Rotational spectra of propargyl alcohol dimer: A dimer bound with three different types of hydrogen bonds

Abstract

Pure rotational spectra of the propargyl alcohol dimer and its three deuterium isotopologues have been observed in the 4 to 13 GHz range using a pulsed-nozzle Fourier transform microwave spectrometer. For the parent dimer, a total of 51 transitions could be observed and fitted within experimental uncertainty. For two mono-substituted and one bi-substituted deuterium isotopologues, a total of 14, 17, and 19 transitions were observed, respectively. The observed rotational constants for the parent dimer [A = 2321.8335(4) MHz, B = 1150.4774(2) MHz, and C = 1124.8898(2) MHz] are close to those of the most stable structure predicted by ab initio calculations. Spectra of the three deuterated isotopologues and Kraitchman analysis positively confirm this structure. Geometrical parameters and "Atoms in Molecules" analysis on the observed structure reveal that the two propargyl alcohol units in the dimer are bound by three different types of hydrogen bonds: O-H⋯O, O-H⋯π, and C-H⋯π. To the best of our knowledge, propargyl alcohol seems to be the smallest molecule forming a homodimer with three different points of contact.

Understanding benzyl alcohol aggregation by chiral modification: the pairing step

“…The most stable structural motif O g π features cooperatively interacting OH• • • OH• • • π hydrogen bonds and is reminiscent of the global minimum of the propargyl alcohol dimer 63,64 . The het variant is slightly less stable despite somewhat stronger hydrogen bonds (based on predicted downshifts and intensity enhancements), indicating a compensating role of dispersion interactions.…”

The Possibility of Forming Propargyl Alcohol in the Interstellar Medium

“…They found PA to have a gauche structure, with Ar located in between the -OH and -C≡C-H groups. In another study, Devendra & Arunan (2014) carried out experiments for the pure rotational spectra of the PA dimer and its three deuterium isotopologues.…”

Microsolvation of anions by molecules forming CH··X− hydrogen bonds

“…Water interacts with the ionic species via its strong H-bonding capacity as well as charge-dipole interactions. On the other hand, a great deal of recent work has shown that the CH group can serve as a potent proton donor in H-bonds (HBs) in parallel fashion to OH and NH donors [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26]. CH••X HBs are quite prevalent in nature, in biological [27][28][29][30][31][32][33][34][35] as well as chemical [36][37][38][39][40][41][42][43][44] contexts.…”