Novel silicon nanorings: Persilacyclacenes at DFT

Abstract

Structures, energies, and aromatic 24 , respectively, at B3LYP levels (n, number of fused benzenoid rings). These are a brand of silicon nanorings that bear a resemblance to the shortest zig-zag silicon nanotubes (SiNTs), henceforth referred to as SiNRs. The NBO results show nearly sp 2 -hybridization for virtually all Si atoms of our SiNRs. This is in contrast to most reports where sp 3 -hybridization is proposed for typical SiNTs. Comparison between the optimized SiNRs and their corresponding planar (polyacenic) forms shows longer bond lengths for the former, due to their curvatures. Except for sterically hindered Si 24 H 12 (n ϭ 6), all even SiNRs (n ϭ 8, 10, and 12), are more aromatic than the odd ones (n ϭ 7, 9, and 11). Such a higher aromaticity is witnessed inside, outside, and on the surface of the scrutinized SiNRs. Also, except for Si 44 H 22 (n ϭ 11), the energy gaps (⌬E HOMOϪLUMO ) for the odd set of SiNRs, as well as the even set, appear inversely proportional to their corresponding diameters, per se. Except for the sterically hindered SiNRs with n ϭ 6 or 7, all the even SiNRs enjoy a higher stability (aromaticity) and conductivity for showing lower ⌬E HOMOϪLUMO than the odd ones. Evidently, the ideal diameter for persilacyclacenes (SiNRs) studied is from 0.92 to 1.42 nm, corresponding to n ϭ 8 -12, respectively. Higher than 1.42 nm causes structural disorders while lower than 0.92 brings about bond localization due to the high-steric effects.

Cyclacenes and short zigzag nanotubes with alternanting Ge―C bonds: theoretical impacts of Ge on the ground state, strain, and band gap

“…Such substitution may be implied by embedding heteroatoms into the open space in the carbon network or by substituting the host atoms with substituents. As we had shown, nitrogen substitutions alter the electronic ground state of some cyclacenes from S os to S cs and appear to decrease their reactivity while increasing their viability . As pointed out, high reactivity of the radicaloid S os ground states and strain energies complicate cyclacene and short CNT syntheses.…”

“…As pointed out, high reactivity of the radicaloid S os ground states and strain energies complicate cyclacene and short CNT syntheses. Hence, following our previous work, our theoretical approach to circumvent these obstacles is the substitution of germanium in cyclacenes and short zigzag CNTs at B3LYP and BPW91 levels of theory. This is in order to modify the electronic ground state of the resulting GeC‐cyclacenes and GeCNTs, respectively.…”

Antibacterial effects of a new dental acrylic resin containing silver nanoparticles

“…This gives a doughy mixture, which is subsequently put into molds and is allowed to polymerize and cure 17. After our recent works on different nanostructures,18–20 in this article, we present a simple and effective method for the preparation of a dental acrylic resin containing elemental Ag NPs. In the first step, elemental Ag NPs were prepared via the chemical reduction of silver ions by an acrylic liquid as a new reducing agent.…”

Reaching for [6]n SiC‐cyclacenes and [6]n SiC‐acenes: A DFT approach

“…Heterocyclic derivatives of cyclacenes and polyacenes were studied through their molecular electronic properties, stabilities, and crystal structures of these materials . Actually, some synthesized heteroatom‐carbon acenes led us to more study in this field …”

“…Heterocyclic derivatives of cyclacenes and polyacenes were studied through their molecular electronic properties, stabilities, and crystal structures of these materials. [12,[28][29][30][31][32] Actually, some synthesized heteroatom-carbon acenes led us to more study in this field. [33,34] In spite of silicon and germanium could be one of the most logical candidates to replace carbon, [35,36] there are few papers on silicon or germanium substitution cyclacenes.…”