Metal organic frameworks (MOFs) are porous solids that are potential high performance carbon capture materials. We have mined a hypothetical MOF database for structures that have exceptional low-pressure CO2 adsorption properties. We have applied the REPEAT method to generate accurate atomic charges that regenerate the ab initio electrostatic potential. We show that large scale screening at high accuracy is feasible for thousands of structures. We identify promising synthesis targets, like a simple combination of chrysene linker and vanadium inorganic unit, and examine in detail structural features that make better performing MOFs from those that would not be synthesisable. We find that, although screening large numbers of hypothetical structures is necessary to provide experimental targets, there are limitations to the suggestion of using the this database directly for synthesis targets and propose improvements and constraints that should be incorporated into the design of further generations of such a building-block algorithm to reach the accuracy required for high-quality CO2 adsorption simulation.