Dipole‐Induced Band‐Gap Reduction in an Inorganic Cage

Abstract

Metal-doped polyoxotitanium cages are a developing class of inorganic compounds which can be regarded as nano- and sub-nano sized molecular relatives of metal-doped titania nanoparticles. These species can serve as models for the ways in which dopant metal ions can be incorporated into metal-doped titania (TiO2 ), a technologically important class of photocatalytic materials with broad applications in devices and pollution control. In this study a series of cobalt(II)-containing cages in the size range ca. 0.7-1.3 nm have been synthesized and structurally characterized, allowing a coherent study of the factors affecting the band gaps in well-defined metal-doped model systems. Band structure calculations are consistent with experimental UV/Vis measurements of the Tix Oy absorption edges in these species and reveal that molecular dipole moment can have a profound effect on the band gap. The observation of a dipole-induced band-gap decrease mechanism provides a potentially general design strategy for the formation of low band-gap inorganic cages.

Novel properties and potential applications of functional ligand-modified polyoxotitanate cages

“…Using recently developed synthetic approaches, the successful synthesis of atomically well-defined polyoxotitanate (POT) cages has allowed chemists to gain new insights into molecular activation using TiO 2 . [7][8][9] Resembling the fragments of bulk TiO 2 , POT cages of the type [Ti x O y (OR) z ] (OR = alkoxide), consisting of Ti x O y inorganic titanium oxide cores encapsulated within an alkoxide ligand periphery, can be considered as models for studying the structural chemistry of bulk TiO 2 , including its crystal growth mechanism, 10,11 the electronic and structural effects of heterometallic doping, [12][13][14][15][16][17][18][19][20][21] and the influence of surface functional ligand modification. [22][23][24][25][26][27][28][29][30][31] While their excellent solubility in common organic solvents allows POTs to be studied using various standard methods (e.g., NMR, 32-34 mass spectrometry 35 ), single-crystal X-ray diffraction is perhaps the preeminent tool for their characterisation (allowing unambiguous characterisation of structural features which can be related to that of bulk TiO 2 itself).…”

New Member of Organic Ligand Functionalized TMSP: Synthesis, Characterized and Properties of Na15[(MnII(COOH))3(AsW9O33)2]·15H2O

“…Although this class of inorganic compounds has been known for more than a 100 years, a great number of novel polyoxonaions with shapes, sizes and properties are still being discovered [6][7][8][9]. In this aspect, transition metal substitute polyoxometalates (TMSP) constitute one of the largest subfamily owing to their various of building blocks, adjustable connection modes and tunable d-or f-metals ions [10][11][12][13][14][15].…”

“…Anal. Calcd for C6 H 39 O 87 As 2 W 18 Mn 3 Na 17 1: C, 1.30; H, 0.71; W, 59.97; Mn, 2.98; Na, 7.08 %; Found: C, 1.33; H, 0.85; W, 59.31; Mn, 2.75; Na, 7.32 % TG analysis indicates that there are about 15 lattice water molecules in the compound 1 (See…”

Ag10Ti28‐Oxo Cluster Containing Single‐Atom Silver Sites: Atomic Structure and Synergistic Electronic Properties

“…[7][8][9][10][11] However,the preparation of single-atom-distributed catalysts is still quite challenging,a nd their characterization is highly dependent on advanced microscopy and synchrotron radiation techniques. [30][31][32][33][34][35][36][37][38][39] Therefore,itishighly desirable to design and synthesize anew type of cluster-stabilized single-atom material by decorating single atoms of catalytically active noble metals on titaniumoxo clusters.I nt his way,t he synergism between the Ti-oxo cluster support and noble-metal active site could lead to unique physical properties (Scheme 1). [14][15][16][17] Accordingly,t he associated and highly desirable structureperformance relationships are still not well understood.…”

“…[24][25][26][27][28][29] Recent developments in the molecular analogues of TiO 2 ,crystalline polyoxotitanium clusters (PTCs), provides us with wonderful opportunities to investigate the structures and reactivities of titanium oxides at the molecular level. [30][31][32][33][34][35][36][37][38][39] Therefore,itishighly desirable to design and synthesize anew type of cluster-stabilized single-atom material by decorating single atoms of catalytically active noble metals on titaniumoxo clusters.I nt his way,t he synergism between the Ti-oxo cluster support and noble-metal active site could lead to unique physical properties (Scheme 1). More importantly, such molecular design could also provide precise models to explore the interactions between the Ti-O support and noblemetal sites.A lthough we have recently encapsulated an Ag 6 cluster within aTi 16 -oxo shell, [40] to the best of our knowledge, the single noble metal atom doping of titanium-oxo clusters with exposed active sites on the surface has not been realized yet.…”