Formation of Rack‐ and Grid‐Type Metallosupramolecular Architectures and Generation of Molecular Motion by Reversible Uncoiling of Helical Ligand Strands

Abstract

The interaction of appropriate metal ions (Pb(II), Zn(II)) with helical ligand strands, obtained by hydrazone polycondensation, generates polymetallic supramolecular architectures of rack and grid types, by uncoiling of the ligand. The interconversion between the helical free ligand and the linearly extended ligand in the complexes produces reversible ion-induced, nanomechanical molecular motions of large amplitude. It has been integrated in an acid-base neutralisation fuelled process, which links the extension/contraction of the ligand strands to alternating changes in pH.

Solid‐State Self‐Assembly of Polymeric Double Helicates Leading to Linear Arrays of Silver(I) Ions and Reversible Strand/Double Helix Interconversion in Solution

“…This behaviour may be compared with the one of the Pb II gridlike complex formed by ligand 1, which on adding of 1-1.5 equivalents of Pb II led to fast conversion into the corresponding rack-type compound. [8] The species distribution graphs resulting from the analysis of the NMR spectra are shown in Figure 4. During the titration, progressive precipitation of the complex 2' may occur.…”

“…[8,16] On the other hand such a solid-state molecular structure (R % 6 %) was obtained for a Ag I dinuclear complex ( Figure 15) [17] of a pyrazine-derived hydrazone-based ligand. [18] It shows indeed the dinuclear nature of the racklike complex, as well as the coordination of Ag I ions by the terpy-like sites.…”

“…[8] With several of these ligands, Ag I was found to bind preferentially to the terminal hyz-py units (which contain the more basic pyridine nitrogen sites; Figure 1) in a distorted tetrahedral fashion, thus conserving the general helical Abstract: Reaction of a bent py-hyzpym-hyz-pym 1 and of a linear py-hyzpy-hyz-pym 3 (py = pyridine; pym = pyrimidine; hyz = hydrazone) ligand strands with silver(I) tetrafluoroborate in CH 3 NO 2 generates double-helical dinuclear 2 and trinuclear 4 complexes. These complexes form polymeric, highly ordered solid-state structures, with wirelike, linear continuous or discontinuous polycationic Ag n + arrays with AgÀAg distances of 2.78 to 4.42 .…”

RuII Multinuclear Metallosupramolecular Rack‐Type Architectures of Polytopic Hydrazone‐Based Ligands: Synthesis, Structural Features, Absorption Spectra, Redox Behavior, and Near‐Infrared Luminescence

“…Synthetic approach and characterization Synthesis of ligands: Ligand 7 was synthesized (Scheme 1) as previously described, [7] by condensation of 2-pyridinecarboxaldehyde (25) with 2-(1-methylhydrazino)pyridine (24), obtained from 2-chloropyridine (23) and methylhydrazine. [8] Reaction of aminopyrazine 20 with N-bromosuccinimide led to 2-amino-5-bromo-pyrazine [9] (19), which, on treatment with Br 2 , HBr, and NaNO 2 , yielded 2,5-dibromopyrazine [10] (18), the reaction of which with methylhydrazine led to 2,5-bis(1-methylhydrazino)pyrazine (17).…”

Star PolyMOCs with Diverse Structures, Dynamics, and Functions by Three‐Component Assembly

“…[9][10][11][12][13][14][15][16][17][18][19][20][21][22] By rational design of the ligands and proper choice of the metal ions, MOCs of different M x L y stoichiometries, sizes, and geometries can be synthesized. [23][24][25][26][27][28][29] Inspired by this structural versatility and potential applications such as mechanical enhancement, catalysis, encapsulation, sensing, etc., much effort has been recently devoted to installing MOCs into polymer networks to provide 'polyMOC' hybrid materials with tunable viscoelasticity and functionality. [30][31][32][33][34][35][36][37] One [30,[38][39][40][41][42] ; however, there is still a great need to understand how polyMOC microstructure translates to bulk material properties such as modulus and relaxation dynamics.…”