Thermal Structure Transformation of Methylammonium Vanadate and it's Application as a Negative Staining Reagent for Observing SARS‐CoV‐2

Abstract

The solid‐state thermal structure transformation of methylammonium vanadate, (CH 3 NH 3 )VO 3 , from −150 °C to 350 °C is reported. Variable‐temperature X‐ray single‐crystal structure analysis at 23, 0, −50, −100, and −150 °C reveal (CH 3 NH 3 )VO 3 comprises of methylammonium cations and “snake‐like” ([VO 3 ] − ) n anion chains propagating along the c ‐direction in the Pna 2 1 space group. In between −150 and −100 °C, we observe a reversible structural transformation due to the re‐orientation of the methylammonium cations in the crystal packing, which is also confirmed by the reversible profiles observed in differential scanning calorimetry. The methylammonium vanadate is stable until at ca. 100 °C and further heating releases methylamine and water and V 2 O 5 is formed at ca. 275 °C . Furthermore, we show that the methylammonium vanadate can be used as a negative staining reagent for visualizing SARS‐CoV‐2, allowing us to discern the spike proteins from the body of the virus using transmission electron microscopy.

Structure Transformation of Methylammonium Polyoxomolybdates via In-Solution Acidification and Solid-State Heating from Methylammonium Monomolybdate and Application as Negative Staining Reagents for Coronavirus Observation

“…In addition to the appearance of H 2 O and CH 3 NH 2 , the degradation and oxidized species of methylammonium such as NH 3 , CO, N 2 , NO, CO 2 , and N 2 O were observed, indicating that a redox reaction between methylammonium and Mo has occurred under inert gas flow. Similar degradation and oxidation reactions of methylamine in methylammonium paradodecatungstate and vanadate under inert gas flow have been observed. , …”

“…Homemade deionized water (Millipore, Elix, MA, USA) was used for all experiments. (CH 3 NH 3 ) 2 [MoO 4 ], (CH 3 NH 3 ) 10 [H 2 W 12 O 42 ], CH 3 NH 3 [VO 3 ], K 14 [P 5 W 30 O 110 Na­(H 2 O)]·23H 2 O, and K 12 [P 5 W 30 O 110 Eu­(H 2 O)]·25H 2 O were prepared according to previously described procedures.…”

“…SARS-CoV-2/JP/HiroC77/2021 [Delta (B.1.617.2-like), EPI_ISL_6316561] was prepared by a previously described method . Virus cultures were grown in the P3 facility of Hiroshima University under Biosafety Level 3 regulations.…”

“…We have previously reported that the reaction of WO 3 and V 2 O 5 with the volatile base methylamine (CH 3 NH 2 ) and subsequent drying produced methylammonium paradodecatungstate, (CH 3 NH 3 ) 10 [H 2 W 12 O 42 ], and methylammonium vanadate, CH 3 NH 3 [VO 3 ] . In our previous communication, we reported that dissolving MoO 3 in aqueous methylamine solution produced monomolybdate, [MoO 4 ] 2– , in solution, which could be isolated as methylammonium salt, (CH 3 NH 3 ) 2 [MoO 4 ] by the addition of dimethylformamide (DMF).…”

Hexalacunary [α‐H2P2W12O48]12− Wells‐Dawson Anion: X‐ray Crystal Structural Evidence and Oligomerization to WO(OH2)4+‐Bridged Dimer and Trimers

“…The powder X-ray diffraction patterns of 1-3 (Figure 3) were in agreement with the theoretical patterns simulated using a single-crystal structure, confirming the phase purity of the bulk solids. The powder pattern of 3 was collected at À 150 °C because at room temperature, most of the diffraction maxima could not be observed (Figure S5) owing to evaporation of crystallization water, re-orientation of methylammonium coun- Chemistry-A European Journal ter-cations, [27] or both. Because the low-temperature powder pattern was collected using a single-crystal diffractometer, the peaks were significantly broadened, hindering the observation of closely separated peaks (for instance, the second diffraction maximum at 2θ = 2.6°is a composite of two peaks that theoretically appear at 2θ = 2.48 and 2.74°).…”