Syntheses, crystal structures and thermal properties of 3D coordination polymers assembled from 1,4,5,8-naphthalenetetracarboxylic acid

Abstract

Two new coordination polymers based on 1,4,5,8-naphthalenetetracarboxylate (ntc) has been prepared by hydrothermal methods. Their crystal structures have been determined from synchrotron powder X-ray diffraction data. Ca 2(C 14H 4O 8)(H 2O) 2, CPO-13, is built around infinite chains of seven coordinated calcium atoms. Zn 2(C 14H 4O 8)(H 2O) 2, CPO-14, is isostructural with Mn 2(C 14H 4O 8)(H 2O) 2, and is built around infinite chains of corner sharing Zn octahedra. Crystal data for CPO-13: Triclinic space group P-1, with a = 5.820 , b = 6.759 , c = 10.168 Å , α = 72.32 ° , β = 86.09 ° , γ = 107.74 ° , V = 357.310 Å 3 and Z = 1 . Crystal data for CPO-14: Orthorhombic space group Pbam, with a = 9.773 , b = 7.060 , c = 9.879 Å , V = 681.729 Å 3 and Z = 2 . The thermal properties were investigated for both compounds. An unusual anisotropic thermal expansion for CPO-14 is caused by the carboxylate groups of the ntc anions gradually bending away from each other.