cm8b00328_si_002.cif (2.21 MB)
Tailoring the Crystal Structure of Nanoclusters Unveiled High Photoluminescence via Ion Pairing
dataset
posted on 2018-03-26, 00:00 authored by Megalamane
S. Bootharaju, Sergey M. Kozlov, Zhen Cao, Aleksander Shkurenko, Ahmed M. El-Zohry, Omar F. Mohammed, Mohamed Eddaoudi, Osman M. Bakr, Luigi Cavallo, Jean-Marie BassetThe
lack of structurally distinct nanoclusters (NCs) of identical
size and composition prevented the mechanistic understanding of their
structural effects on ion pairing and concomitant optical properties.
To produce such highly sought NCs, we designed a new monothiolate-for-dithiolate
exchange strategy that enabled the selective transformation of the
structure of a NC without affecting its metal atomicity or composition.
Through this method, a bimetallic [PtAg28(BDT)12(PPh3)4]4– NC (1) was successfully synthesized from [PtAg28(S-Adm)18(PPh3)4]2+ NC (2) (S-Adm, 1-adamantanethiolate; BDT, 1,3-benzenedithiolate; PPh3, triphenylphosphine). The determined X-ray crystal structure
of 1 showed a PtAg12 icosahedron core and
a partially exposed surface, which are distinct from a face-centered
cubic PtAg12 core and a fully covered surface of 2. We reveal through mass spectrometry (MS) that 1 forms ion pairs with counterions attracted by the core charge of
the cluster, which is in line with density functional simulations.
The MS data for 1, 2, and other NCs suggested
that such attraction is facilitated by the exposed surface of 1. The formation of ion pairs increases the photoluminescence
(PL) quantum yield of 1 up to 17.6% depending on the
bulkiness of the counterion. Unlike small counterions, larger ones
are calculated to occupy ≤90% of the volume near the exposed
cluster surface and to make the ligand shell of 1 more
rigid, which is observed to increase the PL. Thus, the developed synthesis
strategy for structurally different NCs of the same size and composition
allows us to probe the structure–property relationship for
ion pairing and concomitant PL enhancement.