Three ways into the collection
Initiate your small molecule program hit finding in one of three ways.
Diversity screen
Over 400,000 compounds, screened whole or as a subset matched to the target class.
Fragments
2,500 soluble fragments, for targets with no reference compounds in the literature.
Covalent fragments
More than 9,000 commercial covalent fragments, alongside an in-house set of over 1,900.
How a compound
earns a place
The collection includes compounds from niche vendors whose libraries extend beyond the coverage of standard commercial catalogs, and from IRBM’s own chemistry. All of them pass the same gate. Purity is confirmed above 90% before inclusion, and the collection is held at -20 °C in 100% DMSO.
Commercial and in-house structures are assembled as candidates for inclusion.
The filter is the same whatever the source
85% of the collection comes from niche suppliers and 15% from IRBM synthesis. More than 98% is free of PAINS and reactive structures, which is what keeps a primary screen from returning hits that never confirm.
Properties sit where optimization still has room
A mean molecular weight of 380 and a mean polar surface area of 78 leave room to add potency and developability.
Property distributions across the collection. Means: molecular weight 380, AlogP 2.75, HBA 5.4, HBD 1.4, PSA 78, rotatable bonds 5.3.
QED (Quantitative Estimate of Druglikeness) distribution across the collection. Mean 0.8.
What the collection covers
Coverage determines whether a screen yields hits worth pursuing in chemistry. The collection carries more than 140,000 distinct Murcko scaffolds, so a confirmed hit usually has related structures behind it in the same collection.
Shape is selected as well as chemistry
Compounds are distributed across rod, disc and spherical architectures. Shallow and featureless sites need three-dimensional chemistry present in the deck from the start.
Principal moment of inertia plot for the collection, showing coverage between rod, disc and spherical architectures.
Curated subsets plotted against the chemical space covered by the entire collection.
Start with a representative subset, or screen the full collection
Sub-libraries are curated collections of compounds organized according to demonstrated activity against specific targets or relevance to defined areas of application. Compounds are selected and acquired based on the combined expertise of medicinal chemists and the computational chemistry team, who identify the most relevant compounds for each sub-library.
The largest are the RNA and miRNA binder set at more than 40,000 compounds, and the central nervous system set at 9,000. The collection has generated hits against challenging target classes, including protein-protein interactions, phosphatases, and cell-based phenotypic screening assays.
An evolving collection tailored for targeted drug discovery
Focused sets are added, diversity is extended, and the deck is enriched ahead of a campaign.
Two libraries built for hard targets
Some targets return little or no usable chemistry from a diversity screen. For those programs, two focused libraries are available, each built using its own inclusion strategy and scientific rationale.
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Fragment library
2,500
2,500 validated fragments, a quarter of them carrying fluorine, held as powder stocks and in DMSO-d6. The set is optimized for NMR screening, where binding is detected without a functional assay.
Average values across the fragment set.
Held as powder stocks and in DMSO-d6, on the same site as the NMR facility.
Covalent fragment library
9,000+
More than 9,000 commercial covalent fragments directed at cysteine, lysine and histidine, alongside an in-house set of more than 1,900. The in-house set extends chemical space and warhead diversity across reversible and irreversible mechanisms. Properties comply with the rule of three.
Covalent hits are found by high throughput screening. Adduct formation, kinact/Ki and peptide mapping are handled by biophysical approaches.
Screen it at IRBM or in your own lab
Screened at IRBM
The campaign runs on the same research site, with plate-by-plate quality tracking and hit confirmation.
Shipped to you
Supplied as assay-ready plates in high throughput screening formats, with every compound registered under a unique identifier.
Fragment screening
Binding is detected by ligand-observed and protein-observed NMR at IRBM, with the site located on labeled protein.
Carried into chemistry
Confirmed series pass to medicinal chemistry on the same site, and the hits do not change hands.
The IRBM compound library and client compound collections are kept separate.
Client compounds are segregated from the routine IRBM HTS screening collection and are included in screening activities only upon request.
Start with one target
Tell us the target class. We will recommend the collection or subset to screen, the format, and what a confirmed hit should look like before chemistry starts.
Frequently Asked Questions
How large is the IRBM compound collection?
The screening collection holds over 400,000 compounds and more than 140,000 distinct Murcko scaffolds. More than 98% of it is free of PAINS and reactive structures, and it is held in 100% DMSO at -20 °C.
Can we screen a subset instead of the whole collection?
Yes. A focused subset can be screened in place of the whole collection where the target class supports it, and curated subsets exist for the main target classes. A 16,000 compound pilot set is normally screened first to confirm that the assay is robust and reproducable at campaign scale.
Can the library be shipped to us instead of screened at IRBM?
Yes. The collection or any subset can be supplied as assay-ready plates in formats compatible with high throughput screening workflows. Compounds are registered under unique identifiers so results can be reconciled with your own database.
What fragment libraries are available?
Two. A set of 2,500 soluble fragments optimized for NMR screening, a quarter of them carrying fluorine, held as powder stocks and in DMSO-d6. Separately, more than 9,000 commercial covalent fragments and an in-house set of more than 1,900, covering reversible and irreversible warheads against cysteine, lysine and histidine.
Are client compounds kept separate from the IRBM collection?
Yes. The IRBM compound library and client compound collections are kept separate. Client compounds are segregated from the routine IRBM HTS screening collection and are included in screening activities only upon the client’s request.
Where is the collection held, and how is quality maintained?
The collection is held at a single research site in Rome, Italy, alongside the screening and chemistry groups that use it. Compounds enter at above 90% purity, are handled by automated systems, and go through periodic QC campaigns. Client collections are stored separately from the HTS screening collection. The IRBM collection is revised every year with focused sets and diversity additions.
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