C2=C(C=C(C(C)(C)C)C=C2)C2=C1C=CC(C(C)(C)C)=C2

Safety Information

Hazard Codes 

Xn

Risk Statements 

22-36/37/38

Safety Statements 

26

WGK Germany 

3

HS Code 

29339900

3,6-Di-tert-butylcarbazole Usage And Synthesis

Description

3,6-Di-tert-butylcarbazole (DtBuCz) is an electron-donating 9h-carbazole derivative with tert-butyl groups at the 3,6 positions. The bulky tert-butyl group can disrupt the aggregation of dimers or excimers that would otherwise form through π-π interactions by increasing the distance between the carbazole rings, leading to loose molecular stacking in thin films. Carbazoles are generally electrochemically active due to the dimerization and polymerization of the corresponding radical cations at their 3,6 positions. Substitution with tert-butyl groups at the 3,6 positions can also inhibit this reaction. 3,6-Di-tert-butylcarbazole has also been incorporated into semiconducting small molecules for OLED applications to achieve higher glass transition temperatures. The introduction of the tert-butyl unit also effectively separates the molecules, reducing the chance of triplet polaron annihilation and significantly improving device efficiency and stability.

Chemical Properties

gray powder

Uses

3,6-Di-tert-butylcarbazole is mainly used as a monomeric precursor in the syntheses of new carbazole based materials which consist of ethynylphenyl. These materials include 9-(4-bromophenyl)-3,6-di-tert-butylcarbazol and 2-(4-(2-(4-(3,6-di-tert-butyl-9H-carbazol-9-yl)phenyl)ethynyl)benzylidene)malononitrile (PBM) which can be further be used in organic light emitting diodes (OLEDs) and optical switching devices.

Application

3,6-Di-tert-butylcarbazole (DtBuCz) is an electron-donating optoelectronic material, mostly used as a semiconductor intermediate for the preparation of high-performance OLED materials. Specific applications are as follows:
(1) Preparation of complexes by chelation with metal ions. The chelating ligand contains a derivative of 3,6-di-tert-butylcarbazole as a color developer. The resulting complexes have high stability above 200°C. In solvents such as acetone, benzene, and dichloromethane, the complexes exhibit strong π-π*, n-π*, and charge transfer (CT) bands in the range of 200 to 400 nm, while the ligands only exhibit strong π-π* and n-π* bands. In the transition from non-polar solvents to polar solvents, a strong red shift (21-31 nm) in the maximum emission band of the complexes is observed^[6].
(2) Preparation of derivatives of trifluorobiphenyl and 3,6-di-tert-butylcarbazole as potential components of the OLED light-emitting layer. In the solid state, the ionization energy of the compound is between 5.98 and 6.17 eV^[7].

General Description

3,6-Di-tert-butylcarbazole is a carbazole based material with hole transporting characteristics. The 3,6-Di-tert-butyl component of the carbazole results in an increase in the glass transition temperature (T_g) of the compound. It can be used in combination with another carbazole to form novel electroluminescent materials.

Synthesis

9H-carbazole (1) (5.00 g, 29.9 mmol) was dissolved in dichloromethane and tert-butyl chloride (6.6 ml, 59.8 mmol) and anhydrous aluminum chloride (4.00 g, 29.9 mmol) were added sequentially. The reaction mixture was stirred at 25°C for 24 hours. Upon completion of the reaction, the mixture was poured into ice water (100 mL) to quench the reaction. The organic phase was extracted with dichloromethane, dried over anhydrous sodium sulfate and filtered to remove the desiccant. The filtrate was concentrated under reduced pressure at room temperature to give the crude product. The crude product was recrystallized by petroleum ether to give 6.30 g of 3,6-di-tert-butyl-9H-carbazole (2a) as a white solid in 75% yield.

References

[1] New Journal of Chemistry,  2016,  vol. 40,  # 11,  p. 9160 - 9169
[2] Journal of the American Chemical Society,  2006,  vol. 128,  # 17,  p. 5592 - 5593
[3] Chemical Communications,  2012,  vol. 48,  # 28,  p. 3382 - 3384
[4] Chemistry Letters,  2008,  vol. 37,  # 9,  p. 986 - 987
[5] Organic Electronics: physics, materials, applications,  2012,  vol. 13,  # 1,  p. 43 - 52
[6] MATVEY S. GRUZDEV. Schiff base complexes with different metals incorporating derivatives of 3,6-di-tert-butylcarbazole[J]. Applied Organometallic Chemistry, 2021, 35 4. DOI:10.1002/aoc.6145. 
[7] KERUCKIENE R, GUZAUSKAS M, LAPIENYTE L, et al. An experimental and theoretical study of exciplex-forming compounds containing trifluorobiphenyl and 3,6-di-tert-butylcarbazole units and their performance in OLEDs†[J]. Journal of Materials Chemistry C, 2020, 40: 14186-14195. DOI:10.1039/D0TC02777D.

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