Composite Molecular Assemblies: Nanoscale Structural Control and Spectroelectrochemical Diversity

Abstract

The controlled deposition of metal complexes from solution on inorganic surfaces offers access to functional materials that otherwise would be elusive. For such surface-confined interfaces to form, specific assembly sequences are often used. We show here that varying the assembly sequence of two well-defined and iso-structural osmium and ruthenium polypyridyl complexes results in interfaces with strikingly different spectroelectrochemical properties. Successive deposition of redox-active layers of osmium and ruthenium polypyridyl complexes, leads to self-propagating molecular assemblies (SPMAs) with distinct internal interfaces and individually addressable components. In contrast, the clear separation of these interfaces upon sequential deposition of these two complexes, results in charge trapping or electrochemical communication between the metal centers, as a function of layer thickness and applied assembly sequence. The SPMAs were characterized using a variety of techniques, including: UV–vis spectroscopy, spectroscopic ellipsometry, electrochemistry, synchrotron X-ray reflectivity, angle-resolved X-ray photoelectron spectroscopy, and spectroelectrochemistry. The combined data demonstrate that the sequence-dependent assembly is a decisive factor that influences and provides the material properties that are difficult to obtain otherwise.

Photoresponsive Molecular Memory Films Composed of Sequentially Assembled Heterolayers Containing Ruthenium Complexes

“…The utility and scope of spectroelectrochemistry has already been demonstrated in studies on composite molecular assemblies containing Ru and Os on ITO substrates. [38,39] In order to shed more light on the ET processes in the ITO jj(Ru-NP) 4 j (Ru-CP) 4 multilayer heterofilms, spectroelectrochemical measurements were conducted. Initially, the spectrum at the open circuit potential(0.06 Vvs.…”

“…Depending on the structure and/org eometry preferences as well as the coordination mode of the ligands, metal ions, and linkers, the formation of av ariety of surface-confined molecular structures,f or example, molecular wires or layers is observed. [9,22,36,[38][39][40][41][42][43] Similarly,s everal multidentate ligands such as dihydroxamate [44] and dihydroxy-bisquinoline [45] have been used for the preparation of coordination assemblies on solid surfaces, andp hosphonates have also been used as primary layers. [33] For example, aw ell-ordered two dimensionall ayer structurew as constructed on ag old surface by successive reaction with Zr IV ions and diphosphonate linkers.…”

“…Recently,v an derB oom et al reported molecular assemblies based on coordinative PdÀpyridine bonds. They observed rectified ET and charget rapping in sequence-controlled assembled films based on M(bpy) 3 (M = Ru, Os) complexes, [38,39] and reported repeated electrochromic responses of such Ru-Os composite assemblies by using spectroelectrochemistry. However,t he Ru complexes employed in the present study offer severalc haracteristic advantages compared to the previously reported M(bpy) 3 (M = Ru, Os) complexes:1 )bis(tridentate) Ru complexes such as Ru-N or Ru-C do not exhibit optical isomerism;2 )the longer molecular axis of Ru-NP and Ru-CP is alignedp erpendicular to the substrate surface, due to the designo ft he multipodal anchor groups;3 )Ru-NP and Ru-CP adopt as hort, dumbbell-likes tructure with large anchor groups at both ends, which is expected to ensureastable orientation on the surface, as well as the formation of uniform two-dimensional layers; 4) improved charge storage( electrons/ ions) in dinuclear complexes relative to mononuclearc omplexes.…”

A contact active bactericidal stainless steel via a sustainable process utilizing electrodeposition and covalent attachment in water

“…The main component lies at 402.2 eV and is due to the quaternized nitrogen of the C 18 H 37 N + group. [19][20][21][22] The band at 398.2 eV is due to residues of metal nitride. The band at 399.5 eV is due to residues of the unreacted diazonium salt.…”

Rerouting Electron Transfer in Molecular Assemblies by Redox‐Pair Matching

“…In aprevious report, [27] we have shown that asimple twocomponent system consisting of layers of ruthenium and osmium polypyridyl complexes exhibits unidirectional electrochemical behavior based on the sequence of deposition. This system undergoes catalytic redox reactions in one of two possible directions.I nt he present study,w eu se potential matching between different layers and introduce as calable organic spacer.These layers consist of polypyridyl complexes of the Fe/Ru/Os triad or ac ombination thereof.T he spacer allows precise control over the thickness,s eparation, and positioning of the electroactive layers,t he ET pathway,a nd the electrochemical communication between the layers of metal complexes.Ajudicious combination of the independent components results in different modular assemblies that exhibit diverse and controllable ET properties.T hese unique functionalities are not achievable with our twocomponent system without the scalable organic spacer.…”