scholarly journals Regulating the reactivity of black phosphorus via protective chemistry

2020 ◽  
Vol 6 (46) ◽  
pp. eabb4359
Author(s):  
Xiao Liu ◽  
Liangping Xiao ◽  
Jian Weng ◽  
Qingchi Xu ◽  
Wanli Li ◽  
...  
Keyword(s):  
Electron Density ◽  
Self Assembly ◽  
Lone Pair ◽  
High Reactivity ◽  
Black Phosphorus ◽  
The Self ◽  
Two Dimensional ◽  
Inorganic Nanomaterials ◽  
Resistant Layer ◽  
Lone Pair Electrons

Rationally regulating the reactivity of molecules or functional groups is common in organic chemistry, both in laboratory and industry synthesis. This concept can be applied to inorganic nanomaterials, particularly two-dimensional black phosphorus (BP) nanosheets. The high reactivity of few-layer (even monolayer) BP is expected to be “shut down” when not required and to be resumed upon application. Here, we demonstrate a protective chemistry–based methodology for regulating BP reactivity. The protective step initiates from binding Al3+ with lone pair electrons from P to decrease the electron density on the BP surface, and ends with an oxygen/water-resistant layer through the self-assembly of hydrophobic 1,2-benzenedithiol (BDT) on BP/Al3+. This protective step yields a stabilized BP with low reactivity. Deprotection of the obtained BP/Al3+/BDT is achieved by chelator treatment, which removes Al3+ and BDT from the BP surface. The deprotective process recovers the electron density of BP and thus restores the reactivity of BP.

scholarly journals Isostructural rubidium and caesium 4-(3,5-dinitropyrazol-4-yl)-3,5-dinitropyrazolates: crystal engineering with polynitro energetic species

2021 ◽  
Vol 77 (11) ◽  
Author(s):  
Kostiantyn V. Domasevitch ◽  
Vira V. Ponomarova
Keyword(s):  
Crystal Engineering ◽  
Self Assembly ◽  
Energetic Materials ◽  
Lone Pair ◽  
The Self ◽  
Two Dimensional ◽  
Modular Construction ◽  
Dipole Interactions ◽  
Hirshfeld Surfaces ◽  
Counter Ions

In the structures of the title salts, poly[[μ4-4-(3,5-dinitropyrazol-4-yl)-3,5-dinitropyrazol-1-ido]rubidium], [Rb(C6HN8O8)] n , (1), and its isostructural caesium analogue [Cs(C6HN8O8) n , (2), two independent cations M1 and M2 (M = Rb, Cs) are situated on a crystallographic twofold axis and on a center of inversion, respectively. Mutual intermolecular hydrogen bonding between the conjugate 3,5-dinitopyrazole NH-donor and 3,5-dinitropyrazole N-acceptor sites of the anions [N...N = 2.785 (2) Å for (1) and 2.832 (3) Å for (2)] governs the self-assembly of the translation-related anions in a predictable fashion. Such one-component modular construction of the organic subtopology supports the utility of the crystal-engineering approach towards designing the structures of polynitro energetic materials. The anionic chains are further linked by multiple ion–dipole interactions involving the 12-coordinate cations bonded to two pyrazole N-atoms [Rb—N = 3.1285 (16), 3.2261 (16) Å; Cs—N = 3.369 (2), 3.401 (2) Å] and all of the eight nitro O-atoms [Rb—O = 2.8543 (15)–3.6985 (16) Å; Cs—O = 3.071 (2)–3.811 (2) Å]. The resulting ionic networks follow the CsCl topological archetype, with either metal or organic ions residing in an environment of eight counter-ions. Weak lone pair–π-hole interactions [pyrazole-N atoms to NO2 groups; N...N = 2.990 (3)–3.198 (3) Å] are also relevant to the packing. The Hirshfeld surfaces and percentage two-dimensional fingerprint plots for (1) and (2) are described.

Effect of delocalization of nonbonding electron density on the stability of the M–Ccarbene bond in main group metal-imidazol-2-ylidene complexes: a computational and structural database study

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Samuel Tetteh ◽  
Albert Ofori
Keyword(s):  
Electron Density ◽  
Lone Pair ◽  
Main Group ◽  
Binding Energies ◽  
Electrostatic Model ◽  
Group Metal ◽  
Main Group Metal ◽  
Structural Database ◽  
The Stability ◽  
Lone Pair Electrons

Abstract The M–Ccarbene bond in metal (M) complexes involving the imidazol-2-ylidene (Im) ligand has largely been described using the σ-donor only model with donation of σ electrons from the sp-hybridized orbital of the carbene carbon into vacant orbitals on the metal centre. Analyses of the M–Ccarbene bond in a series of group IA, IIA and IIIA main group metal complexes show that the M-Im interactions are mostly electrostatic with the M–Ccarbene bond distances greater than the sum of the respective covalent radii. Estimation of the binding energies of a series of metal hydride/fluoride/chloride imidazol-2-ylidene complexes revealed that the stability of the M–Ccarbene bond in these complexes is not always commensurate with the σ-only electrostatic model. Further natural bond orbital (NBO) analyses at the DFT/B3LYP level of theory revealed substantial covalency in the M–Ccarbene bond with minor delocalization of electron density from the lone pair electrons on the halide ligands into antibonding molecular orbitals on the Im ligand. Calculation of the thermodynamic stability of the M–Ccarbene bond showed that these interactions are mostly endothermic in the gas phase with reduced entropies giving an overall ΔG > 0.

Fabrication and Surface Engineering of Two-Dimensional SnS Toward Piezoelectric Nanogenerator Application

MRS Advances ◽  
2018 ◽  
Vol 3 (45-46) ◽  
pp. 2809-2814 ◽  
Author(s):  
Naoki Higashitarumizu ◽  
Hayami Kawamoto ◽  
Keiji Ueno ◽  
Kosuke Nagashio
Keyword(s):  
Thermal Stability ◽  
Surface Morphology ◽  
Oxide Layer ◽  
Chemical Treatment ◽  
Surface Engineering ◽  
Lone Pair ◽  
Covalent Bonding ◽  
Two Dimensional ◽  
Lone Pair Electrons ◽  
Thermal Stability Of

ABSTRACTMechanical exfoliation is performed to fabricate ultrathin SnS layers, and chemical/thermal stability of SnS layers is discussed in comparison with GeS, toward piezoelectric nanogenerator application. Both SnS and GeS are difficult to be exfoliated under 10 nm using tape exfoliation due to strong interlayer ionic bonding by lone pair electrons in Sn or Ge atoms. Au-mediated exfoliation enables to fabricate larger-scale ultrathin SnS and GeS layers thinner than 10 nm owing to strong semi-covalent bonding between Au and S atoms, but GeS surface immediately degrades during Au etching in an oxidative KI/I2 solution. Although the surface of SnS after the Au-mediated exfoliation reveals several-nm oxide layer of SnOx, the surface morphology retains the flatness unlike the case of GeS. The SnS layers are more robust than GeS against the thermal annealing as well as the chemical treatment, suggesting that SnOx works as a passivation layer for SnS. Self-passivated SnS monolayer can be obtained by a controlled post-oxidation.

Experimental Electron Density Study of NaH2PO4 at 30 K

1998 ◽  
Vol 54 (1) ◽  
pp. 29-34 ◽  
Author(s):  
M. Ichikawa ◽  
T. Gustafsson ◽  
I. Olovsson
Keyword(s):  
Electron Density ◽  
Bond Distance ◽  
Lone Pair ◽  
Peak Height ◽  
Dihydrogen Phosphate ◽  
Sodium Dihydrogen Phosphate ◽  
Deformation Density ◽  
Density Peaks ◽  
Deformation Electron Density ◽  
Lone Pair Electrons

The deformation electron density of sodium dihydrogen phosphate, NaH2PO4, at 30 K has been studied as a reference for the electron-density characteristics of hydrogen-bonded ferroelectrics containing phosphate ions. Clear peaks of deformation electron density (0.3–0.6 e Å−3) are seen in the middle of each P—O bond and electron deficiency (−0.2 to −0.4 e Å−3) on the opposite side of each P—O bond peak. The peak height is higher and the peak shape is more distinct in P—O bonds than in P—O(H) bonds as a whole; the distribution of deformation density in the region of lone-pair electrons is more diffuse. The O—H...O bond deformation-density peaks of around 0.2 e Å−3 appear in the middle of the O—H bond, followed by a deeper electron depletion of around −0.4 e Å−3 on the H...O contract, just outside the H atom. The effective charges, defined as the integral of the deformation electron density, have the following values: around +0.2 for Na, +1.8 for P, −0.8 for O and +0.6 for H. The correlation of the deformation-density peaks and the depth of the negative peak of the H atom with the hydrogen-bond distance are discussed.

Self-assembled atomically thin hybrid conjugated polymer perovskites with two-dimensional structure

2018 ◽  
Vol 6 (31) ◽  
pp. 8405-8410 ◽  
Author(s):  
Furkan H. Isikgor ◽  
Chilla Damodara Reddy ◽  
Mengsha Li ◽  
Hikmet Coskun ◽  
Bichen Li ◽  
...  
Keyword(s):  
Self Assembly ◽  
Conjugated Polymer ◽  
The Self ◽  
Dimensional Structure ◽  
Two Dimensional ◽  
Self Assembled

2D hybrid perovskites are formed through the self assembly of polyaniline with PbI6 octahedra.

Two-dimensional (2D) self-assembly of oligo(phenylene-ethynylene) molecules and their triangular platinum(ii) diimine complexes studied using STM

2017 ◽  
Vol 19 (46) ◽  
pp. 31284-31289 ◽  
Author(s):  
Siqi Zhang ◽  
Yanfang Geng ◽  
Yuanpeng Fan ◽  
Wubiao Duan ◽  
Ke Deng ◽  
...  
Keyword(s):  
Self Assembly ◽  
Scanning Tunneling Microscope ◽  
The Self ◽  
Scanning Tunneling ◽  
Two Dimensional ◽  
Phenylene Ethynylene ◽  
Tunneling Microscope ◽  
Diimine Complexes

The self-assembly of a series of cyclic oligo(phenylene-ethynylene) (OPE) molecules and their triangular Pt(ii) diimine complexes were studied using scanning tunneling microscope (STM).

Effect of the annealing time on the self-assembly of two-dimensional DNA crystals

2013 ◽  
Vol 58 (15) ◽  
pp. 1450-1455
Author(s):  
ChangLong LIU ◽  
ZhiYong SHEN ◽  
Ming ZHOU ◽  
LiZhou ZHUANG ◽  
George AMOAKO ◽  
...  
Keyword(s):  
Annealing Time ◽  
Self Assembly ◽  
The Self ◽  
Two Dimensional ◽  
Dna Crystals
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