Key Takeaways:

• In Cu-catalyzed C(sp³)–H functionalization with NFSI, the Cu-bound •NSI radical is the active HAT reagent and selectively activates benzylic C–H bonds over 3° C–H bonds (superior vs. other HAT reagents like •O^tBu and •Cl).
• The radical functionalization pathway depends on the Cu-bound nucleophile, with options including radical-polar crossover, reductive elimination from a Cu^III organometallic complex, and radical addition to a Cu-bound ligand.
• Comparing 3 routes for transforming benzylic C–H bonds into their respective cations revealed that HAT/ET (relevant to Cu/NFSI chemistry) provides a wider substrate scope than hydride transfer (relevant in high-potential quinones) and sequential ET/PT/ET (employed in photoredox catalysis).

Key Takeaways:

• In perovskite-silicon tandem solar cells, the presence of C₆₀ molecules at the interface with the perovskite layer can create shallow trap states and lead to high levels of interface recombination, reducing the power conversion efficiency (PCE) of the cells.
• Addition of an ultrathin metal-fluoride interlayer at the perovskite/C₆₀ interface can reduce nonradiative recombination and improve electron extraction, resulting in a higher PCE of 29.3%.
• Insertion of an interlayer can also address the issue of a surface dipole at the pristine perovskite/C₆₀ interface, which can hinder electron extraction.
• (MgF₂)_n layers serve as a better “electron sink” than (LiF)_n layers, enabling more efficient charge extraction.

Key Takeaways:

• Large hysteresis and poor field-effect behavior associated with severe ion migration can render perovskite field-effect transistors (FET) unreliable.
• The hot-casting method can be used to control grain size and grain boundary density in perovskite films to improve charge carrier transport.
• Hot-cast Sn(II)-based 2D perovskite FETs containing thiophene-based organic cation spacer TEA showed moderate increases in local hole mobility and significant FET performance improvements.

Key Takeaways:

• Optoelectronic properties of metal halide perovskite nanocrystals (PNCs) with the formula ABX₃ are studied through the effect of B-site doping with Sr²⁺ ions on pristine CsPbBr₃ and Mn²⁺-doped Mn²⁺:CsPb(Br,Cl)₃ PNCs.
• ~2% Sr²⁺ doping improved the photoluminescence quantum yields of CsPbBr₃ and Mn²⁺:CsPb(Br,Cl)₃ PNCs and increased the luminous efficiency of white LEDs constructed with Sr²⁺-doped PNCs by approximately 4.7% compared to undoped PNCs.
• Improved performance of Sr²⁺-doped PNCs is attributed to reduced defect density and attenuated microstrain in the local PNC structure, suggesting that adding a small amount of Sr²⁺ dopant to pristine perovskite materials can be a successful strategy for improving the optical properties of PNCs.

Key Takeaways:

• Surface defect passivation is important for improving optoelectronic properties of lead halide perovskite nanocrystals (LHP NCs).
• Treatment with p-dopant LiTFSI, an organic lithium salt, has multiple benefits for LHP NCs and LEDs derived from them, including higher photoluminescence quantum yields, longer exciton lifetimes, and higher external quantum efficiencies.
• Density functional modeling shows that TFSI^– ligands change the surface dipole moment of slabs, leading to a significant shift in the vacuum level, while also preventing the harmful reduction of Pb²⁺ to Pb⁰ on the surface.

Key Takeaways:

• A molecular probe is developed that can measure temperature in vivo during magnetic resonance imaging (MRI).
• Virtual screening was used to identify organofluorine compounds that could potentially improve the accuracy and sensitivity of ¹⁹F MRI-based temperature monitoring.
• A perfluoro-sulfane-based compound showed a nearly 2-fold increase in temperature responsiveness compared to perfluoro-tributylamine, the current standard ¹⁹F MRI temperature sensor.

Key Takeaways:

• Hybrid nanographene-graphene van der Waals heterostructures are studied for optoelectronic device applications.
• Adjusting the size of synthesized nanographenes controls the strength of van der Waals interactions and interfacial charge transfer in these structures.
• Interfacial charge transfer efficiency and rate increase with nanographene size, despite a reduction in driving interfacial energy. Van der Waals interactions dominate interfacial charge transfer efficiency in these structures, while interfacial energetics and reorganization energy have a minor impact.

Key Takeaways:

• The presence of surface defects and their effect on the fluorescence properties of supercrystals of self-assembled CsPbX₃ (X = Cl, Br) perovskite nanocrystals (PNCs) are investigated.
• At the edges of the supercrystal, a fluorescence blueshift and decreased fluorescence lifetimes are observed due to a loss of structural coherence, atomic misalignment, and compressive strain.
• Minimizing strain during the self-assembly of PNCs into supercrystals is important for lighting applications such as superfluorescent emitters.

Key Takeaways:

• Native surface ligands (oleic acid/oleylamine) on all-inorganic CsPbBrI₂/SiO_x perovskite nanocrystals (PNCs) were replaced with exciton delocalizing mono-functionalized porphyrin derivatives, mMTPP (M = Zn, Mg, H2).
• Electronic interaction between the mMTPP ligand and the inorganic PNC core is evidenced by the dislocation of the “electron” state (LUMO) onto the ligand, which lowers the first excitonic transition energy and contributes to lowering the charging energy.
• The ligand-exchanged PNCs showed increased phase stability and improved optoelectronic properties and were used in an LED with higher current efficacy and improved charge carrier balance.

Key Takeaways:

• Two single-site heterogeneous catalysts were synthesized by immobilizing vanadium oxide (VO_x) species on two MOFs, Zr-NU-1000 and Hf-MOF-808.
• The structure and reactivity of these VO_x-incorporated MOFs, or V-MOFs, towards selective oxidation of benzyl alcohol to benzaldehyde was explored using density functional theory.
• Turnover-limiting C–H activation during benzyl alcohol oxidation was found to involve a concerted proton-coupling electron transfer mechanism.
• Aside from the metal in the node, the MOF node architecture significantly affected the catalytic activity of the two V-MOFs.

Key Takeaways:

• A copper-catalyzed method for benzylic C–H azidation is presented.
• Experimental and density functional studies suggest that the reaction proceeds through a radical-polar crossover pathway involving a Cu^II-azide species and a benzyl radical.
• The method exhibits unique site-selectivity compared to other C–H azidation methods and produces benzyl azides that can be converted into a variety of functional groups, including amines, triazoles, tetrazoles, and pyrroles, for use in target molecule synthesis and medicinal chemistry.

Key Takeaways:

• A copper-catalyzed oxidative cross-coupling reaction was developed to synthesize diverse benzyl ethers by coupling benzylic C–H bonds (limiting reagent) with alcohols.
• Typical reaction conditions resulted in the accumulation of inactive Cu^II, but the use of dialkylphosphites, (MeO)₂P(O)H, as in situ reductants allowed for the regeneration of catalytically active Cu^I.
• This redox buffering strategy may not be specific to this type of reaction and could potentially be used to discover and develop other radical relay C(sp³)–H cross-coupling methods that have a broad range of applications in medicinal chemistry and organic synthesis.

Key Takeaways:

• L²AlOBn and L⁷AlOBn complexes (Bn = benzyl) supported by an analog of salen ligand incorporating indolide arms connected via their 2- and 7-positions, were found to catalyze stereoselective polymerization of rac-lactide to isotactically enriched polylactide.
• NMR spectroscopy, X-ray crystal structures, and density functional theory were used to study the initiation reactions and examine the stereocontrol.
• The stereochemistry of initiation in these complexes is governed thermodynamically, not kinetically.

Key Takeaways:

• Copper(II) carboxylate complexes [LCu^II(O₂CR)]^– with varying R-groups were studied, most with N,N′,N″-coordination by the supporting ligand.
• Redox properties, UV-vis ligand-to-metal charge transfer features, and rates of hydrogen atom abstraction from 2,4,6,-tri-^tbutylphenol using oxidized LCu^III(O₂CR) complexes correlated with the electron donating nature of R.
• The results support an oxidatively asynchronous proton-coupled electron transfer mechanism that is sensitive to the oxidative power of the [Cu^III(O₂CR)]²⁺ core.

Key Takeaways:

• Formally copper(III)–oxygen complexes LCu^III–OH (1), LCu^III–OOCm (2) and LCu^III–O₂CAr (3) can activate X–H bonds (X = C, O).
• Complex 1 reacts the fastest with O–H or C–H based substrates, followed by 3, followed by unreactive 2.
• The reactivity of 1 – 3 varies due to differing oxidizing abilities and X–H bond functionalization mechanisms, which can be either hydrogen-atom transfer (HAT) or concerted proton-coupling electron transfer (cPCET) and vary based on the substrate and copper functionality.

Key Takeaways:

• The structure and electronic properties of palladium single-site heterogeneous catalysts in phosphated and sulfated MOFs are studied.
• The PO₄^2– and SO₄^2– groups in the MOFs stabilize the Pd(II) site and enhance catalytic activity in the oxidative Heck reaction.
• Density functional calculations suggest that acid functionalization of the MOF node can stabilize the Pd(0) intermediate state during the reaction and prevent catalyst deactivation due to Pd(0) aggregation.

Key Takeaways:

• Isosorbide is a rigid, sugar-derived monomer that has potential in high-performance materials.
• Controlled polymerization methods for isosorbide have been lacking.
• This study provides insights into the cationic and quasi-zwitterionic ring-opening polymerization of an annulated isosorbide derivative, allowing for the formation of either linear or cyclic polymers.

Key Takeaways:

• Computational screening was performed to identify aluminum complexes with high activity in ring-opening polymerization (ROP) of ϵ-caprolactone.
• An {N,N,N,N}-aluminum complex with a bis-indolide Schiff-base ligand was predicted to be efficient.
• Prediction was tested and verified through synthesis and characterization of the complex and evaluation of its ROP reactivity.

Key Takeaways:

• Effectiveness of aluminum salen complexes with o-adamantyl substituents in initiating the polymerization of ε-caprolactone was compared to that of similar salen catalysts having o-^tbutyl substituents.
• DFT modeling indicates that the reactivity of the catalyst is influenced by both the length of the backbone linker and the presence of o-aryl substituents on the ligand.
• Bulky o-substituents distorts the pre-catalyst geometry in a favorable way, making it easier to achieve the rate-limiting TS geometry, thus speeding up the reaction.

Key Takeaways:

• Polymerization of rac-lactide (rac-LA) using L^XZn catalysts was studied using kinetic experiments and DFT calculations.
• L^XZn catalysts were effective and relatively selective in polymerizing rac-LA with low dispersities, but the rate of polymerization was less affected by the electronic effects of ligand substituents (controlled by the para substituent X on the bound phenolate donor of the ligand) compared to earlier studies using aluminum catalysts.
• DFT calculations provided insights into the mechanisms of initiation and propagation, helping to explain the high isotacticity and the insensitivity of the rate to the identity of the ligand substituent X.

Key Takeaways:

• Mechanistic studies of the copolymerization of 1-butene oxide and carbic anhydride using a (salph)AlCl/[PPN]Cl catalytic pair showed a first-order dependence of the polymerization rate on the epoxide and zero-order dependence on the cyclic anhydride.
• Model complexes showed that a mixed alkoxide/carboxylate aluminum intermediate preferentially opens cyclic anhydride over epoxide, and ring-opening of epoxide by an intermediate comprising multiple carboxylates was rate-determining.
• A mechanism involving two catalytic cycles is proposed where the copolymerization proceeds via intermediates with carboxylate ligation in common, avoiding a secondary cycle involving a bis-alkoxide species and explaining the lack of side reactions until the polymerization is complete.

Key Takeaways:

• The polymerization of ε-caprolactone (CL) using an aluminum alkoxide catalyst (Al-TMTAA) was found to have a slower rate compared to other aluminum complexes.
• DFT calculations showed that the ligand framework of the catalyst made trans binding of CL difficult, suggesting a concerted coordination–insertion for polymerization.
• The sluggish performance of the catalyst is attributed to a high-framework distortion energy required to deform the ligand geometry, suggesting a need for ligand flexibility in the design of efficient polymerization catalysts.

Key Takeaways:

• Melanin is a pigment found in human skin that can both protect against and contribute to photodamage.
• The ionization energies of melanin monomers, dimers, and oligomers were calculated to determine the threshold energy for ionization, which was found to be in the UV-B range.
• The charge and spin distributions of ionized monomers were examined to understand which ionization channels might promote melanin monomerization.