  Kagome materials have recently drawn great attention due to the interplay
between nontrivial band topology, electron correlations, and Van Hove
singularities related many-body orders. Here we report three new vanadium-based
kagome metals, TiV6Sn6, ZrV6Sn6, and HfV6Sn6, and conduct a comprehensive
investigation of their structural, magnetic, and electrical transport
properties. All three compounds exhibit large unsaturated magnetoresistances
and multiband Hall effects at low temperatures, indicating the existence of
multiple highly mobile carriers. Both the diagonal and off-diagonal resistivity
show quantum oscillations with nontrivial Berry phases and high quantum
mobilities. First-principles calculations together with quantum oscillation
analyses suggest the Van Hove singularities at the M point for the three
compounds all located in close vicinity of the Fermi level, and there also
exist multiple topological nontrivial band crossings, including a nodal ring
and a massive Dirac cone. Our work extends the kagome AM6X6 family and paves
the way for searching possible Van Hove physics in the V kagome lattice.
