Interaction Types in C6H5(CH2)(n)OH-CO2 (n=0-4) Determined by the Length of the Side Alkyl Chain

C6H5(CH2)(n)OH-CO2 complexes have been investigated using rotational spectroscopy (n = 0-2) complemented by quantum chemical calculations (n = 0-4), which implies that the side alkyl chain length can determine the types of intermolecular interactions. Unlike the in-plane C center dot center dot center dot O tetrel bond in phenol-CO2, the pi*(CO2)center dot center dot center dot pi(aromatic) interaction has been shown to link CO2 to phenylmethanol and 2-phenylethanol, which is, to the best of our knowledge, the first time it has been demonstrated by rotational spectroscopy. Further elongations of the side alkyl chain gradually increase the energies of intramolecular hydrogen bonds in 3-phenylpropanol and 4-phenylbutanol so that CO2 cannot break it. CO2 will be pushed farther from the monomers and link with the -OH group through a dominating C center dot center dot center dot O tetrel bond. Our observations would allow, with the choice of the proper length of the side alkyl chain, new strategies for engineering C center dot center dot center dot pi(aromatic)-centered noncovalent bonding schemes for the capture, utilization, and storage of CO2.