In the present work novel concepts are established for the transition from a lamellar to a columnar organization in low molecular weight thermotropic liquid crystalline systems. In a classical sense, rigid rod-like (calamitic) liquid crystals are organized preferably in lamellar (smectic) phases, while rigid disc-like (discotic) liquid crystals exhibit mainly columnar phases. By the synthesis of paracyclophanes with laterally attached alkyl chains resp. ortho-palladated and ortho-platinated metallomesogens, in which beside macrocyclic (paracyclo-phanes) also calamitic structural units (2-phenylpyrimidine-, 2,5-diphenylpyrimidine- and 2-phenylpyridine moieties) are fused with 1,3-diketonate units with a varying number of attached alkyl chains, a stepwise transition between different molecular architectures was realized. Increasing the number of attached alkyl chains leads for most of the systems to a discontinuous transition from a lamellar to a columnar organization in the observed liquid crystalline phases without formation of cubic phases as intermediate phases in between both types of mesophase organizations. A replacement of the Pd-atoms in the series of the ortho-palladated compounds with Pt-atoms leads to a mesophase stabilization resp. induction, as well as to fluorescent and photoconducting materials. Finally, the three decades ago theoretically predicted biaxial smectic A phase (McMillan phase) was for the first time observed and experimentally confirmed in binary mixtures consisting of the electron-rich organometallic compounds and the electron acceptor 2,4,7-trinitrofluoren-9-one (TNF).