Microhydration of heterocyclic aromatic molecules can
be an appropriate
fundamental model to shed light on intermolecular interactions and
functions of macromolecules and biomolecules. We characterize herein
the microhydration process of the pyrrole cation (Py+)
by infrared photodissociation (IRPD) spectroscopy and dispersion-corrected
density functional theory calculations (B3LYP-D3/aug-cc-pVTZ). Analysis
of IRPD spectra of mass-selected Py+(H2O)2 and its cold Ar-tagged cluster in the NH and OH stretch range
combined with geometric parameters of intermolecular structures, binding
energies, and natural atomic charge distribution provides a clear
picture of the growth of the hydration shell and cooperativity effects.
Py+(H2O)2 is formed by stepwise hydration
of the acidic NH group of Py+ by a hydrogen-bonded (H2O)2 chain with NH···OH···OH
configuration. In this linear H-bonded hydration chain, strong cooperativity,
mainly arising from the positive charge, strengthens both the NH···O
and OH···O H-bonds with respect to those of Py+H2O and (H2O)2, respectively.
The linear chain structure of the Py+(H2O)2 cation is discussed in terms of the ionization-induced rearrangement
of the hydration shell of the neutral Py(H2O)2 global minimum characterized by the so-called “σ–π
bridge structure” featuring a cyclic NH···OH···OH···π
H-bonded network. Emission of the π electron from Py by ionization
generates a repulsive interaction between the positive π site
of Py+ and the π-bonded OH hydrogen of (H2O)2, thereby breaking this OH···π
hydrogen bond and driving the hydration structure toward the linear
chain motif of the global minimum on the cation potential.
Organic optoelectronic devices that can be fabricated at low cost have attracted considerable attention because they can absorb light over a wide frequency range and have high conversion efficiency, as well as being lightweight and flexible. Moreover, their performance can be significantly affected by the choice of the charge-selective interlayer material. Nonstoichiometric nickel oxide (NiO x ) is an excellent material for the hole-transporting layer (HTL) of organic optoelectronic devices because of the good alignment of its valence band position with the highest occupied molecular orbital level of many p-type polymers. Herein, we report a simple low-temperature process for the synthesis of NiO x nanoparticles (NPs) that can be well dispersed in solution for long-term storage and easily used to form thin NiO x NP layers. NiO x NP-based organic photodiode (OPD) devices demonstrated high specific detectivity (D*) values of 10 12 −10 13 jones under various light intensities and negative biases. The D* value of the NiO x NP-based OPD device was 4 times higher than that of a conventional poly(3,4ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)-based device, an enhancement that originated mainly from the 16 times decreased leakage current. The NiO x NP-based OPD device demonstrated better reliability over a wide range of light intensities and operational biases in comparison to a device with a conventional sol−gel-processed NiO x film. More importantly, the NiO x NP-based OPD showed long-term device stability superior to those of the PEDOT:PSS and sol−gel-processed NiO x -based devices. We highlight that our low-temperature solution-processable NiO x NP-based HTL could become a crucial component in the fabrication of stable high-performance OPDs.
Yak wool is a smooth, warm, and durable natural protein-structured fiber that could compete with cashmere and other high-end protein-structured fibers on the market. However, it suffers from drawing consumers’ attention due to the lack of color due to the shortfall of the yak wool bleaching technology. Herein, we studied the applicability of various transition metals, i.e., copper (II), cobalt (II), iron (II), and nickel (II) salts, as a mordanting reagent based on their effect on the hydrogen peroxide decomposition reaction and the morphological and mechanical properties of the bleached yak wool with the presence of these transition metal. Our study suggested that the iron (II) ion was the most efficient reagent for the mordant bleaching since it provided less fiber damage, relatively high strength, and elongation to the bleached yak wool with good whiteness, while the Cu (II) was the least favorable agent for the yak wool bleaching process.
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