Tutor profile: Rangika M.
Subject: Organic Chemistry
What is the difference between an electrophile and nucleophile?
Electrophiles are the groups who prefer to gain electrons, while nucleophiles are the groups which prefer to donate electrons. Electrophiles attack electron rich centers while, nucleophiles attack electron deficient centers.
Complexes formed by most of the d block metals are colored. However, complexes formed by Zn2+ ion are colorless. Explain the chemistry behind this phenomenon.
The reason for most of the d block metals to be colored is the crystal field splitting of d orbitals. Surrounding electron rich ligands exert repulsive forces unevenly for 5 d orbitals separating them to two discrete energy levels. d electron transitions between these two levels give rise to the colored solutions that we see. Zn2+ ion has 10 d electrons filling all the d orbitals. As all of them are filled, there are no vacant orbitals to show transitions. Therefore, Zn2+ solutions are colorless.
Explain the main problem associated with treating SARS-CoV-2 with nucleoside analogs like Remdesivir?
Nucleoside analogs act as a normal nucleoside perturbing the nucleoside pool inside cells. They are readily converted to nucleotides by host kinases. These exogenous nucleotides are used by RNA dependent RNA polymerases for the RNA replication mutating the synthesising RNAs. However, the exoribonuclease, which is a proofreading enzyme found in the viral genome, proofreads these mutated RNAs to remove erroneously added nucleotides such as remdesvir. Therefore, high doses of nucleoside analogs have to be used to get effective results.
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