CHEM Semineri: “Graduate Student Seminars”, 12:30 21 Mayıs 2024 (EN)

You are cordially invited to the graduate student seminars of the Chemistry Department.
This week’s speakers are Rana Uzunlar, Yaren Sevval Ozdogan, and Merve Temel.

Please see the seminar information below and the attached abstracts.

1. “Mechanochemical Synthesis of an Antihistamine Active Pharmaceutical Ingredient at Cryogenic Temperatures”

Speaker: Rana Uzunlar
Advisor: Assoc. Prof. Bilge Baytekin

Date : May 21st, 2024, Tuesday
Time : 12:30
Place: SBZ-14

Mechanochemical synthesis allows the productions of materials without solvents or with only minimal amounts of solvent, making it superior over conventional methods. Mechanochemical methods can also enable better efficiencies and rapid processes compared to conventional synthesis. The synthetic diversity of compounds obtained by these methods has been proved over the decades by the preparation of inorganic, organic, polymeric, metal-organic-framework,and organometallic materials. Preparations of active pharmaceutical ingredients (APIs) have also been quite efficient through some mechanochemical methods, which display better output than the conventional synthetic methods. Here, we show that a first-generation H1 antihistaminic API can be synthesized at cryogenic temperature. The reactants are milled in a cryomill for up to 30 min. (The reported conventional synthesis takes 4-24 hours). The yields are between 65-95% and alter depending on the milling time, milling frequency, and milling material. The synthesis is more efficient at cryo conditions than the identical setup at room temperature. This route brings an innovative perspective to synthesizing APIs that are widely
used and have potential applications in the industry.

2. “Ion Specificity on the Aqueous Sugar-Based Macromolecules”
Speaker: Yaren Şevval Özdoğan
Advisor: Asst. Prof. Halil I. Okur

Date : May 21st, 2024, Tuesday
Time : 12:30
Place: SBZ-14

The Hofmeister Series orders ion based on their propensity to enhance (salt-in) or decrease (salt out) the solubility of proteins and other macromolecules in aqueous media. This series is crucial for understanding how ions affect the functioning and aqueous stability of biological components. However, the molecular level mechanisms of ion-macromolecule interactions remain elusive, especially for non-amide based macromolecules. In this seminar, the focus is on the elucidation of the interaction mechanisms between the Hofmeister anions including sodium salts of SO₄²⁻, Cl⁻, and SCN⁻ and sugar-based macromolecules, namely methylcellulose, a water-soluble derivative of cellulose. Both the thermodynamic polymer phase transition temperature and spectroscopic techniques were utilized to elucidate the ion specificity on the sugar-based macromolecules. The phase transition temperature measurements were performed to understand the aqueous phase behavior of methylcellulose, while the hydrogen-Nuclear Magnetic Resonance (H-NMR) measurements were performed to explore the site-specific molecular interactions between Hofmeister ions and sugar-based polymers. Overall, it is observed that the weakly hydrated Hofmeister anions (SCN-, ClO4-, I-) interacts with the side chain of the macromolecules, the methyl groups and facilitate a salting-in behavior. In sharp contrast, the strongly hydrated anions (SO42-, Cl-, F-) show no apparent binding affinity to the macromolecule and cause purely a salting-out effect.

3. “Template-Directed [2+2] Photochemical Cycloaddition of Naphthalene Acrylic Acids & An Investigation of Single-Crystal-to-Single-Crystal Transformation”
Speaker: Merve Temel
Advisor: Asst. Prof. Yunus Emre Turkmen

Date : May 21st, 2024, Tuesday
Time : 12:30
Place: SBZ-14

The criteria for a successful photochemical [2+2] cycloaddition reaction in a solid state were described by Schmidt and co-workers.1 With this purpose, we have utilized a strategy that our group has developed recently, where 1,8-dihydroxynaphthalene is employed as a template to provide optimal distance between the two double bonds.2,3 In this work, [2+2] cycloaddition reaction of naphthalene acrylic acids was investigated. It can be claimed that 1,8-dihydroxynaphthalene is a sufficient template for the cycloaddition reaction of naphthalene acrylic acids.
Additionally, in single-crystal-to-single-crystal (SCSC) reactions, the reactants undergo a transformation without losing their crystallinity in the same solid phase.4 Due to being closely packed in the crystalline structure, molecules cannot move freely. That is why external stimuli are essential for SCSC transformations. We investigated the SCSC transformation of the template-directed [2+2] photochemical cycloaddition of naphthalene-based acrylic acid derivatives. In powder form, the irradiation of compound 1 under the UV light afforded [2+2] cycloadduct 2 with 98% conversion as a single diastereomer. Moreover, irradiation of single crystals of 1 gave cycloadduct 2 quantitatively while retaining its crystal look, which indicates an SCSC transformation.
1. Chaudhary, A.; Mohammad, A.; Mobin, S. M. Recent Advances in Single-Crystal-to-Single-Crystal Transformation at the Discrete Molecular Level. Cryst. Growth Des. 2017, 17, 2893–2910.
2. Yagci, B. B.; Zorlu, Y.; Türkmen, Y. E. J. Org. Chem.2021, 86, 13118-13128.
3.Yagci, B. B.;Munir B.;Zorlu, Y.; Türkmen, Y. E. Synthesis2023, 55,3777-3792.
4. Friščić, T.; MacGillivray, L. R. Single-crystal-to-single-crystal [2 + 2] photodimerizations: From Discovery to design. Z. Kristallogr. Cryst. Mater. 2005, 220, 351–363.