Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry

To investigate the role of the capping group in the solution and solid-state self-assembly of short peptide amphiphiles, dialanine and diphenylalanine have been linked via the N-terminus to a benzene (phenyl) and 3-naphthyl capping groups using five different methylene linkers; (CH₂)n, n = 0-4 for the benezene and three (0, 1 and 2) for the naphthalene capping group. Atomic force microscopy (AFM), oscillatory rheology, circular dichroism (CD) and IR analysis have been employed to understand the properties of these peptide-based hydrogels...

A general procedure for measurement of time-resolved diffusion coefficients of molecular species by NMR is described, including the use of methanol for fast temperature-independent gradient calibration.

In the last decades, a broad family of hydrides have attracted attention as prospective hydrogen storage materials of very high gravimetric and volumetric capacity, fast H2-sorption kinetics, environmental friendliness and economical affordability. However, constraints due to their high activation energies of the different H2-sorption steps and the Gibbs energy of their reaction with H2 has led to the need of high thermal energy to drive H2 uptake and release. High heat leads to significant degradation effects (recrystallization, phase segregation, nanoparticles agglomeration...

An anthraquinone (AQ)-based dimer and trimer linked by a triple bond (-C≡C-) were newly synthesized as active materials for the positive electrode of rechargeable lithium batteries. These synthesized oligomers exhibited an initial discharge capacity of about 200 mAh g-1 with an average voltage of 2.2-2.3 V vs Li(C.E.). These capacity values are similar to that of the AQ-monomer, reflecting the two-electron transfer redox per AQ unit. Regarding their cycling stability, the capacity of the monomer electrode quickly decreased; however, the electrodes of the prepared oligomers showed an improved cycling performance...

In order to accommodate the approach of two NCH bases, a tetrahedral TF₄ molecule (T=Si, Ge, Sn, Pb) distorts into an octahedral structure in which the two bases can be situated either cis or trans to one another. The square planar geometry of TF₄, associated with the trans arrangement of the bases, is higher in energy than its see-saw structure which corresponds to the cis trimer. On the other hand, the square geometry offers an unobstructed path of the bases to the π-holes above and below the tetrel atom so enjoys a higher interaction energy than is the case for the σ-holes approached by the bases in the cis arrangement...

The transfer of nanoscale properties from single-walled carbon nanotubes (SWCNTs) to macroscopic systems is a topic of intense research. In particular, inorganic composites of SWCNTs and metal oxide semiconductors are being investigated for applications in electronics, energy devices, photocatalysis, and electroanalysis. In this work, a commercial SWCNT material is separated into fractions containing different conformations. The liquid fractions show clear variations in their optical absorbance spectra, indicating differences in the metallic/semiconducting character and the diameter of the SWCNTs...

Hydrogen is in limelight as an environmental benign alternative to fossil fuels from few decades. To bring the concept of hydrogen economy from academic labs to real world certain challenges needs to be addressed in the areas of hydrogen production, storage and its use in fuel cells. Crystalline metal-organic frameworks (MOFs) with unprecedented surface areas are considered as potential materials for addressing the challenges in all these three fronts. MOFs combine the diverse chemistry of molecular linkers with their ability to co-ordinate to metal ions and clusters...

We have applied new methods for performing coupled-cluster calculations to small molecules containing iodine atoms; specifically, NI3 and N2I4. Because NI3 is known to be very reactive, attempts to measure its thermodynamic properties have been challenging at best. To date, N2I4 has not been isolated, and our results suggest that its isolation will be just as challenging. We find that the ΔHf[NI3] = +307.7 kJ/mol and ΔHf[N2I4] = +551.6 kJ/mol, confirming that they are unstable with respect to their decomposition products N2 and I2...

The NICS-XY-Scan is a simple and easy tool for the quantitative measurement of the aromaticity of polycyclic aromatic hydrocarbons and identification of the existence of local and global ring currents. We recently introduced an additivity scheme that uses the NICS-XY-Scans of smaller building blocks to predict the aromatic profiles of larger polycyclic aromatic hydrocarbon systems. We now report on an expansion of the methodology to include systems of varying aromatic natures containing the heteroatoms B, N, O, and S...

A series of tunable color of Ca9Ga(PO4)7:Ce3+/Tb3+/Dy3+/Mn2+ phosphors were synthesized in this work, in which Ce3+ acted as a sensitizer. The energy transfer (ET) from Ce3+ to Tb3+/Dy3+/Mn2+ were investigated in details. Tb3+/Dy3+/Mn2+ single doped Ca9Ga(PO4)7 can exhibit green, yellow and red emission, respectively. Incorporating Ce3+ into Tb3+/Dy3+/Mn2+ single doped Ca9Ga(PO4)7 phosphor can remarkably promote the luminous efficiency of Tb3+/Dy3+/Mn2+ ions. The reason for this enhancement originates from efficient ET from Ce3+ to Tb3+/Dy3+/Mn2+...

In this article, the capabilities of soft and hard X-ray techniques, including X-ray absorption (XAS), soft X-ray emission spectroscopy (XES), resonant inelastic soft X-ray scattering (RIXS), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD), and their application to solid-state hydrogen storage materials are presented. These characterization tools are indispensable for interrogating hydrogen storage materials at the relevant length scales of fundamental interest, which range from the micron scale to nanometer dimensions...

Recently it has been proposed that the positron, the anti-particle analog of the electron, is capable of forming an anti-matter bond in a composite system of two hydride anions and a positron [Angew. Chem. Int. Ed. 57, 8859-8864 (2018)]. In order to dig into the nature of this novel bond the newly developed multi-component quantum theory of atoms in molecules (MC-QTAIM) is applied to this positronic system. The topological analysis reveals that this species is composed of two atoms in molecules, each containing a proton and half of the electronic and the positronic populations...

Ambipolar organic semiconductors are considered promising for organic electronics because of their unusual electric properties, but many hurdles remain before they can be used for practical applications, especially because their orientation is hard to control. Here, we demonstrate a method to control the orientation of columnar structures, based on a hydrogen (H)-bonded donor-acceptor complex between a star-shaped tris(triazolyl)triazine and triphenylene-containing benzoic acid, using physicochemical nanoconfinement...

We study the kinetics of hydrogen sorption in Mg-Ti-H nanoparticles prepared by gas phase condensation of mixed Mg-Ti vapors under a H2-containing atmosphere. Four samples with different Ti contents from 14 to 63 at.% Ti are examined in the 100-150 °C range. The hydrogen absorption kinetics coupled with the formation of MgH2 can be described a nucleation and growth model. The activation energy is in the range 43-52 kJ/mol and the rate constant (at 150 °C) increases from 27∙〖10〗^(-3) s-1 to 92∙〖10〗^(-3) s-1 with increasing Ti content...

The click-chemistry capture of volatile aldehydes and ketones by ammonium aminooxy compounds has proven to be an efficient means of analyzing the carbonyl subset in complex mixtures, such as exhaled breath or environmental air. In this work, we examine the carbonyl condensation reaction kinetics of three aminooxy compounds with varying β-ammonium ion substitution using Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). We determined the activation energies for the reactions of the aminooxy compounds ATM, ADMH and AMAH with a panel of ketones and aldehydes that included acrolein and crotonaldehyde...

Smythite (Fe3S4) is an iron-based chalcogenide, having a lamellar structure compared to compositionally same another iron-based chalcogenide mineral greigite (Fe3S4). Because of the abundance of such transition metal based chalcogenides, they offer the low-cost productivity of spintronic-based devices. Here, we have studied the charge transfer processes and complex magnetic ordering in a two dimensional (2D) smythite lattice. We find that Fe2+/Fe3+ redox couple and complex magnetic ordering govern these charge transfer processes...

High quantum yield, photoluminescence tunability, and sensitivity to the environment are the few distinct trademarks that make carbon nanodots (CDs) interesting for fundamental research with potential to replace the prevalent inorganic semiconductor quantum dots. Currently, application and fundamental understanding of CDs are constrained because it is difficult to make a quantitative comparison among different types of CDs simply because their PL properties are directly linked to their size distribution, the surface functionalization, the carbon core structures (graphitic or amorphous) and the number of defects...

Binary combinations of borohydrides have been extensively investigated evidencing the formation of eutectics, bimetallic compounds or solid solutions. In this paper, the investigation was extended to ternary and quaternary systems in the LiBH4-NaBH4-KBH4-Mg(BH4)2-Ca(BH4)2 system. Possible interactions among borohydrides in equimolar composition was explored by mechanochemical treatment. Obtained phases were analysed by X-ray diffraction and the thermal behaviour of the mixtures were analysed by HP-DSC and DTA, defining temperature of transitions and decomposition reactions...

DNA is effectively damaged by radiation, which can on the one hand lead to cancer and is on the other hand directly exploited in the treatment of tumor tissue. DNA strand breaks are already induced by photons having an energy below the ionization energy of DNA. At high photon energies, most of the DNA strand breaks are induced by low-energy secondary electrons. In the present study we quantified photon and electron induced DNA strand breaks in four different 12mer oligonucleotides. They are irradiated directly with 8...

For the last decades, the Hydrogen-Abstraction/ aCetylene-Addition (HACA) mechanism has been widely invoked to rationalize the high-temperature synthesis of PAHs as detected in carbonaceous meteorites (CM) and proposed to exist in the interstellar medium (ISM). By unravelling the chemistry of the 9-phenanthrenyl radical ([C₁₄H₉]•) with vinylacetylene (C₄H₄), we present the first compelling evidence of a barrier-less pathway leading to a prototype tetracyclic PAH - triphenylene (C₁₈H₁₂) - via an unconventional Hydrogen Abstraction - Vinylacetylene Addition (HAVA) mechanism operational at temperatures as low as 10 K...