Guo-Dong Zou

Varied forms of lamellar [Sn3Se7]n2n− anion: the competitive and synergistic structure-directing effects of metal–amine complex and imidazolium cations

Presented are the syntheses, characterizations and properties of a series of selenidostannate compounds directed by metal-amine complex (MAC) cations and/or [Bmmim](+) (Bmmim = 1-butyl-2,3-dimethylimidazolium). Mixtures of the ionic liquid (IL) (Bmmim)Cl and amines, such as ethylenediamine (en) and diethylenetriamine (dien), in various ratios were used to ionothermally/solvothermally prepare four selenidostannates, namely, [Mn(en)3]Sn3Se7 (1), [Mn(dien)2]Sn3Se7·H2O (2), (Bmmim)3[Mn(en)3]2[Sn9Se21]Cl (3) and (Bmmim)6[Mn(dien)2]2Sn15Se35 (4). Single-crystal X-ray diffraction analyses revealed that these compounds exhibit lamellar anionic [Sn3Se7]n(2n-) structures. [Sn3Se7]n(2n-) layers in all 1-4 possess a {6(3)} net, considering [Sn3Se10] semi-cube unit as a 3-connected node; however, diverse multi-membered rings exist there. In compounds 1 and 2, all the [Sn3Se10] units are 3-connected nodes interlinking with each other via edge-sharing two Se atoms to produce six-membered rings. However, in compound 3, the insertion of two [Sn3Se9] units into a six-membered ring results in a novel eight-membered heart-shaped ring, which has never been observed before in the family of chalcogenidostannates. More interestingly, the [Sn3Se7]n(2n-) layer in compound 4 consists of mixed six- and eight-membered rings. The phase composition is strongly dependent on the ratio of IL to MAC in the syntheses, e.g., 1 and 2 were obtained with IL:MAC ratios less than 3:1 and 4:1, while 3 and 4 were obtained when the ratios were increased to 4:1 and 5:1, respectively. The structural variation from 1 to 4 clearly indicates the competitive and synergistic effects between MAC and IL cation on the formation of lamellar selenidostannates. A synthetic approach via varying the ratio of IL to MAC cation as solvent and structure-directing agent will be attractive in the synthesis of novel chalcogenidometallates.

Phosphonate-Stabilized Titanium-Oxo Clusters with Ferrocene Photosensitizer: Structures, Photophysical and Photoelectrochemical Properties, and DFT/TDDFT Calculations

The metal-to-core charge transfer (MCCT) transition in sensitized titanium-oxo clusters is an important process for photoinduced electron injection in photovoltaic conversion. This process resembles most closely the Type II photoinjection in dye-sensitized solar cells. Herein we report the synthesis and photophysical and photoelectrochemical (PEC) properties of the phosphonate-stabilized titanium-oxo clusters containing the ferrocenecarboxylate ligands. These ferrocene-containing clusters exhibit intense visible absorption extended up to 600 nm along with low optical band gaps of ∼2.2 eV. The low-energy transitions of these clusters were systematically investigated by UV-vis spectroscopy and DFT/TDDFT calculations. The combined experimental and computational studies suggest that the ferrocenecarboxylate-substituted titanium-oxo clusters form a donor-acceptor (D-A) system. The low-energy transition of these clusters primarily involves the MCCT from the iron center to TiO cluster core. The TiO core structure and phosphonate ligands both have great influence on the PEC properties of the clusters. This work provides valuable examples for the sensitized titanium-oxo clusters in which electron injection takes place via MCCT transition.

A photoactive {Ti16} metal–organic capsule: structural, photoelectrochemical and photocatalytic properties

A photoactive {Ti16} metal–organic coordination capsule with a cavity length of ∼1.4 nm was synthesized and structurally characterized by single-crystal X-ray diffraction analysis. This {Ti16} coordination capsule has a much enhanced visible-light absorption band with a narrow band gap of 2.1 eV. In this highly porous crystalline coordination capsule, 2,5-dihydroxybenzoate (DHB) photosensitizers and Ti-oxo cluster units can work cooperatively to promote the photoelectrochemical and photocatalytic performance.