This article deals with a coordination approach to three-dimensional assemblies via ‘molecular paneling’. Families of planar exo-multidentate organic ligands (molecular panels) are found to assemble into large three-dimensional assemblies through metal-coordination. In particular, cis-protected square planar metals, (en)Pd²⁺ or (en)Pt²⁺ (en = ethylenediamine), are shown to be very useful to panel the molecules. Metal-assembled cages, bowls, tubes, capsules, and polyhedra are efficiently constructed by this approach.

Solid state reactions offer a unique opportunity for synthesizing complex molecules with amazing regio- and stereo-specificity otherwise difficult to synthesize by conventional organic synthetic methodologies. In particular, the solid state [2 + 2] reaction is a well studied reaction in terms of a crystal engineering perspective. The main challenge in performing solid state reactions is bringing the molecules into reactive orientations such that the reactive groups are within a certain proximal distance. The out surge in organic and inorganic crystal engineering studies offers several strategies for bringing the molecules together in the crystal lattice. These strategies include from weak interactions (halogen bonds, halogen⋯halogen, π⋯π, cation⋯π) to strong hydrogen bonds (O–H⋯O, N–H⋯O, O–H⋯N and N–H⋯N) to coordination complexes/polymers. To date many studies are available which use such strategies for conducting single, double, triple or multiple [2 + 2] reactions, [4 + 4] reactions, Diels–Alder reactions and polymerization reactions of acetylene molecules. Some of the crystal engineering strategies include the use of external templates which can be removed after the reaction and some of the other strategies deals with the modification of reactant molecules. In this review, the current status of various strategies will be outlined with respect to the nature of the interactions involved.

Coordination polymers have attracted an enormous interest among chemists due to their novel physical and chemical properties. This review describes the role of 4,4′-bipyridine in discovering various coordination polymers with novel topologies that range from one-dimensional to three dimensional. The geometries of coordination polymers of bipy include linear, zigzag, four-fold helices, molecular antenna, ladder, railroad, double, triple and quadruple chains, bilayer, square and rectangular grid, honeycomb layers, Lincoln Logs, 3D frames, diamondoid, 4²·8² and cubic networks.

This article highlights the importance of crystal engineering in designing functional materials. Various rational design strategies will be discussed for controlling the molecular architectures of the materials using C–H⋯O, C–H⋯π, O–H⋯O, N–H⋯O and O–H⋯N hydrogen bonds and co-ordination bonds. The results described here show the role of guest molecules in templating the isomeric network structures with one set of molecular components. In particular, the materials that are designed based on strong hydrogen bonds and coordination bonds exhibited zeolite like and clay like properties.