Unactivated Alkyl Chloride Reactivity in Excited-State Palladium Catalysis

By Aidana Gimnkhan

Abstract

Excited-state palladium catalysis is an efficient process for the alkylation of diverse organic compounds via the generation of alkyl radicals from alkyl bromides and iodides. However, the generation of alkyl radicals from more stable alkyl chlorides remains challenging. Herein, we demonstrate the excited-state palladium-catalyzed synthesis of oxindoles and isoquinolinediones via alkylation/annulation reaction by overcoming inherent limitations associated with unactivated C(sp3)−Cl bond activation at room temperature. 

Biography 

I got my bachelor’s degree in chemistry at Nazarbayev University in 2020. I’m currently in my second year of PhD under supervision of Professor Magnus Rueping. The research mainly focuses on the visible light photoredox catalysis.

Engineering Perovskite Single Crystal Growth for Efficient Solar Cells

By Mudeha Khan

Abstract                                                                                           

The photovoltaic efficiency of single-crystal-based perovskite solar cells (PSCs) lags behind its polycrystalline counterpart, unlike the trend observed in other traditional semiconductors. Polycrystalline perovskite solar cells were able to achieve record benchmark efficiencies due to ease in the passivation strategies during film crystallization. On the other hand, single-crystal PSCs benefit from low inherit trap density, long carrier diffusion lengths, and grain-boundary-free charge transport. However, the growth conditions for perovskite single-crystal are challenging, and the lack of passivation strategies during crystallization, and interfacial passivation present bottlenecks for lag in their photovoltaic efficiency. We introduced a hydrophilic polymer on top of self-assembled hole-transport layer (HTL), thereby improving the device performance by passivating the interfacial traps at HTL-perovskite single-crystal interface. Our champion passivated device exhibits high fill factor of 82, large V_oc of 1.08 V, and overall, a PCE of 25%, setting a new records for single-crystal PSCs. This works takes a leaf forward by addressing the challenges associated with passivation strategies in single-crystal PSCs.

Another challenge with single crystal growth is to grow it at a targeted site. Very sophisticated techniques like epitaxial growth and lithography are being used to address this problem but I have used a very simple approach by using a seed mediated growth in a space confined region to grow bigger crystal. I am also trying to grow single crystal at a targeted position via inkjet printing. In addition, my work also focuses on trying different hole transport materials for improving the efficiency and stability of solar cells. I will briefly discuss preliminary results based on NiOx hole transport layer.

Biography

My name is Mudeha Shafat Khan and I come from a small village in Kashmir, India. I have obtained a master’s degree in chemistry from the University of Kashmir. In 2022, I joined PhD program at KAUST under the guidance of Prof. Osman Bakr, focusing on interface engineering of lead halide perovskite single crystal thin-film solar cells and X-ray detection.

Catalytic enantioselective intramolecular hydroamination of alkenes using chiral aprotic cyclic urea ligand on manganese (II)

By Yuxuan Shang

Abstract

Asymmetric catalysis for enantioselective intramolecular hydroamination of alkenes is a critical method in the construction of enantioenriched nitrogen-containing rings, often prevalent in biologically active compounds and natural products. Herein, we demonstrate a facile enantioselective intramolecular hydroamination of alkenes for the synthesis of chiral pyrrolidine, piperidine, and indoline moieties, using a manganese (II) chiral aprotic cyclic urea catalyst. The cyclic ligand hinders the inversion of the N atom of the urea and effectively discriminate between the enantiomers of substrates. High-resolution mass spectrometry, deuterium labeling experiments, and molecular orbital energy analysis clearly reveal the intermediates and mechanism of the transformation. As a key step, oxygen coordination by chiral aprotic urea presents a robust control over the asymmetric intra-HA reaction through the involvement of a convergent assembly of two vital intermediates (Mn-N and C-Mn-Br), providing access to chiral cyclic amine systems in high yields with excellent enantioselectivity.

Biography

Yuxuan Shang is currently in his third year of PhD under the supervision of Professor Cafer Yavuz. He obtained his bachelor degree in 2021 at Sustech, China. His research focused on mechanism studies contain both computation chemistry and experimental results.