The surface of the mesoporous silica SBA-15 (SBA) was modified by a tetra-urea (TU) ligand (SBA@TU), and the palladium ions were anchored within the multidentate pore channels (SBA@TU@Pd(II)) and reduced by NaBH4 (SBA@TU@Pd(0)). Then, the nano-structure reduced catalyst was characterized by FT-IR, EDX, elemental mapping analysis, XRD, SEM, TEM, TGA/DTA/DCS, and BET analysis. After that, the catalytic activity of the SBA@TU @Pd(0) catalyst was successfully studied in the Mizoroki-Heck and Suzuki-Miyaura cross-coupling reactions under mild reaction conditions for preparation of 1(a-l) and 2(a-i), respectively in short reaction times and high yields. Also, the Mizoroki-Heck and Suzuki-Miyaura cross-coupling reactions were performed by the non-reduced nano-catalyst (SBA@TU@Pd(II)) under similar reaction conditions. The reaction yields were the same for both catalysts, but the reaction time was different which was shorter (30 min) for SBA@TU@Pd(0), while for SBA@TU@Pd(II) the reaction times were increased to about 80 and 70 min, respectively. © 2022 Elsevier B.V. All rights reserved. 1. Introduction Urea and its derivatives have found numerous applications in organic, analytical, and medicinal chemistry, polymer sciences, agriculture, and industry [1,2]. During the last years, the use of urea derivatives as catalysts, useful reagents, and structural features in organic chemistry has drastically increased. They have been applied as hydrogen-bonding organo-catalysts [3–5], as lithiation directors [6–8], as amination substrates [9,10], and as a scaffold in supramolecular chemistry [11–16]. In addition, biological urea-based catalysts were used as efficient basic catalysts, coupling with metals as the catalyst, chiral acid catalysts, urea anions catalysts, coupling with ionic liquids, urea polymer catalysts, and nonmagnetic nano-supported catalysts [17]. Nowadays, the heterogenization of metal complexes with catalytic activity within inorganic matrixes (such as SiO2, MCM- 41
