5-(4-pyridyl) phenyl substituted functionalized nitronyl nitroxide biradical ligand holds Mn^II ions and Tb^III/Ho^III ions together to yield 3d-4f-biradical heterospin clusters, namely, [Ln₂Mn₂(hfac)₁₀(NITPhPybis)₂] [Ln=Tb 1, Ho 2], wherein, two NITPhPybis radicals ligate two Mn^II ions via two NO groups and two nitrogen-atoms from pyridine rings. At the same time, each NITPhPybis encapsulates one Ln^III ion through chelating mode with adjacent NO groups, generating an annular centrosymmetric heterometallic tetranuclear system. In addition, the direct current and alternating current magnetic properties and luminescent behavior were systematically studied. Magnetodynamic studies uncover that the cluster 1-TbMn exhibits slow magnetic relaxation. The fluorescence of two polynuclear clusters show the characteristic fluorescence of Tb^III or Ho^III ions.