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

Abstract

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 ErIII emission. The excellent NIR luminescent properties, indicating their promising potential applications as gain medium materials in optical amplification devices.