Photo- and Electrochromism of Polyoxometalates and Related Materials

Abstract

ContentsI. Introduction 307 A. Historical Background 307 B. Scope and Limitations 308 II. Photochromism and Electrochromism of Metal Oxides 309 A. Photoinduced Coloration of Metal Oxides Due to Impurity Effects 309 B. Electrochromism 310 1. WO 3 310 2. Other Metal Oxides 310 III. Photochromism of Polyoxometalate Solids 311 A. Alkylammonium Polyoxomolybdates 311 B. Other Polyoxometalates 314 IV. Electrochromism of Polyoxometalates 314 A. H 3 PW 12 O 40 314 B. K 0.33 WO 3.165 and Peroxopolytungstic Acids 314 V. Photoluminescence and Intramolecular Energy Transfer in Polyoxometalate Solids 315 A. Polyoxometalloeuropates 315 1. Structural Feature 315 2. Intramolecular Energy Transfer from the OfM LMCT States to Eu 3+ 316 B. OfM LMCT Triplet Emission 317 VI. Photoinduced Formation of Heteropoly Blues 318 A. Polyoxomolybdates 318 B. Polyoxotungstates 319 C. Polyoxovanadates and Self-Assembly Encapsulation 321 VII. Conclusions 322 VIII. Acknowledgments 323 IX. References 323

Electrochromic Characteristics of a Nickel Borate Thin Film Investigated by In Situ XAFS and UV/vis Spectroscopy

“…On the other hand, Ni(OH) 2 thin film is also known to exhibit the electrochromic behavior between colorless and brown, where formation of NiOOH from Ni(OH) 2 and its reduction via proton and electron transfer (Ni(OH) 2 § NiOOH + H + + e ¹ ) have been proposed from cyclic voltammetry and infrared absorption spectroscopy. 12,13 Similar electrochromic transitions have been reported for various inorganic materials, such as MoO 3 (colorless-blue), 10,11,14 V 2 O 5 (yellow-blue), 4,5 and Ir(OH) x (blackcolorless). 15,16 The nickel borate compounds Ni 3 (BO 3 ) 2 and Ni(BO 2 ) 2 have been investigated as candidates for several applications based on this unique behavior.…”

“…[1][2][3][4][5][6][7][8] Among these, amorphous WO 3 is one of the most well-known electrochromic substances. 4,5,[9][10][11] The reversible transition of a WO 3 film between colorless and blue results from the formation of M x WO 3 (M = H, Li, Na; x = 0-1) during reduction. On the other hand, Ni(OH) 2 thin film is also known to exhibit the electrochromic behavior between colorless and brown, where formation of NiOOH from Ni(OH) 2 and its reduction via proton and electron transfer (Ni(OH) 2 § NiOOH + H + + e ¹ ) have been proposed from cyclic voltammetry and infrared absorption spectroscopy.…”

Nanocarbon–{[Na10(PrW10O36)]2·130H2O} composite to detect toxic food coloring dyes at nanolevel

“…The ability of Kiggen-type heteropolyanions to form complex with lanthanide and actinide heteroatoms is, therefore, of particular relevance (Craciun and David 2001). More recently, the lanthenopolyoxometalates (Ln-POMs) have received current interest due to their special spectroscopic and magnetic properties, as well as their potential use as luminescent probes and magnetic resonance imaging agent (Yamase 1998;Xu et al 2002;Yamase et al 2006;Clemente-Juan et al 1999).…”

Gas-Phase Fragmentation Pathways of Mixed Addenda Keggin Anions: PMo12-nWnO403– (n = 0–12)

“…Sodium phosphomolybdate hydrate (Na 3 Stock solutions of mixed addenda POMs were prepared by a one-pot synthesis adapted from Altenau et al [33], where specific molar ratios of Mo 12 -POM:W 12 -POM (3:9, 6:6, 9:3) were added to warm (~60-70°C) deionized water and stirred for 30 min. The final mixed addenda POM stock solutions had a concentration of approximately 0.1 M and a pH of 1.…”

“…Introduction P olyoxometalates (POMs) are a class of inorganic materials that are of interest for a variety of applications because of their remarkable redox, photochemical, and magnetic properties [1][2][3][4][5][6][7][8][9]. The Keggin POM [10], a class of stable, redox-active, triply-charged anions comprised of a metal-oxide cage structure (M 12 O 36 ; M = early transition metal) with an internal XO 4 n-group (typically X = Si, P; n = 4, 3, respectively), is one of the most widely studied POM systems.…”