The use of anthraquinone and its derivatives, notably the sulfonate and disulfonate salts, for the detection of DNA via electrochemical techniques, has been the focus of a number of recent articles. This study provides a quantitative model of the two redox systems of anthraquinone-2,6-disulfonate and anthraquinone-2-sulfonate, over the full aqueous pH range (0-13); the model is based upon the theoretical "scheme of squares" for a 2H(+), 2e(-) system, as first proposed by Jacq (Jacq, J. J. Electroanal. Chem. 1971, 29, 149-180). The effect of pH and ionic strength on the observed cyclic voltammetry was investigated experimentally. The variation of the electrochemical response with proton concentration was modeled through use of the commercially available simulation software, DIGISIM; the system was successfully fitted with attention to voltammetric peak height, position, width, and shape. The model demonstrates how the pK(a) values of the anthraquinone intermediates dominate the observed pH dependence of the voltammetry. At high pH (above pH 12), a simple EE process is found to occur. As the pH decreases, the formation of other protonated species becomes possible; this not only causes a Nernstian shift in the measured electrochemical potential for the redox couple but also results in changes in the mechanistic pathway. At pH 10, an EECC process dominates, as the pH is further lowered into the range 4-7, the overall mechanism is an ECEC process, and finally a CECE mechanism operates at around pH 1 and below. This work provides physical insight into the complex mechanistic pathways involved and will aid the future development of more sophisticated and accurate anthraquinone based DNA sensors.

As eries of novel acyclic, macrocyclic and mechanically interlocked luminescent anion sensors have been prepared by incorporationo ft he isophthalamide motif into dipyridylbenzene to obtain cyclometallated complexes of platinum(II) and ruthenium(II). Both the acyclic and macrocyclic derivatives 7·Pt, 7·Ru·PF 6 , 10·Pt and 10·Ru·PF 6 are effective sensorsf or ar ange of halidesa nd oxoanions.T he near-infra red emitting rutheniumc ongenerse xhibited an increased bindings trengthc ompared to platinum due to the cationic charge and thusa dditional electrostatic interactions.I ntramolecular hydrogen-bonding between the dipyridylbenzene liganda nd the amidec arbonyls increases the preorganisation of both acyclic and macrocyclic metal derivativesr esulting in no discernible macrocyclic effect. Interlocked analoguesw ere also prepared,a nd preliminaryl uminescent chloridea nion spectrometric titrations with 12·Ru·(PF 6 ) 2 demonstrate am arked increase in halide binding affinity due to the complementary chloride bindingp ocket of the [2]rotaxane. 1 HNMR bindingt itrationsi ndicatet he interlockedd icationic receptor is capable of chloride recognition even in competitive 30 %a queous mixtures.[a] Dr.