Polyoxometalate (POM)-based, multi-functional, inorganic–organic, hybrid compounds: syntheses and molecular structures of silanol- and/or siloxane bond-containing species grafted on mono- and tri-lacunary Keggin POMs

Abstract

Using 3-mercaptopropyltrimethoxysilane (HS(CH₂)₃Si(OMe)₃) as a silane-coupling agent (SCA), mono- and tri-lacunary Keggin polyoxometalate (POM)-based, multi-functional, inorganic-organic, hybrid compounds, (Et₄N)₃[α-PW₁₁O₃₉{(HS(CH₂)₃Si)₂O}] EtN-1 (the 1 : 2 complex of a POM unit and organosilyl groups), (Bu₄N)₃[A-PW₉O₃₄(HS(CH₂)₃SiOH)₃] BuN-2 (the 1 : 3 complex) and (Bu₄N)₃[A-α-PW₉O₃₄(HS(CH₂)₃SiO)₃(Si(CH₂)₃SH)] BuN-3 (the 1 : 4 complex) were synthesized and unequivocally characterized by elemental analysis, thermogravimetric and differential thermal analyses (TG/DTA), FTIR, solid-state (²⁹Si and ³¹P) CPMAS NMR, solution (²⁹Si, ³¹P, ¹H and ¹³C) NMR, and X-ray crystallography. [Note: The moieties of their polyoxoanions are abbreviated simply as 1-3, respectively.] The X-ray molecular structures of EtN-1 and BuN-3 were determined. In EtN-1, two organic groups connected through a siloxane bond (-Si-O-Si- bond) were grafted on a mono-lacunary site of a Keggin POM, whereas in BuN-3 four organic groups connected through siloxane bonds were grafted on a tri-lacunary site of a Keggin POM. In BuN-2, three organic groups were grafted in the form of silanol (-SiOH) on a tri-lacunary site, i.e., in BuN-2 there was no siloxane bond. BuN-3 was synthesized as BuN-3a and BuN-3b by two methods, respectively; (1) BuN-3a was obtained by a 1 : 1 molar-ratio reaction of BuN-2 and an SCA in CH₃CN, and (2) BuN-3b was prepared by a direct 1 : 4 molar-ratio reaction of a tri-lacunary Keggin POM and SCA in water-CH₃CN. X-Ray crystallography revealed that BuN-3a is the same as BuN-3b. It is probable that BuN-2 is an intermediate in the formation of BuN-3. Terminal -SH groups in 1-3, as well as -OH groups in 2, can be utilized for immobilization of POMs and, also, as building blocks for the formation of novel hybrid compounds.

Manipulation of Self-Assembled Nanostructure Dimensions in Molecular Janus Particles

“…organogermyl63 and organosilyl groups64 ) to introduce reactive groups (e.g., carboxylic acid groups or thiol groups) onto the Keggin POM clusters.Scheme 1. Synthetic routes and chemical structures of KPOM-BPOSS, KPOM-CPOSS and KPOM-2BPOSS a a Reagents and conditions: (i) EEDQ, acetonitrile/THF (v/v = 1/1), 80 °C, 91%; (ii) EEDQ, acetonitrile/THF (v/v = 1/1), 80 °C, 89%; (iii) catalytic amount of triethylamine, acetonitrile/THF (v/v = 1/1), 80 °C, 85%.…”

The Co‐Assembly of Polyoxometalates and Quantum Dots for Hybrid Core‐Shell Nanoparticles

“…Synthesis of {PW 9 }: (Bu 4 N) 3 [PW 9 O 34 {HS(CH 2 ) 3 SiO} 3 {Si(CH 2 ) 3 SH}] ({PW 9 }) was synthesized according to previous literature . In brief, 745 µL (4 mmol) HS(CH 2 ) 3 Si(OMe) 3 was dissolved in 200 mL of CH 3 CN/H 2 O (150 mL/50 mL) mixture solvent.…”

Various Oxygen-Centered Phosphanegold(I) Cluster Cations Formed by Polyoxometalate (POM)-Mediated Clusterization: Effects of POMs and Phosphanes

“…The following reactants were used as received: EtOH, CH2Cl2, Et2O (all from Wako, Osaka, Japan), and DMSO-d6 (Isotec, Miamisburg, OH, USA [25] and the literatures [26,27], and identified by FT-IR, TG/DTA and solution ( 29 Si, 31 P, 183 W) NMR spectroscopy. The [Au(RS-pyrrld){P(m-XPh)3}] (X = F, Me) and [Au(RS-pyrrld){P(p-MePh)3}] precursor complexes were synthesized according to the reported methods using P(m-XPh)3 (X = F, Me) or P(p-MePh)3 [9,12], and characterized by CHN elemental analysis, FT-IR, TG/DTA and solution ( 1 H, 13 C{ 1 H}, 31 P{ 1 H}) NMR spectroscopy.…”