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Numerous metalla‐supramolecular architectures have been designed using coordination‐driven self‐assembly, while the number of analogous organic architectures is still very limited. In this regard, mainly di‐, tri‐ and a few tetra‐aldehydes have been exploited as precursors in combination with appropriate di‐/tri‐amines to obtain the desired structures with limited complexities. We report here facile synthesis of two face‐directed tetrahedral organic cages (TC‐R and TC‐S) that were formed by [4+12] imine condensation of a new hexa‐aldehyde precursor with two enantiomers of 1,2‐diaminocyclohexane separately (CA‐R and CA‐S). The covalent imine cages are very large with an intrinsic porous cavity of ∼1250 Å3 and the faces of the cages consist of aromatic aldehyde units whereas each corner is occupied by three semi‐flexible diamine moieties. Palladium (PdNPs) nanoparticles (3.5±0.3 nm) were synthesized employing the cage TC‐R as a solid support via double‐solvent approach. Furthermore, the cage hosted PdNPs [Pd(0)@TC‐R‐A] exhibited efficient catalytic activity for selective homocoupling of aryl‐ and hetero‐aryl halides with high thermal stability and reusability. [ABSTRACT FROM AUTHOR]

Coordination‐driven self‐assembly of discrete molecular architectures of diverse shapes and sizes has been well studied in the last three decades. Use of dynamic imine bonds for designing analogous metal‐free architectures has become a growing challenge recently. This article reports an organic molecular barrel (OB4R) as a potential template for nucleation and stabilization of very tiny (<1.5 nm) Ag nanoparticles (AgNPs). Imine bond condensation of a rigid tetra‐aldehyde with a flexible diamine followed by imine‐bond reduction yielded the discrete tetragonal organic barrel (OB4R). The presence of a molecular pocket ornamented with eight diamine moieties gives the potential for encapsulation of silver(I). The organic barrel was finally used as a molecular vessel for the controlled nucleation of silver nanoparticles (AgNPs) with fine size tuning through binding of AgI ions in the confined space of the barrel followed by reduction. Transmission electron microscopy (TEM) analysis of the Ag0@OB4R composite revealed that the mean particle size is 1.44±0.16 nm. The composite material has approximately 52 wt % silver loading. The barrel‐supported ultrafine AgNPs [Ag0@OB4R] are found to be an efficient photocatalyst for facile Ullmann‐type aryl‐amination coupling of haloarenes at ambient temperature without using any additives. The catalyst was stable for several cycles of reuse without any agglomeration. The new composite Ag0@OB4R represents the first example of discrete organic barrel‐supported AgNPs employed as a photocatalyst in Ullmann‐type coupling reactions at room temperature. [ABSTRACT FROM AUTHOR]

Two shape-persistent covalent cages (CC1r and CC2r) have been devised from triphenyl amine-based trialdehydes and cyclohexane diamine building blocks utilizing the dynamic imine chemistry followed by imine bond reduction. The cage compounds have been characterized by several spectroscopic techniques which suggest that CC1r and CC2r are [2+3] and [8+12] self-assembled architectures, respectively. These state-of-the-art molecules have a porous interior and stable aromatic backbone with multiple palladium binding sites to engineer the controlled synthesis and stabilization of ultrafine palladium nanoparticles (PdNPs). As-synthesized cage-embedded PdNPs have been characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), and powder X-ray diffraction (PXRD). Inductively coupled plasma optical emission spectrometry reveals that Pd@CC1r and Pd@CC2r have 40 and 25 wt% palladium loading, respectively. On the basis of TEM analysis, it has been estimated that as small as ~1.8 nm PdNPs could be stabilized inside the CC1r, while larger CC2r could stabilize ~3.7 nm NPs. In contrast, reduction of palladium salts in the absence of the cages form structure less agglomerates. The well-dispersed cage-embedded NPs exhibit efficient catalytic performance in the cyanation of aryl halides under heterogeneous, additive-free condition. Moreover, these materials have excellent stability and recyclability without any agglomeration of PdNPs after several cycles. [ABSTRACT FROM AUTHOR]

Cage compounds, Enantiomeric cages, Heterogeneous catalysis, Palladium, Self-assembly Keywords: Cage compounds; Enantiomeric cages; Heterogeneous catalysis; Palladium; Self-assembly EN Cage compounds Enantiomeric cages Heterogeneous catalysis Palladium Self-assembly 1 1 1 03/11/22 20220309 NES 220309 B The Cover Feature b shows the formation of two face-directed truncated tetrahedral enantiopure organic cages by employing dynamic imine condensation reactions of a hexa-aldehyde precursor with I trans i -oriented enantiopure diamines separately. Cover Feature: Face-Directed Tetrahedral Organic Cage Anchored Palladium Nanoparticles for Selective Homocoupling Reactions (Eur. J. Inorg. [Extracted from the article]