Functional Organic Solid State Materials Derived from Designer Host Frameworks
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Functional Organic Solid State Materials Derived from Designer Host Frameworks DMR-0305278 Michael D. Ward, University of Minnesota. Hydrogen-bonded frameworks trap laser dyes.

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Functional Organic Solid State Materials Derived from Designer Host Frameworks

DMR-0305278

Michael D. Ward, University of Minnesota

  • Hydrogen-bonded frameworks trap laser dyes

Figure 1. Solid state structure of the inclusion compound based on the guanidinium biphenyldisulfonate host framework and coumarin 102 guest molecules. Coumarin 102 , which is a commercially available laser dye, packs in the voids of the polar orthorhombic host framework. This framework and others also incorporate pyrene and perylene guest molecules, and the aggregation state of the guests (e.g., H-aggregates vs. J-aggregates) can be regulated through the choice of the pillar-guest combination.

Figure 2. (A) Selectivity profiles of pairwise competition for inclusion of three of the ten dimethylnaphthalene (DMN) isomers by the “chevron” pillar o-diphenylbenzenedisulfonate, for which both sulfonate groups anchor to the same GS sheet to produce bilayer-like architecture with interdigitation of the o-DPB groups. The profiles reveal that inclusion of 1,5-DMN is highly preferred, opposite to behavior observed earlier for other host systems (X = mol fraction in solution; Y = mol fraction included). (B) The crystal structure of the 1,5-DMN inclusion compound.

Fall 2005


  • Broader Impact Y2004 Designer Host Frameworks

  • Michael D. Ward, University of Minnesota

  • Education and Mentoring

  • 2 Graduate students obtained Ph.D.s: Matt Horner (Hutchinson Technologies), Steve Martin (postdoc, MIT)

  • New graduate student Airon Soegiarto

  • 1 Postdoc departed for an industrial position: Sang-Ok Park (Samsung)

  • 1 visiting KOSEF student (Seoul National University): Jinsoo Kim

  • REU (Clemson/GA Tech:DMR-0305278) student Danielle Shacklady

    published her first paper (Crystal Growth & Design, 2005, 5, 995)

  • Outreach

  • Activities revolving around role as director of the University of Minnesota MRSEC (tribal college visits, overseeing overall operation of MRSEC-related outreach programs, including visiting faculty-student teams and individual undergraduates during summer 2003.

  • Industrial connections

  • Eli Lilly

    International and other Activities

  • Associate Editor, Chemistry of Materials

  • Director, University of Minnesota MRSEC

  • Invited paper for the MRS Bulletin Special Issue on “Self-assembly in Materials Synthesis”: “Directing Assembly of Molecular Crystals”

  • Grazing incidence X-ray diffraction studies at the DESY synchrotron facility (Hamburg, Germany) with co-workers from the Weizmann Institute examining 2-D crystalline analogs of our 3-D hydrogen-bonded crystalline materials

  • Asked to serve as a member of the Weizmann Institute advisory board

  • Awarded Binational Science Foundation grant with Weizmann co-workers: “A Stereochemical Approach Towards Control of Crystal Nucleation and Polymorphism”

  • Collaboration with W. Hosseini, Universite’ Louis Pasteur, Strasbourg, France examining new hydrogen-bonded solid state materials and epitaxial growth of isomorphous “core-shell” crystalline composites.

  • Keynote lecturer at the (1) International Conference of the Chemistry of the Organic Solid State, UCLA, July 25, 2005; (2)_ Gordon Conference, Thin Film and Crystal Growth Mechanisms, Mount Holyoke College, June 26, 2005; (3) FMC Lecture series, Princeton University, April 4-5, 2005.

Fall 2005


NOTES Designer Host Frameworks

  • The technical slide (page 1) describes two recent discoveries.

Figure 1. We have found that the hydrogen-bonded frameworks generated from guanidinium cations and a variety of organomonosulfonates and organodisulfonates forms hundreds of inclusion compounds with retention of the hydrogen bond connectivity of the guanidinium-sulfonate sheet. The remarkable persistence of the GS sheet, which is unique in the organic solid state, is attributable to the strength of the charge-assisted hydrogen bonds and the pliable nature of the sheet, which permits “puckering” that accommodates the packing of the organic constituents. Consequently, this system has emerged as a benchmark for organic crystal design, and it continues to surprise while serving as a platform for advancing our understanding of molecular organization in the solid state. Previously we demonstrated the de novo design of polar inclusion compounds with second harmonic generation activity that could be regulated by the choice of guest. Here, we depict a recently discovered inclusion compound that contains the laser dye coumarin 102. Because the guest organization can be controlled by the choice of framework, the inclusion of laser dyes, as well as pyrene and perylene, suggests a new generation of materials with interesting, and possible useful, optical properties.

  • Figure 2: The guanidinium-sulfonate host frameworks can be used for efficient separation of molecular isomers that otherwise are difficult to separate by conventional methods. This can be accomplished simply by adding dissolved host to a solution of the molecular isomers, which prompts crystallization of the inclusion compounds containing one of the guest molecules selectively. The crystals can then be isolated by filtration and the guest retrieved by simply dissolving the framework. This procedure can also be used to separated undesirable guests from a mixture. Here we demonstrate this concept for dimethylnaphthalene (DMN), which has ten isomers that are produced during coal liquefaction. The refinement of DMN by conventional means is particularly difficult owing to the similar physical properties of the individual isomers. The 2,6-DMN isomer is of particular interest because it can be converted readily to 2,6-naphthalenedicarboxylic acid and subsequently polyethylene naphthalate, a valuable thermotropic liquid crystal polymer used for the manufacture of specialty synthetic fibers and functional resins with desirable thermal and mechanical properties. We previously demonstrated that the G2BPDS host selectively trapped the 2,n-DMN isomers, including the desired 2,6-DMN. Here we illustrate that the Inclusion selectivity profiles can be reversed through changes to the host compound. Using a “chevron” bilayer host in which both sulfonate groups of o-diphenylbenzenedisulfonate anchor to the same GS sheet, a pronounced selectivity for 1,5-DMN inclusion is observed, demonstrating a protocol for removing the undesirable 1,n-DMN isomers from a mixture.

GS sheet

Fall 2005


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