Tethering of Cu(II) Schiff base metal complex on mesoporous material MCM-41: catalyst for Ullmann-type coupling reactions Malathy Moorthy 1 • Brundha Kannan 1 • Bharathi Madheswaran 1 • Rajavel Rangappan 1 Ó Springer Science+Business Media New York 2016 Abstract The siloxane-functioned Cu(II) complex derived from 3-aminopropyltrimethoxysilane, tereph- thaldehyde and 2-aminophenol was anchored on hexagonal mesoporous silica MCM-41. The MCM-41 and its Schiff base MCM-41 complex was characterized by FTIR, small- angle X-ray diffraction, SEM-EDX, N 2 adsorption and desorption analysis and TGA. The synthesized Cu-Schiff base MCM-41 catalyst has been successfully applied as a catalyst for Ullmann-type coupling reaction of the aryl halides with aryl halides, phenols, amines and N-hetero- cyclic amines. In the coupling reaction the yields of the products were good and the catalyst was recovered by simple filtration method and can be reused. Keywords 3-Aminopropyltrimethoxysilane Á MCM-41 Á Small-angle X-ray diffraction Á Cu-Schiff base MCM-41 complex Á Aryl halides 1 Introduction Catalytic reactions carried out in the presence of metal complexes as a homogeneous catalyst have disadvantages of difficult product separation from reaction mixture, recovery of catalyst and problems associated with the recycling of the catalyst. One of the simplest approaches is to immobilize the homogeneous catalyst at the surface of an insoluble high surface area solid support [1]. Ordered mesoporous silicas are considered as excellent catalyst supports, due to their high surface area, large pore volumes and well ordered arrangement of pores. Immobi- lization of metallic cations and metallic complexes which have catalytic activities in homogeneous systems onto high surface area materials like ordered mesoporous silica has been widely applied as catalysts. Two of the most well known ordered mesoporous silicas are MCM-41 and SBA- 15 [2, 3]. The structure of the mesoporous molecular sieve, MCM-41, comprises a uniform extended hexagonal pore arrangement. The extremely high surface area and well defined pore structure make MCM-41 as potentially effective host material for a variety of dispersed or sup- ported catalysts. Many Pd based catalytic systems have been developed, which are based on bidentate phosphines or diverse organophosphate derivatives. But these systems have lim- itations since they require the preparation and use of PR3 ligands which are not eco-friendly. Catalytic systems based on other transition metals such as nickel, cobalt and iron have also been studied. These catalytic systems also suffer from certain disadvantages like metal toxicity, low turn- over numbers etc. But there is much interest in the devel- opment of copper based catalytic systems because of the low cost of Cu and use of readily accessible and stable li- gands. Many attractive Cu-catalyzed coupling processes have been reported by various research groups [4]. Tran- sition-metal catalyzed cross-coupling reaction is an effi- cient and versatile tool in organic synthesis for the connection of two fragments through C–C or C–N forma- tion [5, 6]. Among them, Ullmann-type coupling reactions are particularly attractive because they often allow the usage of low-cost starting materials and readily available copper complexes [7]. Ullmann-type coupling reactions between aryl halides and N-containing reactants, phenols & Rajavel Rangappan drrajavel@periyaruniversity.ac.in 1 Department of Chemistry, Periyar University, Periyar Palkalai Nagar, Salem, Tamilnadu 636011, India 123 J Porous Mater DOI 10.1007/s10934-016-0155-6