Postclustering Dynamic Covalent Modification for Chirality Control and Chiral Sensing

Abstract

Cluster-based functional materials are appealing, because clusters are well-defined building units that can be rationally incorporated for the tuning of structures and properties. Postclustering modification (PCM) allows for tailoring properties through the structural modification of a cluster with preorganized funtional groups. By introducing aldehydes into a robust gold-silver cluster via a protection-deprotection process, we manage to synthesize a new cluster bearing six reactive sites, which are available for PCM through dynamic covalent imine bonds formation with chiral monoamines. Chirality is transferred from the amine to the gold-silver cluster. The homochirality of the resulted cluster has been confirmed by X-ray structural determination and CD spetroscopy. Intense CD signals make it practical for chiral recognition and ee value determination of chiral monoamines. The strategy of prefunctionalizing of cluster and the concept of PCM open a broader prospect for cluster design and applications.

Studying mass spectrometric behaviors of {Au6Ag2(C)[PPh2(4‐CH3‐Py)]6}(BF4)4 and {Au8[(PPh3)2O]3(PPh3)2}(NO3)2 by electrospray time‐of‐flight mass spectrometry and electrospray ion trap mass spectrometry

“…As shown in Fig. 3, the fragmentation rate is increasing with the rise of RF amplitude, suggesting there will be more and more fragment ion [Au 5 Ag(C)(L 1 ) 4 …”

“…In order to systemically study the fragments produced by the "collision cooling", a fragmentation rate [the ratio of fragment intensity vs total (precursor plus fragment) intensities of MS signals] [26,27] is introduced. Figure 3 shows a curve plotted of the fragmentation rate against the radiofrequency (RF) amplitude for the pair of precursor ion [Au 6 Ag(C)(L 1 ) 6 3+ ] and fragment ion [Au 5 Ag(C)(L 1 ) 4 2+ ] under three types of buffer gases (helium, nitrogen, and argon) with the same pressure. The details of the match between the precursor ion [Au 6 Ag(C)(L 1 ) 6 3+ ] and fragment ion [Au 5 Ag(C)(L 1 ) 4 2+ ] are shown in the Supporting Information.…”

“…Metal clusters composed by metal cores and organic ligands have brought about an upsurge in research because of their interesting properties, such as catalysis, [1][2][3] chirality, [4,5] electrical conductivity, [6,7] luminescence, [8][9][10] C-H activation, [11] and so on. The properties of metal clusters depend on their structures, chemical compositions, and bondings.…”

Emerging enantiomeric resolution materials with homochiral nano-fabrications

“…48 By mixing the aldehyde groups of metal cluster with chiral amine, homochiral cluster were formed through the dynamic covalent imine bonds (Fig. 6A).…”

“…(C) CD spectra of enantiomers 4a (blue trace) and 4b (red trace), and UV-vis spectrum of 4a (dotted line). Reproduced with permission of the American Chemical Society from ref 48. .…”