Coordination of Pt(IV) by {P₈W₄₈} Macrocyclic Inorganic Cavitand: Structural, Solution, and Electrochemical Studies

Abstract

Hydrothermal reaction of a macrocyclic inorganic POM cavitand Li17(NH4)21H2[P8W48O184] with [Pt­(H2O)2(OH)4] results in coordination of up to six {Pt­(H2O) x (OH)4–x } fragments to the internal surface of the polyoxoanion. The product was isolated as K22(NH4)9H3[{Pt­(OH)3(H2O)}6P8W48O184]·79H2O (1) and characterized by multiple techniques in the solid state (SCXRD, XRPD, XPS, FTIR, and TGA) and in solution (NMR, ESI-MS, and HPLC-ICP-AES). Electrochemical properties were studied both in solution and as components of the paste electrode. The complex shows electrocatalytic activity in water oxidation.

Proton Affinity in the Chemistry of Beta-Octamolybdate: HPLC-ICP-AES, NMR and Structural Studies

“…In this research, we focused on the behavior of the [β-Mo 8 O 26 ] 4− anion toward protonation to answer this question. Some years ago, we suggested a straightforward hyphenated HPCL-ICP-AES technique [ 54 ] as an efficient tool to study the reaction products in different polyoxometalate systems [ 55 , 56 , 57 ]. In the present research, this technique helps us to have control over products’ formation in different conditions.…”

Space-Confined Nucleation of Semimetal-Oxo Clusters within a [H7P8W48O184]33– Macrocycle: Synthesis, Structure, and Enhanced Proton Conductivity

“…It is presumed that due to a larger ionic radius of the Sb III ion (Sb III = 76 pm > As III = 58 pm), more central space needs to be freed up for satisfying the growth of Sb III -oxo clusters, which is not achievable due to the confined area defined by the rigid P 8 W 48 . Therefore, the SbO 3 3– groups choose to reside in the corners, and the resulting structural patterns in Sb 4 and Sb 8 are reminiscent of those discovered in [(Se IV O) 4 P 8 W 48 O 184 ] − and [(Sn II Cl) 8 P 8 W 48 O 184 ], − respectively.…”

“…Of prime interest, the self-condensation of arsenites in POMs has been seldom observed, where the number of As III centers is usually less than three. − In As 10 , the confined microenvironment offered by P 8 W 48 is kind of beneficial to the controlled hydrolysis–condensation reaction of AsO 3 3– , increasing the number of repeating units up to five. To the best of our knowledge, the polyanion of As 10 represents the first semimetal-oxo cluster-substituted P 8 W 48 , − and accommodates the largest As III -oxo cluster yet found in POMs. − …”

“…More importantly, the embedded anionic pocket enables guest capture. The size of the encapsulated components varies from one metal ion to polymetallic species. − In pioneering early experimental work, the confined chemical reactions based on P 8 W 48 led to the creation of a rich array of structures bearing a “cluster@cluster” archetype. − Typical examples include (i) [{Cu 20 X­(OH) 24 (H 2 O) 12 }­(P 8 W 48 O 184 )] 25– (Cu 20 @P 8 W 48 ; X = Cl, Br, and I), , [{Fe 16 (OH) 28 (H 2 O) 4 }­(P 8 W 48 O 184 )] 20– (Fe 16 @P 8 W 48 ), and [{(UO 2 ) 8 (O 2 ) 8 }­(P 8 W 48 O 184 )] 40– (U 8 @P 8 W 48 ) by Kortz et al; (ii) [{Ln 2 (H 2 O) 10 (H 4 W 4 O 12 ) 2 }­(P 8 W 48 O 184 )] 26– (Ln 2 W 8 @P 8 W 48 ; Ln = La, Ce, Pr, and Nd) by Pope et al; (iii) [{V V 8 V IV 4 O 24 (H 2 O) 4 }­(P 8 W 48 O 184 )] 32– (V 12 @P 8 W 48 ) and [{(Mo VI O 2 ) 4 Mo V 8 O 20 (H 2 O) 6 }­(P 8 W 48 O 184 )] 32– (Mo 12 @P 8 W 48 ) by Müller et al; (iv) [{Cu 20 (N 3 ) 6 (OH) 18 }­(P 8 W 48 O 184 )] 24– (Cu 20 -azido@P 8 W 48 ) by Mialane et al. ; (v) [{Mo 4 O 4 S 4 (H 2 O) 3 (OH) 2 } 2 (P 8 W 48 O 184 )] 36– (Mo 8 @P 8 W 48 ) by Cadot et al; (vi) [{Al 16 (OH) 24 (H 2 O) 8 }­(P 8 W 48 O 184 )] 16– (Al 16 @P 8 W 48 ) and [{Ga 16 (OH) 32 }­(P 8 W 48 O 184 )] 24– (Ga 16 @P 8 W 48 ) by Khashab et al; (vii) [{(W 4 O 16 )­K 10 NaLi 4 Mn 10 (H 2 O) 50 Cl 2 }­(P 8 W 48 O 184 )] 15– (W 4 Mn 6 @P 8 W 48 ) by Ibrahim et al; and (viii) [{Cu 16 (OH) 16 (H 2 O) 4 }­(P 8 W 48 O 184 )] 24– (Cu 16 @P 8 W 48 ) by Suzuki et al Apparently, all of the encapsulated guest clusters in P 8 W 48 are made up of metallic cations.…”

NMR-Relaxometric Investigation of Mn(II)-Doped Polyoxometalates in Aqueous Solutions

“…they have a charge transfer character (at 2.198 eV), a delocalization character (at 2.601 eV), and a local excitation character (at 3.625 eV). [34] is a powerful tool to study the reactivity/stability/evolution of different polyoxometalates in aqueous and organic solutions [35][36][37].…”