The exploration of phase formation in the f-element-bearing iodate selenate system has resulted in 14 novel rare-earth-containing iodate selenates, Ln(IO₃)(SeO₄) (Ln = La, Ce, Pr, Nd; LnISeO-1), Ln(IO₃)(SeO₄)(H₂O) (Ln = Sm, Eu; LnISeO-2), and Ln(IO₃)(SeO₄)(H₂O)₂·H₂O (Ln = Gd, Dy, Ho, Er, Tm, Yb, Lu, Y; LnISeO-3), as well as two new thorium iodate selenates, Th(OH)(IO₃)(SeO₄)(H₂O) (ThISeO-1) and Th(IO₃)₂(SeO₄) (ThISeO-2). LnISeO-3 and ThISeO-2 crystallize in the chiral space group P2₁2₁2₁, while LnISeO-1, LnISeO-2, and ThISeO-1 crystallize in the centrosymmetric space group P2₁/c. The numbers of both coordinating and hydrating water molecules crystallized in LnISeO-1, LnISeO-2, and LnISeO-3 increase along these three series, in line with the increasingly negative values of hydration enthalpies of heavier trivalent lanthanide ions. Such a systematic change in compositions, especially the first coordination sphere of Ln, further induces structural rearrangements, including coordination number and dimensional reductions. More specifically, the structures of LnISeO-1, LnISeO-2, and LnISeO-3 have undergone transitions from 2D Ln–oxo layers with 10-coordinate Ln centers to 1D Ln–oxo chains with 9-coordinate Ln centers and then to 0D Ln–oxo monomers with 8-coordinate Ln centers, respectively. The formation and characterization of this large family of Ln/Th iodate selenates suggest that such a mixed-anion system not only exhibits richer structural chemistry but also can be capable of generating intriguing properties, such as the second-harmonic generation (SHG) effect.

中文翻译：

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一大类中心对称和手性含f元素的碘酸盐硒酸盐具有配位数和降维

探索含f元素的碘酸盐硒酸盐体系中的相形成已产生14种新型的含稀土碘酸盐硒酸盐Ln（IO ₃）（SeO ₄）（Ln = La，Ce，Pr，Nd；LnISeO- 1），Ln（IO ₃）（SeO ₄）（H ₂ O）（Ln = Sm，Eu; LnISeO-2）和Ln（IO ₃）（SeO ₄）（H ₂ O）₂ ·H ₂ O（ Ln = Gd，Dy，Ho，Er，Tm，Yb，Lu，Y; LnISeO-3），以及两种新的碘化亚硒酸亚硒酸盐Th（OH）（IO ₃）（SeO ₄）（H ₂ O）（ThISeO-1）和Th（IO₃）₂（SeO ₄）（ThISeO-2）。LnISeO-3和ThISeO-2在手性空间群P 2 ₁ 2 ₁ 2 _1中结晶，而LnISeO-1，LnISeO-2和ThISeO-1在中心对称空间群P 2 ₁ / c中结晶。在LnISeO-1，LnISeO-2和LnISeO-3中结晶的配位和水合分子的数量沿这三个系列增加，这与较重的三价镧系元素离子的水合焓值越来越负相关。这种组成上的系统变化，尤其是Ln的第一个配位范围，进一步引起结构重排，包括配位数和尺寸的减小。更具体地说，LnISeO-1，LnISeO-2和LnISeO-3的结构分别经历了从具有10个坐标Ln中心的2D Ln-oxo层到具有9个坐标Ln中心的1D Ln-oxo链的转变，然后分别转变为具有8个坐标Ln中心的0D Ln-oxo单体。Ln / Th碘酸盐硒酸盐这一大家族的形成和表征表明，这种混合阴离子体系不仅表现出更丰富的结构化学，而且还能够产生引人入胜的特性，例如二次谐波产生（SHG）效应。