Blue-light emitting 1D and 2D based metal–organic frameworks derived from Cis-5-Norbornene-Endo-2,3-dicarboxylic acid and diphenic acid for optoelectronic applications

Title : Blue-light emitting 1D and 2D based metal–organic frameworks derived from Cis-5-Norbornene-Endo-2,3-dicarboxylic acid and diphenic acid for optoelectronic applications

Abstract:

The development of thermally stable, single-component luminescent metal–organic frameworks (MOFs) is an important strategy for advancing optoelectronic and energy-related materials. Herein, two MOFs with distinct dimensionalities were reported. A one-dimensional Zn(II) MOF, [Zn(DPA)(H₂O)] (1), was synthesized from diphenic acid (DPA) via a solvothermal method in water. Single-crystal X-ray diffraction analysis revealed that 1 crystallizes in the monoclinic crystal system with P2₁/c space group. Compound 1 adopts a helical chain structure with tetrahedrally coordinated Zn(II) centers, and the structure is stabilized by intermolecular hydrogen bonding. A 2D-MOF, namely [Cd(NDA)H₂O]?0.5H₂O (2), was synthesized by the solvothermal reaction of norbornene-based ligand, cis-5-norbornene-endo-2,3-dicarboxylic acid (NDA) and Cd(NO₃)₂?6H₂O in N,N-dimethylformamide (DMF) and water. The compound 2 was constructed by the coordination of distorted octahedral Cd(II) centers and carboxylic group of the NDA ligand. The Cd(II) centers are connected with the NDA ligand to form a 2D network with hcb (6,3) topology.  Photoluminescence measurements in solid-state indicate that 2 displayed blue-light emission with the excitation wavelength at 365 nm. The CIE diagram of 2 locates the emission in the blue-light region with chromaticity coordinates at (0.17, 0.14) whereas 1 shows intense blue emission with CIE coordinates of (0.17, 0.19), consistent with a ligand-to-metal charge transfer (LMCT) process.  The thermogravimetric analysis confirmed the stability of 1 up to 500 °C. DFT and TD-DFT calculations of 2 reveal that this blue-light emission arises from ligand-to-metal charge transfer (LMCT) process, where the HOMO is localized on the organic linker and the LUMO on the Cd(II) center, highlighting the key role of cadmium in tuning the photophysical properties. These results demonstrate that both compounds possess suitable characteristics as a standalone blue-light emitting material for future optoelectronic applications.

Keywords: Metal-organic frameworks (MOFs), Cd(II), Zn(II), cis-5-Norbornene-endo-2,3-dicarboxylic acid, photoluminescence.

Biography:

Shakeeba Cholikadam is a PhD researcher in the Department of Chemistry at King Fahd University of Petroleum & Minerals (KFUPM), Saudi Arabia. She holds Bachelor's and Master’s degrees in chemistry and specializes in the design, synthesis, and characterization of metal–organic frameworks (MOFs) for optoelectronic and luminescent applications. Her research focuses on understanding the structure–property relationships of functional materials using advanced characterization techniques. She has co-authored peer-reviewed publications in international journals and presented her work at scientific conferences. Her research interests include coordination chemistry, crystal engineering, photoluminescence, and the development of advanced functional materials for sensing and optical applications.