Unique solvatochromism of cyanine/saponite hybrid systems: Fid-Bau Portal

Unique solvatochromism of cyanine/saponite hybrid systems

Czímerová, A. / Sas, S. / Čeklovský, A.

AbstractThe present study is primarily focused on the investigation of spectral properties of cationic cyanine dye (1,1′-diethyl-4, 4′-carbocyanine iodide, denoted as “NK5”) adsorbed into the structure of synthetic clay mineral (Sumecton SA, denoted as “SUM”) as a host matrix. The hybrid systems were investigated by means of absorption and fluorescence spectroscopy. Beside the solvent effect, the influence of dye/saponite ratio on the formation of specific dye species was studied in detail. It was found that used solvents have greatly affected the spectral properties of prepared hybrids. The NK5/saponite systems in ethanol and methanol were dominated by isolated dye cations. In the NK5/saponite systems in acetone and acetonitrile, the formation of higher aggregates was significantly suppressed. Moreover, the fluorescence spectra showed evidence of the formation of highly fluorescent J-aggregates. Finally, the fluorescence quantum yields of the NK5/saponite systems in various solvents were calculated. It was found that polar protic solvents as ethanol and methanol could stabilize the hybrid cyanine/saponite system with higher quantum yields as in case of used aprotic solvents.

Graphical abstractEmission spectra of NK5 in presence of SUM in different solvents, EtOH (a), MeOH (b), AN (c) and ACON (d) measured 1min after mixing dye solutions with saponite dispersions. Spectra are arranged from top-to-bottom in increasing the dye/saponite ratio of 0.01 (solid line), 0.02 (dash line), 0.05 (dot line), 0.1 (dash dot), 0.2 (dash dot dot line) and 0.5 (short dot line) mmol/g.

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Highlights•Solvatochromism of cyanine/saponite hybrid systems was investigated.•Dye/saponite ratio has a negligible effect on the formation of specific dye species.•Aprotic solvents suppressed the formation of high-sized aggregates in hybrids.•Fluorescence quantum yield was higher in systems containing protic solvents.