Dear Fatemeh Sadegh, After doing a rapid bibliographic search, these shifts are attributed to intermolecular interactions (maily H-bonding) and molecular aggregation (exemple proteins folding). For more details, please check the following links. My Regards

https://www.researchgate.net/post/what_is_the_blue-shift_in_UV-vis

https://www.researchgate.net/post/How_to_interpret_blue_shifted_emission_and_red_shift_UV-vis

https://www.sciencedirect.com/topics/earth-and-planetary-sciences/blue-shift

https://doi.org/10.1021/ja067545z

https://doi.org/10.1039/B815431G

https://doi.org/10.1080/14328917.2020.1728485

Hi Fatemeh, basically we are looking at different things by using UV-Vis spectroscopy and FTIR spectroscopy. With FTIR, we look at the vibrational energies of the bonds present in the molecule. So, any shift in the FTIR peak would signify the change in the bond strength. While with UV-Vis, we look at the electronic transitions shown by the material. Hence, we can correlate any shift in UV-Vis peaks with the change in band gap or presence/absence of excited electronic energy states in the material.

So, to answer your question, yes it is possible to show blue/red shift in FTIR while red/blue shift in UV-Vis by the same material system.

You might find following discussions helpful:

https://www.researchgate.net/post/What_does_the_shift_of_IR_peak_to_higher_wavenumber_indicate

https://www.researchgate.net/post/How_to_interpret_blue_shifted_emission_and_red_shift_UV-vis

Dear Fatemeh Sadegh

Please do not correlate these two techniques. Each have its own analogy as Mr. Pitambar already explained.

regards

Dear Fatemeh Sadegh,

Both techniques are differ to each other as well as differs with principle. So my opinion is that it should not be correlated to each other.

Workman Jr, Jerry, ed. The Handbook of Organic Compounds, Three-Volume Set: NIR, IR, R, and UV-Vis Spectra Featuring Polymers and Surfactants. Elsevier, 2000.

I am also of the opinion that UV-Vis and FTIR spectroscopy are different technique and have different principle. Any blue or Red shift will have different meaning in each case. So it can not be correlated.