Stereoisomers of C13Cl2 exhibiting helical orbitals around a ring of carbon atoms were synthesized by atom manipulation on NaCl surfaces. We resolved the enantiomeric geometries of the singlet states ...

Inclusion of a fused pyridine ring onto the core motif of an azaphosphinine heterocycle, as well as functionalization with an N-acetamide group, furnishes a chiral, quadruple hydrogen bonding face that is capable of strong homodimerization. Eleven different azaphosphinine derivatives were prepared with variable electron donor and acceptor functionalization. Contrary to simple DA azaphosphinine dimers, trends from substituent effects showed that the hydrogen bond acceptors (A) were more sensitive to the substituents than the hydrogen bond donors (D). With electron donating groups appended onto the azaphosphinine scaffold, dimerization constants rose to as high as 209 M–1 in 10% DMSO-d6 in water-saturated CDCl3. X-ray crystallographic data unexpectedly showed that the quadruply hydrogen bonding system preferred the theoretically less stable donor–acceptor–donor–acceptor (DADA) H-bond orientation despite having the capability to tautomerize to the potentially more stable DDAA structure. Computational analysis revealed that maintaining pyridine aromaticity was more stabilizing than the secondary interactions that would be created from a DDAA dimer. Additionally, these molecules associate as the first examples of R,R- and S,S-azaphosphinine homodimers, compared to the R,S-heterodimers typically found for simple azaphosphinines. This observation was explained by computational analysis, which found a geometric difference between the nitrogen atoms adjacent to the phosphorus chiral center of the Homo and Hetero dimer, leading to a stronger hydrogen bonding interaction in the Homo dimer. Further understanding of this quadruply hydrogen bonding core will allow us to explore further applications that integrate this strongly hydrogen bonding system into larger and more complex supramolecular frameworks such as supramolecular polymers or capsules.

The trihydrogen cation, H3+, is unique in the Universe. It serves as the primary proton reservoir, driving essential astrochemical reactions, and it functions as a thermostat for giant gas planets. H3...

Augmented pentalene structure could be a molecular Schrödinger's cat, aromatic and antiaromatic at the same time

Geminal hyperconjugation can play an important role in heavy-atom tunnelling reactions that involve three-membered rings. We demonstrate this relationship in a case study of the equilibrium between ox...