Hydrothermal Synthesis and Characterization of Two Novel Lead(II) Frameworks: From 1D Infinite Helical Pb–(O–C–O)–Pb Linkage to 3D Infinite Pb–X–Pb Network (X = O and Br)

摘要

Two aliphatic dicarboxy1ic acid ligands, iminodiacetic acid (H_2L_1) and 3,3-thiodipropionic acid (H_2L_2), were used to construct two novel lead(II) frameworks, namely, [Pb(μ_4-L_1)Br]_n (1) and [Pb_3(μ_9-L2_)(μ_2-Br)_2Br_2]n (2), under hydrothermal conditions. It has to be noted that for 1 the central Pb~(II) ions are bridged by L~(2–) ligands resulting in infinite right- and left-handed helical Pb–(O–C–O)–Pb linkage. Compound 2 represents a novel 3D hybrid luminescent lead(II) framework with I~3O~0 type connectivity. For 2 infinite 2D Pb–O–Pb inorganic layers and trinuclear Pb_3Br_4 clusters are inter-linked forming a 3D inorganic connectivity. In 1 the five-coordinate central Pb~(II) ions adopt a hemi-directed coordination arrangement, whereas in 2 six-coordinate Pb1, six-coordinate Pb2, and four-coordinate Pb3 atoms adopt hemidirected coordination arrangements. The variable lead(II) coordination environment and flexible coordination modes of carboxy1ic acid ligands such as H_2L_1 and H_2L_2 also reveal great potential for constructing novel inorganic-organic hybrid materials. Furthermore TGA, FT-IR, PXRD, elemental analysis, and photo-luminescent properties of 1 and 2 were investigated.