Indicator-displacement assays based on the organometallic complex [{Cp*RhCl2}2] (Cp*=pentamethylcyclopentadienyl) and the dye gallocyanine were used to sense amino sugars and aminoglycosides in buffered aqueous solution by conducting UV-visible spectroscopy. The data of three assays at pH 7.0, 8.0, and 9.0 were sufficient to distinguish between the amino sugars galactosamine, glucosamine, mannosamine and the aminoglycosides kanamycin A, kanamycin B, amikacin, apramycin, paromomycin, and streptomycin. Furthermore, the assays were used to characterize mixtures of aminoglycosides and obtain quantitative information about the respective analytes.

A simple but powerful method for the sensing of peptides in aqueous solution has been developed. The transition‐metal complexes [PdCl2(en)], [{RhCl2Cp*}2], and [{RuCl2(p‐cymene)}2] were combined with six different fluorescent dyes to build a cross‐reactive sensor array. The fluorescence response of the individual sensor units was based on competitive complexation reactions between the peptide analytes and the fluorescent dyes. The collective response of the sensor array in a time‐resolved fashion was used as an input for multivariate analyses. A sensor array comprised of only six metal–dye combinations was able to differentiate ten different dipeptides in buffered aqueous solution at a concentration of 50 μM. Furthermore, the cross‐reactive sensor could be used to obtain information about the identity and the quantity of the pharmacologically interesting dipeptides carnosine and homocarnosine in a complex biological matrix, such as deproteinized human blood serum. The sensor array was also able to sense longer peptides, which was demonstrated by differentiating mixtures of the nonapeptide bradykinin and the decapeptide kallidin.

Dynamic mixtures of Rh-dye complexes can be used to determine the history of chemical events such as the addition of ATP and ADP by UV-vis spectroscopy.

A dynamic combinatorial library of metal-dye complexes was obtained by reacting aqueous solutions of the dyes Methyl Calcein Blue, Arsenazo I, and Xylenol Orange with CuCl 2 and NiCl 2 . The mixture gave a characteristic UV-Vis response upon addition of the peptide hormones angiotensin I and angiotensin II. This allowed distinguishing pure samples of peptide hormones from mixtures. The discriminatory power of the sensor was enhanced when the several UV/Vis measurements were performed during the equilibration process of the library.