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The limits of polarization transfer efficiency are explored for systems consisting of three isotropically coupled spins 1/2 in the absence of relaxation. An idealized free evolution and control Hamiltonian is studied, which provides an upper limit of transfer efficiency (in terms of transfer amplitude and transfer time) for realistic homonuclear spin systems with arbitrary Heisenberg-type coupling constants J12, J13, and J23. It is shown that optimal control based pulse sequences have significantly improved transfer efficiencies compared to conventional transfer schemes. An experimental demonstration of optimal polarization transfer is given for the case of the carbon spin system of fully 13C labelled alanine at 62.5 MHz Larmor frequency.
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http://dx.doi.org/10.1016/j.jmr.2006.03.021 | DOI Listing |
Adv Mater
September 2025
State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012, P. R. China.
Helicene-based circularly polarized luminescence (CPL) materials suffer from severely low color purity in circularly polarized organic light-emitting diodes (CP-OLEDs). Here, a novel molecular engineering strategy is introduced by replacing helicene containing continuous fused benzene rings with a multiple resonance (MR) framework comprising discontinuous fused benzene rings. This approach effectively suppresses high-frequency C─C bond stretching vibrations and enhances short-range charge transfer, enabling high color purity, CPL activity, and efficient thermally activated delayed fluorescence (TADF).
View Article and Find Full Text PDFBioessays
September 2025
MY Small G Protein Research Group, Bioprocess Technology Division, School of Industrial Technology, Universiti Sains Malaysia, Pulau Pinang, Malaysia.
Advanced biosensing technologies, such as Förster resonance energy transfer (FRET) and bioluminescence resonance energy transfer (BRET), have enabled real-time, high-resolution tracking of Rho GTPase activity, surpassing traditional methods like pull-down assays. However, current biosensors mainly detect the GTP-bound active state through effector interactions, without directly measuring Rho GTPase expression or identifying related biomarkers of abnormal activation. Small Rho GTPases are essential molecular switches that regulate key cellular processes such as cytoskeletal organization, cell movement, polarity, vesicle trafficking, and the cell cycle.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
September 2025
Hefei National Research Center for Physical Sciences at the Microscale, School of Chemistry and Materials Science, State Key Laboratory of Precision and Intelligent Chemistry, National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui, 230026, China.
The construction of C─N bonds from simple precursors under ambient conditions is a fundamental challenge in green chemistry, especially when it comes to avoiding energy-intensive protocols. Here, we present a continuous flow photocatalytic platform that enables the efficient coupling of C─N bonds between methanol and ammonia at ambient temperature and pressure. By synergistically engineering a Pd clusters-decorated TiO photocatalyst (1Pd/TiO) and a mass transfer-enhanced gas-liquid-solid Taylor flow reactor, the system achieves a remarkable formamide productivity of 256.
View Article and Find Full Text PDFJ Phys Chem Lett
September 2025
Collaborative Innovation Center of Advanced Microstructures, National Laboratory of Solid State Microstructures, College of Engineering and Applied Sciences, Nanjing University, No. 22 Hankou Road, Nanjing, Jiangsu 210093, P. R. China.
The oxygen evolution reaction (OER) performance of commercial TiO-supported IrO (IrO/TiO) suffers from the high electron transfer barriers at the IrO/TiO interface. Herein, we develop a cathodic polarization strategy to protonate TiO (p-TiO) in a commercial IrO/TiO catalyst. The high-density Ti-OH polaronic states on the surface of protonated TiO greatly contribute to the decrease in the electron transfer barriers at the IrO/TiO interface.
View Article and Find Full Text PDFJ Am Chem Soc
September 2025
Department of Chemistry and Biochemistry, The University of Texas at Dallas, Richardson, Texas 75080-3021, United States.
The direct transformation of C-H bonds into C-C bonds via cross-dehydrogenative coupling (CDC) represents a powerful strategy in synthetic chemistry, enabling streamlined bond construction without the need for prefunctionalized substrates. While traditional CDC approaches rely on polar mechanisms and preactivation of one of the C-H partners, recent advances have introduced radical-based strategies that employ a hydrogen atom transfer (HAT) approach to access carbon-centered radicals from unactivated substrates. Herein, we report a nickel-catalyzed CDC reaction between aldehydes and alkenes for the synthesis of skipped enones, leveraging aryl radicals as intermolecular HAT agents.
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