The analysis of the third shell, the structure of the corner shared polyhedra, is more difficult to determine; even for the highly crystalline samples the calculated third-shell coordination number is ∼5 (c- NIn–In* ≈ 5), see the Supporting Information.
During the shelling process, a fresh mixture of the shell precursors was mixed with the original reaction medium containing the core NCs for the completion of the first shell growth reaction, and the resulting NCs were denoted as "a" and used as "core" NCs for the next growth reaction.
Based on excellent agreement between EXAFS experimental results and MD liquid quench simulations obtained for the first and second shells of a-IO, important conclusions about the third shell (corner-shared In–In) were derived from the MD simulations.
The MD simulations themselves can be used as a source of information about the third shell if the simulation can be validated by good agreement with the EXAFS results for the first and second shells.
The importance of the second-shell residues for the reactivity in the native enzymes has been well-documented 15a, 21 and stabilization of the dissociated catecholate in a 4 B b-like intermediate may well be facilitated by strong hydrogen bonding with for example, Arg-221 in 1,2-catechol dioxygenase.
Estimated errors for the first shell are ± 20% for coordination number, ± 0.01 Å for bond distance and ± 0.001 Å2 for Debye Waller factors, and for second shell ± 40% for coordination numbers, ± 0.04 Å for bond distances and ± 0.005 Å2 for Debye Waller factors.
The trend in R̅In–In agrees well with the experimental observation for the second shell RIn–In, Figure 9b, where the lowest value of 3.28 Å was observed for the structure deposited at 0 °C.
These difficulties in data interpretation are greatly compounded for the second shell where multiscattering effects and the suppression of the Fourier transform at the higher R-range require additional simplifying assumptions.
