The "tailor effect" of fluoride, exclusively as a terminal rather than a bridge, was applied successfully to design low-dimensional structures in the system of transition metal germanophosphates for the first time. Two series of new compounds with low-dimensional structures are reported herein. K[(MGe)-Ge-II(OH)(2)(H0.5PO4)(2)] (M = Fe, Co) possess flat layered structures built from single chains of edge-sharing (MO6)-O-II and GeO6 octahedra interconnected by HPO4 tetrahedra. Their fluorinated derivatives, K-4[(MGe2F2)-Ge-II(OH)(2)(PO4)(2)(HPO4)(2)]center dot 2H(2)O (M = Fe, Co), exhibit band structures of two four-membered ring germanium phosphate single chains sandwiched by (MO6)-O-II octahedra via corner-sharing. Both of these structures contain anionic chains of the condensation of four-membered rings built from alternating GeO4 Phi(2) (Phi = F, OH) octahedra and PO4 tetrahedra via sharing common GeO4 Phi(2) (Phi = F, OH) octahedra, the topology of which is the same as that of the mineral krohnkite [Na2Cu(SO4)(2)center dot 2H(2)O]. Note that the switch from the two-dimensional layered structure to the one-dimensional band structure was performed simply by the addition of a small amount of KF center dot 2H(2)O to the reaction mixture. This structural alteration arises from the incorporation of one terminal F atom to the coordination sphere Of Ge, which breaks the linkage between the transition metal and germanium octahedra in the layer to form the band structure.