This week’s speakers are Gözde Ceran, Emir Utku Şekercioğlu and Umut Mert Karacaoğlu.
Please see the seminar information and the abstracts below.
1.Preparation and Characterization of Transition Metal Salt-H4P2O7-P123 (M=Co, Ni, and Mn) Mesophases and Mesoporous Mn2-xMxP2O7 (M=Co and Ni) Electrodes
Gözde Ceran
Advisor: Prof. Ömer Dağ
Time: April 29, 2025, 12:30, SBZ14
Abstract: Transition metal phosphates and pyrophosphate materials have gained considerable interest in battery and supercapacitor applications.1-3 In this study, metal nitrates (Co(II), Mn(II) and Ni(II)) pyrophosphoric acid (PPA) and pluronic (P123) solutions are prepared in several alcohols (ethanol, methanol, butanol and trifluoroethanol) to obtain liquid crystalline mesophases (1:30:15, P123:M(II):H4P2O7). As the solutions are unstable and undergo precipitations, the precipitate and homogeneous solution phases are separated by centrifugation process, calcined, and characterized using various characterization techniques (XRD, ATR-FTIR, SEM, EDX, TEM, N2-adsorption-desorption techniques). Upon coating of these solutions on FTO and graphite rod substrates and calcination, the electrodes are further characterized by electrochemical methods, i.e., cylic voltammetry, galvanostatic charge-discharge, multistep-chronoamperometry, multistep-chronopotentiometry. The results show that by changing the metal center or by changing the solvent, the particle size and porosity can be tuned as well as their capacitive behaviour and oxygen evolution reaction (OER) performance. Especially, the synthesized mesoporous nickel pyrophosphates have a large surface area (410 m2/g) and its transformation to nickel hydroxide makes it very effective as an electrocatalyst for enhanced OER in alkaline media.
Similar synthesis methods and characterization techniques are used for manganese-rich binary metal pyrophosphates (Mn2-xMxP2O7, M=Co, Ni), which were specifically synthesized to suppress the manganese disproportionation reaction. Although manganese pyrophosphates have low surface area, are unstable on FTO or graphite rod substrates and have low current densities, we demonstrated binary metal pyrophosphates have high surface area, are stable over these substrates during cyclic voltammetry, CA and CP measurements and have higher current densities.
2.Covalent Coordination of Pentacyanoiron Group Red-Shifts and Increases the Lifetime of the MLCT of Iron-NHC Complex
Emir Utku Şekercioğlu
Advisor: Assoc. Prof. Ferdi Karadaş
Time: April 29, 2025, 12:30, SBZ14
Abstract: Since their discovery in 2013, iron N-heterocyclic carbene (NHC) complexes have become a focal point in photosensitizer research, offering a potential alternative to rare-earth metal-based systems such as ruthenium. A key challenge in this field is achieving sufficiently long excited-state lifetimes with iron complexes. Here, we propose a simple but effective approach to coordinate a secondary metal center -pentacyanoiron- to the Iron-NHC complex to form a multimetallic complex (Fe-Fe). This coordination is designed to red-shift the metal-to-ligand charge transfer (MLCT) band and increase the excited-state lifetime in accordance with the energy gap law. According to the UV-vis spectroscopy measurements, secondary metal coordination provides an MLCT state stabilization around 0.4 eV and increases the absorptivity coefficients. Transient Absorption Spectroscopy measurements show that an energy transfer process occurs if the complex is excited from the high-energy native MLCT (without any secondary metal) that provides longer lifetimes. The synthetic pathway of the pentacyanoiron approach and a detailed analysis of the photophysics of the Fe-Fe system will be discussed.
3.Diaza-Nazarov Cyclization: An Umpolung Approach to Access Multi-substituted Pyrazoles
Umut Mert Karacaoğlu
Advisor: Asst. Prof. Yunus Emre Türkmen
Time: April 29, 2025, 12:30, SBZ14
Abstract: The Nazarov reaction is a 4- thermal conrotatory electrocyclization reaction which is used to obtain five-membered ring structures1. Among the heterocyclic variants for this pericyclic reaction is the aza-Nazarov reaction developed by Türkmen Research Group2, 3 which incorporates a nitrogen atom into the ring, making it possible to access heterocyclic structures. To elaborate this concept, this project focuses on the development of a variant which is scarcely studied on, namely the diaza-Nazarov reaction. The substrate for the electrocyclization is prepared in 5 steps to construct the N-acyl azo derivative 1, and we discovered that the treatment of this compound with 1 equivalent of TFA at room temperature gives the corresponding pyrazole derivative with high yields.