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Environmental Science

Entry Probe Studies for Ice-Giants

Profile image of Parul AgrawalParul Agrawal

2017

https://doi.org/10.6000/1929-5030.2017.06.03.1
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7 pages

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Abstract

Insulation Layer Planet Uranus Uranus Neptune Neptune Neptune Entry Parameters Design # 1 Design # 2 Design # 3 Design # 4 Design # 5 Hyperbolic excess velocity (km/s) 9.9 8.4 12.3 11.3 11.4 Relative entry velocity (km/s) 23.1 21.9 28.8 28.4 28.5 Entry Flight Path Angle, gamma (deg) -35.0 -30.0 -34.0 -20.0 -16.0 Max deceleration (g loads) 216.7 164.8 454.9 208.7 124.5 Stg Pressure (bar) 12.0 9.0 25.0 11.5 6.8 Total Peak Heat Flux (W/cm) 3456.

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    Aleksey Kuznetsov

    Pure and Applied Chemistry, 2022

    The important and perspective molecular building blocks composed of hexaphenylbenzenes (HPBs) or their oxidized derivatives, hexa-peri-hexabenzocoronenes (HBCs), and metalloporphyrins have recently received significant attention of the researchers. In this study, motivated by recent findings, we have addressed the modifications of structures and properties of HBC-porphyrin compounds by using instead of aromatic porphyrins antiaromatic 20π isophlorin derivatives of thiophene or selenophene. We have reported the first comparative computational investigation of the following systems: (i) HBC with one non-metallated aromatic porphyrin, P(N4H2), unit, HBC-P(N4H2), (ii) HBC with one S-core-modified antiaromatic porphyrin (S-isophlorin), PS4, unit, HBC-PS4, and (iii) HBC with one Se-core-modified antiaromatic porphyrin (Se-isophlorin), PSe4, unit, HBC-PSe4. The study has been done employing the B3LYP/6-31G* approach (in the gas phase and in the implicit solvents, benzene and dichloromethane), and comparison with the B3LYP/6-31G** and B3LYP/6-311G* approaches was performed, where relevant. The effects of the core-modified antiaromatic isophlorins on the structures, electronic, and other properties, potentially including reactivity, of the whole building block HBC-isophlorin have been shown to be quite pronounced and to be noticeably stronger than the effects of the original aromatic non-metallated porphyrin. Thus, we have demonstrated theoretically that the complete porphyrin core-modification with other elements, this time with S and Se leading to the formation of the antiaromatic isophlorins, should be considered as a promising way for modifying and tuning structures, electronic properties and reactivity of the hexabenzocoronene-porphyrin(s) building blocks.

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