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499-83-2
futurechemical
499-83-2
Pyridine-2,6-dicarboxylic acid (also known as 2,6-pyridinedicarboxylic acid, 2,6-dipyridinecarboxylic acid, dipicolinic acid, 2,6-pyridinedicarboxylic acid, 2,6-dicarboxypyridine, DPAC, pydcH2), with the chemical formula C7H5NO4, a molecular weight of 167.12, CAS number 499-83-2, EINECS 207-894-3, UNII UE81S5CQ0G, InChIKey WJJMNDUMQPNECX-UHFFFAOYSA-N, is a dicarboxylic acid containing two carboxyl groups at positions 2 and 6 of the pyridine ring. It belongs to the pyridine carboxylic acid class of organic compounds and is also a natural marker molecule (dipicolinic acid, DPA) in the bacterial spore cortex. It is an important raw material for fine chemicals and analytical chemicals: a white crystalline powder with a melting point of approximately 248-250℃ (decomposes), slightly soluble in cold water, soluble in hot water, ethanol, and dilute alkaline solutions, and capable of sublimation. Due to its tridentate chelate coordination structure composed of pyridine nitrogen and two carboxyl groups, its strong complexing ability with metal ions, its sensitizing and luminescent ability for rare earth elements, and its labeling properties for bacterial spores, industrial-grade pyridine-2,6-dicarboxylic acid is mainly used in biological indicators and sterilization validation, spore detection, ion chromatography eluent ligands, chemical sensors, metal complexing agents, metal-organic framework materials, catalyst ligands, and rare earth separation.
Basic identification information : Chemical formula C7H5NO4; Molecular weight 167.12; CAS number 499-83-2; EINECS 207-894-3; UNII UE81S5CQ0G; InChIKey WJJMNDUMQPNECX-UHFFFAOYSA-N; IUPAC name pyridine-2,6-dicarboxylic acid; ChEBI 46837; ChEMBL 284104; DrugBank DB04267; Synonyms: pyridine-2,6-dicarboxylic acid, 2,6-pyridinedicarboxylic acid, 2,6-dipyridinecarboxylic acid, dipicolinic acid, 2,6-dicarboxypyridine, DPAC, pydcH2, NSC-176, etc.
Structurally , pyridine-2,6-dicarboxylic acid consists of two carboxyl groups (-COOH) at the 2 and 6 positions of the pyridine ring and a nitrogen atom on the ring. The three coordinating atoms (one pyridine nitrogen and two carboxyl oxygens) naturally form a stable tripentate chelate ligand, which forms a five-membered chelate ring with metal ions. The two carboxyl groups are electron-withdrawing groups and can be deprotonated in sequence, giving the molecule both coordination sites and pH responsiveness.
Physically , pyridine-2,6-dicarboxylic acid is a white crystalline powder with a melting point of approximately 248-250℃ (decomposes simultaneously); it is slightly soluble in cold water, soluble in hot water, ethanol, dilute alkaline solutions, and organic solvents, but insoluble in ether and chloroform; it sublimes upon heating; it has an extremely low vapor pressure; it is weakly acidic, and the pH of its aqueous solution varies with the degree of deprotonation; as a high-purity product for ion chromatography, its purity can reach over 99.5%.
Chemically , pyridine-2,6-dicarboxylic acid is a multidentate chelating ligand: the pyridine nitrogen and two carboxyl oxygen groups can coordinate with metal ions such as calcium, iron, zinc, copper, aluminum, and rare earth elements to form stable five-membered chelate ring complexes (such as the Ca-DPA complex in spores); the two carboxyl groups can be deprotonated and participate in derivatization reactions such as esterification and acylation; after coordination with lanthanide ions (europium, terbium), it sensitizes rare earth luminescence through the antenna effect; multiple coordination sites enable it to bridge metal ions to form one-dimensional to three-dimensional coordination polymers and metal-organic frameworks (MOFs); it is also a natural marker component of bacterial spore cortex, giving spores heat resistance; at the same time, it has antibacterial activity and can inhibit spore germination and microbial growth.
Why does pyridine-2,6-dicarboxylic acid play these roles in various industrial fields? Its mechanism of action mainly includes the following:
Tridentate chelation coordination mechanism : The nitrogen atom of the pyridine ring and the two carboxyl oxygen atoms form a tridentate coordination site, which forms a stable five-membered chelate ring with metal ions. It has a strong complexing ability for metals such as calcium, iron, zinc, and lanthanides. After coordination, the overall molecular structure becomes rigid and stable, which is the basis for its use as a metal complexing agent, ligand and building block of materials.
Rare earth sensitized luminescence mechanism : After pyridine-2,6-dicarboxylic acid coordinates with lanthanide ions such as europium and terbium, the ligand absorbs ultraviolet light and transfers energy to rare earth ions (antenna effect), producing characteristic fluorescence emission with a large Stokes shift, making it possible to detect ultra-low concentration metal ions with fluorescence.
Coordination polymerization and framework construction mechanism : Two carboxyl groups can be deprotonated and bridge multiple metal ions, extending along space to form a one-dimensional chain, two-dimensional layer or three-dimensional porous framework (coordination polymer/metal-organic framework), with adjustable pore size and channels, used for gas adsorption, separation, catalysis and sensing materials.
pH response and ion exchange mechanism : The two carboxyl groups have different pKa and can be deprotonated in a stepwise manner, so that they can compete with metal ions for coordination as eluent ligands in ion chromatography and elute and separate cations in sequence according to the difference in affinity; the same property is also used in pH-responsive materials and controlled release systems.
Antibacterial and germination inhibition mechanism : Pyridine-2,6-dicarboxylic acid can inhibit bacterial growth and spore germination by chelating essential metal ions for microbial growth and interfering with spore germination signaling pathways, thus exhibiting broad-spectrum antibacterial activity.
Corresponding products: high-pressure steam sterilization biological indicator, ethylene oxide sterilization indicator, irradiation sterilization validation indicator, dry heat sterilization indicator, disinfection efficacy validation tablet, sterilization validation kit, etc.
Why it can be used for this purpose: The biological indicator uses heat-resistant spores as a carrier. During the sterilization process, the spores are inactivated and release pyridine-2,6-dicarboxylic acid (DPA) markers. By detecting whether DPA can still be detected, it can be determined whether all spores have been killed, thereby verifying whether the sterilization process meets the standards. It is a key quality control method for sterilization and release in the food industry.
Corresponding products: spore detection kits, bacterial spore staining reagents, foodborne spore detection kits, milk spore detection kits, environmental spore monitoring tablets, biological pollution early warning reagents, etc.
Why it can be used for this purpose: Pyridine-2,6-dicarboxylic acid is a specific marker of spore cortex. Detecting the DPA content in a sample can quickly determine the presence and quantity of spores. It is used for monitoring spore contamination in food, dairy products, drinking water, and clean environments, and is faster and more specific than traditional culture methods.
Corresponding products: ion chromatography eluent, cation analysis eluent, transition metal separation eluent, ion chromatography standard reagent, high-purity pyridine-2,6-dicarboxylic acid (purity above 99.5%), etc.
Why it can be used for this purpose: Pyridine-2,6-dicarboxylic acid acts as an eluent ligand in ion chromatography, forming complexes with alkali metal, alkaline earth metal and transition metal ions with different stabilities, and eluting and separating them sequentially according to the difference in affinity. It is a classic eluent component for ion chromatography analysis of cations and metal ions.
Corresponding products: rare earth sensitized fluorescent probes, europium/terbium complex fluorescent labeling reagents, metal ion fluorescent sensors, water quality heavy metal detection reagents, biofluorescent probes, chemiluminescence analysis reagents, etc.
Why it can be used for this purpose: Pyridine-2,6-dicarboxylic acid coordinates with rare earth elements such as europium and terbium, and then sensitizes and emits light through the antenna effect. The fluorescence intensity is related to the concentration of the analyte, and it can be used to construct a highly sensitive fluorescence sensor to detect metal ions, biomolecules and harmful substances for environmental and biological analysis.
Corresponding products: metal complexing agents, chelating agents, water treatment scale inhibitors, metal ion collectors, surface treatment complexing agents, electroplating complexing agents, mineral flotation collectors, etc.
Why it can be used for this purpose: The tridentate chelate structure allows pyridine-2,6-dicarboxylic acid to form stable complexes with metal ions such as calcium, iron, copper, zinc, and aluminum. It is used to complex metal ions, prevent scale and precipitation, control the concentration of metal ions, and can also be used as a complexing agent for electroplating and surface treatment.
Corresponding products include: metal-organic framework materials, porous coordination polymers, gas adsorption and storage materials, hydrogen energy storage materials, MOF separation membranes, MOF sensors, catalyst support materials, fluorescent MOF materials, etc.
Why it can be used for this purpose: Pyridine-2,6-dicarboxylic acid constructs one-dimensional to three-dimensional porous frameworks by bridging metal ions with dicarboxyl groups, resulting in metal-organic frameworks with large specific surface areas and adjustable pore sizes, which can be used for the development of functional materials such as gas adsorption and separation, hydrogen and carbon dioxide storage, sensing and catalysis.
Corresponding products: metal complex catalysts, oxidation reaction catalysts, polymerization catalysts, organic synthesis catalytic systems, asymmetric catalytic ligands, photocatalytic complexes, etc.
Why it can be used for this purpose: Pyridine-2,6-dicarboxylic acid forms stable chelate complexes with transition metals, regulating the electronic environment and spatial configuration of the metal center. As a ligand for homogeneous or supported catalysts, it can be used for catalytic reactions such as oxidation, polymerization, and coupling, thereby improving activity and selectivity.
Corresponding products: antibacterial agents, antibacterial finishing agents, preservatives, daily chemical antibacterial additives, industrial bactericides, spore germination inhibitors, feed mold inhibitors, etc.
Why it can be used for this purpose: Pyridine-2,6-dicarboxylic acid inhibits bacterial growth and spore germination by chelating essential metal ions for microorganisms and interfering with spore germination signals, exhibiting broad-spectrum antibacterial activity and can be used in antibacterial, preservative and antifungal formulations.
Corresponding products: lanthanide separating agents, rare earth extractants, light rare earth/heavy rare earth separation reagents, nuclear fuel reprocessing chemicals, lanthanide purification ligands, rare earth metallurgical additives, etc.
Why it can be used for this purpose: Pyridine-2,6-dicarboxylic acid forms complexes with different lanthanide ions that have slightly different stability. This difference can be used to achieve the stepwise separation and purification of lanthanide elements, which can be used for lanthanide separation in rare earth metallurgy and nuclear industry.
Pyridine-2,6-dicarboxylic acid (CAS 499-83-2) is a pyridine carboxylic acid with two carboxyl groups at the 2 and 6 positions of the pyridine ring. Its core structure is a tridentate chelate structure of "one pyridine nitrogen + two carboxyl oxygens," exhibiting strong coordination, rare-earth-sensitized luminescence, spore labeling, coordination polymerization, and antibacterial properties. Industrially, it is mainly used as a biological indicator and for sterilization validation, spore detection, ion chromatography eluent, chemical sensor, metal complexation, MOF materials, catalyst ligands, and rare-earth separation. Understanding its tridentate coordination structure and the deprotonation capability of the two carboxyl groups explains why it can stably complex metal ions, sensitize rare-earth luminescence, construct porous materials, and detect spores—this is why it spans analytical chemistry, materials science, catalysis, and biological detection.
