Part 11: Solvent Effects in the UV Visible Spectroscopy

In this video, I have explained the effect of polarity of the solvents on the Absorption Max and Epsilon Max. Polar solvents are capable of forming Hydrogen bonding with non bonding electron very effectively followed by ground state pi orbitals as they are polar in nature, thus previous one is most stabilized than the later
one, while pi anti bonding orbitals are least stabilized. Thus hydrogen bond increases the energy of the transition which gives Hypsochromic i.e Blue shift in case of n to pi transition.

[@MahimaLahariaPacificchemistry]

Easy explanation sir.

[@ameeshanigam8563]

Nicely explained the concept but I felt it confusing for the hydrogen bonding part. Everything else was nicely explained.

[@PoojaSingh-xe5od]

You explain very well sir. Main Bahut Der Se hua Y. R Sharma padh rahi thi usne mujhe nh samajh mein a raha tha.

[@abuhanif8656]

Very very effective this. Thanks

[@devmunshi6192]

nicely explained sir. Thank you very much.

[@radhapatel1170]

Good explain Sir you clear my all doubt

[@shankarmewani4443]

Thank you so much Sir

[@tamilvalam4458]

great explanation.

[@ramanswami7263]

Nicely explained🙏🙏🙏

[@neichoihoilhouvum8744]

Why for n to pi* transition polar solvents stabilise the ground state more? Or why the ground state is more polar for n to pi*?

[@TETRAHEDRONCHEMISTRYCLASSES]

For n to pi* transitions, you may take eg of carbonyl compound, C=O, this functional group is polar due to Oxygen, in the ground state (polarity is there, dipole moment can be calculated) polar solvent like water forms hydrogen bond with lone pairs, in the excited state that is pi*, one electron from lone pair get excited thus oxygen is electron deficient now, hence polarity is less in case of excited state than ground state. Hope this is the answer of your question. Thank you.

[@devendrabisht9108]

Nice

[@krishnendujas2672]

Hydrogen bonding generally increases the wavelemght max

[@TETRAHEDRONCHEMISTRYCLASSES]

No, it's depends upon type of transition, for example non bonding to sigma antibonding transitions undergoes blue shift ie towards shorter wavelength, while π-π* undergoes red shift ie towards longer wavelength due to hydrogen bonding.

[@krishnendujas2672]

@@TETRAHEDRONCHEMISTRYCLASSES thank you for your clearance

[@TETRAHEDRONCHEMISTRYCLASSES]

You are most welcome

[@sangitakar6836]

Sir is solvent shift and solvent effect same?

[@TETRAHEDRONCHEMISTRYCLASSES]

Yes

[@lameessaud2869]

what suitable solvent to be used in the measurement of the UV absorption of cyclohexanone?

[@TETRAHEDRONCHEMISTRYCLASSES]

Purpose of taking solvent is to get better solubility so that we get a good spectrum. So for cyclohexanone also check it's solubility in standard solvents used in UV Visible spectroscopy and record spectrum, also check for solvent correction. I hope you got the answer.

[@akshaym7901]

Sir you have content, but explanation could be improved. Anyway nice class.

[@venkatkaluva8811]

Thanks a lot sir!!!

[@TETRAHEDRONCHEMISTRYCLASSES]

Your welcome, this was my commitment to you....

[@rezaulkarim-fm5cb]

tnx a lot

[@arshadiqbal3840]

Nyc👌👌👌👌👌