Stable, crystalline, porous, covalent organic frameworks as a platform for chiral organocatalysts

Stable, crystalline, porous, covalent organic frameworks as a platform for chiral organocatalysts - pp905 - 912

Hong Xu, Jia Gao & Donglin Jiang

doi:10.1038/nchem.2352

 

Covalent organic frameworks (COFs) feature periodic layers and ordered pores that make them promising for applications in catalysis, but they typically suffer from poor stability. Now, adding methoxy groups to its pore walls has been shown to strengthen a COF's interlayer interactions, resulting in a stable, crystalline, porous material that can be further converted into chiral organocatalysts.

 

Abstract

The periodic layers and ordered nanochannels of covalent organic frameworks (COFs) make these materials viable open catalytic nanoreactors, but their low stability has precluded their practical implementation. Here we report the synthesis of a crystalline porous COF that is stable against water, strong acids and strong bases, and we demonstrate its utility as a material platform for structural design and functional development. We endowed a crystalline and porous imine-based COF with stability by incorporating methoxy groups into its pore walls to reinforce interlayer interactions. We subsequently converted the resulting achiral material into two distinct chiral organocatalysts, with the high crystallinity and porosity retained, by appending chiral centres and catalytically active sites on its channel walls. The COFs thus prepared combine catalytic activity, enantioselectivity and recyclability, which are attractive in heterogeneous organocatalysis, and were shown to promote asymmetric C–C bond formation in water under ambient conditions.

 

http://www.nature.com/nchem/journal/v7/n11/full/nchem.2352.html

A Highly Efficient Heterogenized Iridium Complex for the Catalytic Hydrogenation of Carbon Dioxide to Formate

A Highly Efficient Heterogenized Iridium Complex for the Catalytic Hydrogenation of Carbon Dioxide to Formate (pages 3410–3413)
Kwangho Park, Gunniya Hariyanandam Gunasekar , Natarajan Prakash, Dr. Kwang-Deog Jung and Prof. Dr. Sungho Yoon
Article first published online: 25 AUG 2015 | DOI: 10.1002/cssc.201500436

Complex in New Basket: A new, highly porous, industrially viable, heterogenized Ir catalyst has been synthesized and characterized, and the coordination environment is confirmed to be similar to that of its homogeneous counterpart. The catalyst efficiently converts CO₂ to formate through hydrogenation at high turnover frequencies (TOFs) and turnover numbers (TONs) and shows good stability during the recycling process.

Abstract

A heterogenized catalyst on a highly porous covalent triazine framework was synthesized and characterized to have a coordination environment similar to that of its homogeneous counterpart. The catalyst efficiently converted CO₂ into formate through hydrogenation with a turnover number of 5000 after 2 h and an initial turnover frequency of up to 5300 h⁻¹; both of these values are the highest reported to date for a heterogeneous catalyst, which makes it attractive toward industrial application. Furthermore, the synthesized catalyst was found to be stable in air and was recycled by simple filtration without significant loss of catalytic activity.
 

http://onlinelibrary.wiley.com/doi/10.1002/cssc.201500436/full

Xylochemistry—Making Natural Products Entirely from Wood

Authors

Daniel Stubba, Günther Lahm, Mario Geffe, Dr. Jason W. Runyon, Prof. Dr. Anthony J. Arduengo III, Prof. Dr. Till Opatz

First published: 21 October 2015
DOI: 10.1002/anie.201509446

http://onlinelibrary.wiley.com/doi/10.1002/anie.201509446/full

Abstract

“Carving” molecules out of wood. The synthesis of chemical materials from sustainable resources in an environmentally responsible way is an important grand challenge for a modern chemical infrastructure. In their Communication (DOI: 10.1002/anie.201508500), T. Opatz, A.J. Arduengo, et al. tackle the first of four aspects of xylochemistry. The cover metaphorically depicts the process of creating a natural product, Ilicifoline B, exclusively from wood-based starting materials (cover image: Jason W. Runyon).

Silatranes for binding inorganic complexes to metal oxide surfaces
Kelly L. Materna, Bradley J. Brennan and Gary W. Brudvig

Dalton Trans., 2015, Advance Article
DOI: 10.1039/C5DT03463A, Communication
First published online : 16 Oct 2015
http://pubs.rsc.org/en/content/articlepdf/2015/dt/c5dt03463a?page=search

Abstract:
A ruthenium complex containing silatrane functional groups has been synthesized and covalently bound to a conductive metal oxide film composed of nanoparticulate ITO (nanoITO). The silatrane-derived siloxane surface anchors were found to be stable in the examined range of pH 2 to 11 in aqueous phosphate buffer, and the ruthenium complex was found to have stable electrochemical features with repeated electrochemical cycling. The noncoordinating properties of the silatrane group to metals, which facilitates synthesis of silatrane-labeled coordination complexes, together with the facile surface-binding procedure, robustness of the surface linkages, and stability of the electrochemical properties suggest that incorporating silatrane motifs into ligands for inorganic complexes provides superior properties for attachment of catalysts to metal oxide surfaces under aqueous conditions

Identification of active sites in CO oxidation and water-gas shift over supported Pt catalysts

1. Kunlun Ding1, 
2. Ahmet Gulec2, 
3. Alexis M. Johnson1, 
4. Neil M. Schweitzer3, 
5. Galen D. Stucky4, 
6. Laurence D. Marks2,
7. Peter C. Stair1,5,*

1. ¹Department of Chemistry, Northwestern University, Evanston, IL 60208, USA.
2. ²Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208, USA.
3. ³Department of Chemical and Biological Engineering, Northwestern University, Evanston, IL 60208, USA.
4. ⁴Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA 93106, USA.
5. ⁵Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, IL 60439, USA.

1. ↵*Corresponding author. E-mail: pstair{at}northwestern.edu

Science 9 October 2015: 
Vol. 350 no. 6257 pp. 189-192 
DOI: 10.1126/science.aac6368

https://www.sciencemag.org/content/350/6257/189.short

ABSTRACT

Identification and characterization of catalytic active sites are the prerequisites for an atomic-level understanding of the catalytic mechanism and rational design of high-performance heterogeneous catalysts. Indirect evidence in recent reports suggests that platinum (Pt) single atoms are exceptionally active catalytic sites. We demonstrate that infrared spectroscopy can be a fast and convenient characterization method with which to directly distinguish and quantify Pt single atoms from nanoparticles. In addition, we directly observe that only Pt nanoparticles show activity for carbon monoxide (CO) oxidation and water-gas shift at low temperatures, whereas Pt single atoms behave as spectators. The lack of catalytic activity of Pt single atoms can be partly attributed to the strong binding of CO molecules.

Rhodium(III)-Catalyzed Directed ortho-C-H Bond Functionalization of Aromatic Ketazines via C-S and C-C Coupling

Rhodium(III)-Catalyzed Directed ortho-C-H Bond Functionalization of Aromatic Ketazines via C-S and C-C Coupling

Jing Wen, An Wu, Mingyang Wang, and Jin Zhu*

Department of Polymer Science and Engineering, School of Chemistry and Chemical Engineering, State Key Laboratory of Coordination Chemistry, Nanjing National Laboratory of Microstructures, Nanjing University, Nanjing 210093, China

J. Org. Chem. 
DOI: 10.1021/acs.joc.5b01154

http://pubs.acs.org/doi/pdf/10.1021/acs.joc.5b01154

Abstract:

Described herein is a convenient and efficient method for sulfuration and olefination of aromatic ketazines via rhodium-catalyzed oxidative C−H bond activation. A range of substituted substrates are supported, and a possible mechanism is proposed according to experimental results of kinetic isotopic effect, reversibility studies, and catalysis of rhodacycle intermediate c1.

TOC:

Rhodium(III)-Catalyzed Directed peri-C−H Alkenylation of Anthracene Derivatives

Jaganathan Karthikeyan and Naohiko Yoshikai*
Publication Date (Web): July 28, 2014 (Article)
DOI: 10.1021/ol501926b

ABSTRACT:

Rhodium(III)-catalyzed oxidative coupling reactions of anthracene-9-carboxylic acid derivatives with electron-deficient olefins are reported. A cationic rhodium(III) catalyst, in combination with a copper(II) oxidant, promotes selective monoalkenylation of anthracene-9-carboxamide, affording 1-alkenylanthracene-9-carboxamide in moderate to good yields. A similar catalytic system also promotes the reaction of anthracene-9-carboxylic acid and an electron-deficient olefin, which affords a lactone derivative through C−H alkenylation followed by intramolecular conjugate addition.

TOC:

Organometallic Complexes Anchored to Conductive Carbon for Electrocatalytic Oxidation of Methane at Low Temperature


Madhura Joglekar, Vinh Nguyen, Svitlana Pylypenko, Chilan Ngo, Quanning Li, Matthew E. O’Reilly, Tristan S. Gray, William A. Hubbard, T. Brent Gunnoe, Andrew M. Herring, and Brian G. Trewyn
Publication Date (Web): October 22, 2015 (Article)
DOI: 10.1021/jacs.5b06392
ABSTRACT:


Low-temperature direct methane fuel cells (DMEFCs) offer the opportunity to substantially improve the efficiency of energy production from natural gas. This study focuses on the development of well-defined platinum organometallic complexes covalently anchored to ordered mesoporous carbon (OMC) for electrochemical oxidation of methane in a proton exchange membrane fuel cell at 80 °C. A maximum normalized power of 403 μW/mg Pt was obtained, which was 5 times higher than the power obtained from a modern commercial catalyst and 2 orders of magnitude greater than that from a Pt black catalyst. The observed differences in catalytic activities for oxidation of methane are linked to the chemistry of the tethered catalysts, determined by X-ray photoelectron spectroscopy. The chemistry/activity relationships demonstrate a tangible path for the design of electrocatalytic systems for C−H bond activation that afford superior performance in DMEFC for potential commercial applications.

http://pubs.acs.org/doi/10.1021/jacs.5b09824

Complete Switch of Selectivity in the C–H Alkenylation and Hydroarylation Catalyzed by Iridium: The Role of Directing Groups

Jiyu Kim†‡, Sung-Woo Park*‡†, Mu-Hyun Baik‡†, and Sukbok Chang*‡†

† Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Korea
‡ Center for Catalytic Hydrocarbon Functionalizations, Institute for Basic Science (IBS), Daejeon 305-701, Korea

J. Am. Chem. Soc., Article ASAP
DOI: 10.1021/jacs.5b09824
Publication Date (Web): October 8, 2015

A complete switch in the Cp*Ir(III)-catalyzed paths between C–H olefination and hydroarylation was found to be crucially dependent on the type of directing groups. This dichotomy in product distribution was correlated to the efficiency in attaining syn-coplanarity of olefin-inserted 7-membered iridacycles. Theoretical studies support our hypothesis that the degree of flexibility of this key intermediate modulates the β-H elimination, which ultimately affords the observed chemoselectivity.

Hey Pluto...Your spot is showing!

http://www.sciencemag.org/content/350/6258/aad1815.abstract

 

Science 16 October 2015:
Vol. 350 no. 6258
DOI: 10.1126/science.aad1815

The Pluto system: Initial results from its exploration by New Horizons

1. S. A. Stern¹,*,
2. F. Bagenal²,
3. K. Ennico³,
4. G. R. Gladstone⁴,
5. W. M. Grundy⁵,
6. W. B. McKinnon⁶,
7. J. M. Moore³,
8. C. B. Olkin¹,
9. J. R. Spencer¹,
10. H. A. Weaver⁷,
11. L. A. Young¹,
12. T. Andert⁸,
13. J. Andrews¹,
14. M. Banks⁹,
15. B. Bauer⁷,
16. J. Bauman¹⁰,
17. O. S. Barnouin⁷,
18. P. Bedini⁷,
19. K. Beisser⁷,
20. R. A. Beyer³,
21. S. Bhaskaran¹¹,
22. R. P. Binzel¹²,
23. E. Birath¹,
24. M. Bird¹³,
25. D. J. Bogan¹⁴,
26. A. Bowman⁷,
27. V. J. Bray¹⁵,
28. M. Brozovic¹¹,
29. C. Bryan¹⁰,
30. M. R. Buckley⁷,
31. M. W. Buie¹,
32. B. J. Buratti¹¹,
33. S. S. Bushman⁷,
34. A. Calloway⁷,
35. B. Carcich¹⁶,
36. A. F. Cheng⁷,
37. S. Conard⁷,
38. C. A. Conrad¹,
39. J. C. Cook¹,
40. D. P. Cruikshank³,
41. O. S. Custodio⁷,
42. C. M. Dalle Ore³,
43. C. Deboy⁷,
44. Z. J. B. Dischner¹,
45. P. Dumont¹⁰,
46. A. M. Earle¹²,
47. H. A. Elliott⁴,
48. J. Ercol⁷,
49. C. M. Ernst⁷,
50. T. Finley¹,
51. S. H. Flanigan⁷,
52. G. Fountain⁷,
53. M. J. Freeze⁷,
54. T. Greathouse⁴,
55. J. L. Green¹⁷,
56. Y. Guo⁷,
57. M. Hahn¹⁸,
58. D. P. Hamilton¹⁹,
59. S. A. Hamilton⁷,
60. J. Hanley⁴,
61. A. Harch²⁰,
62. H. M. Hart⁷,
63. C. B. Hersman⁷,
64. A. Hill⁷,
65. M. E. Hill⁷,
66. D. P. Hinson²¹,
67. M. E. Holdridge⁷,
68. M. Horanyi²,
69. A. D. Howard²²,
70. C. J. A. Howett¹,
71. C. Jackman¹⁰,
72. R. A. Jacobson¹¹,
73. D. E. Jennings²³,
74. J. A. Kammer¹,
75. H. K. Kang⁷,
76. D. E. Kaufmann¹,
77. P. Kollmann⁷,
78. S. M. Krimigis⁷,
79. D. Kusnierkiewicz⁷,
80. T. R. Lauer²⁴,
81. J. E. Lee²⁵,
82. K. L. Lindstrom⁷,
83. I. R. Linscott²⁶,
84. C. M. Lisse⁷,
85. A. W. Lunsford²³,
86. V. A. Mallder⁷,
87. N. Martin²⁰,
88. D. J. McComas⁴,
89. R. L. McNutt Jr.⁷,
90. D. Mehoke⁷,
91. T. Mehoke⁷,
92. E. D. Melin⁷,
93. M. Mutchler²⁷,
94. D. Nelson¹⁰,
95. F. Nimmo²⁸,
96. J. I. Nunez⁷,
97. A. Ocampo¹⁷,
98. W. M. Owen¹¹,
99. M. Paetzold¹⁸,
100. B. Page¹⁰,
101. A. H. Parker¹,
102. J. W. Parker¹,
103. F. Pelletier¹⁰,
104. J. Peterson¹,
105. N. Pinkine⁷,
106. M. Piquette²,
107. S. B. Porter¹,
108. S. Protopapa¹⁹,
109. J. Redfern¹,
110. H. J. Reitsema²⁰,
111. D. C. Reuter²³,
112. J. H. Roberts⁷,
113. S. J. Robbins¹,
114. G. Rogers⁷,
115. D. Rose¹,
116. K. Runyon⁷,
117. K. D. Retherford⁴,
118. M. G. Ryschkewitsch⁷,
119. P. Schenk²⁹,
120. E. Schindhelm¹,
121. B. Sepan⁷,
122. M. R. Showalter²¹,
123. K. N. Singer¹,
124. M. Soluri³⁰,
125. D. Stanbridge¹⁰,
126. A. J. Steffl¹,
127. D. F. Strobel³¹,
128. T. Stryk³²,
129. M. E. Summers³³,
130. J. R. Szalay²,
131. M. Tapley⁴,
132. A. Taylor¹⁰,
133. H. Taylor⁷,
134. H. B. Throop⁹,
135. C. C. C. Tsang¹,
136. G. L. Tyler²⁶,
137. O. M. Umurhan³,
138. A. J. Verbiscer³⁴,
139. M. H. Versteeg⁴,
140. M. Vincent¹,
141. R. Webbert⁷,
142. S. Weidner⁴,
143. G. E. Weigle II⁴,
144. O. L. White³,
145. K. Whittenburg⁷,
146. B. G. Williams¹⁰,
147. K. Williams¹⁰,
148. S. Williams⁷,
149. W. W. Woods²⁶,
150. A. M. Zangari¹,
151. E. Zirnstein⁴

+ Author Affiliations

1. ¹Southwest Research Institute, Boulder, CO 80302, USA.
2. ²Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO 80303, USA.
3. ³National Aeronautics and Space Administration (NASA) Ames Research Center, Space Science Division, Moffett Field, CA 94035, USA.
4. ⁴Southwest Research Institute, San Antonio, TX 28510, USA.
5. ⁵Lowell Observatory, Flagstaff, AZ 86001, USA.
6. ⁶Department of Earth and Planetary Sciences, Washington University, St. Louis, MO 63130, USA.
7. ⁷Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723, USA.
8. ⁸Universität der Bundeswehr München, Neubiberg 85577, Germany.
9. ⁹Planetary Science Institute, Tucson, AZ 85719, USA.
10. ¹⁰KinetX Aerospace, Tempe, AZ 85284, USA.
11. ¹¹NASA Jet Propulsion Laboratory, La Cañada Flintridge, CA 91011, USA.
12. ¹²Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
13. ¹³University of Bonn, Bonn D-53113, Germany.
14. ¹⁴NASA Headquarters (retired), Washington, DC 20546, USA.
15. ¹⁵University of Arizona, Tucson, AZ 85721, USA.
16. ¹⁶Cornell University, Ithaca, NY 14853, USA.
17. ¹⁷NASA Headquarters, Washington, DC 20546, USA.
18. ¹⁸Rheinisches Institut für Umweltforschung an der Universität zu Köln, Cologne 50931, Germany.
19. ¹⁹Department of Astronomy, University of Maryland, College Park, MD 20742, USA.
20. ²⁰Southwest Research Institute, Boulder, CO 80302, USA.
21. ²¹Search for Extraterrestrial Intelligence Institute, Mountain View, CA 94043, USA.
22. ²²Department of Environmental Sciences, University of Virginia, Charlottesville, VA 22904, USA.
23. ²³NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA.
24. ²⁴National Optical Astronomy Observatory, Tucson, AZ 26732, USA.
25. ²⁵NASA Marshall Space Flight Center, Huntsville, AL 35812, USA.
26. ²⁶Stanford University, Stanford, CA 94305, USA.
27. ²⁷Space Telescope Science Institute, Baltimore, MD 21218, USA.
28. ²⁸University of California, Santa Cruz, CA 95064, USA.
29. ²⁹Lunar and Planetary Institute, Houston, TX 77058, USA.
30. ³⁰Michael Soluri Photography, New York, NY 10014, USA.
31. ³¹Johns Hopkins University, Baltimore, MD 21218, USA.
32. ³²Roane State Community College, Jamestown, TN 38556, USA.
33. ³³George Mason University, Fairfax, VA 22030, USA.
34. ³⁴Department of Astronomy, University of Virginia, Charlottesville, VA 22904, USA.

1. ↵*Corresponding author. E-mail: astern@boulder.swri.edu

Abstract

The Pluto system was recently explored by NASA’s New Horizons spacecraft, making closest approach on 14 July 2015. Pluto’s surface displays diverse landforms, terrain ages, albedos, colors, and composition gradients. Evidence is found for a water-ice crust, geologically young surface units, surface ice convection, wind streaks, volatile transport, and glacial flow. Pluto’s atmosphere is highly extended, with trace hydrocarbons, a global haze layer, and a surface pressure near 10 microbars. Pluto’s diverse surface geology and long-term activity raise fundamental questions about how small planets remain active many billions of years after formation. Pluto’s large moon Charon displays tectonics and evidence for a heterogeneous crustal composition; its north pole displays puzzling dark terrain. Small satellites Hydra and Nix have higher albedos than expected