Installation and operational experiences with MACCS (Molecular Access System)

Computerised chemical substructure searching began at Shell Research Sitting‐bourne during the 1960s with a file of chemical structures coded in string form using the IUPAC (Dyson) chemical notation. Work on the coding of structures in this notation had begun about 1961 when the definitive rules were first published, and whilst the file was being created it was also being searched for compounds containing similar chemical fragments by using once‐off programs. In order to evolve into a fully fledged computer system, certain drawbacks in the notation had to be overcome and, based on a modified notation, a series of programs had been written by 1966 to enable registration, substructure searching, molecular formula checking and other activities to be carried out. After many years of use, it was decided that a move towards an interactive graphics system should be made, and several ideas were followed up. When, during these deliberations, Molecular Design Limited (MDL) announced their product MOLEX this was examined and assessed to be a suitable replacement for the old system provided that the structures and data already stored could be satisfactorily transferred. Molex, which is now known as MACCS (Molecular ACCess System), was subsequently purchased and has now been in use at Sittingbourne Research Centre for a year and a half.