Assembling Polyiodides and Iodobismuthates Using a Template Effect of a Cyclic Diammonium Cation and Formation of a Low-Gap Hybrid Iodobismuthate with High Thermal Stability
oleh: Tatiana A. Shestimerova, Andrei V. Mironov, Mikhail A. Bykov, Anastasia V. Grigorieva, Zheng Wei, Evgeny V. Dikarev, Andrei V. Shevelkov
| Format: | Article |
|---|---|
| Diterbitkan: | MDPI AG 2020-06-01 |
Deskripsi
Exploiting a template effect of 1,4-diazacycloheptane (also known as homopiperazine, Hpipe), four new hybrid iodides, (HpipeH<sub>2</sub>)<sub>2</sub>Bi<sub>2</sub>I<sub>10</sub>·2H<sub>2</sub>O, (HpipeH<sub>2</sub>)I(I<sub>3</sub>), (HpipeH<sub>2</sub>)<sub>3</sub>I<sub>6</sub>·H<sub>2</sub>O, and (HpipeH<sub>2</sub>)<sub>3</sub>(H<sub>3</sub>O)I<sub>7</sub>, were prepared and their crystal structures were solved using single crystal X-ray diffraction data. All four solid-state crystal structures feature the HpipeH<sub>2</sub><sup>2+</sup> cation alternating with Bi<sub>2</sub>I<sub>10</sub><sup>4–</sup>, I<sub>3</sub><sup>–</sup>, or I<sup>–</sup> anions and solvent water or H<sub>3</sub>O<sup>+</sup> cation. HpipeH<sub>2</sub><sup>2+</sup> assembles anionic and neutral building blocks into polymer structures by forming four strong (N)H···I and (N)H···O hydrogen bonds per cation, with the H···I distances ranging from 2.44 to 2.93 Å and H···O distances of 1.88–1.89 Å. These hydrogen bonds strongly affect the properties of compounds; in particular, in the case of (HpipeH<sub>2</sub>)<sub>2</sub>Bi<sub>2</sub>I<sub>10</sub>·2H<sub>2</sub>O, they ensure narrowing of the band gap down to 1.8 eV and provide high thermal stability up to 240 °C, remarkable for a hydrated molecular solid.