Synthesis of Chiral Self-Assembling Rhombs and Their Characterization in Solution, in the Gas Phase, and at the Liquid−Solid Interface

Abstract

Chiral, enantiopure metallo-supramolecular rhombs self-assemble in solution through coordination of bis-pyridyl-substituted ligands with (en)M(NO3)2 (en = ethylenediamine, M = Pd(II), Pt(II)). Characterization by NMR and CD spectroscopy in solution and by ESI-FT-ICR mass spectrometry in the gas phase suggests that an equilibrium exists in water/methanol of a major 2:2 complex and a minor 3:3 complex of ligands and metal corners. In the gas phase, doubly charged 2:2 complexes fragment into two identical singly charged halves followed by metal-mediated C-H and C-C bond activation reactions within the ethylenediamine ligands. Electrochemical scanning tunneling microscopy (EC-STM) provides in situ imaging of the complexes even with submolecular resolution. Flat-lying rhombs are deposited under potential control from an aqueous electrolyte on a Cu(100) electrode surface precovered by a tetragonal pattern of chloride anions from the supporting electrolyte. Chirality induces the formation of only one domain orientation. Density functional calculations help to interpret the STM images.

Mixed‐Metal (Platinum, Palladium), Mixed‐Pyrimidine (Uracil, Cytosine) Self‐Assembling Metallacalix[n]arenes: Dynamic Combinatorial Chemistry with Nucleobases and Metal Species

“…From the + 2 and + 3 charge states, which still carry two and one nitrate counterions, respectively, the loss of HNO 3 is observed, a result indicating deprotonation of the ethylenediamine ligands at the Pt centers, as observed earlier for other similar coordination compounds. [27] Fragmentation of the parent ions occurs to some extent but does not give rise to major signals in the mass spectrum. A lowintensity signal also appears for a triply charged dimer.…”

Organic layers at metal/electrolyte interfaces: molecular structure and reactivity of viologen monolayers

“…The interfacial behavior becomes even more complex when reactants and/or products of the electron transfer process remain adsorbed on the anion-modified electrode surface prior to or during the reaction. Provided the anions retain to a large extent their negative charge upon specific adsorption, the subsequent adsorption of cationic reactants from the electrolyte onto the electrode surface will be facilitated through electrostatic attraction, thus, giving rise to the formation of 'paired'anion-cation layers [6]- [10], which remain stable even during an ongoing electron transfer reaction of the 'bulk' solution species [7,11]. Such an anion-cation layering has recently been reported for the adsorption and subsequent reaction of redox-active viologens [12,13] (1,1 -disubstituted-4,4 -bipyridinium molecules) on a chloridemodified Cu(100) electrode surface [7,8,10].…”

Supramolecular Helical Columns from the Self‐Assembly of Chiral Rods

“…[18,19] Compound (R,R)-4, which is based on an opened chiral group, and (R,R)-5, which is Scheme 1. Synthesis of the CBRs.…”

“…[18] The basic synthetic methodology to generate such a flexible dendrimer employed a facile convergent route, as reported previously. [19] The first step was performed by the etherification of 4,4'-bromohydroxy biphenyl with the tosylated dendron under basic conditions.…”