In generals, What methods are there to create a J-aggregation of dyes (for example Rhodamine) on a glass substrate?
and how can I use L-B technique for that?
Dear Nasrin,
Dyes will stack in case a template or guiding motive is present. The dye will bind to this motive by electrostatic interaction and the proximity of the charges on the template will guide the dye to arrange in either J- or H-stacks. I my research, so far, I've only seen H-stacks.
Rhodamine is a cationic dye, so the template should be negatively charged. For this you may use a polyanion like poly(styrene sulfonate sodium). There is a possibility that this already will give J-stacks. I just went through my literature and found one case where they report J-stacks of Rhodamine onto smectites and clays (https://doi.org/10.1180/claymin.1997.032.1.11).
So here's how I would go about this:
1. Wash the glass slide in dilute sodium hydroxide to bring out its negative charges, this may already give J-stacks when contacted with Rhodamine, you may want to check already at this stage (to do this skip steps 2 and 3).
2. Wash off the excess sodium hydroxide with distilled water and next dip the glass slide in an 0.1 (w/w)% poly(ethyleneimine) solution; this will coat the glass with a positively charged anchoring group.
3. Wash off the excess PEI and next dip the glass slide in a solution of poly(styrene sulfonate sodium) or a nano clay dispersion containing smectites; this is the guiding motive for Rhodamine. Wash off any excess by rinsing with distilled water again.
4. Finally dip the glass slide into a diluted solution of rhodamine (40 µM or less is needed).
VIS spectrometry should be able to show you whether or not you succeeded in making J-stacks, if yes you should see a distinct spectral shift to higher wavelengths.
Good luck with your experiments !! Kind regards, Leo
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