A pentanuclear coordination complex assembled from any palladium(II) component and non-chelating ligands is hitherto unreported. The pentanuclear complex [Pd5(L1)5(L2)5](BF4)10, 1 reported here was prepared by the spontaneous complexation of [Pd(DMSO)4](BF4)2 with the non-chelating bidentate ligands 1,4-phenylenebis(methylene) diisonicotinate, L1 and 4,4′-bipyridine, L2 in a one-pot method at room temperature. The planar polycyclic complex 1 with outer diameters of ≈3 nm is termed as a “molecular star” owing to its resemblance with a pentagram shape. Interim paths leading to the star were also probed to decipher related dynamics of the system. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Dillip Kumar Chand

Department Of Chemistry

chelation

Complexation

Coordination reactions

Ligands

Palladium

Self assembly

Stars

Bidentate ligands

Chelating ligands

Coordination complex

Dynamic behaviors

One-pot method

Outer diameters

Pentanuclear

Pentanuclear complexes

Palladium compounds

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IIT Madras

Chemistry - A European Journal

Metal-driven self-assembly is one of the most effective approaches to lucidly design a large range of discrete 2D and 3D coordination architectures/complexes. Palladium(II)-based self-assembled coordination architectures are usually prepared by using suitable metal components, in either a partially protected form (PdL′) or typical form (Pd; charges are not shown), and designed ligand components. The self-assembled molecules prepared by using a metal component and only one type of bi- or polydentate ligand (L) can be classified in the homoleptic series of complexes. On the other hand, the less explored heteroleptic series of complexes are obtained by using a metal component and at least two different types of non-chelating bi- or polydentate ligands (such as La and Lb). Methods that allow the controlled generation of single, discrete heteroleptic complexes are less understood. A survey of palladium(II)-based self-assembled coordination cages that are heteroleptic has been made. This review article illustrates a systematic collection of such architectures and credible justification of their formation, along with reported functional aspects of the complexes. The collected heteroleptic assemblies are classified here into three sections: 1) [(PdL′)m(La)x(Lb)y]-type complexes, in which the denticity of La and Lb is equal; 2) [(PdL′)m(La)x(Lb)y]-type complexes, in which the denticity of La and Lb is different; and 3) [Pdm(La)x(Lb)y]-type complexes, in which the denticity of La and Lb is equal. Representative examples of some important homoleptic architectures are also provided, wherever possible, to set a background for a better understanding of the related heteroleptic versions. The purpose of this review is to pave the way for the construction of several unique heteroleptic coordination assemblies that might exhibit emergent supramolecular functions. © 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Palladium(II)-Based Self-Assembled Heteroleptic Coordination Architectures: A Growing Family

A Truncated Molecular Star

Bis(pyridin-3-ylmethyl) pyridine-3,5-dicarboxylate (L) possessing one internal and two terminal pyridine moieties displayed differential coordination ability when combined with suitable PdIIcomponents. The compound L acted as a bidentate chelating ligand to form mononuclear complexes when combined with cis-[Pd(tmeda)(NO3)2] or Pd(NO3)2in calculated ratios. The combination of Pd(NO3)2with L in a ratio of 3:4, however, afforded the trinuclear “double-decker” cage [(NO3)2⊂Pd3(L)4](NO3)4, in which L acts as a nonchelating tridentate ligand and the counter anion (i.e., NO3–) acts as template. The encapsulated NO3–can be replaced by F–, Cl–, or Br–but not by I–. The F–-encapsulated cage could not be isolated due to its reactivity, whereas the Cl–or Br–encapsulated cages could be isolated. Although anionic guests such as NO3–, Cl–, or Br–stabilized the cages, the presence of excess Cl–or Br–(not NO3–) facilitated decomplexation reactions releasing the ligand. The complexation of Pd(Y)2(Y = BF4–, PF6–, CF3SO3–, or ClO4–) with L afforded the corresponding mononuclear complexes under appropriate conditions. However, these counter anions could not act as templates for the construction of double-decker cages. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

European Journal of Inorganic Chemistry

Double-Decker Coordination Cages

Complexation of 1,4-phenylenebis(methylene) diisonicotinate, L1, with cis-protected PdII components, [Pd(L′)(NO3)2], in an equimolar ratio yielded binuclear complexes, 1 a-d of [Pd2(L′)2(L1)2](NO3)4 formulation where L′ stands for ethylenediamine (en), tetramethylethylenediamine (tmeda), 2,2′-bipyridine (bpy), and phenanthroline (phen). The combination of 4,4′-bipyridine, L2, with the cis-protected PdII units is known to yield molecular squares, 2 a-d. However, 2 b-d coexist with the corresponding molecular triangles, 3 b-d. Combination of an equivalent each of the ligands L1 and L2 with two equivalents of cis-protected PdII components in DMSO resulted in the D-shaped heteroligated complexes [Pd2(L′)2(L1)(L2)](NO3)4, 4 a-d. Two units of the D-shaped complexes interlock, in a concentration dependent fashion, to form the corresponding [2]catenanes [Pd2(L′)2(L1)(L2)]2(NO3)8, 5 a-d under aqueous conditions. Crystal structures of the macrocycle [Pd2(tmeda)2(L1)(L2)](PF6)4, 4 b′′, and the catenane [Pd2(bpy)2(L1)(L2)]2(NO3)8, 5 c, provide unequivocal support for the proposed molecular architectures. Interlock game: A series of D-shaped self-assembled molecules are prepared from a three-component mixture of cis-protected PdII, rigid rod-like and flexible C-shaped ligands in a 2:1:1 ratio in DMSO. These molecules are considered as molecular karabiners bearing coordination bond loaded gates. The D-shaped molecules are interlocked in aqueous conditions, forming the corresponding [2]catenanes (see figure). © 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Reversible Mechanical Interlocking of D-Shaped Molecular Karabiners bearing Coordination-Bond Loaded Gates: Route to Self-Assembled [2]Catenanes

The pyridine-appended non-chelating bidentate ligands 1,4-bis(3-pyridyl) benzene (1) and 4,4′-bis(3-pyridyl) biphenyl (2) were complexed with a naked PdII ion for the construction of molecular cage compounds. Prior to these experiments, the complexation of the ligands with cis-[Pd(en)(NO3)2] was also examined, because self-assemblies from the cis-protected PdII ion were expected to be simple motifs that constitute the assemblies from naked PdII ion. The structures of the self-assembled compounds resulting from 1 and [Pd(en)(NO 3)2] depended on the solvent employed. In aqueous solution, an M2L2 trenchlike compound was obtained. In dimethyl sulfoxide, however, a mixture of the M2L2 trench and an M3L3 macrocycle was found in equilibrium, the dynamic nature of which was confirmed by the concentration-dependent nature of the species. At higher concentration, an M4L4 macrocycle was mostly observed. The complexation of 1 with naked PdII ions was expected to produce novel structures that are combinations of the M nLn type frameworks. A peculiar tetrahedral M 4L8 assembly was obtained quantitatively from 1 and Pd(NO3)2, rather than the smallest possible M 3L6 double-walled triangle. Interestingly, the use of Pd(CF3SO3)2 resulted in the sole formation of the latter structure. Thus, the anion is important as a template in the formation of these assemblies. Ligand 2, which contains an extra p-phenylene unit compared to 1, behaved in a similar manner when treated with [Pd(en)(NO3)2], but showed subtle differences with naked PdII ions. With Pd(NO3)2, 2 gave mostly a tetrahedron along with a double-walled triangle. With Pd(CF3SO 3)2, this longer ligand formed a double-walled triangle with a negligible amount of tetrahedra. A single discrete assembly of a perfect tetrahedron was obtained from 2 and PdII ions by choosing p-tosylate as a counterion. © 2006 Wiley-VCH Verlag GmbH &amp; Co. KGaA.

Chemistry - An Asian Journal

Dynamic self-assembly of an M3L6 molecular triangle and an M4L8 tetrahedron from naked PdII ions and bis(3-pyridyl)-substituted arenes

Journal of the American Chemical Society

Fe–Pt Twisted Heterometallic Bicyclic Supramolecules via Multicomponent Self-Assembly

Journal	Data powered by TypesetChemistry - A European Journal
Publisher	Data powered by TypesetWiley-VCH Verlag
ISSN	09476539
Open Access	No