Chemphyschem最新文献

The Cover Feature shows chlorine-modified soluble melem-based graphitic carbon nitrite (CNCl), which showed better photocatalytic performance than g-C₃N₄ in the decomposition of methyl orange. CNCl showed much improved dispersibility and solubility in water, DMSO and other solvents. Time-resolved two-dimensional infrared vibrational spectroscopy and other analytical methods were used to understand the photocatalytic performance of CNCl on a microscopic level. More information can be found in the Research Article by J. Wang and co-workers (DOI: 10.1002/cphc.202400356).

CH₃NH₃PbI₃ (MAPbI₃), as a promising candidate of photovoltaic materials, has attracted extensive interests due to its excellent photoelectric properties and low preparation cost. However, the relationship between synthesis parameter and performance is still unclear due to the overlook of exposed surface characteristics, limiting the mass-production and commercialization of MAPbI₃. Therefore, it is necessary to clarify the stability and photoelectric properties of different exposed surfaces of MAPbI₃ under humid environment. In this work, the stability and photoelectric properties of the MAI-terminated and PbI₂-terminated of MAPbI₃ (001) were thoroughly investigated using density functional theory calculation. To study the stability of exposed surface, adsorption energy of water molecules, ab initio molecular dynamics (AIMD), mean square displacement (MSD) and X-ray diffraction (XRD) were calculated. MSD of PbI₂-terminated surface is greater by two orders of magnitude compared to MAI-terminated surface. For the photoelectric properties of MAPbI₃, the bandgap, absorption coefficients, joint density of states (JDOS) and dielectric constants were investigated. The inhibitory effect of water on the photoelectric performance for PbI₂-terminated surface is more significant than that of MAI-terminated surface. Although the photoelectric properties of water molecules adsorption on MAI-terminated surface is basically unchanged, the diffusion of water molecules reduces the photoelectric properties of MAPbI₃. Overall, the stability and photoelectric properties of MAI-terminated surface are superior to PbI₂-terminated surface. Therefore, we strongly advocate paying attention to the exposed surface of MAPbI₃ during the thin film production process and adjusting synthesis parameters to prepare MAI-terminated surface dominated thin film, which should substantially improve the performance of MAPbI₃ in the application.

The Cover Feature shows a vacancy combined with nitrogen dopants on graphite. The two spectra correspond to the resonant state of a vacancy with (red) or without (yellow) nitrogen doping. In the presence of nitrogen, the vacancy state shifts from an unoccupied to an occupied energy level. More information can be found in the Research Article by J. Lagoute and co-workers (DOI: 10.1002/cphc.202400221).

The Front Cover artistically illustrates different excited-state lifetimes of the cations of 1-cyanoadamantane and amantadine—nitrogen-containing derivatives of the adamantane cation. In their Research Article (DOI: 10.1002/cphc.202400331), B. Roy, E. Titov, and P. Saalfrank relate how the nonadiabatic dynamics and electronic spectra were studied by using surface-hopping molecular dynamics simulations and quantum chemical calculations.

Phycobilisome (PBS) is a pigment-protein complex utilized by red algae and cyanobacteria in photosynthesis for light harvesting. A cyanobacterium Synechocystis sp. PCC 6803 contains PBS with a tricylindrical core built of allophycocyanin (APC) disks where six phycocyanin (PC) rods are attached. The top core cylinder is seemingly involved in attaching four PC rods and binding orange carotenoid protein (OCP) to quench excess of excitation energy. In this study, we have deleted the third linker domain (LD3) of ApcE subunit of PBS which assembles four APC discs into the top core cylinder. The mutation resulted in PBS with bicylindrical core, structurally comparable to the naturally existing PBS from Synechococcus 7942. Lack of LD3 and the top APC cylinder reduces the excitation energy transfer between PC and APC in the mutant. Moreover, these PBSs are more prone to light induced-photodamage and do not bind to the photoactivated orange carotenoid protein (OCP), a known PBS excitation quencher. These findings highlight the complex and elegant interplay between PBS architecture and functional efficiency, suggesting that in PBSs with naturally tri-cylindrical cores, the top cylinder has essential roles in recruiting the rods and proper binding of OCP and recruitment of the four PC rods.

This work investigates the influence of structural and electronic modification on the electrochemical performance of conversion and alloying materials. The CuSbSe2, a promising 2D layered conversion-and-alloying material is being investigated with references to parent pristine Sb2Se3 and a doped version of later Sn0.2Sb1.8Se3 for their sodium-ion battery performance. The CuSbSe2 with layered structure is well known to accommodate lattice distortions via inter-layer movement, potentially mitigating distortions brought about by the Alkali ion (Na in this case) insertion. In contrast, the parent conversion-cum-alloying material Sb2Se3 with its one-dimensional crystal structure leads to structural disintegration during battery operation. The Sn-doped analog, Sn0.2Sb1.8Se3, comparatively exhibits enhanced kinetics owing to the reduced long-range order. The 2D layered, CuSbSe2 despite exhibiting  2D long-range order exhibits superior electrochemical performance owing to the favorable electronic and structural features. The CuSbSe2 exhibits a reversible capacity of 881 mAh g-1 compared to 516 mAh g-1 for Sn0.2Sb1.8Se3 and 429 mAh g-1 for Sb2Se3, with an improved Coulombic efficiency as well. The transient electrochemical investigations of Electrochemical Impedance Spectroscopy (EIS) and Galvanostatic intermittent titration techniques (GITT) reveal that better performance exhibited by CuSbSe2 may well be attributed to kinetics owing to enhanced diffusion coefficients in the intercalation and conversion regime.

A polymerizable diacetylene gelator, containing urea and urethane groups, that congeals various non-polar solvents was synthesized. The gelator molecules self-assemble forming non-covalent polymers through intermolecular hydrogen bonding, as evidenced from FT-IR and concentration-dependent 1H NMR spectroscopy. The self-assembly positions the diyne units of adjacent molecules at proximity and in a geometry suitable for their topochemical polymerization. UV irradiation of the gel resulted in topochemical polymerization, transforming the non-covalent polymer to a covalent polymer, in situ, in the gel state. The polymerization was confirmed by characterizing the polydiacetylene (PDA) using UV-Vis and Raman spectroscopy. Time-dependent rheological studies revealed gradual strengthening of the gel with the duration of irradiation, suggesting that the degree of polymerization increases with the duration of irradiation. The PDA formed is a semiconductor, which might be useful for various applications.

The presence of ions in the complexation of molecules can profoundly affect the structure, resulting in changes to functionality and stability. These non-covalent interactions drive many biological processes both necessary and inimical and require extensive research to understand and predict their effects. Protonated and alkali metalated complexes of glycine (Gly) and 1-methyluracil (1-mUra) were studied using infrared multiphoton dissociation (IRMPD) spectroscopy and density functional theory (DFT) calculations. The experimental and simulated vibrational spectra were compared to help elucidate the structure of each complex. The lowest energy structure for [(Gly)(1-mUra)]H+ consists of amine protonated Gly bound to O4 of canonical 1-mUra through a single ionic hydrogen bond with another, intraglycine ionic hydrogen bond between the protonated amine group and the carbonyl oxygen. For [(Gly)(1-mUra)]Li+, [(Gly)(1-mUra)]Na+ and [(Gly)(1-mUra)]K+, the experimental spectra are most consistent with the metal cations binding in a trigonal planar geometry with 1-mUra bound to the metal cation via the O4 carbonyl. In [(Gly)(1-mUra)]Li+ and [(Gly)(1-mUra)]Na+, the metal cation is bound to canonical Gly via the carbonyl oxygen and amine nitrogen, but in [(Gly)(1-mUra)]K+, Gly is bound through both oxygens and contains an intraglycine hydrogen bond from the hydroxyl to the amine nitrogen.

2D materials have rapidly become the building blocks for the next generation of semiconducting materials and devices, with chemical vapor deposition (CVD) emerging as a prefered method for their synthesis. However, the predictable and reproducible growth of high quality, large 2D monolayers remains challenging. An important facet is controlling the local environment at the surface of the substrate - here, space-confinement techniques have emerged as promising candidates. We demonstrate that space-confined CVD growth using microstructured MoO_x grown on Ni foam is an appealing approach for rapid growth of high quality MoS₂ monolayers; a very important subset of 2D materials. This method eschews the use of powders which can be more difficult to control. By incorporation of a porous barrier in the Ni foam support, the rate of delivery of both the Mo and S source to the substrate is dampened, leading to coverage of large, high quality, mono-to-few layer triangular domains as confirmed by Raman and photoluminescence (PL) spectroscopies together with atomic force microscopy (AFM) height measurements.

Dispersing ferrofluids in liquid crystals (LCs) produces unique systems which possess magnetic functionality and novel phenomena such as droplet chaining. This work reports the formation of ferrofluid droplet chains facilitated by the topological defects within the LC director field, induced by the dispersed ferrofluid. The translational and rotational motion of these chains could be controlled via application of external magnetic fields. The process of the droplet chain formation in LCs can be stabilized by the addition of surfactants. The magnetic colloidal particles in the ferrofluid located at the interface between the ferrofluid and the LC are arranged so that a boundary layer was formed. The velocities and boundary layer thickness values of ferrofluid droplet chains in nematic 5CB (4-Cyano-4'-pentylbiphenyl) were investigated for varying average droplet sizes and number of droplets in a chain. The creation and behaviour of ferrofluid droplet chains in 5CB with the addition of the surfactant polysorbate 60 (Tween-60) and without, was comparatively investigated. The integration of liquid crystals and ferrofluids along with the incorporation of functional materials facilitates the innovative development of advanced materials for future applications.