Inducing polarity in [VO3]nn− chain compounds using asymmetric hydrogen-bonding networks

1,4-Bis(3-aminopropyl)piperazine, (R)-3-aminopiperidine and (S)-3-aminopiperidine were used in the syntheses of [C10H26N4][VO3]2·2H2O, [(R)-C5H14N2][VO3]2 and [(S)–C5H14N2][VO3]2, which all contain similar [VO3]nn− chains. Inversion symmetry within the 1,4-bis(3-aminopropyl)piperazine allows for crystallization of [C10H26N4][VO3]2·2H2O in a centrosymmetric space group, while the use of enantiomerically pure sources of either (R)-3-aminopiperidine or (S)-3-aminopiperidine forces crystallographic noncentrosymmetry. Moreover, asymmetry in the hydrogen-bonding networks between the metavanadate chains and either [(R)-3-aminopiperidineH2]2+ or [(S)-3-aminopiperidineH2]2+ cations directs alignment of the chains and crystallization in a polar space group (C2, no. 5). Component and net dipole moments were calculated using iterative-Hirshfeld partial atomic charges. [(R)-C5H14N2][VO3]2 and [(S)-C5H14N2][VO3]2 both display type 1 phase-matching capabilities and exhibit second harmonic generation activities of ∼140×α-SiO2.