The discrete supertetrahedral chalcogenido
Tn clusters can be regarded as a type of quantum
dot (QD) with precise structure and uniform size. They were commonly
studied in the solid state because of their poor solubility or highly
negative charge that leads to instability in common solvents. These
drawbacks limit their potential applications as efficient photocatalysts.
Herein we first obtained a sulfide compound via an ionic-liquid-assisted
precursor method, namely, (BMMim)9(Cd3In17S31Cl4) (T4-1, BMMim =
1-butyl-2,3-dimethylimidazolium). T4-1 is characteristic
of the discrete anionic T4 cluster and is insoluble in common solvents.
Introducing Se into the structure resulted in compounds (BMMim)9(Cd3In17S13Se18Cl4) (T4-2) and (BMMim)9(Cd3In17Se31Cl4)(4,4′-bpy)
(T4-3) with narrower band gaps. Moreover, T4-2 and T4-3 were soluble in dimethyl sulfoxide (DMSO)
probably because of weaker interactions between cations and anions
than in T4-1. The solution stability of these clusters
has been confirmed by mass spectrometry. Further characterization
reveals that the highly dispersed T4 clusters exposed more active
sites in solution, so their rates of relevant H2 production
were improved to be ∼5 times that in the solid state. To our
knowledge, this is the first time that highly dispersed Tn clusters have been applied in photocatalytic H2 generation.
Presented are the ionothermal syntheses, characterizations, and properties of a series of two- and three-dimensional selenidostannate compounds synergistically directed by metal-amine complex (MAC) cations and ionic liquids (ILs) of [Bmmim]Cl (Bmmim=1-butyl-2,3-dimethylimidazolium). Four selenidostannates, namely, 2D-(Bmmim)3 [Ni(en)3 ]2 [Sn9 Se21 ]Cl (1, en=ethylenediamine), 2D-(Bmmim)8 [Ni2 (teta)2 (μ-teta)]Sn18 Se42 (2, teta=triethylenetetramine), 2D-(Bmmim)4 [Ni(tepa)Cl]2 [Ni(tepa)Sn12 Se28 ] (3, tepa=tetraethylenepentamine), and 3D-(Bmmim)2 [Ni(1,2-pda)3 ]Sn8 Se18 (4, 1,2-pda=1,2-diaminopropane), were obtained. Single-crystal X-ray diffraction analyses revealed that compounds 1 and 2 possess a lamellar anionic [Sn3 Se7 ]n (2n-) structure comprising distinct eight-membered ring units, whereas 3 features a MAC-decorated anionic [Ni(tepa)Sn12 Se28 ]n (6n-) layered structure. In contrast to 1-3, compound 4 exhibits a 3D open framework of anionic [Sn4 Se9 ]n (2n-) . The structural variation from 1 to 4 clearly indicates that on the basis of the synergistic structure-directing ability of the MACs and ILs, variation of the organic polyamine ligand has a significant impact on the formation of selenidostannates.
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