Effect of nature of addends and ionic dopant on magnetic properties of multifunctional star-like hemi-ortho ester derivatives of fullerenol

Effect of alkyl/aryl substitution at carbonyl carbon and doping effect of tetra butyl ammonium hydroxide (TBAH used as phase transfer catalyst during two phase synthesis) on magnetic properties of multiple double bonds terminated acyclic hemi-ortho esters derivatives of fullerenol is reported. Strong π–π interactions between vinylic double bonds and fullerene core induce higher g-value (2.002–2.58), larger peak width (ΔHPP = 1375–9) and fast spin–spin relaxation (T2) compared to pristine fullerenol at room temperature. Steric hindrance owing to bulky alkyl/aromatic groups at carbonyl carbon substantially affects the g-value and ultimately the magnetic properties. Iso-propylene unit in vinyl ester produces interesting diamagnetic character at low temperature (25–300 K) and paramagnetic behavior at room (300 K) as well as at very low temperature (10–25 K). Low temperature paramagnetic behavior (45–300 K) and anti-ferromagnetic character below Curie temperature (Tc at 45 K) in vinyl acetate hemi-ortho ester is substantiated through SQUID measurement. Partial quenching of paramagnetism lowers the experimental spin-only magnetic moment value (μB = 4.47 B.M.) compared to theoretical μB-value (4.89 B.M.) for S = 2 spin system (four unpaired electron) at 300 K for hemi-ortho ester in the solid state.