Fragment Library

Rule of 3 compliant compounds for fragment-based drug discovery


The ChemBridge® Fragment Library set offers more than 5,000 compounds that can be individually selected based on your criteria, allowing researchers to build fragment sets of size and composition best suited to their research objectives and methodologies. ChemBridge can also assist in the selection of diverse sub-sets. This collection of small molecule fragments provides compounds for use in fragment-based screening and drug discovery using high-throughput X-ray crystallography, NMR, SPR and high concentration bioassay methodologies. Compounds can be provided in mg or umol equivalent amounts and delivered undissolved or as DMSO solutions.

View Fragment Library Data Sheet

Compounds included in the Fragment Library set were chosen based upon the commonly accepted Astex Rule of Three¹, additional physiochemical property filters, and proprietary ChemBridge substructure filters. ChemBridge has applied Rule of T hree considerations (MW ≤300, H-bond donors ≤3, H-bond acceptors ≤3, cLogP ≤3) along with rotatable bond count and calculated TPSA limits.

High Solubility Subset

Approximately half of the Fragment Library compounds meet the criteria for the High Solubility Subset (HSS). These fragments have a minimum DMSO solubility of 200mM and minimum solubility in phosphate buffered saline (PBS; pH 7.4) of 200uM (with many fragments soluble at 1mM in PBS). The remaining fragments have DMSO solubility of less than 200mM or PBS solubility of less than 200uM.

Fragment Library Values Average Property Value
Molecular Weight150 to 300Molecular Weight225.06
H-donors≤ 3H-donors1.22
H-acceptors≤ 3H-acceptors2.33
cLogP≤ 3cLogP1.27
Rotatable Bonds≤ 3Rotatable Bonds2.01
cLogSw≥ -2.50cLogSw-1.68
TPSA≤ 120TPSA49.66

¹Carr, R.A.E. et al., Drug Discovery Today, 2005, 10, 987-992.


  • Download structures and custom select from more than 5,000 Fragment Library compounds.
  • Compounds are available in mg or umol amounts undissolved (mostly powders, some oils), as DMSO solutions in standard or deuterated DMSO or as dry film and formatted to your requirements.
  • All compounds have a minimum purity of 90% by NMR or by LC-MS/ELSD.
  • Follow-up stock is available for resupply, subject to availability.

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