Density functional study on chirospectra of hydrogen-bonded systems X− (H2O)3 (X = F, Cl, Br, I)

Abstract

This paper calculates the molecular structures, infrared, Raman, circular dichroism spectra and optical rotatory powers of some hydrogen-bonded supramolecular systems as a cyclic water trimer, (H2O)3 and its pyramidal halide complexes, X− (H2O)3 (X = F, Cl, Br, I) with the gradient-corrected density functional theory method at the B3LYP/6–311++G(2d,2p) and B3LYP/Aug–cc–pVTZ levels. It finds that the complexation of halide anions with the water trimer can efficiently modulate the chirally optical behaviors. The calculated vibrational circular dichroism spectrum illuminates that the vibrational rotational strength of S(+)–(H2O)3 mostly originates from the O–H rocking modes, whereas chirality of S(–)–X− (H2O)3 (X = F, Cl, Br, I) has its important origin in the O–H stretching modes. The calculated optical rotatory power demonstrates that S(+)–(H2O)3 and S(+)–F−(H2O)3 are positively chiral, whereas S(–)–X−(H2O)3 (X = Cl, Br, I) are negatively chiral. With the polarizable continuum model, calculated bulk solvent effect in the solvents water and carbontetrachloride and argon shows that the positive chirality of S(+)–(H2O)3 is enhanced and the negative chirality of S(–)–X−(H2O)3 (X = Cl, Br, I) and the positive chirality of S(+)–F−(H2O)3 are reduced with an augmentation of the solvent dielectric constant.