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MODELING OF ENERGETICAL PROPERTIES OF BIS-AZO COMPOUNDS. ROLE OF TAUTOMERIZATION

MODELING OF ENERGETICAL PROPERTIES OF BIS-AZO COMPOUNDS. ROLE OF TAUTOMERIZATION. Alytis Gruodis, Nurija Kelminskien ė Department of General Physics and Spectroscopy, Vilnius university. Material. 8th decade of XX century– electrophotographic dyes

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MODELING OF ENERGETICAL PROPERTIES OF BIS-AZO COMPOUNDS. ROLE OF TAUTOMERIZATION

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  1. MODELING OF ENERGETICAL PROPERTIESOF BIS-AZO COMPOUNDS.ROLE OF TAUTOMERIZATION Alytis Gruodis, Nurija Kelminskienė Department of General Physics and Spectroscopy, Vilnius university

  2. Material 8th decade of XX century– electrophotographic dyes 1th decade of XXI century– molecular device (SC!) (in poled polymer matrix, 1MV/cm) Bisazo π-conjugated derivative – Stable, no photochemistry 2,7-diamino-fluorenone bisazo-pigmentum NA1 , containing [-O-Me], EE,EQ,QQ conformers (tautomers) GU3 , containing two [–Cl], EE,EQ,QQ conformers (tautomers).

  3. NA1 (R=[-C6H4-OMe]) GU3 (R=[-C6H4Cl2]), where fluorenone is connectedin position 2 and 7 via [-N=N-] bridge to quinine.

  4. Maintask Probable geometry of molecule in layered structures Explanation of experimental absorption spectrum Molecular energetics

  5. Techniqueofmodeling • Quantum chemical methods • Gaussian09 software • 6/31G(d) basisset Optimization of molecular geometry Density functional B3LYP method Calculation of electronic excitation Semiempirical ZINDO method for singlets only Evaluation of charge redistribution Semiempirical TD method for siglets only

  6. Intramolecularprotontransfer • Enol-Quininetautomerisation • Trans-cistransition Proton acceptor Proton donor

  7. Secondtask How many different forms? EE, EQ, QQ ?

  8. Two molecular motions • 1) proton jump in tautomerization process allows the existence ofboth - hydrazone-quinine form (Q) and azo-enolform (E); 2)conformational rotation of quinine fragment allows the existenceof partially ’broken’ pi-conjugatedsystem: Generally, three type of differenttautomers(EE, EQ, QQ) for NA1 and GU3 derivatives must beanalyzed

  9. Problem: EE, EQ, QQ ?

  10. 1. Geometryoptimization • Gaussian09 • B3LYP/6-311G(d,p) opt

  11. NA1

  12. GU3

  13. Optimizationofgeometry • Threetautomiricforms: EE,EQ,QQ. Nineformsexcluded EQ ir QQ – could be non-planartautomers. Benzenederivatives ( [-O-Me] ir [–Cl]) are orientedby angle 60 deg

  14. 2. Electronicexcitation Semiempirical ZINDO method STO-3G basis

  15. Acid solution Basis solution Basis solution

  16. 3. Chargeredistribution Whatabout CT state inregionof 2 eV? Gaussian09, TD(singlets,nstate=6) HF/6-31G sp Chargeredistributionbetweenquinine, fluorenoneandquinine, Derivatives R are notincluded ( partialskeletonredistribution)

  17. Conclusions EQ form

  18. Coexixtence of both: EE and EQ forms depending of the pH of media

  19. Conclusions • Coexistence of both: EE and EQ forms depending of the pH of media • Fragmental rotation in range 30 deg (15 deg from equilibrium) like swinging. Excluding of band et 2 eV from 40 deg. • Partially broken pi-conjugated system • CT transition for EQ form

  20. Thank you for attention

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