[Kaladiscope]

Hi colleagues,

I am checking by fluoresence the conversion of one reaction. My starting material has a fluorophore (NBD) and it reacts with another compound which have two benzyl groups. I am afraid about the influence of these benzyl groups in the fluorescence detection. In other words, I am not really sure how accurate would be the quantification if I am adding these cromophores....

Thanxs

[discodermolide]

Hi colleagues,

I am checking by fluoresence the conversion of one reaction. My starting material has a fluorophore (NBD) and it reacts with another compound which have two benzyl groups. I am afraid about the influence of these benzyl groups in the fluorescence detection. In other words, I am not really sure how accurate would be the quantification if I am adding these cromophores....

Thanxs

This link may help.

http://www.google.ch/url?sa=t&rct=j&q=bathochromic%20shift%20chemistry&source=web&cd=2&ved=0CDsQFjAB&url=http%3A%2F%2Fwww2.chemistry.msu.edu%2Ffaculty%2Freusch%2FVirtTxtJml%2FSpectrpy%2FUV-Vis%2Fspectrum.htm&ei=y5MTT4XBE7LY4QSkucXBAw&usg=AFQjCNEIlEwvrZvdkjxsyWW_Cnd2o_LSqw

[Kaladiscope]

I took a look and still I don't know whether the influence is important or not. I would expect that adding nitrobenzyl groups could also increase the intensity of these peaks and then making less accurate the quantification of the final product vs starting material. But as long as I know NBD chloride emits light in a range of 465nm-535nm, which is too far of this arylgroups emissions....

Any help?

[discodermolide]

I took a look and still I don't know whether the influence is important or not. I would expect that adding nitrobenzyl groups could also increase the intensity of these peaks and then making less accurate the quantification of the final product vs starting material. But as long as I know NBD chloride emits light in a range of 465nm-535nm, which is too far of this arylgroups emissions....

Any help?

Hysopchromic or bathyochromic shifts in the wave length of the adsorption are dependant on the functional groups attached to the chromophore.

[Polytriazole]

Are the added benzyl groups going to be in direct conjugation with the NBD fluorophore?  If not, then I don't think they will interfere with the NBD.  Is it possible to quantify the reaction progress in some other way to verify the fluorescence data? 

[Kaladiscope]

Polytriazole:

Let's say that the benzyl groups are placed quite far from the NBD fluorophore. I could also quantify by MS....but quantification by MS is always less accurate (I would say...)

Kaladiscope:

It has one methoxy and one nitro group attached to the benzyl...

[Honclbrif]

If the aromatics aren't in conjugation with the fluorophore I don't think they'd have a huge effect on the spectrum, but if they are chromophores you may get FRET pairing. I'd read up on FRET to see if you can expect any such interactions.

If quenching/FRET is not an issue, you might also be able to monitor your progress with something as simple as TLC. Look for the disappearance of the fluorescent starting material spot and the appearance of a second fluorescent product spot. I've done this with Fmoc deprotections. Works with HPLC too.

Finally, you may just have to run the reaction and determine the fluoresence spectrum of the product and use that to quantify the products when you do this in the future.

[Polytriazole]

Polytriazole:

Let's say that the benzyl groups are placed quite far from the NBD fluorophore. I could also quantify by MS....but quantification by MS is always less accurate (I would say...)

Kaladiscope:

It has one methoxy and one nitro group attached to the benzyl...

Are you using o-nitrobenzyl photocleavage as part of your experiment?  Because those types of compounds frequently display this behavior. Looking at the absorption/emission characteristics of NBD, I don't think the absorption/emission of the benzyl groups overlaps very much, if at all.