Optical Properties of Hybrid Nanomaterials

We have recently initiated a detailed research program on the design of nanoparticle conjugates of organic/inorganic molecules which enable the coupling of the intrinsic functionalities of molecular systems (binding, self-assembly, switching etc.) with the size and shape dependent optoelectronic properties of nanomaterials.1 The presentation will provide examples of modulating the optical properties of nanomaterials by integrating them into higher order assemblies using electrostatic/supramolecular/covalent approaches.2-11 The presentation will also highlight our recent efforts to understand the interfacial properties of these hybrid nanomaterials. 

Recent studies from our group have shown that the organization of molecules on surfaces can be fine tuned by introducing proper functional moieties and these aspects will be discussed.12-14 We have recently developed a novel strategy for inducing chirality to metal nanoparticle assembly by growing them on chiral surfaces having reduced elements of symmetry. The surface plasmon coupled circular dichroism observed in these systems originate from the asymmetric organization of metal nanoparticles on surface resulting in bisignated CD signals.15 Mirror image relationship in the CD spectra indicates that the chiral molecules on the D- and L- peptide nanotubes drive the organization of nanoparticles in two different ways and these aspects will be discussed.

1.	K. G Thomas, P. V. Kamat, Acc. Chem. Res. 2003, 36, 888.
2.	K. G. Thomas, chapter entitled “Surface plasmon resonances in nanostructured materials,” in Nanomaterials chemistry: Novel aspects and new directions, C.N.R. Rao, A. Mueller. A. K. Cheetham (Eds.) Wiley-VCH (2007) pp 185-216.
3.	S. T. S. Joseph, B. I. Ipe,  P. Pramod, K. G. Thomas, J. Phys. Chem. B 2006, 110, 150.
4.	P. K. Sudeep, S. T. S. Joseph, K. G. Thomas, J. Am. Chem. Soc. 2005, 127, 6517.
5.	P. Pramod, S. T. S. Joseph, K. G. Thomas, J. Am. Chem. Soc. 2007, 129, 6712. 
6.	R. Vinayakan, T. Shanmugapriya, P. V. Nair, P. Ramamurthy, K. G. Thomas, J. Phys. Chem. C  2007, 111, 10146.
7.	P. V. Nair, K. G. Thomas, J. Phys. Chem. Lett. 2010, 111, 2094.
8.	B. I. Ipe, K. Yoosaf, K. G. Thomas, J. Am. Chem. Soc. 2006, 128, 1907.
9.	K. Yoosaf, B. I. Ipe,  C. H. Suresh,  K. G. Thomas, J. Phys. Chem. C 2007, 111, 12839. 
10.	P. Pramod, K. G. Thomas, Adv. Mater.  2008, 20, 4300.
11.	C. C. Soumya, P. Pramod, K. G. Thomas, Adv. Mater 2010 (submitted).
12.	K. Yoosaf,  P. V. James, A. R. Ramesh, C. H. Suresh, K. G. Thomas, J. Phys. Chem. C. 2007; 111, 14933.
13.	K. Yoosaf,  A. R. Ramesh, J. George, C. H. Suresh,  K. G. Thomas, J. Phys. Chem. C. 2009, 113, 11836.
14.	A. R. Ramesh, K. G. Thomas, Chem. Commun., 2010, 46, 3457. 
15.	J. George, K. G. Thomas,  J. Am. Chem. Soc., 2010, 132, 2502.