Covalent Grafting of Eosin Y to the Giant Keplerate {Mo132} through an Organosilicon Linker in Homogeneous Regime

The template effect of giant polyoxometalates (POM) shows promising results towards the supramolecular design hybrid materials suitable for photocatalytic reactions. Here, we demonstrate a novel synthetic approach covalently grafting xanthene dye eosin Y (EY) to nanoscale Keplerate POM {Mo132} via an organosilicon linker (3-aminopropyltrimethoxysilane, APTMS) in homogeneous regime. Using phase transfer agent, tetrabutylammonium bromide, solubilize modified with six {Si(CH2)3NH2} groups, {Mo132}@Si6, series organic solvents—acetonitrile, acetone, tetrahydrofuran, and dichloromethane—to perform post-functionalization by using NHS-ester EY. Both IR Raman spectroscopy affirm preservation POM’s structure showcase amide bond formation between EY obtained conjugate {Mo132}@Si6@EY@TBA. Grafting’s success is observed through significant downfield shifting EY’s aromatic protons’ signals on 1H NMR spectrum as compared spectra EY-NHS. current enables us exercise precise control stoichiometry POM-dye conjugates—1:1 POM-EY system—as confirmed elemental analysis. Comprehensive photophysical analysis {Mo132}@Si6@EY@TBA means UV-Vis steady-state time-resolved fluorescence measurements points existing strong interaction molecular orbitals {Mo132}, leading photoinduced electron transfer, partial quenching, elongation excited state’s lifetime. These findings that APTMS tandem can be readily applied routine procedure various dyes or other molecules bearing carboxylic group their surface variety aprotic solvents.