Reaction of the ligands 2-phenyl-1H-1,3,7,8-tetraazacyclopenta[l]phenanthrene (PTCP) and benzene-1,3-dicarboxylic acid (m-H 2 BDC) with Ln 2 O 3 under hydrothermal conditions lead to three isomorphous coordination polymers [Ln 2 (PTCP) 2 (m-BDC) 3 ·H 2 O] n (Ln = Tm, 1; Nd, 2; Ce, 3). The coordination polymers crystallize in monoclinic, space group P2 1 /m with a = 9.8340(2), b = 17.9140(4), c = 15.6050(3) Å, β = 100.51(3)°for 1, with a = 9.8423(3), b = 18.3562(4), c = 15.6209(3) Å, β = 102.138(3)°for 2, and with a = 9.8620(2), b = 18.4960(4), c = 15.6530(3) Å, β = 102.42(3)°for 3,