Search

Metalladiazamacrocycles, coordination driven potential supramolecular host systems, can be obtained via cyclic linkages of the metal ions and the bridging ligands, N-acylsalicylhydrazides. The nuclearity and the shape of the metallamacrocycles could be modulated by controlling the steric interactions caused by N-acyl tails of the ligands. The macrocycles could be utilized for recognition of small organic guest molecules using their hydrophobicity/hydrophilicity, the size and shape/symmetry of the cavities. In addition, these macrocycles can be used as the supramolecular building blocks for the construction of systematically tuned metal-organic frameworks since these clusters have several replaceable solvent sites which could serve as connecting nodes for the formaton of network structures. [ABSTRACT FROM AUTHOR]

Hexanuclear, octanuclear, and decanuclear manganese metalladiazamacrocycles have been prepared by reacting a series of pentadentate ligands, N-acylsalicylhydrazides (N-(3-methylbutanoyl)salicylhydrazide (H33-mbshz), N-(phenylacetyl)salicylhydrazide (H3pashz), N-(3,3-dimethylbutanoyl)salicylhydrazide (H33-dmbshz), N-(2-methylpropanoyl)salicylhydrazide (H32-mpshz), N-((R,S)-2-methylbutanoyl)salicylhydrazide (H3RS-2-mbshz), N-((S)-2-methylbutanoyl)salicylhydrazide (H3S-2-mbshz), and N-(2,2-dimethylpropanoyl)salicylhydrazide (H32-dmpshz)), with manganese(II) acetate tetrahydrate. The self-assembled, supramolecular complexes assume a nearly planar cyclic structure with an -(Mn-N-N)n backbone and measure ∼2.1, ∼2.3, and ∼2.6 nm in outer diameters for n = 6, 8, and 10, respectively. The chiralities of the manganese centers on the metalladiazamacrocycle occur in alternating ⋯ΛΔΛΔ⋯ configurations. While β-branched N-acylsalicylhydrazides (H33-mbshz, H3pashz, H33-dmbshz) with a sterically flexible Cα methylene group yield 18-membered hexanuclear manganese metalladiazamacrocycles of S6 point group symmetry, α-branched N-acylsalicylhydrazides lead to 24-membered octanuclear manganese metalladiazamacrocycles or 30-membered decanuclear manganese metalladiazamacrocycles depending on the size of the N-acyl substituents. The α-branched H32-mpshz ligand with the sterically least demanding isopropyl tail at the N-acyl position yields a 24-membered octanuclear manganese metalladiazamacrocycle of S8 point group symmetry, but other α-branched N-acylsalicylhydrazides such as H3RS-2-mbshz, H3S-2-mbshz, and H32-dmpshz lead to 30-membered decanuclear manganese metalladiazamacrocycles of S10 point group symmetry. The magnetic properties of the metalladiazamacrocycles are characterized by a weak antiferromagnetic exchange interaction, with Jeff = -8.5 to -3.8 K between the Mn3+ ion spins with S = 2 in the cyclic system. [ABSTRACT FROM AUTHOR]

A Pd 2 L 4 type supramolecular coordination driven self assembly was constructed using a dipodal pyridyl terminal ligand L [ L = N 2 , N 6 -dimethyl- N 2 , N 6 -bis((pyridin-4-yl)methyl)naphthalene-2,6-dicarboxamide] and palladium nitrate. The self-assembly was fully characterized by 1D and 2D NMR, ESI-MS, IR, TGA, HR-TEM and elemental analysis. The geometry optimization was performed using the Hartree–Fock method. The assembly acts as an efficient, reusable, heterogeneous catalyst for Buchwald–Hartwig amination reaction in toluene under phosphine free condition and aerobic medium. [ABSTRACT FROM AUTHOR]

An abstract of the study "A Coordination Driven Supramolecular Pd2L4 Self-Assembly as Heterogeneous Catalyst for Buchwald-Hartwig Amination Reaction" by S. Pradhan and colleagues is presented.