Structural Modulation of Nonlinear Absorption in Tailored Linkers and MOFs: Synthesis, Characterization and Structure-Activity Relationship

• Applicant: Dr. Kirti Singh, Ph.D.
• Subject Area: Solid State and Surface Chemistry, Material Synthesis
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 557860438

Nonlinear optics (NLO) play a crucial role in applications such as photodynamic therapy, secure communications, and catalysis. However, the development of effective molecules is often hindered by issues with performance and stability. Metal-Organic Frameworks (MOFs) present a promising solution, as their rational design enables the creation of thermally and photostable materials with customizable properties. By modifying network topologies, degrees of interpenetration, packing densities, and chromophore arrangements, the photonic properties of these materials can be finetuned. This project aims to investigate the two-photon absorption (TPA) characteristics of new MOFs that incorporate two types of donor-acceptor ligands. We will specifically focus on carbazole ligands with varying π-component lengths and types to assess their impact on TPA. Additionally, we will develop MOFs with branched alkyne linkers to enhance π-bridging, delocalization length, and charge transfer effects in TPA. By utilizing redox-inactive metal centers such as Zn(II), Ba(II), and Zr(IV), we will examine the structure-activity relationships between linkers and NLO properties. The optical and photoluminescence properties of the synthesized ligands and MOFs will be thoroughly analyzed. TPA will be assessed using nonlinear fluorescence emission techniques. This detailed investigation will improve our understanding of the structure-activity relationship for each MOF and its corresponding ligands, paving the way for the modification and development of new, more effective molecules.

• DFG Programme: WBP Position