Dual-Emission 2D Blue Luminescent Organic Silver Chalcogenide for Highly Selective Pb²⁺ Detection in an Aqueous Medium

Crystalline organic metal chalcogenides (OMCs) are a class of organic–inorganic hybrid semiconducting materials with continuous M–X (X = S, Se, Te) networks formed by the combination of metal nodes and chalcogen atoms from the organic ligands, which display great potentials in the fields of optoelectronics, catalysis, sensing, as well as energy conversion and storage. Here, we synthesized a wave-like 2D OMC material, [(AgBF4)2Me6BHS]n (Ag-BHSMe), from AgBF4 and 1,2,3,4,5,6-hexa(methylselanyl)benzene (Me6BHS) through a simple homogeneous reaction. In the solid state, Ag-BHSMe exhibits both fluorescence emission at room temperature and phosphorescent emission at 77 K. TEM, SEM, and confocal microscopy revealed that it is an intrinsic blue luminescent microcrystalline material. In addition, we found that it exhibited a highly selective fluorescence enhancement response to Pb2+ in an aqueous solution in the range of 10–4 to 10–2 mol L–1, which demonstrates its potential as a turn-on probe for the detection of lead ions

Confirmation of Phase Transitions and Laser-Assisted Chemical Reaction for Pyridine under High Pressure

The high-pressure behavior of pyridine has been controversial for many years. In the current paper, Raman and infrared spectra under high pressure proposed a liquid-to-solid transition at about 1 GPa, followed by solid-to-solid transitions at about 2.5, 10.9, and 17.1 GPa. The synchrotron high-pressure XRD patterns of pyridine confirmed these phase transitions. On one-way loading up to 50 GPa, no other new phase is observed. With laser-assisted irradiation, pressure-induced reactions can occur, and the pressure threshold of the chemical reaction of pyridine is reduced to 1.5 GPa, less than 23 GPa from the single compression at room temperature. After release of the various solid phases of pyridine under high pressure to ambient conditions, two distinct chemical reaction products are obtained. Carbon nitride nanothreads and amorphous forms are obtained by slow and fast decompression, respectively. The experimental results reveal that only a laser with a suitable wavelength can induce chemical reactions, regardless of power. The laser-induced reactions were not chain reactions. Liquid chromatography–mass spectrometry of the products suggested that pyridine first opens the ring through the C–N bond being broken and then transforms into the products that probably contained molecules like 1-allylpyridinium nitrides and its multiple polymers

High Spatial Resolution 2D Imaging of Current Density and Pressure for Graphene Devices under High Pressure Using Nitrogen-Vacancy Centers in Diamond

Current density imaging is helpful for discovering interesting electronic phenomena and understanding carrier dynamics, and by combining pressure distributions, several pressure-induced novel physics may be comprehended. In this work, noninvasive, high-resolution two-dimensional images of the current density and pressure gradient for graphene ribbon and hBN-graphene-hBN devices are explored using nitrogen-vacancy (NV) centers in diamond under high pressure. The two-dimensional vector current density is reconstructed by the vector magnetic field mapped by the near-surface NV center layer in the diamond. The current density images accurately and clearly reproduce the complicated structure and current flow of graphene under high pressure. Additionally, the spatial distribution of the pressure is simultaneously mapped, rationalizing the nonuniformity of the current density under high pressure. The current method opens a significant new avenue to investigate electronic transport and conductance variations in two-dimensional materials and electrical devices under high pressure as well as for nondestructive evaluation of semiconductor circuits