Are there any alternatives to DNA in a fluorine environment?

Question

In this fluorine life that I have been trying to make, are there any possible alternatives to DNA that could exist in these cells? The Environment: What I have so far is that these cells would exist at temperatures of around -50 to -30 Celsius. They would use hydrogen fluoride as a solvent. On this world, there would be no(Or just unnoticeable amounts) of sunlight, UV, or and light of higher wavelengths, as these would be absorbed by the upper fluorine atmosphere, so the only source of warmth comes from the planet itself, which is kept by greenhouse gasses(Still working on the exact mechanism for where the heat will specifically come from) As for what you have to play with: Any of the nonmetals, if there are any other elements you would like to have in building the DNA, fine by me. Although keep in mind there is fluorine around, so the DNA is gonna need to not be broken down by fluorine gas.

Answer 1

The biggest problem for using Earthling DNA in HF solvent is that HF will want to attack the backbone linkages by hydrolization. (Water does that, too, but it's slow.)

So, you need a different backbone that won't be subject to that sort of chemical attack. There are probably tons of options, if we accept the possibility of radically different biochemistry at all, and there's a serious lack of empirical study of how different replicable polymers behave in HF solution... but here are just a few which have seriously been proposed as possible alternate foundations for a genetic polymer in the synthetic biology and astrobiology literature*, and which might survive in that environment:

1. Schiff base polymers connected by -N-(CO)- backbone links rather than phosphate esters. The simplest version would use simple aniline rings (or perfluoroaniline rings) with either a -CH (or CF, with an H-to-F substitution for fluorine gas resistance) or -N half-rung group, with CH (/CF) groups bonding to N groups from opposite helices, giving you a 2-base-type genetic code. This is considerably simpler than the sugar-bonded-to-nucleobase-with-binding-sites model of DNA; the backbone and the nucleobase are the same thing. You could expand the code replacing simple aniline rings with polyaromatic structures of different widths, thus requiring complementary geometry as well as terminal atom type (C vs. N) across the rung, just as DNA relies on both complementary geometry and hydrogen bonding sites, or you could look at introducing different terminal atoms and bond types, apart from just the C=N bond. Since HF dissolves lots of metals, maybe you go with different types of coordinated metal ligands to define the different rung types!

2. Diacetylene backbones. Nucleotides end up linked by triple-bonded carbons with a single bond on each end, R-(CC)-R. The nucleobases themselves have the structure X-(C-)=(C-)-R, where "X" is an external group (probably something charged, maybe just a polar F- bond or something), dangling parenthesized hyphens are the bonds that attach to the linking acetylenes, and "R" is the information-storing nucleotide. Pre-polymerized nucleotides would have the structure X-(CC)-(CC)-R. The individual nucleobases still need designing, but they could plausibly be very similar to Earthling nucleobases (possibly with some H-to-F substitutions for F2 resistance), linked by hydrogen bonding to form two-base rungs (with hydrogens attached to nitrogen heteroatoms in aromatic rings that are not subject to hydrolytic damage, attracted to other ring-nitrogens, or exposed =O groups). Those triple carbon bonds are pretty high energy, though, and may be subject to attack from F2; there are two plausible ways around that: first, the system could evolve in an anfluoric environment, and develop resistance mechanisms that actively exclude F2 from interacting with the genetic molecule, just as Earthlife arose in an anoxic environment and later developed oxygen tolerance; second, polyacetylene could be replaced with polyfluoroethene, where the linkages use double bonded carbons with extra bonding sites saturated with fluorine in X-FC=CF-R units, which should reduce free fluorine reactivity.

[*] Specifically, see Cairns-Smith, A. G. (1977). In Cairns-Smith, AG and Davies, CJ. The Design of Novel Replicating Polymers.