Two New NIR Luminescencent Er(III) Coordination Polymers with Potential Application Optical Amplification Devices

Two new Er(III)-cluster-based coordination compounds have been synthesized by hydrothermal technique using monosodium 2-sulfoterephthalate (2-stp) and 4,4 '-bipyridyl (4,4 '-bpy) ligands. Depending on synthetic procedure, monomeric and polymeric Er(III) products, isolated as {[Er(2-stp)(2)(H2O)(6)]0.2(4,4 '-bipy)0.4(H2O)}, 1 and {[Er(2-stp)(4,4 '-bipy)(H2O)](H2O)}(n), 2. Both compounds have been characterized by elemental analysis, FT-IR, UV-visible and single-crystal X-ray diffraction and solid-state photoluminescence. The X-ray structure analyses show that Er atom is surrounded by two 2-stp ligands which have monodentate connection mode forming a monomeric structure in compound 1. However, in compound 2, Er atoms are coordinated by four bridging 2-stp ligands which adopt a hexadentate connection mode to form a central symmetrically dimeric building unit. The photoluminescence spectrums of the compounds have been exhibited intense blue emission for 1 and cyan-blue emission for 2. The band observed in NIR region at 1532 nm (for 1) and 1540 nm (for 2) are the typical Er-III emission. The excellent NIR luminescent properties, indicating their promising potential applications as gain medium materials in optical amplification devices.