Abstract: The subject of this dissertation focuses on understanding the influence of link angle, one of the geometric parameters of an organic linker, on the crystal structures of metal-organic polyhedra (MOPS) and metal-organic frameworks (MOFs) and utilizing link angle to control the syntheses of MOPS and MOFs. This goal is accomplished by the theoretical analysis of the ideal link angles for the construction of some of the most important target structures, specifically, nine polyhedral shapes having only one kind of edge, and the underlying nets of zeolites, and the experimental demonstration of the construction using either a flexible organic linker that provides the required link angle in a certain conformation or a rigid organic linker that inherently possesses the ideal angle. This dissertation reports the crystal structures of a metal-organic octahedron (MOP-28) obtained by linking the square planar Cu₂(COO) ₄ paddle-wheel units with the flexible 2,2':5',2'-terthiophene-5,5'-dicarboxylate linker in its cis, cis conformation having a link angle of 90° and Zeolitic Imidazolate Frameworks (ZIFs; ZIF-2 with the zeolite BCT topology and ZIF-6 with the zeolite GIS topology) achieved by joining the tetrahedral Zn2+ vertices with the rigid imidazolate linker having a link angle close to 144°. The influence of link angles of flexible organic linkers is further demonstrated in a series of MOF crystal structures containing oligothiophenedicarboxylate linkers (2,2'-bithiophene-5,5'-dicarboxylate for IRMOF-21 and MOF-69d; 3',4'-ethylenedioxy-2, 2':5',2'-terthiophene-5,5'-dicarboxylate for MOF-371; 1,3-bis(5-carboxylate-2-thienyl)benzene for MOF-372) in which the various conformers of the linkers all exhibit special link angles that are multiples of 30°. The influence of link angle of the rigid imidazolate linker is further exemplified in the crystal structure of ZIF-5 with the garnet topology, and in the determination of the default topology for extended frameworks composed of alternating tetrahedra and octahedra. Additionally, this dissertation reports gas adsorption characterization for MOP-28 and two prototypical ZIF structures, namely ZIF-8 (zeolite SOD topology) and ZIF-11 (zeolite RHO topology). Most importantly, MOP-28 has a Langmuir surface area of 1100 m2/g; ZIF-8 shows a Langmuir surface area of 1810 m2/g and a saturation hydrogen uptake of 3.1 wt% at 77 K and 55 bar.