Influence of rhodamine B on interaction behaviour of lanthanide nitrates with 1st tier dendrimer in aqueous DMSO: A physicochemical, critical aggregation concentration and antioxidant activity study

Abstract

Density, viscosity, sound velocity, and molar conductivity for hexahydrate nitrates of gadolinium, samarium and neodymium from (0.0012–0.0072) mol∙kg−1 in (a) 40% (v/v) aq. DMSO (b) Trimesoyl 1,3,5-tridimethyl malonate (TTDMM) from (0.00010–0.00030) mol∙kg−1+40% (v/v) aq. DMSO (c) Rhodamine B (RB)+40% (v/v) aq. DMSO (d) RB+TTDMM from (0.00010–0.00030) mol∙kg−1+40% (v/v) aq. DMSO at 298.15K and atmospheric pressure are reported. By using these primary parameters; the apparent molar volume, limiting apparent molar volume, apparent molar isentropic compressibility, viscosity B-coefficient, and limiting molar conductivity have been calculated. The trends of these physicochemical parameters are discussed in terms of solute-solvent and solute-solute interactions. The trends inferred weaker solute-solvent interactions in presence of RB with TTDMM+aq. DMSO, causing structural changes. The aggregation tendency of TTDMM was studied using conductivity measurements, well supported by RB based UV–visible absorption spectroscopy through the L-form to Z-form shifting dynamics. To the best of our knowledge, this is the first attempt reporting the impact of trivalent lanthanide ions on the critical aggregation concentration of a 1st tier dendrimer (TTDMM) in aq. DMSO. This work is the first report, as far as we know, on the influence of Ln(NO3)3 towards the antioxidant activity of dendrimer, wherein the IC50 value of TTDMM was found in range with ascorbic acid. Our study with such significant outcomes may hold great promise for various biological applications.