What Is Chlorotricarbonyl(2,2''-bipyridine)rhenium(I)?

Chlorotricarbonyl(2,2''-bipyridine)rhenium(I), commonly written as fac-[Re(bipy)(CO)₃Cl], is a rhenium(I) coordination complex in which the metal center adopts an octahedral geometry. The ligand set consists of one bidentate 2,2'-bipyridine (bipy) ligand, three facial carbonyl (CO) ligands, and one chloride (Cl⁻) ligand. The rhenium center is in the +1 oxidation state with a d⁶ electronic configuration, which confers exceptional photophysical and photochemical stability.

This compound belongs to the extensively studied family of fac-[Re(N^N)(CO)₃X] complexes, where N^N is a diimine ligand and X is a halide or other anionic ligand. Its well-characterized luminescence, arising from a metal-to-ligand charge transfer (MLCT) excited state, makes it a benchmark compound in inorganic photochemistry.

Photophysical and Chemical Properties

The complex exhibits strong visible-light absorption attributable to a ¹MLCT transition, followed by rapid intersystem crossing to the long-lived ³MLCT excited state. This produces a characteristic orange-to-yellow luminescence in solution, with emission maxima typically in the 550–650 nm range depending on solvent and substitution, though readers should consult primary literature for precise values for specific conditions.

Key photophysical characteristics include:

• MLCT-based emission: Relatively long excited-state lifetime (hundreds of nanoseconds to microseconds range), enabling time-resolved luminescence measurements.
• Sensitivity to environment: Emission intensity and lifetime are sensitive to oxygen, solvent polarity, pH, and analyte binding, underpinning sensing applications.
• Photostability: The fac-tricarbonyl framework provides robust stability compared to many organic fluorophores.
• Infrared signature: Characteristic strong C≡O stretching bands in the 1880–2050 cm⁻¹ region provide a convenient spectroscopic handle for characterization and reaction monitoring.

The compound is an air-stable solid under standard laboratory conditions, though solutions should be handled with care to avoid prolonged exposure to strong light sources prior to use.

Applications in Research

fac-[Re(bipy)(CO)₃Cl] and its derivatives are employed across a broad spectrum of research disciplines:

• Photocatalytic CO₂ reduction: The complex and its analogues are benchmark photocatalysts and electrocatalysts for the selective reduction of CO₂ to CO or formate. The bipyridine and carbonyl ligands play critical roles in facilitating multi-electron processes.
• Luminescence sensing: Its sensitivity to analytes such as oxygen, anions, cations, and biological molecules makes it useful as a luminescent sensor scaffold. Emission lifetime-based sensing is particularly advantageous for eliminating background fluorescence.
• Bioimaging and bioconjugation: Rhenium tricarbonyl complexes can be functionalized and conjugated to biomolecules for cellular imaging, exploiting their long emission lifetime for time-gated microscopy.
• Radiopharmaceutical research: The fac-[M(CO)₃]⁺ core (Re and its congener ^99mTc) is a key motif in nuclear medicine and radiopharmaceutical development.
• Photophysical benchmark studies: The complex serves as a standard reference compound for validating new spectroscopic methods and photophysical models.

Handling, Storage, and Safety Considerations

While fac-[Re(bipy)(CO)₃Cl] is generally considered an air-stable solid, the following best practices are recommended for laboratory handling:

• Storage: Store in a cool, dry, well-ventilated location away from direct light and moisture. Follow the conditions specified on the product Certificate of Analysis (CoA).
• Personal protective equipment: Use appropriate PPE including gloves, safety eyewear, and a laboratory coat when handling the compound. Rhenium compounds should be treated with standard caution appropriate for heavy-metal-containing materials.
• Waste disposal: Dispose of rhenium-containing waste in accordance with local institutional and governmental regulations for heavy metal waste. Do not dispose of down the drain.
• Photochemical precautions: When working with solutions of this complex under irradiation, ensure adequate ventilation as photochemical reactions may generate CO gas.
• Consult the SDS: Always refer to the Safety Data Sheet (SDS) provided by Aladdin Scientific for complete hazard information before use.

Note: Specific hazard classifications and GHS pictograms should be verified against the current product SDS.

Ordering and Product Information

Chlorotricarbonyl(2,2''-bipyridine)rhenium(I) is available from Aladdin Scientific under SKU C283075, corresponding to Strem Catalog Number 75-2360. When placing an order, please note the following:

• Purity and specification: Refer to the current Certificate of Analysis (CoA) available on the product page for confirmed purity, appearance, and analytical data.
• Available quantities: Contact Aladdin Scientific sales or check the product listing for available pack sizes and pricing.
• Custom requirements: For bulk quantities or specific purity grades, contact our technical sales team.
• Lead time: Lead times may vary; confirm availability and estimated delivery at time of order.
• Export considerations: Rhenium-containing compounds may be subject to export control regulations in certain jurisdictions. Buyers are responsible for compliance with applicable import/export laws.

For technical questions regarding this product, please contact Aladdin Scientific's technical support team who can provide application-specific guidance.