Victoria Blue R | CAS 2185-86-6 | ≥98%

Victoria Blue R (C.I. 44040, Basic Blue 11) is a cationic triarylmethane dye of the Victoria Blue family bearing two p-dimethylaminophenyl donors and a 4-(ethylamino)-1-naphthyl substituent at the central methine carbon, giving an iminium chloride of formula C₂₉H₃₂ClN₃ (MW 458.04). The dye is supplied as a dark blue powder, slightly soluble in cold water, soluble in hot water with a deep blue colour, and soluble in ethanol to give intensely blue-violet solutions. Extension of the chromophore through the fused naphthyl donor places the visible absorption maximum near 615 nm, characteristic of the Victoria Blue series, with a blue-to-yellow colour change in strongly acidic media (pH < 1). The dye should be distinguished from its close relatives Victoria Blue B (CAS 2580-56-5, Basic Blue 26; N-phenyl naphthylamine donor), Victoria Blue 4R (CAS 2185-87-7, Basic Blue 8; N-methyl-N-phenyl naphthylamine donor), and Victoria Blue BO (CAS 2390-60-5, Basic Blue 7; same N-ethyl naphthylamine donor as Victoria Blue R but with diethylamino in place of dimethylamino on the phenyl donors); the family members are historically close in name and are sometimes substituted for one another in staining formulations.

Histological and Cytological Staining

Victoria Blue R is a cationic basic dye used in specialised histological methods for tissue sections and smears, with its strongest documented applications in elastic and connective-tissue chemistry rather than in routine general staining. In the phosphomolybdic / phosphotungstic acid–Victoria Blue R method, the dye differentiates two histochemically distinct collagens by staining them dense dark blue and loose areolar pale green. Commercial alcoholic Victoria Blue staining protocols are used to demonstrate elastic fibres, connective tissue, and fibrosis in paraffin-embedded sections, and to visualise copper-associated protein in liver sections. Classical biological-stain references additionally describe Victoria Blue R in combination with Bismarck Brown Y as a counterstain for acid-fast microorganisms. Mounting-medium compatibility is protocol-dependent: alcoholic Victoria Blue staining protocols tolerate standard alcohol dehydration and resinous mounting, whereas direct aqueous Victoria Blue stains can be removed during alcohol dehydration unless preserved by phosphomolybdic / phosphotungstic afterchroming.

Spectrophotometric and Analytical Chemistry Applications

Victoria Blue R has been reported as a cationic ion-pairing dye in extractive spectrophotometric chemistry. In gold analysis, the dye forms an extractable ion-association complex with tetrachloroaurate(III), AuCl₄⁻, in hydrochloric acid medium for determination of trace gold. In lipid analysis, non-choline phospholipids form Victoria Blue R complexes that selectively partition into the chloroform phase of a chloroform / ethylene glycol / glycerol biphasic solvent system and are quantified at 590 nm, providing a sensitive single-tube extraction-and-estimation assay. More broadly, bulky cationic triarylmethane dyes are used in extractive spectrophotometric methods for anionic species, with method selectivity governed by buffered pH, ionic strength, and choice of extraction solvent.

Photocatalysis and Wastewater Treatment Research

Victoria Blue R is used as a model cationic dye pollutant in photocatalysis and water-treatment research. Its strong visible absorption and triarylmethane dye structure make it a useful probe for evaluating TiO₂-based, modified-TiO₂, iron-oxide, and other semiconductor photocatalysts in cationic-dye degradation under UV, visible-light, or simulated-sunlight irradiation, depending on the catalyst system. Mechanistic studies of Victoria Blue R photocatalytic degradation over nano-TiO₂ have identified numerous intermediates by HPLC–PDA–ESI-MS. The dye is also employed as a target adsorbate in studies of low-cost removal materials, including mineral or bio-derived sorbents, magnetic microparticles, and semiconductor or graphene-oxide hybrid photocatalysts for cationic-dye removal from aqueous media.