The recent terrorist attacks using
Novichok agents and subsequent
operations have necessitated an understanding of its physicochemical
properties, such as vapor pressure and toxicity, as well as unascertained
nerve agent structures. To prevent continued threats from new types
of nerve agents, the organization for the prohibition of chemical
weapons (OPCW) updated the chemical weapons convention (CWC) schedule
1 list. However, this information is vague and may encompass more
than 10 000 possible chemical structures, which makes it almost
impossible to synthesize and measure their properties and toxicity.
To assist this effort, we successfully developed machine learning
(ML) models to predict the vapor pressure to help with escape and
removal operations. The model shows robust and high-accuracy performance
with promising features for predicting vapor pressure when applied
to Novichok materials and accurate predictions with reasonable errors.
The ML classification model was successfully built for the swallow
globally harmonized system class of organophosphorus compounds (OP)
for toxicity predictions. The tuned ML model was used to predict the
toxicity of Novichok agents, as described in the CWC list. Although
its accuracy and linearity can be improved, this ML model is expected
to be a firm basis for developing more accurate models for predicting
the vapor pressure and toxicity of nerve agents in the future to help
handle future terror attacks with unknown nerve agents.
The formation of Ag(I)-1,2,4,5-tetrazines(ttz) based coordination polymers via the Ag−N coordination and anion−π interactions is described. Coordination-driven self-assembly is a key step to construct coordination polymers, and ttz, an electron-deficient aromatic ring compound, forms interesting anion−π interactions. In this study, a series of silver salts, AgX [X = BF 4 , PF 6 and CF 3 SO 3 (OTf)], is introduced to determine the influence of shape and size of anions on the formation of coordination polymers, {[Ag(ttz)] (BF 4)} n (1), {[Ag 2 (ttz) 3 ](PF 6) 2 } n (2) and {[Ag 2 (ttz) 3 (OTf)](OTf)} n (3). It shows different types of channels in polymers and the coordination modes of ttz (μ, μ 3 , and μ 4). The structure of coordination polymers and the influence of anion−π interactions are revealed by single crystal X-ray diffraction. In particular, 3 shows not only the anion−π interaction but also the coordination between the anion and Ag(I) which contributes to the unique framework compared to 1 and 2.
B3LYP, PBE, M06-2X, B2PLYP, BN2PLYP-D, ωB97X-D, and MP2 levels of theory, in combination with the 6-311++G(d,p) and cc-pVTZ basis sets were comprehensively assessed for their ability to reproduce experimental FOX-7 structural and detonation data. ωB97X-D/cc-pVTZ, B3LYP/cc-pVTZ, and M06-2X/cc-pVTZ provided highly accurate optimized structure predictions. M06-2X/cc-pVTZ and ωB97X-D/cc-pVTZ reproduced experimentally determined detonation properties (detonation velocity and detonation pressure) with high accuracy. The results of this study demonstrate that more accurate structure calculation levels provide more reliable detonation property predictions. Moreover, the results show that detonation property prediction is largely dependent on the calculation level. This investigation demonstrates that using a wide range of calculation levels enables the reliable prediction and modeling of novel types of HEDMs.
The multitopic ligand, 5-(pyridine-3-yloxy)isophthalic acid (m-POiPH 2 , 1), containing two different coordination sites of pyridine and isophthalic acid linked by the C-O-C bond, is prepared. The reaction of 1 with half sandwich complexes of [Cp*Rh(OAc) 2 ] (Cp* = η 5 -C 5 Me 5 ), [Cp*Ir(OAc) 2 ], and [(p-cymene) Ru(OAc) 2 afford the construction of binuclear metallocyclophanes [(Cp*Ir) 2 (m-POiP) 2 ] (2), [(Cp*Rh) 2 (m-POiP) 2 (3), and [((p-cymene)Ru) 2 (m-POiP) 2 ] (4) in high yields. Crystal structures of 2, 3, and 4 illustrate binuclear metallocyclophanes constructed by cyclometallation by ortho-C-H activation and coordination of N-donor with metals which is confirmed by a single crystal X-ray diffraction (SC-XRD). Each metallocyclophanes shows unique packing structure by intermolecular hydrogen bonding; 2 and 3 shows 1D linear chain network, while the packing of 4 presents the 2D sheet.
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