SYNTHESIS AND OPTICAL PROPERTIES OF THE NOVEL Ho(5-SSA), (5-SSA = 5-SULFOSALICYLIC ACID) CAGE STRUCTURE

In recent years, intensive studies have been made on metal-organic frameworks (MOFs) which is kind of spongy structures having excellent original architectures formed by ligands in organic forms and metal centers classified as binders. The main reason for this condensation is due to the great huge potential for such materials to be used in many technological application areas such as sensors, gas storage, photo-catalysis, organic light emitting diodes (OLEDs), solar cells (SCs) and luminescent emitting devices. The properties of the metal-organic frameworks depend on the selected organic ligands and metal ions. Therefore, new research and technology development (R-T-G) fields can be discovered with these materials that can be originally synthesized. In this work, Ho(III)-based metal-organic framework (Ho-MOF; [Ho(5-SSA)], 5-SSA = 5-sulfosalicylic acid) was synthesized by hydrothermal method. The structural characterization has been made by powder X-ray diffraction, a room temperature solid-state UV and FT-IR spectroscopy. In addition, the solid-state photoluminescence measurements have been taken at room temperature in the UV-visible and near-infrared region (NIR) and the energy transfer mechanism from 5-SSA ligand to the Ho+3 ion is investigated in detail. Under the excitation of UV light (at 349 nm), 5-SSA ligand exhibited a broad navy-blue emission while its Ho-MOF complex exhibited several characteristic emissions of the Ho+3 ion in the UV-Visible and NIR region. The excellent luminescent performances make this compound very good candidate for efficient luminescence materials