E(HOMO) = -4.26 eV

[Trans.Nonferrous Met.Soc.China 20(2010)1993-99].

{Find value at page 1998 in the table}.

E(LUMO)= -2.72 eV

ΔE =2.54eV(488nm).

Sorry; a typographical error:

E(LUMO)= -1.72 eV

and not

E(LUMO)= -2.72 eV

Thank you so much.

Thank you so much. I request you please to provide me this article.

Just to know if data were provided form vacum or NHE scale?

My friend- I have already given the reference of the said paper in my answer.

1. As required by goodself, I attach the reference giving LUMO energy of Congo red

(See page -1998, Table-4- look –Cogo red and find its E(LUMO).

I was feeling guilty that I could not send you the reference due to some domestic pre occupation.

2. Click:

[PDF]

Chapter 16: Molecules with Conjugated vs. Unconjugated π ...

www.winnersmd.com/bbs/download.php?bbs_table=prof_s_8...

UV Excitation of Electrons from HOMO to LUMO in trans-1,3-Pentadiene ... One example of a biological stain is Congo red, which ... Congo Red (λmax = 488 nm).

o know the energy difference between HOMO/LUMO=488 nm

Convert 488nm into eV directly[ a fomula easy to remember

=1240/ wave length in nm]

[3] It comes to 1240/488=2.54

So enegy HUMO= -4.26 + 2.72= -1.72eV

Dear Monohar S.;

Thank you so much for all what have you done.

Are the values satisfy your requirements? Rgds.

I think no, to my knowledge, Congo Red has λmax in the range= 497-500 nm. I think that LUMO and HOMO values are over estimated.

May I dare put forwad a few observations for your kind perusal?

1. Assumimg the value is 497 nm. Then energy difference will come out to be 2.496eV . This makes error =1.5% ;which in no way is beyond any permissible limit.

2. I may further add that depending upon the solvent, the LOMO/HUMO transition (being some what polar (pi/Pi* ) under goes bathochromic shift.

3. LOMO of Congo Red is correctly reported.

4. So 1.5% error can be ignored.