Guest water molecules confined in channels of porous coordination polymer crystals [Ln(2)Cu(3)-(IDA)(6)]center dot nH(2)O (Ln = La, Nd, Sm, Gd, Ho, Er; IDA = [NH(CH(2)COO)(2)](2-); n approximate to 9) exhibited large dielectric constants (epsilon) and antiferroelectric behaviors at high temperatures (e.g., epsilon(Sm) approximate to 1300 at 400 K). In addition, plots of the temperature dependence of E showed broad peaks at similar to 170 K, below which epsilon became very small. These puzzling temperature dependences of epsilon are consistent with the results of molecular dynamics simulations, suggesting the "freezing of thermal motion" of water molecules at similar to 170 K.