Crystalline Sponge Gallery

G043 · Tropolone derivative

Puberulic acid

C8H6O6 · 198.13 g mol−1

First crystal structure · Angewandte Chemie International Edition 2026 · compound 32 →

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INTERACTIVE 3D STRUCTURE

Explore Puberulic acid in its crystalline sponge

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CHONCage
2D chemical structure of Puberulic acid
Puberulic acid · 2D chemical structure
3D crystal structure of Puberulic acid determined by the crystalline-sponge method
Puberulic acid · crystalline-sponge guest structure
Puberulic acid inside a crystalline sponge coordination cage
Puberulic acid · coordination-cage host–guest structure

Puberulic acid resolved by the crystalline-sponge method.

A deceptively small fungal tropolone with an unusually long history of structural and synthetic investigation.

Molecular formula
C8H6O6
Molecular weight
198.13 g mol−1
CCDC accession
2462985 ↗
Host
Pd6L4 cage
Study
Angew. Chem. 2026
Compound in publication
32

MOLECULAR HISTORY

A fungal pigment problem spanning nearly a century

Puberulic acid is a highly oxygenated tropolone metabolite. Its compact formula conceals an unusual electronic structure that made it important to the emergence of non-benzenoid aromatic chemistry.

  1. 1932

    Isolation from a blue-green mould

    Birkinshaw and Raistrick isolated puberulic acid from the metabolic products of Penicillium puberulum and established its empirical composition.1

  2. 1950

    The tropolone framework emerges

    Corbett, Johnson and Todd connected puberulic acid with the then-new chemistry of tropolones, rationalizing its unusual acidity and reactivity through a seven-membered conjugated ring.2

  3. 2014

    A concise total synthesis

    A protecting-group-free, eight-step synthesis from commercially available material delivered puberulic acid in 54% overall yield and provided a modern chemical confirmation of its connectivity.3

  4. 2026

    First definitive crystal structure

    The crystalline sponge ordered the native metabolite sufficiently for single-crystal X-ray analysis, furnishing its first definitive crystallographic structure.4

WHY THIS STRUCTURE MATTERS

Chemical degradation, spectroscopy and total synthesis had built a persuasive structural case, but the native metabolite still lacked direct crystallographic confirmation. The crystalline-sponge result closes that long-standing gap.

References

  1. Birkinshaw, J. H.; Raistrick, H. “Studies in the Biochemistry of Micro-organisms: Puberulic Acid.” Biochem. J. 1932, 26, 441–453. DOI 10.1042/bj0260441 ↗
  2. Corbett, R. E.; Johnson, A. W.; Todd, A. R. “Puberulic and Puberulonic Acids. Part II. Structure.” J. Chem. Soc. 1950, 6–9. DOI 10.1039/JR9500000006 ↗
  3. Sennari, G.; Hirose, T.; Iwatsuki, M.; Ōmura, S.; Sunazuka, T. “A Concise Total Synthesis of Puberulic Acid, a Potent Antimalarial Agent.” Chem. Commun. 2014, 50, 8715–8718. DOI 10.1039/C4CC03134B ↗
  4. He, W.; Takezawa, H.; Fujita, M. Angew. Chem. Int. Ed. 2026, 65, e202524615. DOI 10.1002/anie.202524615 ↗

SOURCE PUBLICATION

Second-Generation Crystalline Sponges Enabling Consistent Structure Analysis Under Standardized Conditions for Diverse Molecules

Angewandte Chemie International Edition 2026

DOI 10.1002/anie.202524615 ↗