Although it's not easy to answer without knowing the structure of your probe, what you describe (changes in wavelength and intensity with polarity) is typical of TICT probes. There are a number of good reviews on those fluorophores:

M. A. Haidekker, T. P. Brady, D. Lichlyter, E. A. Theodorakis, Bioorg. Chem. 2005, 33, 415–425.

A. S. Klymchenko, Acc. Chem. Res. 2017, 50, 366–375.

It is due to a very well known phenomena called Aggregation Induced Emission Enhancement (AIEE). You should search as much literature as possible on AIEE. Here are a few for you.

Bests

Hi, just like the other last contributor said, aggregation could induce an enhancement in the FL intensity of your probe. You can welcome this conclusion with the structure of your probe and its nature (QDs or NPs / inroganic-organic compound based probes). Cheers!

Thank you very much for all contributions. The probe I am working with is Monobromobimane (MBBr). And it shows severe increase in intensity and blue shift in DMSO compare to water. 

My main question is that, I have expected that if probe goes from hydrophile environment into "low" hydrophobe environment I should see few increase in intensity and few blue shift, while translocation into "high" hydrophobe environment, should cause great increase in intensity and great blue shift. But what I have seen is that, in condition 1 few increase in intensity was along with great blue shift, and in condition 2 great increase in intensity was along with few blue shift. This problem make the interpretation of these conditions very difficult. Is there any idea to justify this contradiction?

Thank you very much for your consultation beforehand,

Bests,

Have you confirmed the structural integrity of the probe?. For what I have seen your "fluorophore" is basically non-fluorescent until the bromine is displaced by a thiol (that is its main use), so you might be having a modification of the fluorophore structure. I'd check that. There shouldn't be any AIEE since MBBr is supposedly soluble in DMSO.

Yes M. Eugenio Vazquez. Thanks for your contribution. The probe is bonded to a Cysteine residue of the target protein and unbound probes were eliminated by desalting method before the experiment.

it would be nice to provide all the data when you are asking questions. It's very unproductive to guess what's going on if you do not describe your system appropriately.

If the probe is attached to a protein then you are probably seeing effects of conformational changes of the protein in the microenvironment of the probe. The local polarity and interactions do not necessarily correspond to the polarity of your solvent. You must be very careful drawing conclusions when performing experiments with proteins in non-aqueous environments.

Dear Prof. M.Eugenio Vazequez. Thank you for your answer. Yes I apologies for limit information I have provided. As questions need to be brief here, I avoided to explain details, since I thought it is a general question independent of details, but it seems I was wrong. 

I actually know that the effect is because of conformational changes, as we study amyloid aggregation phenomenon. My view was that translocation of probe into more hydrophobic region (covered by amino-acid residues) is the only cause of fluorescent intensity change or blue shifting. But according to answers here I understand that even "restriction of interamolecular motion" can also cause less waste of energy and blue shift in emission. But still I do not understand the reason for elevation in intensity. I would appreciate your guidance on this.

Also I would be most grateful if you could recommend me a reference for more studying about the chemistry basis of fluorescence modulations of fluorescent probes. I have read the book of "introduction to Fluorescence" but author has not discussed the details of mechanisms behind events.

Best regards,

There are different reasons for blue shift and for enhancement of fluorescence. These are two different phenomena. Restriction of intramolecular motion usually causes enhanced fluorescence while the change in environment of fluorophore or restriction of TICT causes the shifting of spectra. When the aggregates are formed the solvent moves out of the aggregates so the fluorophore is now facing different environment. If the polarity of environment is lesser in aggregates then we observe blue shift. If somehow your fluorophore has TICT state, then aggregation can cause restriction of TICT state and leads to enhanced fluorescence and blue shift.

Thank you very much Prof. Gopal Singh. Is there any reference book which discussed TICT, RIM and other similar phenomenon in details?

In my previous answer I have attached a review also (from advanced materials). In that review almost every aspect has been discussed. You can find more references from there also.

Best wishes

Check out B. Valeur's Molecular Fluorescence: Principles and Applications

http://onlinelibrary.wiley.com/book/10.1002/3527600248

To obtain a fair assessment: Quantum yield should be measured instead of intensity, secondly time resolved measurements be done as intensity is not always a very good parameter as it depends on various factors. For confrontational change and possibility of TICT /PICT change in FWHM, Stokes' shift may provide further clarity ; besides time resolved analysis may provide conclusive evidence about conformational changes taking place.