Structure builder. Many MOFs and COFs have non-trivial geometry and are composed of rather large, sometimes bulky, molecules. Several methods have been developed to stitch these building blocks together to form a framework, including AuToGraFS , zeo++ , and MOFplus. Coupling framework generation to a force field is essential to produce starting structures that should be followed by higher-level methods. In this work we employed the Universal Force Field (UFF) extended for MOFs and hydrogen bonds. There are various other forcefield alternatives available for MOFs, which typically perform superior for a particular MOF subclass, but do not provide the almost complete range of elements that are covered by extended UFF. Some can, however, produce superior structures that are comparable to those of quantum chemical approaches. For an overview on alternatives, we refer to a recent review by Boyd et al. For COFs, incorporating only 1 st and 2 nd row atoms, a large variety of standard force fields are available.