Environmental effects on the aggregation of some xanthene dyes used in lasers

Dye-cosensitized graphene/Pt photocatalyst for high efficient visible light hydrogen evolution

“…The absorption spectrum of EY displays a low-energy visible band at 518 nm and exhibits a higher molar extinction coefficient ( 3) of 74112 M À1 cm À1 , while the maximum absorption of RB appears at 550 nm with a 3 of 56787 M À1 cm À1 , due to pep* transitions of the conjugated molecules [50]. The shoulder bands at about 485 nm and 510 nm for EY and RB are also observed, which are characteristics of the aggregated xanthene dyes species [50,51]. The absorption of ER cosensitizer exhibits both spectral features of individual dyes, resulting in an extended photo-absorption from 430 to 590 nm that ensures a good light harvesting for visible light induced H 2 evolution reaction.…”

“…Photoluminescence spectra of EY, RB, and ER show intensive emission peaks located at 549, 586 and 585 nm, respectively, due to the strong recombination of excited charge pairs upon light excitation [50,51]. The introduction of graphene will result in a considerable fluorescence quenching of dyes.…”

“…It is well known that the dye concentration is related with its aggregated forms and the number of excited electrons transferring to driven the photocatalytic H 2 evolution. The concentration range used in this study was from 1.5 Â 10 À4 M to 6.0 Â 10 À4 M, thus, partial EY and RB molecules might be exist in a dimer involving stacked monomers [51]. When the dye concentration increases, the photocatalytic activities increases first and then decreases, and reached a maximum at 3.0 Â 10 À4 M. Initially, with the increase in the dye concentration, the adsorption number of dye molecules on graphene sheets increases, which boosts the antenna effect of dye to absorb light, thus, the H 2 evolution activity increases.…”

Spectroscopic characterization and aggregation of azine compounds in different media

“…These kind of aggregates, are called Jaggregates [11,23]. [29], who affirmed that the tetrabromoderivative (eosin Y) had a greater tendency to aggregate than its precursor (fluorescein), and consequently halogenations were found, which were able to promote the aggregation of xanthene dyes.…”

Efficient one-pot synthesis of 14-aryl-14H-dibenzo[a,j]xanthene derivatives promoted by niobium pentachloride

“…These compounds have also been employed as sensitisers in photodynamic therapy (Neckers, 1989;Gutiérrez & García, 1998;Chang et al, 2008), in the food industry as additives (Tanaka, 2001;Chequer et al, 2012;Odo et al, 2012;Qi et al, 2012), in laser technologies (Ahmad et al, 2002;De et al, 2005) and as fluorescent materials for the visualisation of biomolecules (Knight & Stephens, 1989;Liu et al, 2001;Hilderbrand & Weissleder, 2007). In addition, xanthenes and their derivatives can be used as sensitisers in dye-sensitised solar cells (DSSCs) (Hara et al, 2000;Pradhan et al, 2007;Guillén et al, 2008;Sharma et al, 2009) and as hole-transporting materials in organic light-emitting devices (OLEDs) (Chu et al, 2012).…”