Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warszawa, Poland.
Univ. Rennes, Ecole Nationale Supérieure de Chimie de Rennes, CNRS, ISCR-UMR6226, F-35000 Rennes, France.
Molecules. 2021 Nov 15;26(22):6870. doi: 10.3390/molecules26226870.
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 N 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, OHN and OHN, 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.
我们报告了在 4.7-16.5GHz 下用超音速扩展傅里叶变换微波光谱法对 2-氨基吡啶和水（AMW）之间 1:1 簇的旋转光谱的观察和分析。还将 2-氨基吡啶单体（AMP）的测量扩展到 333GHz，以解决由于存在两个 N 四极核而导致的超精细分裂。还对 AMP 和 AMW 进行了超音速扩展测量，用于两种合成的同位素，其苯环上只有一个氘化。AMW 还解析了核四极超精细结构，得出的分裂常数可作为结构分析的辅助手段。通过三组可用的旋转常数确定了 AMW 簇的结构，并将氢键构型与具有类似大小单环分子的水的簇进行了比较。实验结果结合量子化学计算得出的结论是，水分子通过两个氢键，OHN 和 OHN，与 AMP 的 NCNH 原子链异常强地结合，有可能取代与 CT 和 AT 核酸碱基对中相同结构片段的氢键。
