DBU-functionalized MCM-41-coated nanosized hematite (DBU-F-MCM-41-CNSH) was successfully prepared as a new magnetically separable and reusable mesoporous basic nanocatalyst and characterized by various techniques such as FT-IR, XRD, HR-TEM, FESEM, BET, VSM and elemental analyses (CHN and ICP-OES). The prepared nanocatalyst was then successfully applied for the synthesis of some nucleoside-containing pyrido[2,3-d]pyrimidines, [2,3-d:6,5-d']dipyrimidine and pyrimido[4,5-b]quinolines via one-pot multicomponent reactions under solvent-free conditions. In all cases, applied catalyst was recovered and reused several times without any changes in chemical and physical structures as well as the catalytic activity. The biggest achievement of this research is the conversion of DBU as a widely used catalyst in organic synthesis from a toxic, not-recyclable and funky liquid to a recoverable and reusable solid material with the same catalytic characters. (C) 2019 Elsevier Inc. All rights reserved.