In this paper two conjugated polymers containing polyfluorene chain with pendant carboxyl group (P1 and P2) are synthesized via Suzuki reaction, and then two corresponding polymers containing the pendant Mn-12 cluster core (Mn-12-P1 and Mn-12-P2) are obtained through exchange of the pendant carboxyl group in the polymers with acetate ligand of Mn-12-Ac. All the polymers show similar UV-vis absorption spectra with maximum peak at 388 nm and fluorescence emission spectra with maximum peak at 419 nm and a shoulder at 443 nm that can be attributed to the polyfluorene chain. The cyclic voltammetry measurement indicates that Mn-12-P1 or Mn-12-P2 exhibit similar electrochemical behavior to that of the corresponding P1 or P2. These indicate that the introduction of Mn-12 cluster at the side-chain of the conjugated polymers has little influence on the photophysical and electrochemical properties of the conjugated main-chain. However, compared with pristine Mn-12-Ac the magnetic properties of the modified Mn-12 cluster has been changed after substitution of acetate group by the pendant carboxyl group of the polymer. Both of the Mn-12 clusters modified by the conjugated polymer (Mn-12-P1 and Mn-12-P2) show paramagnetism in the range of 2-300K, and no SMM magnetic behavior is observed at low temperature. (C) 2011 Elsevier Ltd. All rights reserved.