Ligand scanning

These dendrimers show one oxidation, due to Ru(III)/Ru(II) couple, and two reduction processes, attributed to the first and second reduction of the ligands. Scanning the potential to more negative values, adsorption onto Pt electrode occurs and charge trapping peaks are observed. These peaks likely arise from redox centers that are electronically isolated from the electrode surface, so that their redox reactions are mediated by adjacent redox sites. Morphological changes of the deposited film have been observed upon application of a potential difference and they have been attributed to the deposition or dissolution of the dendrimer and/or to ejection or adsorption of counterions and/or solvent into the film. 

Bregman H, Carroll PJ, Meggers E (2006) Rapid access to unexplored chemical space by ligand scanning around a ruthenium center discovery of potent and selective protein kinase inhibitors. J Am Chem Soc 128 877-884... 

Selectivity Selectivity in voltammetry is determined by the difference between half-wave potentials or peak potentials, with minimum differences of+0.2-0.3 V required for a linear potential scan, and +0.04-0.05 V for differential pulse voltammetry. Selectivity can be improved by adjusting solution conditions. As we have seen, the presence of a complexing ligand can substantially shift the potential at which an analyte is oxidized or reduced. Other solution parameters, such as pH, also can be used to improve selectivity. 

Complex optimization of the ligand-protein interactions require to scan large areas of the chemical space. Thus, the combinatorial chemist aims not at the preparation of single compounds but of chemical libraries. Chemical libraries can be produced as collections of single compounds or as defined mixtures. 

The next smaller ligand-protected nanocluster that was investigated by scanning tunneling spectroscopy (STS) was the four-shell cluster Pt309phen 36O20 [20,21]. The diameter of the Pt core is 1.8 nm, about a tenth of the former example. However, even here a Coulomb blockade could only be observed at 4.2 K, i.e. at room temperature the particle still has metallic behaviour. Since... 

The electrochemical behavior of an aqueous/ethanol solution of [Ir(sat)2]Cl, satH = salicylaldehyde thiosemicarbazone (235), has been studied on mercury. A two-electron, ligand-based reduction at —1.09 V vs. SCE (independent of pH) is observed at fast scan rates.406... 

NIR region (see Chapter 9.13), complexes of 1,2-dithiolene (DT) and related ligands have attracted considerable attention for their (largely cubic) NLO properties. The complex (156) (a.k.a. BDN) is a highly photochemically stable, saturable absorber and has hence found extensive applications in laser Q-switching. The cubic NLO properties of (156) have been studied by DFWM148,403-407 and more recently, Z-scan.408 Time-resolved DFWM has been applied to square planar Co, Ni, Cu, or Pt complexes of 1,2-benzenedithiolate (BDT) or 1,2-aminobenzenethiolate ligands by Lindle and co-workers.409,410... 

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