Steven Tait Research Collection
Permanent link for this collectionhttps://hdl.handle.net/2022/26906
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Item Redox-active on-surface polymerization of single-site divalent cations from pure metals by a ketone-functionalized phenanthroline(The Journal of Chemical Physics, 2015) Skomski, Daniel; Tempas, Christopher D.; Bukowski, Gregory S.; Smith, Kevin A.; Tait, StevenMetallic iron, chromium, or platinum mixing with a ketone-functionalized phenanthroline ligand on a single crystal gold surface demonstrates redox activity to a well-defined oxidation state and assembly into thermally stable, one dimensional, polymeric chains. The diverging ligand geometry incorporates redox-active sub-units and bi-dentate binding sites. The gold surface provides a stable adsorption environment and directs growth of the polymeric chains, but is inert with regard to the redox chemistry. These systems are characterized by scanning tunnelling microscopy, non-contact atomic force microscopy, and X-ray photoelectron spectroscopy under ultra-high vacuum conditions. The relative propensity of the metals to interact with the ketone group is examined, and it is found that Fe and Cr more readily complex the ligand than Pt. The formation and stabilization of well-defined transition metal single-sites at surfaces may open new routes to achieve higher selectivity in heterogeneous catalysts.Item Sequence-Defined Macrocycles for Understanding and Controlling the Build-up of Hierarchical Order in Self-Assembled 2D Arrays(Journal of the American Chemical Society, 2019) Dobscha, J. R.; Castillo, H. D.; Li, Y.; Fadler, R. E.; Taylor, R. D.; Brown, A. A.; Trainor, C. Q.; Tait, Steven; Flood, A. H.Anfinsen's dogma that sequence dictates structure is fundamental to understanding the activity and assembly of proteins. This idea has been applied to all manner of oligomers but not to the behavior of cyclic oligomers, aka macrocycles. We do this here by providing the first proofs that sequence controls the hierarchical assembly of nonbiological macrocycles, in this case, at graphite surfaces. To design macrocycles with one (AAA), two (AAB), or three (ABC) different carbazole units, we needed to subvert the synthetic preferences for one-pot macrocyclizations. We developed a new stepwise synthesis with sequence-defined targets made in 11, 17, and 22 steps with 25, 10, and 5% yields, respectively. The linear build up of primary sequence (1°) also enabled a thermal Huisgen cycloaddition to proceed regioselectively for the first time using geometric control. The resulting macrocycles are planar (2° structure) and form H-bonded dimers (3°) at surfaces. Primary sequences encoded into the suite of tricarb macrocycles were shown by scanning-tunneling microscopy (STM) to impact the next levels of supramolecular ordering (4°) and 2D crystalline polymorphs (5°) at solution-graphite interfaces. STM imaging of an AAB macrocycle revealed the formation of a new gap phase that was inaccessible using only $C_3$-symmetric macrocycles. STM imaging of two additional sequence-controlled macrocycles (AAD, ABE) allowed us to identify the factors driving the formation of this new polymorph. This demonstration of how sequence controls the hierarchical patterning of macrocycles raises the importance of stepwise syntheses relative to one-pot macrocyclizations to offer new approaches for greater understanding and control of hierarchical assembly.Item Two-dimensional metal-organic coordination networks of Mn-7,7,8,8-tetracyanoquinodimethane assembled on Cu(100): Structural, electronic, and magnetic properties(Physical Review B, 2009) Tseng, Tzu-Chun; Lin, Chensheng; Shi, Xingqiang; Tait, Steven; Liu, Xiong; Starke, Ulrich; Lin, Nian; Zhang, Ruiqin; Minot, Christian; Van Hove, M. A.; Cerda, Jorge I.; Kern, KlausItem Living on the edge: Tuning supramolecular interactions to design two-dimensional organic crystals near the boundary of two stable structural phases(The Journal of Chemical Physics, 2015) Hirsch, Brandon E.; McDonald, Kevin P.; Flood, Amar H.; Tait, StevenOne of the benefits of supramolecular assemblies that form at dynamic interfaces is the opportunity to develop condensed phase systems that respond to environmental stimuli. A prerequisite of this responsive behavior is that the supramolecular system be designed to sit very near the stability of two or more crystal structures. We have created such a bi-phasic system with aryl-triazole oligomers by investigating how phase morphology is controlled by the interplay between interactions that involve the oligomer's dipolar cores ($\Delta\mu$ = 3.5 debye), van der Waals contacts of their pendant alkyl chains ($C_4$-$C_{18}$), and close-contact hydrogen bonding. Scanning tunneling microscopy experiments conducted at the solution-graphite interface allow sub-molecular resolution of the ordered monolayers to unambiguously determine the packing and structure of two principle phases, $\alpha$ and $\beta$. The system is balanced very near the edge of phase stability, evidenced by co-existent phases present over short time frames and by the changes in preference between the two 2D supramolecular assemblies that occur with small modifications to the molecular structure. We demonstrate that the bi-phasic behavior can be understood as a balance between electrostatic interactions and van der Waals contacts, two variables within a larger parameter space, allowing synthetic design to move this solution-surface system across the stability boundary of different condensed-phase structures. These findings are a foundation for the development of environmentally responsive 2D supramolecular arraysItem Reaction selectivity of homochiral versus heterochiral intermolecular reactions of prochiral terminal alkynes on surfaces(Nature Communications, 2019) Wang, T.; Huang, J.; Feng, L.; Zhang, W.; Han, D.; Xu, Q.; Zhu, J.; Lv, H.; Shan, H.; Mao, Y.; Wang, J.; Du, P.; Zhao, A.; Wu, X.; Tait, StevenControlling selectivity between homochiral and heterochiral reaction pathways on surfaces remains a great challenge. Here, competing reactions of a prochiral alkyne on Ag(111): two-dimensional (2D) homochiral Glaser coupling and heterochiral cross-coupling with a Bergman cyclization step have been examined. We demonstrate control strategies in steering the reactions between the homochiral and heterochiral pathways by tuning the precursor substituents and the kinetic parameters, as confirmed by high-resolution scanning probe microscopy (SPM). Control experiments and density functional theory (DFT) calculations reveal that the template effect of organometallic chains obtained under specific kinetic conditions enhances Glaser coupling between homochiral molecules. In contrast, for the reaction of free monomers, the kinetically favorable reaction pathway is the cross-coupling between two heterochiral molecules (one of them involving cyclization). This work demonstrates the application of kinetic control to steer chiral organic coupling pathways at surfaces.Item Redox-active ligand controlled selectivity of vanadium oxidation on Au(100)(Chemical Science, 2018) Tempas, C.D.; Morris, T.W.; Wisman, D.L.; Williams, C.G.; Polezhaev, A.V.; Caulton, K.G.; Tait, Steven; Le, D.; Din, N.U.; Rahman, T.S.; Wang, M.Item 𝑛-alkanes on Pt(111) and on C(0001) / Pt(111): Chain length dependence of kinetic desorption parameters(The Journal of Chemical Physics, 2006) Tait, Steven; Dohnalek, Zdenek; Campbell, Charles T.; Kay Bruce D.Item 𝑛-alkanes on MgO(100). II. Chain length dependence of kinetic desorption parameters for small 𝑛-alkanes(The Journal of Chemical Physics, 2005) Tait, Steven; Dohnalek, Zdenek; Campbell, Charles T.; Kay Bruce D.Item Growth and sintering of Pd clusters on α-$A1_2$ $O_3$ (0001)(The Journal of Chemical Physics, 2005) Tait, Steven; Ngo, Lien T.; Yu, Qiuming; Fain, Samuel C.; Campbell, Charles T.Item 𝑛-alkanes on MgO(100). I. Coverage-dependent desorption kinetics of 𝑛-butane(Journal of Chemical Physics, 2005-04-27) Tait, Steven; Dohnálek, Zdenek; Campbell, Charles; Kay, Bruce