Among the various reported post synthetic modifications of colloidal nanocrystals, cation exchange (CE) is one of the most promising and versatile approaches for the synthesis of nanostructures that cannot be directly synthesized from their constitutive precursors. Numerous studies have reported on the qualitative analysis of these reactions, but rigorous quantitative study of the thermodynamics of CE in colloidal nanoparticles is still lacking. We demonstrate using isothermal titration calorimetry (ITC), the thermodynamics of the CE between cadmium selenide (CdSe) nanocrystals and silver in solution can be quantified. We survey the influence of CdSe nanocrystal diameter, capping ligands and temperature on the thermodynamics of the exchange reaction. Results obtained from ITC provide a detailed description of overall thermodynamic parameters-equilibrium constant ( K ), enthalpy (Δ H), entropy (Δ S) and stoichiometry ( n)-of the exchange reaction. We compared the free energy change of reaction (Δ G) between CdSe and Ag obtained directly from ITC for both CdSe bulk and nanoparticles with values calculated from previously reported methods. While the calculated value is closer to the experimentally obtained Δ G for bulk particles, nanocrystals show an additional Gibbs free energy stabilization of ∼-14 kJ/mol Se. We discuss a thermochemical cycle elucidating the steps involved in the overall cation exchange process. This work demonstrates the application of ITC to probe the thermochemistry of nanoscale transformations under relevant solution conditions.

The direct catalytic conversion of olefins into cyclic carbonates using peroxide and carbon dioxide is demonstrated using continuous flow reactors.

A method for the synthesis of α-amino acids by direct reductive carboxylation of aromatic imines with CO2 is described. The protocol employs readily available commercial reagents and serves as a one-step alternative to the Strecker synthesis.

X-ray photoelectron spectra were obtained for a series of M-TiO 2 samples in which transition metal ions are directly attached to the surface of anatase TiO 2 nanocrystals. The samples were prepared using CrCl 3 .nH 2 O, MnCl 2 .nH 2 O, FeCl 2 .nH 2 O, CoCl 2 .nH 2 O, NiCl 2 .nH 2 O, and CuCl 2 .nH 2 O as metal sources. We observed spontaneous air oxidation of the metal for the Mn-TiO 2 and Fe-TiO 2 samples as indicated by rapid color changes. X-ray photoelectron spectroscopy (XPS) data confirms the oxidation states of the metals Cr, Co, and Ni are unchanged from the precursor, Mn and Fe are oxidized, and Cu is in a more reduced state. The reduction of Cu likely arises during the XPS experimenta phenomenon well-documented in the literature; whereas UV-visible data of the Cu-TiO 2 dispersions are consistent with Cu 2+ .