Functional Organic Molecules: Towards Biosensors and Phototherapeutics

Design of dye molecules that absorb in the long wavelength region (> 650 nm) has been the subject of active research in recent years, because such efficient molecules can have potential optoelectronic and biomedical applications. Of particular interest systems are the squaraine and croconaine dyes that exhibit strong absorption in the near-infrared (NIR) and infrared (IR) regions. Our investigations on the photophysical properties of a few novel heavy atom substituted NIR absorbing squaraine dyes revealed that these dyes can have potential application as sensitizers in photodynamic therapy.1

       Another area of our interest has been the designing of novel functional organic systems which can act as selective probes for biologically important molecules such as nucleotides, nucleic acids and proteins. Of the various molecules investigated; the design of water soluble cyclophanes that undergo selective interactions with biomolecules has been challenging in recent years. In this context, we designed a few novel cyclophane derivatives and have investigated their interactions with important biomolecules. Our studies demonstrate that these molecules undergo selective interactions with nucleotides such as GTP and ATP and also with DNA depending on the spacer and bridging units as compared to proteins and micelles.2 This presentation will highlight our efforts towards the design, photophysical, photobiological and light harvesting properties of various squaraine and croconaine dyes as well as the bimolecular recognition abilities of novel functionalized cyclophanes.

1Selected recent references: Jisha, V. S.; Arun, K. T.; Hariharan, M.; Ramaiah, D. J. Am. Chem. Soc. 2006, 128, 6024; Adarsh, N.; Avirah, R. R.; Ramaiah, D.  Org. Lett. 2010, 12, 5720; Avirah, R. R.; Jyothish, K.; Suresh, C. H.; Suresh, E.; Ramaiah, D. Chem. Commun. 2011, 47, 12822; Avirah, R. R.; Jayaram, D. T.; Adarsh, N.; Ramaiah, D. Org. Biomol. Chem. 2012, 10, 911; D. T. Jayaram, B. H. Shankar and D. Ramaiah, RSC Adv., 2013, 3, 13463; Suneesh C. Karunakaran, P. S. Saneesh Babu, Bollapalli Madhuri, Betsy Marydasan, Albish K. Paul, Asha S. Nair, K. Sridhar Rao, Alagar Srinivasan, Tavarekere K. Chandrashekar, Ch. Mohan Rao, Radhakrishna Pillai and D. Ramaiah   ACS Chem. Biol., 2013, 8, 127.

2Selected recent references: Neelakandan, P. P.; Hariharan, M.; Ramaiah, D. J. Am. Chem. Soc. 2006, 128, 11334; Neelakandan, P. P.; Ramaiah, D. Angew. Chem., Int. Ed. 2008, 47, 8407; Sanju, K. S.; Neelakandan, P. P.; Ramaiah, D. Chem. Commun. 2011, 47, 1288; Sanju, K. S.; Neelakandan, P. P.; Ramaiah, D. Chem. Commun. 2011, 47, 1288; B. Marydasan, A. K. Nair and D. Ramaiah, RSC Adv., 2013, 3, 3815.