Love Connection
by Jessen Yu, Stribs
Answer: IPHONE BATTERY
Each profile prompts the user to enter a name to check if there is a match. The app will check the name and if it is correct (ignoring capitalization and spacing), will present the solver with a short message indicating where to find the match. Solvers need to realize that each profile represents a chemical compound and the desired name has a very specific constraint: the number of letters (none of the compounds have digits in the desired name) is exactly equal to the number of heavy atoms in the molecule. The desired name is taken from the title of the wikipedia page for that compound.
Once a solver enters the correct name, the app responds with "It's a match!" and gives some information about where to find their date. This location information hints at a specific atom within the molecule.
Additionally, each match is accompanied by an animation of the "compatibility factors" which read acrostically "INCHI". This refers to InChI, the International Chemical Identifier. The animation also associates the five letters of InChI with positions around the pentagonal ring graphic (cyclohexane). Looking into the specification of InChI will lead solvers to the realization that InChI specifies a canonical ordering of the heavy atoms in a molecule (modulo symmetrically equivalent atoms, which we astutely avoid in this puzzle). There are several methods which allow you to input InChI strings and will show you the atom numbering (note that because of the way InChI treats hydrogens, these apps will frequently display non-standard tautomers, e.g. imidic acids instead of amides, and you will still need to transfer numbering back to a more standard diagram by comparing the heavy-atom connectivity):
- The Marvin JS Demo allows you to paste in InChI strings and then view atom indices (under the gear icon).
- The NIH has an online CACTVS app which can render the InChI indices (directly replace the InChI string in the URL to render other molecules):
https://cactus.nci.nih.gov/chemical/structure/InChI=1/C5H10/c1-2-4-5-3-1/h1-5H2/image?asymbol=label&bgcolor=white - The open source chemistry software Open Babel can
render InChI strings to numbered molecules with the command line:
obabel -iinchi -:"InChI=1S/C9H17NO5/c1-9(2,5-11)7(14)8(15)10-4-3-6(12)13/h7,11,14H,3-5H2,1-2H3,(H,10,15)(H,12,13)" -O panto_acid.svg -xi
Mapping the letters in the desired name to the atoms in the canonical ordering given by InChI, we can then extract a single letter per molecule using the atom highlighted in the "match" results.
This leads to the answer to the puzzle: IPHONE BATTERY
| Molecule Name | Numbered Atoms | Index | Letter | Notes |
| PANTOTHENIC ACID |  | 14 | I | Pantothenic derives from the Greek for "from everywhere". The location refers to the secondary alcohol. |
| PARACETAMOL |  | 1 | P | Better known as acetaminophen in the US, PARACETAMOL fits the letter/atom constraint. The location refers to the alpha carbon, relative to the amide carbonyl. |
| ORNITHINE |  | 6 | H | AA refers to Amino Acid, ornithine is a non-coded amino acid that is rumored to stimulate growth hormone. The location refers to the terminal amine, at the other end of the molecule from the carboxylic acid group. |
| ISOFLURANE |  | 3 | O | Isoflurane is commonly used as a veterinary general anesthetic, typically for dogs. The location refers to the carbon bonded to three fluorine atoms. |
| FURAN |  | 5 | N | Furan is one of the simplest heterocyclic compounds, its name derives from furfur, Latin for bran. The location refers to the two lone pairs on the oxygen atom, one of which participates in the aromatic system and one which does not. |
| CYTOSINE |  | 8 | E | Cytosine forms three hydrogen bonds with Guanine in nucleic acid base pairing. We want the hydrogen-bond acceptor not in the middle, the oxygen atom. |
| BETA-CARBOLINE |  | 1 | B | Who knew scorpions fluoresced? The location is the carbon atom four bonds away from the nitrogens (all the rest are 3 or less bonds away from a nitrogen atom). |
| UREA |  | 4 | A | Friedrich Wohler's inorganic synthesis of urea in the 19th century has been associated with the downfall of vitalism (this is not historically accurate, but has been part of organic chemistry lore for ages). The location refers to the oxygen which atom has the most electron density in the molecule. |
| TOLUENE |  | 1 | T | Toluene is used as paint thinner and a commonly abused inhalant. Trinitrotoluene is the well known explosive TNT. The location refers to the exocyclic carbon atom. |
| LYSERGIC ACID DIETHYLAMIDE |  | 16 | T | Lysergic acid diethylamide, more commonly known as LSD or acid, is famously associated with acid trips and flashbacks that can occur over a year later. The location refers to the carbon across from the stereocenter in the fused-ring system. While the bond forming the ortho-fusion is not typically referred to as a "bridge", the definition on wikipedia is inclusive of these fusion bonds (and no, I did not edit the article to make it so). |
| DIPROPYLTRYPTAMINE |  | 18 | E | Followers of the Temple of the True Inner Light use dipropyltryptamine as a religious sacrament. The location refers to the nucleophilic tertiary amine. The indole nitrogen is typically not considered nucleophilic. |
| ALENDRONIC ACID |  | 6 | R | Alendronic acid (brand name Fosamax) is a commonly prescribed treatment for Paget's disease of bone. The phrase "avoid salt/sodium" clues the free acid form (as opposed to the sodium salt formulation). The location refers to Hydrox cookies, not the imitation Oreos that were invented afterwards. This indicates the hydroxyl group between the two phosphonates. |
| GLYPHOSATE |  | 3 | Y | Glyphosate, commercially sold as Roundup, has been controversially associated with colony collapse disorder, cancer, and Monsanto. The location refers to the Fischer-Speier esterification, one step of which is a nucleophilic attack on the carbonyl carbon. |