The dielectric properties of coordination polymers has been a topic of recent interest, but the role of different functional groups on the dielectric properties of these polymers has not yet been fully addressed. Herein, the effects of electron-donating (R=NH2) and electron-withdrawing (R=NO2) groups on the dielectric behavior of such materials were investigated for two thermally stable and guest-free Zn-based coordination polymers, [Zn(L1)(L2)]n ( 1 ) and [Zn(L1)(L3)]n ( 2 ) [L1=2-(2-pyridyl) benzimidazole (Pbim), L2=5-aminoisophthalate (Aip), and L3=5-nitroisophthalate (Nip)]. The results of dielectric studies of 1 revealed that it possesses a high dielectric constant (κ=65.5 at 1 kHz), while compound 2 displayed an even higher dielectric constant (κ=110.3 at 1 kHz). The electron donating and withdrawing effects of the NH2 and NO2 substituents induce changes in the polarity of the polymers, which is due to the inductive effect from the aryl ring for both NO2 and NH2. Theoretical results from density functional theory (DFT) calculations, which also support the experimental findings, show that both compounds have a distinct electronic behavior with diverse wide bandgaps. The significance of the current work is to provide information about the structure-dielectric property relationships. So, this study promises to pave the way for further research on the effects of different functional groups on coordination polymers on their dielectric properties. 相似文献
We characterize the completeness and frame/basis property of a union of under-sampled windowed exponentials of the form
$$ {\mathcal{F}}(g): =\bigl\{ e^{2\pi i n x}: n\ge 0\bigr\} \cup \bigl\{ g(x)e^{2\pi i nx}: n< 0\bigr\} $$
for \(L^{2}[-1/2,1/2]\) by the spectra of the Toeplitz operators with the symbol \(g\). Using this characterization, we classify all real-valued functions \(g\) such that \({\mathcal{F}}(g)\) is complete or forms a frame/basis. Conversely, we use the classical non-harmonic Fourier series theory to determine all \(\xi \) such that the Toeplitz operators with the symbol \(e^{2\pi i \xi x}\) is injective or invertible. These results demonstrate an elegant interaction between frame theory of windowed exponentials and Toeplitz operators. Finally, we use our results to answer some open questions in dynamical sampling, and derivative samplings on Paley-Wiener spaces of bandlimited functions.
Journal of Solid State Electrochemistry - Self-supporting porous Ni film with uniform honeycomb-like micropores and a thickness of up to 66 μm is electrodeposited by dynamic hydrogen... 相似文献
Eco-friendly lead-free organic–inorganic manganese halides (OIMHs) have attracted considerable attention in various optoelectronic applications because of their superior optical properties and flexible solution processibility. Herein, we report a novel pseudo-2D layered OIMH (MTP)2MnBr4 (MTP: methyltriphenylphosphonium), which exhibits intense green emission under UV/blue or X-ray excitation, with a near-unity photoluminescence quantum yield, high resistance to thermal quenching (I150 °C=84.1 %) and good photochemical stability. These features enable (MTP)2MnBr4 as an efficient green phosphor for blue-converted white light-emitting diodes, demonstrating a commercial-level luminous efficiency of 101 lm W−1 and a wide color gamut of 116 % NTSC. Moreover, these (MTP)2MnBr4 crystals showcase outstanding X-ray scintillation properties, delivering a light yield of 67000 photon MeV−1, a detection limit of 82.4 nGy s−1, and a competitive spatial resolution of 6.2 lp mm−1 for X-ray imaging. This work presents a new avenue for the exploration of eco-friendly luminescent OIMHs towards multifunctional light-emitting applications. 相似文献
Methicillin-resistant Staphylococcus aureus (MRSA) can induce multiple inflammations. The biofilm formed by MRSA is resistant to a variety of antibiotics and is extremely difficult to cure, which seriously threatens human health. Herein, a nanoparticle encapsulating berberine with polypyrrole core and pH-sensitive shell to provide chemo-photothermal dual therapy for MRSA infection is reported. By integrating photothermal agent polypyrrole, berberine, acid-degradable crosslinker, and acid-induced charge reversal polymer, the nanoparticle exhibited highly efficient MRSA infection treatment. In normal uninfected areas and bloodstream, nanoparticles showed negatively charged, demonstrating high biocompatibility and excellent hemocompatibility. However, once arriving at the MRSA infection site, the nanoparticle can penetrate and accumulate in the biofilm within 2 h. Simultaneously, berberine can be released into biofilm rapidly. Under the combined effect of photothermal response and berberine inhibition, 88.7% of the biofilm is removed at 1000 µg mL−1. Moreover, the nanoparticles have an excellent inhibitory effect on biofilm formation, the biofilm inhibition capacity can reach up to 90.3%. Taken together, this pH-tunable nanoparticle can be employed as a new generation treatment strategy to fight against the fast-growing MRSA infection. 相似文献