FILTER is a molecular screening and selection tool that uses a combination of physical-property calculations and functional-group knowledge to assess compound collections. In selection mode, FILTER can be used to choose reagents appropriate for specific syntheses. In filter mode, it quickly removes compounds with undesirable elements, functional groups, or physical properties. FILTER is a command line utility that reads and writes many file formats including SDF, Mol, Mol2, SMILES, and OEBinary. Filter is supported on Linux, Windows and IRIX; other platforms are available upon request.

Filter currently has the ability to select or reject compounds based on:

• Number of predefined or user-defined substructures
• Molecular weight
• Ring size and number
• Allowed elements
• Rotatable bonds
• Hydrogen-bond donors and acceptors
• Formal charges
• Chromophores
• XlogP [1], XlogS and Polar Surface Area [2]
• Predefined functional groups including: acid halide, aldehyde, alkyl halide, anhydride, azide, azo, di-peptide, long chains, michael-acceptors, beta-halo-carbonyl, nitro, peroxide, phosphonic acid, sulfonic acid, triphenyl-phosphene, epoxide, sulfonyl halide, aziridine, imine, oxalyl, thiol, urea, aniline, aryl halide, carbamate, ester, ether, hydrazine, hydrazone, hydroxylamine, nitrile, sufide, sulfone, sulfoxide, thiourea, thioamide

[1] XlogP: Wang, R., Fu, Y., and Lai, L., JCICS 1997, 37:615-621.

[2] Polar Surface Area: Ertl, P, Rohde, B, and Selzer, P, JMC 2000, 43:3714-3717.