Meso-2,3-dimercaptosuccinic acid: from heavy metal chelation to CdS quantum dots

Abstract

DMSA (meso-2,3-dimercaptosuccinic acid) a prescription drug and a heavy-metal chelating agent, is shown to act both as a sulfur source and a capping agent in the aqueous synthesis of CdS quantum dots under mild conditions. Release of sulfur from DMSA depends on the solution pH and the reaction temperature. Combination of 70 C and pH 7.5 was determined as the best reaction conditions for a well-controlled reaction. Changing the SH/Cd ratio from 2.5 to 7 provides QDs emitting from blue to orange with 6-9% quantum yield with respect to Rhodamine 2B. Viability tests performed with HeLa and MCF-7 cell lines indicate a very low cytotoxicity. Mild reaction conditions and biocompatibility makes these particles valuable candidates for bio applications.

Sensitization of SnO2 Single Crystals with Multidentate‐Ligand‐Capped PbS Colloid Quantum Dots to Enhance the Photocurrent Stability

“…The FTIR spectrum of unbound DMSA also has a characteristic C=O stretching mode at 1688.7 cm −1 , but the peak is also suppressed in the spectrum of DMSA‐bound PbS and is replaced by the peaks at 1560.2 cm −1 and 1385.7 cm −1 that respond to the asymmetric and symmetric stretching modes of −COO − from DMSA. Similar spectral changes were also reported in the literature . The replacement of the peak at 1688.7 cm −1 is attributed to the carboxyl groups’ coordination with the QD surface.…”

“…The replacement of the peak at 1688.7 cm −1 is attributed to the carboxyl groups’ coordination with the QD surface. The peak at around 3420 cm −1 for −OH is not clear for neat DMSA but is observed upon anchoring to the QDs surface in accordance with what Sevinc, et al . and Negishi, et al .…”

“…This result is similar to DMSA capped CdS QDs, and Au nanoclusters reported previously. Possible explanations for this observation are (1) the deprotonation of the thiol groups through the use of triethylamine during the ligand exchange, and (2) large amounts of thiol group are bound to the surface of PbS QDs . The FTIR spectrum of OA‐capped PbS QDs reveals sharp peaks for C−H stretch (ca.…”

“…reported. The vibrational mode of the S−C bond, at around 1090 and 1020 cm −1 for DMSA‐PbS, indicates that the ligand in the system is indeed DMSA instead of oleic acid …”

“…Using multidentate ligands is advantageous over the more commonly used monodentate ligands due to their highly decreased lability, multifunctional structure, and their ability to strongly complex metal ions, the so‐called chelate effect . However, previous studies found a large distribution of particle sizes on CdS, Ag 2 S, PbS, and PbSe QDs capped with DMSA or other multidentate ligands that have been used directly as native multidentate in the synthesis. To the best of our knowledge, there are no reports on DMSA‐capped QDs obtained through a solution ligand exchange method.…”