Surface modification with multiphilic ligands at detectable well defined active positions of nano-object of giant wheel shaped molybdenum blue showing third-order nonlinear optical properties

The reaction of an aqueous solution of sodium molybdate with L-tyrosine in the presence of reducing agent results in the formation of a new compound of the formula of Na8CO3[Mo-126(VI) (Mo28O462H14)-O-V(H2O)(46)(HOC6H4CH2CH(NH3+)COO-)(12)]center dot ca. 200H(2)O. The compound contains nanosized ring-shaped clusters with tyrosine ligands possessing different types of functional groups (one -CO2, one NH3+ and one -ArOH) coordinated through the carboxylate groups at the active sites of the inner cavity. Importantly, the result demonstrates that not only active sites/areas of the cluster surface under a specified condition can be directly monitored and detected but also novel type surfaces within the cavity of a nano-structured ring-shaped cluster can be generated simultaneously. The nonlinear optical properties of the new cluster are studied using the well-known Z-scan technique at a wavelength of 532 nm with laser pulse duration of 18 ps. The results show that the new cluster exhibits interesting self-focusing nonlinear optical response with the real and imaginary parts of the third-order nonlinear optical susceptibility chi((3)) being 1.069 x 10(-13)(esu) and 2.529 x 10(-15)(esu), respectively, which may find application in material science. (C) 2010 Elsevier B.V. All rights reserved.