4,5-Di-9H-carbazol-9-yl-1,2-benzenedicarbonitrile
[CAS# 1416881-50-9]

Identification

• Classification: Organic raw materials >> Nitrile compound
• Name: 4,5-Di-9H-carbazol-9-yl-1,2-benzenedicarbonitrile
• Molecular Formula: C₃₂H₁₈N₄
• Molecular Weight: 458.51
• CAS Registry Number: 1416881-50-9
• EC Number: 891-325-4
• SMILES: C1=CC=C2C(=C1)C3=CC=CC=C3N2C4=C(C=C(C(=C4)C#N)C#N)N5C6=CC=CC=C6C7=CC=CC=C75

Properties

• Solubility: Insoluble (8.7E^-7 g/L) (25 ºC), Calc.^*
• Density: 1.26±0.1 g/cm³ (20 ºC 760 Torr), Calc.^*
• Boiling point: 622.9±55.0 ºC 760 mmHg (Calc.)^*
• Flash point: 330.5±31.5 ºC (Calc.)^*
• Index of refraction: 1.725 (Calc.)^*

^* Calculated using Advanced Chemistry Development (ACD/Labs) Software.

Safety Data

• Hazard Symbols: GHS07 Warning
• Hazard Statements: H315-H319-H335
• Precautionary Statements: P261-P264-P264+P265-P271-P280-P302+P352-P304+P340-P305+P351+P338-P319-P321-P332+P317-P337+P317-P362+P364-P403+P233-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Eye irritation	Eye Irrit.	2	H319
Skin irritation	Skin Irrit.	2	H315
Specific target organ toxicity - single exposure	STOT SE	3	H335

Discovory and Applicatios

4,5-Di-9H-carbazol-9-yl-1,2-benzenedicarbonitrile is an organic molecule combining two carbazole donor units with a phthalonitrile acceptor core. The benzene ring bears nitrile (–C≡N) groups at the 1 and 2 positions, and the 4 and 5 positions are substituted with carbazol-9-yl moieties. This donor–acceptor architecture yields a molecule with spatially separated highest occupied and lowest unoccupied molecular orbitals, which is a design principle that enables efficient reverse intersystem crossing and thermally activated delayed fluorescence (TADF).

The first reports of carbazole-substituted benzenedicarbonitriles emerged in the early 2010s amid efforts to develop purely organic TADF emitters for organic light-emitting diode (OLED) applications. Synthesis typically proceeds by palladium-catalyzed Buchwald–Hartwig coupling of 4,5-dichlorophthalonitrile with carbazole, or via nucleophilic aromatic substitution using the sodium salt of carbazole. Reaction conditions are optimized to preserve the nitrile functionality and to ensure selective formation of the bis(carbazol-9-yl) product. Purification is often achieved by column chromatography, yielding the target compound as a crystalline solid.

Photophysical studies of this compound revealed a small singlet–triplet energy gap on the order of 0.1 to 0.2 electronvolts, which is consistent with efficient reverse intersystem crossing at room temperature. The molecule exhibits strong photoluminescence in the blue region, with an emission maximum typically around 470 to 490 nanometers when doped into appropriate host matrices. The absolute photoluminescence quantum yield in dilute film is often reported above 70 percent. These properties established the molecule as one of the early benchmarks for TADF emitters, demonstrating that purely organic materials could rival phosphorescent metal complexes in light-emitting applications.

In device architectures, 4,5-di-9H-carbazol-9-yl-1,2-benzenedicarbonitrile has been employed both as an emissive dopant and as a host material for phosphorescent emitters. When used as an emitter in conventional multilayer OLEDs, external quantum efficiencies exceeding 15 percent have been achieved for blue emission, with Commission Internationale de l'Eclairage (CIE) coordinates near (0.15, 0.20). Device stability under continuous operation has also been improved relative to earlier organic emitters, owing to the molecule’s rigid structure and resistance to photochemical degradation.

Beyond OLEDs, the compound has found utility in photocatalysis and sensing applications. The combination of donor and acceptor units facilitates photoinduced charge separation, making it a candidate for visible-light-driven photocatalytic transformations such as oxidative coupling reactions. Its nitrile groups also serve as coordination sites for metal ions, enabling its use in fluorescence-based detection of certain metal contaminants in solution. The rigid, planar structure promotes self-assembly into ordered thin films, which has been explored for applications in organic photodetectors and field-effect transistors.

Further modifications of the basic scaffold—such as introduction of alkyl or aryl substituents on the carbazole units—have been investigated to tune solubility, emission wavelength, and device performance. Derivatives with extended conjugation or different donor strengths exhibit shifted emission profiles and altered TADF characteristics. This versatility underscores the role of 4,5-di-9H-carbazol-9-yl-1,2-benzenedicarbonitrile as a platform for the rational design of next-generation organic optoelectronic materials.

References

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DOI: 10.1007/s12274-024-6947-0

2023. Bifunctional organic photocatalysts for enantioselective visible-light-mediated photocatalysis. Nature Synthesis, 2, 1162�1173.
DOI: 10.1038/s44160-023-00398-0

2023. Highly efficient quantum dot light-emitting diodes with the utilization of an organic emission layer. Nano Research, 16, 2350�2358.
DOI: 10.1007/s12274-023-5638-6