Merocyanine dyes Synthesis , properties , application

1. Merocyanine dyesSynthesis, properties, application m Eugenij Poronik

2. Introduction Brooker’s merocyanine J Am Chem Soc 73(1951) 5326 Merocyanine 540 • Merocyanine dyes are considered as a superposition of neutral (I) and zwitterionic (III) forms. • There is an ideal state, so-called “cyanine limit”,which relates to equal contributions of the polyene-type andthe zwitterionic resonance structures. • Merocyanines in the cyanine limit arealso dyes with most favorable absorption properties, that is,intense absorption bands at the longest possible wavelengthfor a given polymethine chain, and they possessenhanced thermal and photochemical stability owing toequalized bond orders

3. Synthesis Simple Merocyanines(n = 0) 87% J Am Chem Soc 73 (1951) 5326 50% Bull Korean ChemSoc24 (2003) 569 Zeromethine merocyanines (n = 0) are commonly prepared by the reactionof nitrogen heterocycles containing a leaving groupwith active methylene bases.

4. J Chem Soc, Perkin Trans 2(1997) 1055 Tetr. Lett39(1998) 1763

5. Merocarbocyanines (n = 1) Russ Chem Bull, Int Ed54 (2005) 2417 DyesPigm60 (2004) 215 Dyes Pigm 58 (2003) 83 J Mater Chem9 (1999) 2991 The classical route for the synthesis ofmerocarbocyanine dyes is a reaction of heterocyclic enamines orcorrespondingsalts with hydroxybenzaldehydes or their heterocyclic analogs.

6. Dyes Pigm 58 (2003) 83 The capability of merocyanines to produce salts is used for their isolation

7. Using of aldehyde analogous A versatile method for the preparation of merocyanine dyes involves thetreatment of methyl-substituted quaternary salts of nitrogen heterocycleswith anilinomethylene derivatives of heterocyclic ketones.

8. Acetanilidomethylene-substituted heterocyclesare useful, versatile synthones,and they have been extensively used for the preparation of merocyaninedyes

9. Dimethylaminomethylene derivatives prepared by treatment of carboandheterocyclic ketones with DMF-DMA or with DMF in acetic anhydridehave been used for the synthesis of various merocyanine dyes

10. Tetr. Lett. 42(2001) 6129 This reaction is suitable for the preparation of symmetrical merocyanines (ketocyanines), difunctionalized ketones are condensed with two equivalents of quaternary salt Russ Chem Bull45(1996)164

11. From w-aldehydes Org Lett5(2003) 3143 Angew Chem Int Ed 36(1997) 2765 The condensation of w-aldehydeswithactive methylene compounds in in the absence of the base leads to merocyanines in moderate yields J Am Chem Soc121(1999) 8146 Aza derivatives of w-aldehydes are the most utilizedstarting materials for the preparation of merocyanine dyes since thefirst merocyanine syntheses

12. Synthesis(1999) 2103 Angew Chem Int Ed 38(1999) 1649 • A versatile one-pot synthesis of merocyaninesbased on multi-step reaction of nitrogen heterocycles with activemethylene compoundsand DMF in acetic anhydride [45, 59]. • The process is uninfluenced by impurities in starting compounds, includingwater, and can be used in combinatorial synthesis.

13. 51% Tetrahedron 55(1999)14421

14. Heterocycl Commun11(2005) 129

15. Long-Bridge Merocyanines J Chem Soc, Faraday Trans 93(1997) 3653 Similar methodology as utilized for the synthesis of simple merocyanines is useful for the preparation of their cyclic higher vinilogues.

16. J Appl Spectroscopy 71(2004)641

17. Structure and Isomerization • Merocarbocyanines can exist as four transoid isomers with regard to two double bonds of the bridge fragment.

18. Solvatochromism Acetone, 96 % ethanol, acetic acid, water, DMF, acetonitrile, 2-propanol, methanol, THF and DMSO Solvatochromic merocyanines exhibit bathochromic or hypsochromic shifts in solvents of various polarities. Other characteristics such as dipole moments, fluorescence, and NLO properties change as well.

19. Ion Sensors Titration with Ni2+

20. Anal ChimActa 504(2004) 227 Calcium-sensitive chromogenic crown ethers. The water-soluble dye (R = CH3) can be used for calcium ion sensing in solution while lipophilized derivative (R = C12H25) has been successfully applied to ion-exchange type optode PVC membranes.

21. Molecular Aggregation • Molecular aggregates are self-assemblies of molecules by non-covalent interactions. • They have significant technological applications such as molecularoptoelectronic devices, fluorescence probes for mitochondrial membrane,and as models of antenna systems that function to transfer energy and electronsin biological systems

22. Langmuir 20 (2004) 5718-5723 Aggregation processes of merocyanine dyes on lyposomes (artificial cellmembranes)

23. Spiropyrans

24. 3D data storage media Schematic representation of a cross-section through a 3D optical storage disc (yellow) along a data track (orange marks). Four data layers are seen, with the laser currently addressing the third from the top. The laser passes through the first two layers and only interacts with the third, since here the light is at a high intensity. No commercial product based on 3D optical data storage has yet arrived on the mass market,although several companies are actively developing the technology and claim that it may become available "soon".

25. Photodynamic therapy Merocyanine 540 J Photochem Photobiol B 32 (1996) 27-32

26. Non-linear properties d = 115 GM d = 25 GM d = 35 GM d = 125 GM at 1064 nm Optics Commun 281 (2008) 6072-6079

27. n = 1; dmax = 2300 GM (at 826 nm) n = 2; dmax = 5000 GM (at 900 nm) n = 3; dmax = 10000 GM (at 980 nm) J. Mater. Chem. 19 (2009) 7503–7513

28. Conclusions • Merocyanine dyes with nitrogen donor and carbonyl acceptor fragments have found a wide application in various areas of science and technology, including optical and fluorescent sensors, silver halide photography, optical data storage, and photodynamic therapy. • The synthetic methods on merocyanines preparation allow to obtain dyes with a wide variety of electron donor and acceptor parts, and hence with various properties. • Recent progress in computer science and nanotechnology have stimulated new investigations, including the studies in non-linear optics, and new areas of medicine.

29. Thank you for your attention