Crystal structure, vibrational and optic properties of 2-N-methylamino-3-methylpyridine N-oxide - Its X-ray and spectroscopic studies as well as DFT quantum chemical calculations

Liquid Metal-Ionogel Core-Shell Fibers for Reflection-Suppressed Electromagnetic Interference Shielding and Strain Sensing

Electromagnetic interference (EMI) shielding fibers are crucial in practical uses for their flexibility and one-dimensional form. However, their application is limited by poor compatibility between EMI shielding components and fiber substrates, and high electromagnetic wave reflectivity. Herein, a core/shell-structured EMI shielding fiber is introduced, featuring a core of Ga-In-Sn-Zn alloy, Carbopol, and air bubbles, and a shell of ionogel formed from copolymerized acrylamide and acrylic acid. A single fiber achieves a total shielding effectiveness of ∼35 dB within the 2-18 GHz range, which increases to ∼70 dB when three fibers are stacked. Remarkably, the fiber demonstrates enhanced EMI shielding performance following stretching and recovery. Additionally, it exhibits excellent impedance matching, with a reflection power coefficient as low as 0.14 at 10 GHz. The fiber's EMI shielding mechanism encompasses reflection shielding, absorption shielding─attributable to conduction loss and polarization loss─and multiple reflection shielding. Furthermore, the fiber shows potential as a strain sensor. This research offers an effective strategy for creating flexible fibers with high EMI shielding capabilities and low EM wave reflection.

Structure and Optical Properties of New 2-N-Phenylamino-methyl-nitro-pyridine Isomers

Two new 2-N-phenylamino-(4 or 6)-methyl-3-nitropyridine derivatives were synthesized. Their structures were characterized on the basis of X-ray diffraction, IR, and Raman spectra as well as electron UV-Vis and emission spectra measurements. The experimental results were analyzed in terms of theoretical data in which the quantum chemical DFT and NBO calculations were applied. To elucidate the relaxation pathways of electronically excited states, multiple excitation wavelengths were employed to probe energy dissipation mechanisms in the studied compounds. A systematic analysis was conducted to evaluate how variations in methyl substituent positioning modulate both the structural architecture and photophysical behavior of the isomeric systems. The spectroscopic, structural and theoretical considerations allow us to propose the potential technological applications derived from the unique properties of these isomers.

Structural, spectroscopic properties ant prospective application of a new nitropyridine amino N-oxide derivative: 2-[(4-nitropyridine-3-yl)amino]ethan-1-ol N-oxide

A new nitropyridine amino N-oxide derivative 2-[(4-nitropyridine-3-yl)amino]ethan-1-ol N-oxide was synthesized and its structural and optical properties were described. Its structure obtained from the X-ray diffraction (XRD) studies was related to the Infrared spectroscopy (IR), Raman spectroscopy (RS), electron Ultraviolet-Visible spectroscopy (UV-VIS) and emission spectra measurements. The experimental results were analyzed in terms of theoretical data obtained from quantum chemical Density Functional Theory (DFT) and Natural Bond Orbital (NBO) calculations. The 6-311G(2d,2p) basis set with the B3LYP functional was used to discuss its optimized structure and vibrational properties. Femtosecond excitation was used to recognize the depopulation mechanism of the electron excited states in the studied compound. It was found that the intermolecular interactions strongly influence the physicochemical properties and application of the new nitropyridine amino N-oxide derivative.