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Fragment-based Library

General Information

Fragment-based lead discovery is a new lead discovery approach in which much lower molecular weight (100-300Da) compounds are screened relative to HTS campaigns. Fragment-based hits are typically weak inhibitors (10μM-mM), and therefore need to be screened at higher concentration using very sensitive biophysical detection techniques such as protein crystallography and NMR as the primary screening techniques, rather than bioassays. Compared with HTS hits, these fragments are simpler, less functionalized compounds with correspondingly lower affinity. However, fragment hits typically possess high ‘ligand efficiency’ (binding affinity per heavy atom) and so are highly suitable for optimization into clinical candidates with good drug-like properties.

Rules of Selection

Compounds must fulfill a certain number of criteria (structural, substructural and special medicinal chemistry filters) before they are included in our corporate database. Organochem’s Fragment-based Library has been designed based upon the commonly accepted "Rule-of-Three" and other physicochemical and structural properties. Compounds were filtered on molecular weight (MW <300); number of H-bond donors ≤ 3; hydrophobicity as the calculated octanol/water partition coefficient (cLogP <3); number of rotatable bonds ≤ 3; number of H-bond acceptors ≤ 4; molecular polar surface area (PSA < 80); calculated aqueous solubility (LogSW > -5) (high aqueous solubility is essential for practical reasons during screening particularly in HCS).


In general, the available weights of the fragment based library's compounds range up to 100 mg.

Delivery time

5-14 business days for in-stock compounds and 2-8 weeks for resynthesized compounds.


The chemical structure is confirmed and the purity must be at least 90%. Most compounds though have purity higher than 95%.

If you are interested to obtain this library or you need extra information, do not hesitate to contact us via e-mail:

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Latest News

    • Are you interested in exclusive Building Blocks? Organochem's unique Building Blocks and Synthons are now available which are ideal for combinatorial chemistry with several points of diversity for decoration or library expansion. They are typical fragmented drug-like building blocks with low molecular weight which are ideal for lead optimization, and many may also suitable for fragment-based screening.

    • Search molecules in our online catalogue
      Organochem Ltd reports significant progress in development of efficient online search and ordering system.