A rare variety of self-assembled molecular triangle [Pd3(bpy)3(imidazolate)3](NO3)3, 1 is prepared by the combination of Pd(bpy)(NO3)2 with imidazole, at 1:1 ratio, in acetonitrile-water. Deprotonation of imidazole happened during the course of the complexation reaction where upon the metallomacrocycle is formed. The bowl-shaped trinuclear architecture of 1 is crafted with three peripheral bpy units capable of π-π stacking interactions. While the solution state structure of 1can be best described as a trinuclear complex, in the solid-state well-fashioned intermolecular π-π and CH- π interactions are observed. Thus, in the solid-state further self-assembly of already self-assembled molecular triangle is witnessed. The triangular panels are arranged in a linear manner utilizing intermolecular π-π interactions where upon two out of three bpy units of each molecule participated in the chain formation. © 2014 Indian Academy of Sciences.

Dillip Kumar Chand

Department Of Chemistry

Mili C. Naranthatta

Venkatachalam Ramkumar

Complexation

Palladium compounds

Bipyridyl

COMPLEXATION REACTION

imidazole

METALLOMACROCYCLES

MOLECULAR TRIANGLE

Pi interactions

Stacking interaction

Trinuclear complex

Self assembly

Fulltext

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Journal of Chemical Sciences

A series of binuclear palladium(II)-based self-assembled metallomacrocycles of Pd2L′2L2 type compositions were synthesized by complexation of an imidazole appended non-chelating bidentate ligand L with different cis-protected palladium(II) components (i.e. PdL′). The complexes [Pd2(en)2(L)2](NO3)4, 1, [Pd2(tmeda)2(L)2](NO3)4, 2, [Pd2(bpy)2(L)2](NO3)4, 3, and [Pd2(phen)2(L)2](NO3)4, 4 were characterized by NMR spectroscopy and their nuclearities were established with the help of ESI-MS. Solid state structures of the complexes 2, 3 and [Pd2(phen)2(L)2](OTf)4, 4′ were established by the single-crystal XRD technique. These metallomacrocycles could act as tectons for crystal engineering by using the available π-surface on their architectures. The crystal packing of these molecules revealed the importance of the π-surface on the ligand moiety as well as on the cis-protecting moiety. Utilization of the π-surfaces afforded 1D to 3D supramolecular networks in solid state. © 2018 Elsevier B.V.

Inorganica Chimica Acta

Crystal engineering with palladium(II)-based self-assembled binuclear complexes as tectons

Supramolecular gels prepared from low-molecular-weight gelators have been extensively explored. However, the exploitation of discrete or polymeric metal complexes as gelators is a relatively recent trend. The synthesis of self-assembled coordination complexes from palladium(II) and selected ligands is well established, but the potential of these complexes as gelators is a less explored treasure. Herein we focus on the gelation abilities of some self-assembled palladium(II) complexes and the resulting unique properties. First, discrete complexes with PdL, PdL2, Pd2L, Pd2L2, Pd2L4, and Pd3L6 compositions are discussed. Second, gelation behavior promoted by coordination-polymer-like gelators formed in situ is explored. These gel samples have been employed in catalysis and the uptake of organic and dye molecules from the solution and gas phases. It is concluded that untapped unique properties can be realized by further exploration of designer palladium(II) complexes. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Chemistry - An Asian Journal

Discrete and Polymeric Self-Assembled Palladium(II) Complexes as Supramolecular Gelators

A self-assembled discrete Pd3L′3L3 type circular helicate of hitherto unknown architecture is disclosed in this work where L′ stands for 1,10-phenanthroline (phen) and L for a triazole appended bidentate nonchelating ligand, i.e., 1,4-bis((1H-1,2,3-triazol-1-yl)methyl)benzene. The coordination environment of palladium(II) in any given PdN4 coordination planes of the helicate is described by one phen moiety and two triazole moieties belonging to different ligand strands. All the three bound phen moieties are uniquely turned inside and lodged in the internal cavity of the molecule; hence the term "intro-vertere circular helicate" is introduced. One of the PdN4 square planes is sandwiched between the other two via phen-inspired intramolecular π-stacking making a cylindrical stacking arrangement. A racemic pair designated as MPP and PMM isomers, where M and P stand for the handedness of the ligand L, is observed in the crystal structure. In the crystal packing, the trinuclear intro-vertere circular helicate molecules are arranged in a columnar hexagonal stacking. The two exposed phen moieties of a given molecule participated in the intermolecular π-stacking. The MPP and PMM isomers are arranged in an alternate manner in the stacks. © 2017 American Chemical Society.

Crystal Growth and Design

Trinuclear Intro-Vertere Circular Helicate and Its Columnar Hexagonal Stacking

All of the reported self-assembled complexes of cis-Pd2L′2L2 formulation, where L′ stands for a chelating bidentate ligand and L for a nonchelating bidentate ligand, are "non-helical". We disclose here the debut of the long awaited "helicate" type architecture of the cis-Pd2L′2L2 formulation. In the present work, the term L′ stands for tetramethylethylenediamine (tmeda) and L stands for a (1H-imidazolyl)methyl-appended bidentate nonchelating ligand having a rigid spacer. The torsion angle between the two coordination PdN4 planes of a given "helicate" is considered here as its magnitude of helicity. Length of spacer unit (i.e., 1,4-benzene, 4,4′-biphenyl and 4,4′-p-terphenyl) crafted in the backbone of L is found to impart such conformation to the bound ligand moieties that the magnitude of helicity is modulated. © 2016 American Chemical Society.

Double-Stranded Binuclear Helicates and Helicity Modulation

Self-assembled molecular triangles [Pd3(phen)3(imidazolate)3](NO3)3, 1a and [Pd3(phen)3 (imidazolate)3](PF6)3, 1b are prepared by the combination of imidazole with Pd(phen)(NO3)2 and Pd(phen) (PF6)2, respectively. Imidazole was deprotonated during the complexation reactions and the imidazolate so formed acted as a bis-monodentate bridging ligand to form the bowl-shaped trinuclear architectures of 1a/b. Relative orientation of the imidazolate moieties can be best described as syn,anti,antias observed in the crystal structure of 1b. However, in solution state, slow conformational changes are assumed on the basis of 1HNMR spectral data. The molecular triangles are crafted with three peripheral phen units capable of π-π stacking interactions. Well-fashioned intermolecular π-π interactions are observed in the solid-state, wherein further self-assembly of already self-assembled triangle is observed. © 2015 Indian Academy of Sciences.

Journal	Data powered by TypesetJournal of Chemical Sciences
Publisher	Data powered by TypesetSpringer India
ISSN	09743626
Open Access	Yes