**1. Introduction**

The amide bonds existing in a large number of structures and forming the backbone of the biologically essential proteins are the most basic building blocks of chemistry in nature [1]. The amide is also essential due to its role in the peptide bonds in pharmaceuticals, proteins, and natural products [1]. Amide bonds are characteristically synthesized by combining carboxylic acids and amines; however, the association of these two functional groups does not occur at room temperature [2]. Over the past decades, many researchers have proposed alternative synthesis methods, such as the Staudinger

reaction [3], direct amidation of aldehydes [4], transition-metal-catalyzed aminocarbonylation [5], and hydrating coupling of alkynes with azides [6], esters [7], alcohols [8], and alkynes with amines [9]. Pyridyl benzamides are one of the most critical types of N-heterocyclic amides and play an essential role in the composition of many important medicines (e.g., antiulcer agents, kinetoplastid inhibitors, antifungal agents, and luciferase inhibitors) [10]. Lately, the number of methods for the synthesis of pyridyl benzamides has been rising significantly. Typical examples include the Cu-catalyzed oxidation of methyl ketones [11], Cu-catalyzed oxidative coupling of 2-aminopyridines and terminal alkynes with visible light mediation [12], and the direct oxidative amidation reaction of aldehydes with amines [13]. Since N-heterocyclic amides are increasingly being used in medicine, the discovery of a more effective approach to synthesize pyridyl benzamides is of great importance in the medical industry and has thus been attempted via numerous routes. Xiao-Lan Xu et al. synthesized N-pyridinyl benzamide from benzoylformic acid and aniline using a transition metal catalyst, AgOTf [14]. Additionally, Leiling Deng et al. also created N-pyridinyl benzamide from 2-aminopyridine and phenylacetic acid in the presence of a Cu salt catalyst [15]. Very recently, Zhengwang Chen et al. performed a reaction to synthesize N-pyridinyl benzamide from 2-aminopyridine and *trans*-β-nitrostyrene by utilizing Ce(NO3)3·6H2O catalyst in the absence of any oxidant or additive [16].

Metal–organic frameworks (MOFs), a class of porous materials with excellent potential, have been increasingly used in gas storage and separation because of their high capacity and selectivity properties [17]. MOF crystals are built through the formation of secondary building units (SBUs) consisting of organic linkers and metal ions/clusters. Numerous MOF structures have been designed to obtain different features such as enlarged surface areas [18], enhanced catalytic activity and electrical conductivity [19], better interaction at the open metal sites [20], and improved adsorption [21]. Notably, the application of MOFs as effective catalysts for organic reactions has received much attention [22]. MOFs with metal nodes (metal ions/clusters) can act as the active catalytic sites for many organic reactions such as oxidation reactions, C–C coupling reactions, and hydrogenation reactions. However, the fabrication of a MOF structure with high activity and selectivity still requires further investigation.

Recently, a new bimetallic metal–organic framework (BMOF) with a synergistic effect between different metal ions was developed. Different from the synthesis of MOFs where only one metal ion is combined with organic ligands, the synthesis process of a BMOF produces the pure phase of the BMOF by combining two different metal ions with organic ligands [23]. The BMOFs are expected to have improved stability, activity, and surface area and could be applicable in catalysis. For example, an Fe/Co mixed Hofmann MOF with coupling effects between Co2<sup>+</sup> and Fe2<sup>+</sup> ions was found to exhibit enhanced catalytic activity for an oxygen evolution reaction compared to that exhibited by the original single-metal MOFs [24]. Despite this, the catalysis applications of BMOFs have not been investigated so far.

The main aim of this study was to appraise the effect of a new BMOF (Fe2Ni-1,4-Benzenedicarboxylic, Fe2Ni-BDC) as a heterogenous catalyst for organic synthesis reactions. Fe2Ni-BDC was generated by bridging iron (III) cations and nickel (II) cations with 1,4-Benzenedicarboxylic anions (BDC−) to create a porous three-dimensional structure [25,26]. We also investigated the synthesis of N-pyridinyl benzamide via the amidation process of *trans*-β-nitrostyrene and 2-aminopyridine using Fe2Ni-BDC as an effective heterogeneous catalyst, without using added reducing agents or oxidizing agents. This catalyst might be reused for the creation of N-pyridinyl benzamide by the amidation reaction without significant depreciation in its efficiency. Fe2Ni-BDC is also satisfactory from the view of green chemistry, as the solid catalyst used for the reaction can be easily recovered and reused. To the best of our knowledge, C=C double bond cleavage has not previously been performed using heterogeneous catalysis.
