Given the condition Selleck E7080 that oleylamine was excessive in the reaction systems, a plausible deduction was that the oleylamine-indium acetate complex was responsible for the formation of ITO nanocrystals. We tested this hypothesis by conducting controlled

experiments in which 2-ethylhexanate acid was absent in the reagents. No nanocrystals but agglomerations with poor colloidal stability were formed, implying an exorbitantly fast reaction kinetics of the oleylamine-indium acetate complex. Therefore, the presence of 2-ethylhexanate acid in the starting materials was critical to obtain high-quality ITO nanocrystals for the Masayuki method. This was also reflected by the fact that ITO flowers, instead of nanoparticles, formed when n-octanoic acid, instead of 2-ethylhexanate acid, was used in the starting materials (Additional file 1: Figure S1). We suspect that although majority of the 2-ethylhexanate acid reacted with oleylamine to form ammonium carboxylate salts, considering the reversible nature of the acid-base reaction, 2-ethylhexanate acid may impact in the formation of the oleylamine-indium carboxylate complex with

adequate reaction kinetics. Nevertheless, such a process is complicated. Modifications on the Masayuki method that induce evident evolutions of the metal precursors are desirable. In this regard, we designed a hot-injection approach, which separated the ligand replacements CP673451 research buy of the indium acetate and the aminolysis reactions of the metal precursors. Indium acetate was reacted with 2-ethylhexanate acid at 150°C for 1 h, allowing sufficient conversion of the indium precursor. Then, the injection of the oleylamine at 290°C initiated

the aminolysis processes to obtain ITO nanocrystals. Temporal evolution of FTIR analyses (Figure 3) on the reaction mixtures from the injection approach demonstrated the validity of our proposed reaction pathways of ligand replacements. Figure 3 Temporal evolution of the FTIR spectra of the hot-injection approach. The synthesis of ITO nanocrystals starting with 10 mol.% of tin precursor in the reagents were used as an example for Ketotifen the products obtained by the hot-injection approach. We conducted a time-dependent study of the particle morphological formation [38, 39]. The corresponding TEM images (Additional file 1: Figure S4) revealed the generation of small crystals at 3 min after the injection of oleylamine. The small particles gradually developed into nanocrystals with decent size distributions. The final product after 2 h of reaction had an average diameter of 11.4 ± 1.1 nm (Figure 4a,b). The monodisperity of ITO nanocrystals from the hot-injection approach is moderately improved compared with that of the ITO nanocrystals obtained using the Masayuki method (Additional file 1: Figure S5). HRTEM analyses reveal the high crystalline nature of the ITO nanocrystals.