4CzIPN (Photocatalyst) | CAS 1416881-52-1 | ≥97%

Technical Specifications

Product Description & Scientific Applications

4CzIPN (2,4,5,6-tetra(9H-carbazol-9-yl)isophthalonitrile; 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene) is a metal-free organic photoredox catalyst built on a donor–acceptor architecture. Four electron-rich carbazole donors surround an electron-poor dicyanobenzene core, producing a small singlet–triplet energy gap (ΔEST < 0.1 eV) and thermally activated delayed fluorescence (TADF) with a long-lived emissive excited state. Under visible blue light, 4CzIPN participates in both oxidative and reductive quenching cycles, giving access to a broad redox window through its excited-state and radical-ion chemistry. A single organic chromophore can therefore replace ruthenium or iridium polypyridyl photocatalysts in many visible-light single-electron-transfer workflows. With reported photoluminescence quantum yields above 90% in suitable media and good thermal stability, 4CzIPN is a benchmark metal-free photoredox catalyst and a reference green TADF emitter, with additional use in energy-transfer and metallaphotoredox chemistry.

Applications

Visible-light photoredox catalysis (single-electron transfer). Under blue-light irradiation at low catalyst loading, 4CzIPN generates open-shell intermediates by single-electron transfer. Well-documented applications include decarboxylative couplings, acylations and radical cyclisations involving carboxylic acids, α-keto acids and aldehydes, Giese-type additions to electron-poor alkenes, and radical fluorination, trifluoromethylation and trifluoromethoxylation. The broad redox profile supports both oxidative and reductive quenching cycles in common polar organic solvents.

Metallaphotoredox (dual) catalysis. 4CzIPN is most strongly established in nickel dual-catalytic cross-coupling, where the photocatalyst supports radical generation and turnover of organometallic intermediates for C–C and C–heteroatom bond formation. It has also been used with copper and palladium co-catalysts for related radical and C–H functionalisation chemistry. Combined with cobaloxime catalysts it can sensitise hydrogen-evolution and dehydrogenative transformations.

Energy-transfer photocatalysis. 4CzIPN can act as a triplet sensitiser, driving reactions through energy transfer rather than electron transfer, including reported [2+2] cycloadditions, E/Z isomerisations and sensitisation of substrates that resist direct single-electron pathways.

TADF emitter and optoelectronic materials. As a donor–acceptor molecule with a small singlet–triplet gap and efficient reverse intersystem crossing, 4CzIPN is a reference green thermally activated delayed fluorescence emitter, studied as emissive and host material in organic light-emitting diode (OLED) research.

Further applications.

• Electrochemiluminescence (ECL): emissive TADF luminophore for annihilation- and co-reactant ECL, including aqueous ECL systems after polymer encapsulation, relevant to sensing-oriented ECL materials research.
• Triplet–triplet annihilation upconversion (TTA-UC): heavy-atom-free triplet sensitiser that, paired with an annihilator such as pyrene, converts lower-energy visible light into higher-energy emission, including visible-to-UV upconversion.

Photophysical and electrochemical reference data

Ground-state potentials (vs SCE): E(PC•+/PC) ≈ +1.49 V; E(PC/PC•−) ≈ −1.24 V. Excited-state potentials (vs SCE): E(PC*/PC•−) ≈ +1.35 to +1.43 V, corresponding to photo-oxidising ability; E(PC•+/PC*) ≈ −1.18 V, corresponding to photo-reducing ability. Reported values vary with solvent and measurement method. Singlet–triplet gap ΔEST ≈ 0.08 eV; green emission λem ≈ 507 nm; photoluminescence quantum yield above 90% in degassed toluene.

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