Herein, it was aimed to synthesize three organic-inorganic hybrids (DILPOM-1/2/3), developed from assembly of -SO3H functionalized dicationic imidazolium ionic-liquid having variable methylene connecting spacers with inorganic 12-molybdophosphoric acid. DILPOM-1/2/3 are 2-methyl-1-(3-(2-methyl-3-sulfo-1H-imidazol-3-ium-1-yl)propyl)-3-sulfo-1H-imidazol-3-ium phosphomolybdate, 2-methyl-1-(4-(2-methyl-3-sulfo-1H-imidazol-3-ium-1-yl)butyl)-3-sulfo-1H-imidazol-3-ium phosphomolybdate, 2-methyl-1-(12-(2-methyl-3-sulfo-1H-imidazol-3-ium-1-yl)dodecyl)-3-sulfo-1H-imidazol-3-ium phosphomolybdate respectively. Incorporation of various lengths of the connecting spacers make their thermal stability window wider as verified from thermogravimetric analysis and thus can be used as efficient catalysts in high temperature reactions. Extent of hydrogen bond interactions within the -SO3H group and the PMo12O403- anion strategically controls the acidic sites. And together with the methylene linkages provide heterogeneous nature to the hybrids making them easily recyclable and thermally stable acid catalyst. The one with longest methylene connecting spacer (n=12), was found to be more efficient as acid catalyst than the shorter ones towards solvent-free Michael-Like addition of indole with chalcones obtained via Claisen-Schmidt condensation.

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