Jay Siegel - Cochemist

Diindenocorannulenes: Curved Aromatics Blending Bowl-in-Bowl Assembly and Nanocarbon Material Properties

Co-reporter:Xiaoqi Tian;Loïc M. Roch;Kim K. Baldridge;Jay S. Siegel

European Journal of Organic Chemistry 2017 Volume 2017(Issue 19) pp:2801-2805

Publication Date(Web):2017/05/18

DOI:10.1002/ejoc.201700606

Directed synthesis, X-ray crystal structures, computational analysis, and characterization of dimethyldiindenocorannulene (15), cyclooctenodiindenocorannulene (16), and N-heptyldiindenocorannulenemaleimide (17) motivate a model for curved aromatics, blending bowl-in-bowl assemblies with nanocarbon material properties.

Phase Behavior of a Designed Cyclopropyl Analogue of Monoolein: Implications for Low-Temperature Membrane Protein Crystallization

Co-reporter:Livia SalvatiManni;Dr. Alexru Zabara;Dr. Yazmin M. Osornio;Jendrik Schöppe;Dr. Alexer Batyuk;Dr. Andreas Plückthun;Dr. Jay S. Siegel;Dr. Raffaele Mezzenga;Dr. Ehud M. Lau

Angewandte Chemie International Edition 2015 Volume 54( Issue 3) pp:1027-1031

Publication Date(Web):

DOI:10.1002/anie.201409791

Abstract

Lipidic cubic phases (LCPs) are used in areas ranging from membrane biology to biodevices. Because some membrane proteins are notoriously unstable at room temperature, and available LCPs undergo transformation to lamellar phases at low temperatures, development of stable low-temperature LCPs for biophysical studies of membrane proteins is called for. Monodihydrosterculin (MDS) is a designer lipid based on monoolein (MO) with a configurationally restricted cyclopropyl ring replacing the olefin. Small-angle X-ray scattering (SAXS) analyses revealed a phase diagram for MDS lacking the high-temperature, highly curved reverse hexagonal phase typical for MO, and extending the cubic phase boundary to lower temperature, thereby establishing the relationship between lipid molecular structure and mesophase behavior. The use of MDS as a new material for LCP-based membrane protein crystallization at low temperature was demonstrated by crystallizing bacteriorhodopsin at 20 °C as well as 4 °C.

Phase Behavior of a Designed Cyclopropyl Analogue of Monoolein: Implications for Low-Temperature Membrane Protein Crystallization

Co-reporter:Livia SalvatiManni;Dr. Alexru Zabara;Dr. Yazmin M. Osornio;Jendrik Schöppe;Dr. Alexer Batyuk;Dr. Andreas Plückthun;Dr. Jay S. Siegel;Dr. Raffaele Mezzenga;Dr. Ehud M. Lau

Angewandte Chemie 2015 Volume 127( Issue 3) pp:1041-1045

Publication Date(Web):

DOI:10.1002/ange.201409791

Abstract

Lipidic cubic phases (LCPs) are used in areas ranging from membrane biology to biodevices. Because some membrane proteins are notoriously unstable at room temperature, and available LCPs undergo transformation to lamellar phases at low temperatures, development of stable low-temperature LCPs for biophysical studies of membrane proteins is called for. Monodihydrosterculin (MDS) is a designer lipid based on monoolein (MO) with a configurationally restricted cyclopropyl ring replacing the olefin. Small-angle X-ray scattering (SAXS) analyses revealed a phase diagram for MDS lacking the high-temperature, highly curved reverse hexagonal phase typical for MO, and extending the cubic phase boundary to lower temperature, thereby establishing the relationship between lipid molecular structure and mesophase behavior. The use of MDS as a new material for LCP-based membrane protein crystallization at low temperature was demonstrated by crystallizing bacteriorhodopsin at 20 °C as well as 4 °C.

Die Brgenstock-Tagung seit 50 Jahren Ziel einer wissenschaftlichen Pilgerfahrt

Co-reporter:Dr. Jay S. Siegel

Angewandte Chemie 2015 Volume 127( Issue 17) pp:5058-5059

Publication Date(Web):

DOI:10.1002/ange.201501954

Half a Century of the Brgenstock Conference: A Pilgrims Tale

Co-reporter:Dr. Jay S. Siegel

Angewandte Chemie International Edition 2015 Volume 54( Issue 17) pp:4974-4975

Publication Date(Web):

DOI:10.1002/anie.201501954

Synthesis of Bioconjugated sym-Pentasubstituted Corannulenes: Experimental and Theoretical Investigations of Supramolecular Architectures

Co-reporter:Martin Mattarella, Laura Berstis, Kim K. Baldridge, and Jay S. Siegel

Bioconjugate Chemistry 2014 Volume 25(Issue 1) pp:115

Publication Date(Web):December 9, 2013

DOI:10.1021/bc400408d

Applications of supramolecular architectures span a broad range of fields from medicinal chemistry to materials science and gas storage, making the design and synthesis of such structures a goal of high interest. The unique structural and symmetric properties of corannulene and the recent synthetic developments of C5-symmetric pentafunctionalized derivatives motivate efforts to synthesize bioconjugated-corannulene systems and investigate their supramolecular assembly properties. Herein is presented the synthesis of sym-pentasubstituted corannulenes functionalized with sugar (galactose and ribose), oligopeptide, nucleosides (thymidine and deoxyadenosine), and palindromic oligonucleotide strands. Experimental and theoretical results demonstrate capability of supramolecular assembly formation in these constructs. Ab initio theoretical modeling enables further evaluation of structure and energetics of oligonucleotide-functionalized corannulene formation. Results indicate formation of aggregates, although icosahedral supramolecular formation is not observed. Analyses suggest future improvements to synthetic routes to achieve icosahedral architectures.

Cu(I) and Ag(I) complexes of 7,10-bis-N-heterocycle-diazafluoranthenes: programmed molecular grids?

Co-reporter:Nelli Rahanyan, Simon Duttwyler, Anthony Linden, Kim K. Baldridge and Jay S. Siegel

Dalton Transactions 2014 vol. 43(Issue 28) pp:11027-11038

Publication Date(Web):27 May 2014

DOI:10.1039/C4DT01460J

Reactions of 7,10-disubstituted diazafluoranthene derivatives with three different silver(I) salts AgX (X = [PF6]−, [SbF6]−, [CB11HCl11]−) and [Cu(CH3CN)4]PF6 afforded complexes exhibiting five different motifs. The crystal structures of the free ligands and nine new complexes from this series of reactions are reported. The use of 2,5-di-tert-butyl-7,10-di(pyridin-2-yl)-8,9-diazafluoranthene as a ligand leads to the formation of the tetranuclear compounds [Ag4(C32H30N4)4][PF6]4·3C6H6·4MeCN, [Ag4(C32H30N4)4][SbF6]4·4C5H12 and [Cu4(C32H30N4)4][PF6]4·8C3H6O, which exhibit “propeller” and saddle-type geometry, respectively, as well as a dinuclear complex [Ag2(C32H30N4)2][CHB11Cl11]2·4C6H4Cl2·CH2Cl2. The reactions involving the less sterically hindered 2,5-di-tert-butyl-7,10-di-(pyrimidin-2-yl)-8,9-diazafluoranthene and 2,5-di-tert-butyl-7,10-di(thiazol-2-yl)-8,9-diazafluoranthene afforded crystals of the dinuclear complexes [Ag2(C30H28N6)2][PF6]2·0.5CH2Cl2·0.5C6H5Cl·0.5C6H12, [Ag2(C30H28N6)2][SbF6]2·C3H6O·0.5C6H14·0.5C6H6, the polymeric species [Ag2(C28H26N4S2)2]n·2n[PF6]n·nC3H6O and the tetranuclear compounds [Cu4(C26H25N4S2)4][PF6]4·2CHCl3·2C3H6O and [Cu4(C30H28N6)4][PF6]4·2.17H2O, which possess saddle and grid-like architectures, respectively. Conformational analysis of the free ligands showed that they exhibit N–C–C–N torsion angles ranging from syn clinal (58°) to fully anti-periplanar conformations; the syn clinal conformation dominates in the complexes. The relative energies of the possible structural conformations of the synthesized ligands, as well as of oxazole disubstituted diazafluoranthenes, were calculated using density functional theory at the B97D/Def2-TZVPP level of theory.

Gear-Meshed Tiling of Surfaces with Molecular Pentagonal Stars

Co-reporter:Quirin Stöckl ; Davide Bandera ; Craig S. Kaplan ; Karl-Heinz Ernst ;Jay S. Siegel

Journal of the American Chemical Society 2013 Volume 136(Issue 2) pp:606-609

Publication Date(Web):December 27, 2013

DOI:10.1021/ja411279r

The assembly of the chiral pentagonal-star-shaped 1,3,5,7,9-pentaphenylcorannulene on a Cu(111) surface has been studied with scanning tunneling microscopy. Two different long-range ordered phases coexist at 60 K, most likely racemic and homochiral phases. The principal motifs emulate a network of meshed gears. One of the observed structures resembles the densest packing of five-fold symmetric stars.

Cu(I) and Ag(I) complexes of 7,10-bis-N-heterocycle-diazafluoranthenes: programmed molecular grids?

Co-reporter:Nelli Rahanyan, Simon Duttwyler, Anthony Linden, Kim K. Baldridge and Jay S. Siegel

Dalton Transactions 2014 - vol. 43(Issue 28) pp:NaN11038-11038

Publication Date(Web):2014/05/27

DOI:10.1039/C4DT01460J

Reactions of 7,10-disubstituted diazafluoranthene derivatives with three different silver(I) salts AgX (X = [PF6]−, [SbF6]−, [CB11HCl11]−) and [Cu(CH3CN)4]PF6 afforded complexes exhibiting five different motifs. The crystal structures of the free ligands and nine new complexes from this series of reactions are reported. The use of 2,5-di-tert-butyl-7,10-di(pyridin-2-yl)-8,9-diazafluoranthene as a ligand leads to the formation of the tetranuclear compounds [Ag4(C32H30N4)4][PF6]4·3C6H6·4MeCN, [Ag4(C32H30N4)4][SbF6]4·4C5H12 and [Cu4(C32H30N4)4][PF6]4·8C3H6O, which exhibit “propeller” and saddle-type geometry, respectively, as well as a dinuclear complex [Ag2(C32H30N4)2][CHB11Cl11]2·4C6H4Cl2·CH2Cl2. The reactions involving the less sterically hindered 2,5-di-tert-butyl-7,10-di-(pyrimidin-2-yl)-8,9-diazafluoranthene and 2,5-di-tert-butyl-7,10-di(thiazol-2-yl)-8,9-diazafluoranthene afforded crystals of the dinuclear complexes [Ag2(C30H28N6)2][PF6]2·0.5CH2Cl2·0.5C6H5Cl·0.5C6H12, [Ag2(C30H28N6)2][SbF6]2·C3H6O·0.5C6H14·0.5C6H6, the polymeric species [Ag2(C28H26N4S2)2]n·2n[PF6]n·nC3H6O and the tetranuclear compounds [Cu4(C26H25N4S2)4][PF6]4·2CHCl3·2C3H6O and [Cu4(C30H28N6)4][PF6]4·2.17H2O, which possess saddle and grid-like architectures, respectively. Conformational analysis of the free ligands showed that they exhibit N–C–C–N torsion angles ranging from syn clinal (58°) to fully anti-periplanar conformations; the syn clinal conformation dominates in the complexes. The relative energies of the possible structural conformations of the synthesized ligands, as well as of oxazole disubstituted diazafluoranthenes, were calculated using density functional theory at the B97D/Def2-TZVPP level of theory.

Intramolecular C–H insertion vs. Friedel–Crafts coupling induced by silyl cation-promoted C–F activation

Co-reporter:Oliver Allemann, Kim K. Baldridge and Jay S. Siegel

Inorganic Chemistry Frontiers 2015 - vol. 2(Issue 9) pp:NaN1021-1021

Publication Date(Web):2015/07/03

DOI:10.1039/C5QO00170F

Silyl cation-promoted aryl C–F activation can lead to formal C–H activation and the formation of new C(ar)–C(alkyl) bonds. Deuterium-labeling experiments suggest an insertion of a phenyl cation into the C–H bond. From competition experiments, a relation between reaction rate and C–H bond strength could be established. Mechanistic parallels are drawn to the Mascarelli reaction.

Correction: Boronic esters of corannulene: potential building blocks toward icosahedral supramolecules

Co-reporter:Sara Da Ros, Anthony Linden, Kim K. Baldridge and Jay S. Siegel

Inorganic Chemistry Frontiers 2015 - vol. 2(Issue 6) pp:

Publication Date(Web):

DOI:10.1039/C5QO90018B

Boronic esters of corannulene: potential building blocks toward icosahedral supramolecules

Co-reporter:Sara Da Ros, Anthony Linden, Kim K. Baldridge and Jay S. Siegel

Inorganic Chemistry Frontiers 2015 - vol. 2(Issue 6) pp:NaN633-633

Publication Date(Web):2015/03/24

DOI:10.1039/C5QO00009B

Direct iridium-catalyzed multi-borylation provides a valuable tool for the symmetric functionalization of various polycyclic aromatic hydrocarbons, inter alia, regular fivefold derivatization of corannulene. In this paper, highly efficient microwave-assisted synthesis of 1,3,5,7,9-(Bpin)5-corannulene is reported, resulting in a significant decrease in reaction time compared to the routine bench-top preparation. In addition, conversion to more reactive boron species, such as the corresponding pentatrifluoroborate and pentaboronic acid, was realized under mild conditions in excellent yields. 1,3,5,7,9-corannulene pentaboronic acid gave further access to a series of boronic esters of corannulene via simple alcohol exchange. This convenient methodology to 1,3,5,7,9-corannulene pentaboronic acid portends its ability to serve as a key building block for formation of icosahedral supramolecules, alone or together with suitable bridging ligands.

Conformations of large macrocycles and ring-in-ring complexes

Co-reporter:Jeremy K. Klosterman, Janis Veliks, Derik K. Frantz, Yoshizumi Yasui, Michael Loepfe, Eli Zysman-Colman, Anthony Linden and Jay S. Siegel

Inorganic Chemistry Frontiers 2016 - vol. 3(Issue 6) pp:NaN666-666

Publication Date(Web):2016/03/23

DOI:10.1039/C6QO00024J

A kinetically directed, stepwise approach towards molecular Borromean links enabled the isolation and structural characterization of synthetic intermediates along the way. Here we report the synthesis and crystal structures of three flexible macrocyclic intermediates and a new ring-in-ring complex, anchored together through ruthenium(II) centers, which contains open terpyridine caps in the inner Ring II. Terpyridines circumvent the conformational cis/trans limitations of bipyridines and the new ring-in-ring complex forms tetrametallic complexes with Zn(II), Pt(II) and Ru(III) metal ions. Analysis of the four macrocyclic structures provides a good foundation for the conformational flexibility in these complexes and demonstrates the robust applicability of the terpyridine design elements towards the engineered synthesis of ring-in-ring topologies.