A new method for the synthesis of fused dithiin and thiophene heterocycles, starting from 1,8-diketones and using Lawesson’s reagent (LR) and P4S10 has been developed in our laboratory. This method has uncovered two interesting reactions of LR and P4S10 which has led to the development of new fused heterocyclic rings, two types of which are particularly important in material chemistry i) tetrathiafulvalene (TTF) and ii) dithienothiophene (DTT).

Part of our research involves the synthesis of analogues of tetrathiafulvalene (TTF) and bisethylenedithiotetrathiafulvalene (BEDT-TTF). There has been continuous interest in the synthesis of derivatives of tetrathiafulvalene. This is due to metallic behavior of its radical cation salts with mono anions and electron acceptors such as TCNQ, which exhibit semi-conducting, conducting and superconducting properties. Electron-donating property of TTF has led to the synthesis of its various analogues with different potential applications such as chromophores for dyes, nonlinear optics, synthetic light-harvesting systems, liquid crystals, dendrimers, phthalocyanines, polymers, and supramolecular switches. In our laboratory various analogues of TTF have been synthesized, which involved introduction of hydrogen bonding groups and 1,4-dithiin and thiophene rings obtained through our 1,8-diketone ring formation reaction. Some of the TTF analogues are given below

Due to its interesting electrochemical and optical properties, DTT has been receiving an increasing attention. As such compounds are rich in sulfur, three “S” atoms, they are electron rich species, which make them good electron donor and important building blocks of a wide variety of materials for electronic and optical applications such as electroluminescence, two-photon absorption, exited fluorescence, photochromism, nonlinear optical chromophores, transistors with high mobilities of on/off ratios, conducting polymer and charge-transfer complexes. Easy oxidation of the thiophene sulfur of the middle one acquires the molecule fluorescence property which makes them good candidates for labelling, particularly important for biological systems, and for materials for organic light emitting devices (OLED). We have developed the DTT derivatives given below. Electropolimerization of some of them have been performed.

1. Ozturk, T.; Ertas, E.; Mert, O. Tetrahedron, 2005, 61, 1105
2. Olcay Mert, Elif Sahin, Erdal Ertas, Turan Ozturk, Engin A. Aydin, Levent Toppare, J. Electroanal. Chem., 2006, 591, 53-58.
3.E. Sezer, F. Turksoy, U. Tunca, T. Ozturk, Electrochemical Acta, 2004, 570, 101-105. 4. E. Ertas, T. Ozturk, Tetrahedron. Lett., 2004, 45, 3405-3407. 5. F. Turksoy, J. D. Wallis, U. Tunca, T. Ozturk, Tetrahedron, 2003, 59, 8012. 6.N. Saygili, R. J. Brown, P. Day, R. Hoelzl, P. Kathirgamanathan, E. R. Mageean, T. Ozturk, M. Pilkington, M. M. B. Qayyum, S. S. Turner, L. Vorwerg, J. D. Wallis, Tetrahedron, 2001, 57, 5015. 7. T. Ozturk, N. Saygili, S. Ozkara, M. Pilkington, C. R. Rice, D. A. Tranter, F. Turksoy, J. D. Wallis, J. Chem. Soc., Perkin Trans. 1, 2001, 407. 8. E. Ertas, T. Ozturk, J. Chem. Soc., Chem. Commun. 2000, 2039. 9. T. Ozturk, F. Turksoy, E. Ertas, Phosphorous, Sulfur, Silicon and Related Elements, 1999, 153-154, 417. 10. G. A. Horley, T. Ozturk, F. Turksoy, J. D. Wallis, J. Chem. Soc., Perkin I, 1998, 3225. 11. F. Leurguin, T. Ozturk, M. Pilkington and J. D. Wallis, J. C. S. Perkin Trans. I., 1997, 3173. 12. T. Ozturk, D. C. Povey and J. D. Wallis, Phosphorus and Sulfur, 1997, 122, 313. 13. T. Ozturk, Tetrahedron Lett., 1996, 37, 2821. 14. T. Ozturk, C. R. Rice, and J. D. Wallis, J. Materials Chem., 1995, 5, 1553. 15. T. Ozturk, D. C. Povey and J. D. Wallis, Tetrahedron, 1994, 50, 11205.

3-Hydroxyflavones (3HF) 1 are important candidates as fluorescent molecular sensors since they have interesting fluorescent properties, resulting from their excited state intramolecular proton transfer (ESIPT) reaction.1 This property leads to two well-separated, highly intense and solvent-dependent emission bands, the ratio of the intensities of which is strongly sensitive to the polarity and hydrogen bonding perturbations1c in proteins,2 micelles,3 and polymers.4 These bands originate from the normal excited form (N*) and the phototautomer (T*).1a,5 It has been disclosed that the introduction of an electron donor groups to the 4’-position of the 3HF increases the sensitivity of fluorescence spectra of the molecule, which has attracted the interest of research groups as two-band fluorescent dyes with a ratiometric response to different perturbations.6 This resulted in a variety of applications for substituted 3HFs as ion sensors7 and probes in the studies of organized systems such as micelles8 and phospholipid vesicles.3,9 Our group has developed various analogues of 3HF.6d-g,10,

1. a) Sengupta, P. K.; Kasha, M. Chem. Phys. Lett. 1979, 68, 382-385; b) Woolfe, G. E.;
Thistlewaithe, P. G. J. Am. Chem. Soc. 1981, 103, 6916-6923; c) Chou, P.; McMorrow, D.; Aartsma, T. J.; Kasha, M. J. Phys. Chem. 1984, 88, 4596-4599; d) McMorrow, D.; Kasha, M. J. Am. Chem. Soc. 1983, 105, 5133-5134; e). McMorrow, D.; Kasha, M. J. Phys. Chem. 1984, 88, 2235-2243; f). Strandjord, A. J. G; Barbara, P. F. J. Phys. Chem. 1985, 89, 2355-2361.
2. Sytnik, A.; Gormin, D.; Kasha, M. Proc. Natl. Acad. Sci. USA 1994, 91, 11968-11972.
3. Sarkar, M.; Ray, J. G.; Sengupta, P. K. Spectrochim. Acta A, 1996, 52, 275-278.
4. Dharia, J. R.; Johnson, K. F.; Schlenoff, J. B. Macromolecules, 1994, 27, 5167-5172.
5. Formosinho, J. S.; Arnaut, G. L. J. Photochem. Photobiol. A: Chem. 1993, 75, 21-48.
6. a) Chou, P.-T.; Martinez, M. L.; Clements, J. H. J. Phys. Chem. 1993, 97, 2618-2622; b) Swiney, T. C.; Kelley, F. D. J. Chem. Phys., 1993, 99, 211-221; c) Ormson, S. M.; Brown, R. G.; Vollmer, F.; Rettig, W. J. Photochem. Photobiol. A: Chem. 1994, 81, 65-72; d) Klymchenko, A. S.; Ozturk, T.; Pivovarenko, V. G.; Demchenko, A. P. Can. J. Chem. 2001, 79, 358-363; e) Klymchenko, A. S.; Ozturk, T.; Pivovarenko, V. G.; Demchenko, A. P. Tetrahedron Lett. 2001, 42, 7967-7970; f) Klymchenko, A. S.; Ozturk, T.; Demchenko, A. P. Tetrahedron Lett. 2001, 43, 7079-7082; g) Klymchenko, A. S.; Pivovarenko, V. G.; Ozturk, T.; Demchenko, A. P. New J. Chem. 2003, 27, 1336-1343; h) Klymchenko, A. S.; Demchenko. A. P. Phys. Chem. Chem. Phys. 2003, 5, 461-468.
7. Roshal, A. D.; Grigorovich, A. V.; Doroshenko, A. O.; Pivovarenko, V. G.; Demchenko, A. P. J. Phys. Chem. A, 1998, 102, 5907-5914.
8. a) Pivovarenko, V. G.; Tuganova, A. V.; Klymchenko, A. S.; Demchenko, A. P. Cell. Mol. Biol. Lett. 1997, 2, 355-364; b) Klymchenko, A. S.; Demchenko, A. P. Langmuir, 2002, 18, 5637-5639.
9. a) Bondar, O. P.; Pivovarenko, V. G.; Rowe, E. S. Biochem. Biophys. Acta 1998, 1369, 119-130; b) Duportail, G.; Klymchenko, A. S.; Mely, Y.; Demchenko, A. P. FEBS Lett. 2001, 508, 196-200; c) Duportail, G.; Klymchenko, A. S.; Y. Mely, Y. Demchenko, A. P. J. Fluorescence, 2002, 12, 181-185.
10.Klymchenko, A. S.; Duportail, G.; Ozturk, T.; Pivovarenko, V. G.; Mely, Y.; Demchenko, A. P. Chenistry and Biology 2002, 9, 1199
11. M’Baye, G.; Klymchenko, A. S.; Yushcheno, D. A.; Shvadchak, V. V.; Ozturk, T.; Mely, Y.; Duportail, G. Photochem. Photobiol. Sci., 2007, 6, 71-76