From Molecular to Cluster Properties: Rotational Spectroscopy of 2-Aminopyridine and of Its Biomimetic Cluster with Water

Abstract

We report the observation and analysis of the rotational spectrum of a 1:1 cluster between 2-aminopyridine and water (AMW) carried out with supersonic expansion Fourier transform microwave spectroscopy at 4.7–16.5 GHz. Measurements of the 2-aminopyridine monomer (AMP) were also extended up to 333 GHz for the room-temperature rotational spectrum and to resolved hyperfine splitting resulting from the presence of two 14N quadrupolar nuclei. Supersonic expansion measurements for both AMP and AMW were also carried out for two synthesized isotopic species with single deuteration on the phenyl ring. Nuclear quadrupole hyperfine structure has also been resolved for AMW and the derived splitting constants were used as an aid in structural analysis. The structure of the AMW cluster was determined from the three sets of available rotational constants and the hydrogen bonding configuration is compared with those for clusters with water of similarly sized single-ring molecules. Experimental results aided by quantum chemistry computations allow the conclusion that the water molecule is unusually strongly bound by two hydrogen bonds, OH...N and O...HN, to the NCNH atomic chain of AMP with the potential to replace hydrogen bonds to the identical structural segment in cytosine and adenine in CT and AT nucleic acid base pairs.

Investigation into Solubility and Solvent Effect of 2-Aminopyridine in Different Mono-Solvents Over Temperatures from 273.15 to 313.15 K

“…2-Aminopyridine (CAS Reg. no., 504-29-0; structure, Figure ) is widely employed in a variety of applications of pharmaceuticals’ synthesis, especially for antihistamines, antiflammatories, and other drugs. , Brominated 2-aminopyridine attracted considerable attention for its applications as useful intermediates or building blocks for pharmaceuticals. − In particular, 2-aminopyridine also serves as an useful raw material for some liquid crystals. , Regardless of its wide applications, there has been little research into the thermodynamic properties of 2-aminopyridine in neat and mixed solvents. 2-Aminopyridine is generally obtained through the reduction of 2-nitropyridine or 2-halopyridine in various solvents such as ethanol, , methanol, acetonitrile, N -methyl-2-pyrrolidine (NMP), and so on.…”