Transformation Pathway from CdSe Magic‐Size Clusters with Absorption Doublets at 373/393 nm to Clusters at 434/460 nm

Abstract

Divergent interpretations have appeared in the literature regarding the structural nature and evolutionary behavior for photoluminescent CdSe nanospecies with sharp doublets in optical absorption. We report ac omprehensive description of the transformation pathway from one CdSe nanospecies displaying an absorption doublet at 373/393 nm to another species with ad oublet at 433/460 nm. These two nanospecies are zero-dimensional (0D) magic-sizec lusters (MSCs) with 3D quantum confinement, and are labeled dMSC-393 and dMSC-460, respectively.S ynchrotron-based small-angle X-rays cattering (SAXS) returns ar adius of gyration of 0.92 nm for dMSC-393 and 1.14 nm for dMSC-460, and indicates that both types are disc shaped with the exponent of the SAXS form factor equal to 2.1. The MSCs develop from their unique counterpart precursor compounds (PCs), whichare labeled PC-393 and PC-460, respectively.For the dMSC-393 to dMSC-460 transformation, the proposed PCenabled pathwayiscomprised of three key steps,dMSC-393 to PC-393 (Step 1), PC-393 to PC-460 (Step 2i nvolving monomer addition), and PC-460 to dMSC-460 (Step 3). The present study provides af ramework for understanding the PC-based evolution of MSCs and howP Cs enable transformations between MSCs.

Evolution of Two Types of ZnTe Magic-Size Clusters Displaying Sharp Doublets in Optical Absorption

“…We believe that the transformation pathway from ZnTe dMSC-389 to ZnTe dMSC-420 is similar to that from CdSe dMSC-393 to CdSe dMSC-460, which is PC-enabled. 7 The present study provides both an understanding of, and evidence for, the two-pathway model proposed for semiconductor QDs, 4,5,15−18 as well as the formation of EPPh 2 H via eq 2 with high M-to-E feed molar ratios. 23,24 Similar to the advance of organic chemistry with the hypothesis of reaction intermediates of single-(S N 1) and bimolecular (S N 2) nucleophilic substitutions, 30…”

“…For the Figure 1 reaction of Zn(OA) 2 + TeTOP + HPPh 2 + HOAc (with the Te feed molar ratio of 60 mmol/kg), we now discuss the effect of HOAc. Eight reactions of 4Zn(OA) 2 + 1Te4TOP + 1HPPh 2 + xHOAc (x = 0 (1), 4 (2), 8 (3), 16 (4), 24 (5), 30 (6), 40 (7), and 48 (8)) were explored (Figure S5-1), with sampling performed the same as that for the Figure 1 Hence, sample-to-sample comparison was performed for the eight reactions. The optical absorption spectra of the samples extracted at 180, 200, and 220 °C are presented in Parts a−c of Figure 5, respectively.…”

“…For NMR and TEM analyses, we thank Analytical and Testing Center, Sichuan University, and especially Dr. Yong Luo and Dr. Shanling Wang for their TEM assistance. (5), 30 (6), 40 (7), and 48 ( 8)) (Figure S5-1). The reactions had the Te feed molar ratio of 60 mmol/kg.…”