Reaction Monitoring and Structural Characterisation of Coordination Driven Self-Assembled Systems by Ion Mobility-Mass Spectrometry

Nature creates exquisite molecular assemblies, required for the molecular-level functions of life, via self-assembly. Understanding and harnessing these complex processes presents an immense opportunity for the design and fabrication of advanced functional materials. However, the significant industrial potential of self-assembly to fabricate highly functional materials is hampered by a lack of knowledge of critical reaction intermediates, mechanisms, and kinetics. As we move beyond the covalent synthetic regime, into the domain of non-covalent interactions occupied by self-assembly, harnessing and embracing complexity is a must, and non-targeted analyses of dynamic systems are becoming increasingly important. Coordination driven self-assembly is an important subtype of self-assembly that presents several wicked analytical challenges. These challenges are “wicked” due the very complexity desired confounding the analysis of products, intermediates, and pathways, therefore limiting reaction optimisation, tuning, and ultimately, utility. Ion Mobility-Mass Spectrometry solves many of the most challenging analytical problems in separating and analysing the structure of both simple and complex species formed via coordination driven self-assembly. Thus, due to the emerging importance of ion mobility mass spectrometry as an analytical technique tackling complex systems, this review highlights exciting recent applications. These include equilibrium monitoring, structural and dynamic analysis of previously analytically inaccessible complex interlinked structures and the process of self-sorting. The vast and largely untapped potential of ion mobility mass spectrometry to coordination driven self-assembly is yet to be fully realised. Therefore, we also propose where current analytical approaches can be built upon to allow for greater insight into the complexity and structural dynamics involved in self-assembly

Gas phase synthesis and reactivity of dimethylaurate

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)A combination of multistage mass spectrometry experiments and DFT calculations were used to examine the synthesis and reactivity of dimethylaurate. Collision induced dissociation (CID) of [(CH(3)CO(2))(4)Au](-) proceeded via reductive elimination of acetylperoxide to yield the diacetate [CH(3)CO(2)AuO(2)CCH(3)](-), which in turn underwent sequential CID decarboxylation reactions to yield the organoaurates [CH(3)CO(2)AuCH(3)](-) and [CH(3)AuCH(3)](-). The unimolecular chemistry of the dimethylaurate proceeds via a combination of bond homolysis to yield the methyl aurate radical anion [CH(3)Au](center dot-) as well as formation of the gold dihydride [HAuH](-). DFT calculations reveal that the latter anion is formed via a 1,2-dyotropic rearrangement to yield the isomer [CH(3)CH(2)AuH](-), followed by a beta-hydride elimination reaction. Ion-molecule reactions of [CH(3)AuCH(3)](-) with methyl iodide did not yield any products even at relatively high concentrations of the neutral substrate and longer reaction times, indicating a reaction efficiency of less than 1 in 20 000 collisions. DFT calculations were carried out on two different potential energy surfaces (PES) for the reaction of [CH(3)AuCH(3)](-) with CH(3)I: (i) an S(N)2 mechanism proceeding via a side-on transition state; and (ii) a stepwise mechanism proceeding via oxidative addition followed by reductive elimination. Both pathways have significant endothermic barriers, consistent with the lack of C-C bond coupling products being formed in the experiments. Finally, the reactivity of [CH(3)AuCH(3)](-) is compared to the previously studied [CH(3)AgCH(3)](-) and [CH(3)CuCH(3)](-), as well as condensed phase studies on dimethylaurate salts.o TEXTO COMPLETO DESTE ARTIGO, ESTARÁ DISPONÍVEL À PARTIR DE AGOSTO DE 2015.393786558662ARC [DP0558430]Faculty of Science for a Science Faculty ScholarshipUniversity of MelbourneFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)ARC [DP0558430