Zinc15 to zinc20 transition
We moved from ZINC15 to ZINC20 officially on April 18, 2020, in the early days of Coronavirus.
The last molecule added to ZINC15 (that is also in ZINC20) was ZINC1,848,444,290.
From April 20, 2020 to June 21, 2021, we did add some molecules to ZINC15 that were never replicated to ZINC20. They had numbers between 1,848,444,291 and 1,865,085,643. (16.6 million numbers, but only about 16M actual molecules)
On June 21, 2021, these molecules were deleted from ZINC15 because they were confusing. They were mostly MCULE and a few other small vendors.
We did not export 2d or 3d with these molecules, so there should be no trace of them.
By the way, the last molecule in ZINC12 was around 98,000,000. We started ZINC15 at 100,000,000 so we did not have this problem.