Synthesis and optical properties of guanosine 5'-monophosphate-mediated CdS nanostructures: an analysis of their structure, morphology, and electronic properties.

The present manuscript reports the synthesis, characterization, and analysis of electronic properties of water-soluble guanosine 5'-monophosphate (GMP)-mediated CdS quantum dots (Q-dots). The morphology, size, and size distribution of these particles have been analyzed by transmission electron microscopy. These particles display the onset of absorption at 2.7 eV and emission at 2.2 eV. In comparison to other monophosphates of RNA (AMP, UMP, and CMP), GMP-mediated CdS exhibits enhanced electronic properties. The participation of different functional groups of GMP in the stabilization of CdS nanoparticles has been analyzed by FTIR and (1)H and (31)P NMR spectroscopic techniques. Two types of binding sites involving phosphorus centers are indicated by IR and (31)P NMR studies. The conversion of CdS Q-dots to nanorods has been monitored by using electron microscopy, steady-state optical and fluorescence measurements, and a fluorescence lifetime system coupled with anisotropy accessories. The observed change in the morphology and electronic behavior of GMP- and RNA-mediated CdS nanostructures is discussed on the basis of their structural difference.