I have managed rather large medchem projects in Excel, it is quicker and easier than many large, expensive programs. You can even paste Chemdraw or other structures into cells. I would create taps for each molecule group and then create a template molecule with a few R groups, R1, R2, R3 in each cell and then the mol formula, MW, etc, then have space for purity, amount, etc. Then put your screening/biology data next. That will allow you to see trends by R groups, as well as other data. Most good software for doing that (like what is used at Merck or Pfizer) costs $1000/s per user, and takes multiple people just to support. Excel is quick, easy, and cheap, and can do much of the same.