1
050
H. DETERT, O. SADOVSKI AND E. SUGIONO
3
1
reduced in the excited state. The fluorescence of OPVs
with a pronounced acceptor–donor–acceptor structure
has been reported to be influenced by the solvent.
Increasing polarity resulted in bathochromism and de-
creasing fluorescence efficiencies due to stabilisation via
4. Gurge RM, Hickl M, Krause G, Lahti PM, Hu B, Yang Z, Karasz
FE. Polym. Adv. Technol. 1998; 9: 504–510.
5
. Krasovitskii BM, Bolotin BM. Organic Luminescent Materials.
VCH: Weinheim, 1988.
6. Kauffman JM, Moyna G. J. Org. Chem. 2003; 68: 839–853.
7
. M u¨ llen K, Wegner G. Electronic Materials: The Oligomer Ap-
proach. Wiley-VCH: Weinheim, New York, 1998.
15
intramolecular charge transfer in the excited state. The
UV-spectra of aza-DSBs 2–7 are only slightly shifted to
lower energies compared with the isocyclic 1, indicating
minor effects of the ꢃ-electron-deficient heterocycles. On
protonation, the electron-accepting ability of the hetero-
cyclic units increases greatly, thus facilitating stabilisa-
tion of the excited state via charge transfer and non-
radiative decay.
8
. Drefahl G, Pl o¨ tner G, Buchner G. Chem. Ber. 1961; 94: 1825–1833.
9. Drefahl G, Pl o¨ tner G, Hertzer H. Chem. Ber. 1961; 94: 1833–
839.
0. Kelley CJ, Ansu K, Budisusetyo W, Ghiorghis A, Qin Y,
1
1
Kauffman JM. J. Heterocyc. Chem. 2001; 38: 11–23.
11. Hall JH, Chien JY, Kauffman JM, Litak PT, Adams JK, Henry
RA, Hollins RA. J. Heterocycl. Chem. 1992; 29: 1245–1273.
2. Kauffman JM, Khalaj A, Litak PT, Bajwa GS, Novinski JA.
1
J. Heterocycl. Chem. 1994; 31: 957–965.
13. Siegrist AE, Meyer HR, Gassmann P, Moss S. Helv. Chim. Acta
980; 63: 1311–1334.
1
1
1
4. Detert H, Sugiono E. J. Phys. Org. Chem. 2000; 13: 587–590.
5. Detert H, Schollmeyer D, Sugiono E. Eur. J. Org. Chem. 2001;
2927–2938.
CONCLUSION
1
6. Strehmel B, Sarker AM, Detert H. ChemPhysChem 2003; 4: 249–
2
59.
7. Detert H, Schollmeyer D. Synthesis 1999; 999–1004.
1
,4-Bis(pyridylethenyl)benzenes with electron donating
1
or withdrawing side chains on the central ring were
prepared via Horner olefinations. Solvatochromism of
the electronic transitions is small but protonation en-
hances the electron-attracting power of the azines and
results in bathochromism of absorption and fluorescence
and reduced quantum yields. As for other N-heterocyclic
bases, the basicity of chromophores 2–6 that contain
pyridine rings increases upon excitation, whereas the
quinoline 7 is a stronger base in its ground state.
18. Detert H, Sugiono E, Kruse G. J. Phys. Org. Chem. 2002; 15:
38–641.
9. Lindauer H, Czerney P, Mohr GJ, Grummt U-W. Dyes Pigments.
994; 26: 229–235.
20. Lindauer H, Czerney P, Grummt U-W. J. Prakt. Chem. 1995; 337:
16–221.
6
1
1
2
2
2
1. Czerney P, Grummt U-W. Sensors Actuators B 1997; 39: 395–400.
2. Horner L, Hoffmann H, Klink W, Ertel H, Toscano VG. Chem.
Ber. 1962; 95: 581–601.
2
2
3. Stalmach U, Detert H. J. Prakt. Chem. 2000; 342: 10–16.
4. Peng Z, Gharavi AR, Yu L. J. Am. Chem. Soc. 1997; 119: 4622–
4
632.
5. Detert H, Sugiono E. J. Prakt. Chem. 1999; 341: 358–362.
6. Feit T. J. Heterocycl. Chem. 1974; 11: 295–297.
7. Reichardt C. Solvents and Solvent Effects in Organic Chemistry
2
2
2
REFERENCES
(
2nd edn). VCH: Weinheim, 1988; 286–311.
8. Lackowicz JR. Principles of Fluorescence Spectroscopy (2nd
edn). Kluwer: New York, 1999.
2
1
2
3
. Burroughes JH, Bradley DDC, Brown AR, Marks RN, Mackay K,
Friend RH, Burn PL, Holmes AB. Nature 1990; 347: 539–541.
. Jenekhe SA, Wynne KJ (eds). Photonic and Optoelectronic
Polymers. ACS Symp. Ser. 672: Washington, 1997.
29. F o¨ rster Th. Z. Elektrochem. 1950; 54: 43.
30. Becker HGO. Einf u¨ hrung in die Photochemie (2nd edn). Thieme:
Stuttgart, 1983.
31. Jaff e´ HH, Orchin M. Theory and Application of Ultraviolet
Spectroscopy. Wiley: New York, 1970; 425.
. Kraft A, Grimsdale AC, Holmes AB. Angew. Chem. 1998; 110:
4
16–443; Angew. Chem., Int. Ed. Engl. 1998; 37: 402–408.
Copyright # 2004 John Wiley & Sons, Ltd.
J. Phys. Org. Chem. 2004; 17: 1046–1050