A Series of New Phases Containing Three Different Asymmetric Building Units

Systematic explorations of the new phases in the PbII/BiIII−TM(d0/d1)−SeIV−O systems by hydrothermal syntheses led to five new quaternary phases whose structures are composed of three different asymmetric building units, namely, Pb2VV2Se2O11 (1), Pb2VIV3Se5O18 (2), Pb2NbV2Se4O15 (3), Bi2VV2Se4O16 (4), and Bi2MoVI2Se2O13 (5). The structure of 1 features a 3D network built by 1D anionic chains of [V2O5(SeO3)2]4− interconnected by Pb2+ ions with six-membered-ring (MR) tunnels along the b axis. The structure of 2 features a 3D anionic framework composed of VIVO6 octahedra corner-sharing with SeO3 anions, with the Pb2+ ions located at the resultant 8-MR tunnels. The oxidation state of the vanadium cation is 4+ due to the partial oxidation of V2O3 by SeO2 at high temperature. The structure of 3 features novel 1D double chains of [Nb2O3(SeO3)4]4− that are interconnected by Pb2+ ions, forming a 3D network with 12-MR tunnels along the c axis. 4 features a 3D framework composed of 2D layers of [Bi2(SeO3)2]2+ and 1D [(VO2)2(SeO3)2]2− double chains. The structure of 5 features a 3D network composed of bismuth(III) selenite with large 10-MR tunnels along the a axis that are occupied by Mo2O10 dimers. The results of optical diffuse-reflectance spectrum measurements and electronic structure calculations based on density functional theory methods indicate that all five compounds are wide-band-gap semiconductors. Luminescent property measurements for compounds 1−5 and magnetic measurements for compound 2 were also made.