The coordinatively unsaturated sites (CUS) are vital in metal-centered catalysis. Metal–organic frameworks (MOFs) provide a unique opportunity to generate and stabilize CUS due to their robust structure. Generally, the generation of CUS in MOFs needs prior activation under heat and high vacuum to remove labile molecules occupying the catalytic sites. Herein, we report a solvothermal synthesis of a ready-to-use copper MOF containing accessible pre-existing CUS that does not need activation. The single crystal X-ray diffraction structure reveals a square planar Cu­(II) center with two N-methylimidazoles (Mim) and one benzenedicarboxylic acid (BDC) with the formula unit [CuII(BDC)­(Mim)2] n (Cu-1D) forming an infinite one-dimensional (1D) chain along the c axis. The 1D chains are stabilized by noncovalent π–π, CH···π, and H-bonding interaction to give 2D (sheet-like) and 3D networks in the solid state. The quantification of non-covalent interaction is studied by Hirshfeld surface analysis, and the formation of a higher architecture in the solid state is confirmed by SEM analysis. The reported Cu-1D MOF acts as a solid heterogeneous catalyst and exhibits efficient catalytic activity in intermolecular and intramolecular cross-coupling reactions. Intermolecular C-heteroatom cross-coupling of a variety of N-heterocycles, aliphatic, aromatic, alicyclic amines and amides (C–N), phenols (C–O), and thiols (C–S) with aryl halides (halide = I, Br) was achieved with 70 to 95% yield, better than the state-of-the-art Cu-based homogenous system. The C–N coupling catalytic cycle is initiated by the in situ reduction of Cu­(II) by KOH/DMSO to Cu­(I) species. Subsequently, Cu­(I) undergoes oxidative addition followed by reductive elimination to form a cross-coupled product. High stereoselectivity was found for the intramolecular C–N coupling reaction to give tetrahydroquinoxalines with an enantiomeric excess (ee) of more than 99%. For a broader application, Cu-1D was applied as the catalyst for the synthesis of a library of aziridines that gives yields of up to 99% with more than 93% recyclability for each cycle.

We report synthesis of highly stable CsPbBr3 QDs based photocatalysts using dibromoisocyanuric acid (DBI) as benign non-toxic bromide precursor. The QDs were applied as visible light photocatalyst for intramolecular cyclisation...

The role of coordinatively unsaturated sites (CUS) in metal−organic framework (MOF)-catalyzed organic transformation is vital; however, the design and generation of such sites are challenging. We, therefore, report the synthesis of a novel two-dimensional (2D) MOF, [Cu(BTC)(Mim)] n (Cu-SKU-3), with pre-existing unsaturated Lewis acid sites. The presence of these active CUS facilitates a ready-to-use attribute in Cu-SKU-3, thereby subsiding the lengthy activation processes associated with MOF-based catalysis. The material has been completely characterized using single crystal X-ray diffraction (SCXRD), powder XRD (PXRD), thermogravimetric analysis (TGA), carbon, hydrogen, and nitrogen (CHN), Fourier-transform infrared (FTIR), and Brunauer−Emmett−Teller (BET) surface area analyses. We directly utilize Cu-SKU-3 for the synthesis of biologically valued chiral imidazolidine motifs in a one-pot fashion starting from aziridines. The chiral imidazolidines are synthesized in good yield (up to 89%) and with high optical purity (ee > 98−99%). Mechanistically, the transformation proceeds in a tandem fashion through stereospecific ring-opening of aziridines followed by the intramolecular cyclization (via sp 3 C−H functionalization) reaction forming chiral imidazolidines. The material has an excellent heterogeneous attribute and can be reused several times for one-pot catalytic cycles.