Directed Organization of Dye Aggregates in Hydrogen-Bonded Host Frameworks

Abstract

Organic laser dyes coumarin 1, coumarin 2, coumarin 102, coumarin 314, and coumarin 334 have been included in crystalline guanidinium organodisulfonate (GDS) host frameworks, forming stable inclusion compounds with lamellar architectures. The GDS hosts consist of 2D quasihexagonal hydrogen-bonded sheets with topologically complementary guanidinium (G) ions and the sulfonate (S) moieties of a variety of organodisulfonates that serve as "pillars" that connect opposing GS sheets, thus generating inclusion cavities between the sheets. These host frameworks display a variety of architectural isomers, including the so-called bilayer, simple brick, zigzag brick as well as two heretofore unreported framework isomers: double zigzag brick and a "chevron" brick. These isomers vary with respect to the connectivity between opposing GS sheets and the corresponding shape of the inclusion cavities. The preference for the framework isomers reflects a systematic templating role for the guest molecules, largely based on their steric requirements. The coumarin guests exhibit a distinct arrangement in each host-guest combination, resulting in a range of fluorescence emission wavelengths that differ from that observed for the monomeric form in dilute solutions. For example, the bilayer framework, which has narrow 1D pores, enforces the alignment of coumarin guests as head-to-tail arrays resembling J-aggregates. The simple brick structure, however, has wider 1D channels that permit the formation of linear arrays of face-to-face coumarin dimers resembling H-aggregates. The coumarin guests in the zigzag brick architecture are confined within isolated inclusion cavities as face-to-face dimers. In general, the maxima of the emission bands of the coumarin dyes in the bilayer structure are blue-shifted, while those in the simple brick and zigzag brick structures are red-shifted. The fluorescence reflects the unique guest-guest packing in each framework isomer as well as interactions between the coumarin guest and the organodisulfonate pillar. The ability to include laser dyes in high concentrations in a robust host framework with regulation of intermolecular association between the dye molecules may lead to new solid-state lasing materials that overcome some of the barriers encountered for dyes embedded as dilute solutes in amorphous solid-state matrices such as polymers, zeolites, and sol-gel glasses.

Structural Correspondence of Solution, Liquid Crystal, and Crystalline Phases of the Chromonic Mesogen Sunset Yellow

“…Like many aromatic LCLCs, SSY mesophases have an X-ray scattering peak at 3.4 Å indicative of close stacking of planar π systems in the aggregates. 89,90 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 7 78 Despite a considerable effort at structure determination by small angle XRD, multinuclear NMR spectroscopy, magnetochemistry, rheology, dynamic light scattering, optical absorption spectroscopy, neutron scattering, and polarized light microscopy, no complete picture has emerged from experiment.…”

RhIII‐Catalyzed Synthesis of Isoquinolones and 2‐Pyridones by Annulation of N‐Methoxyamides and Nitroalkenes

“…(Guanidinium) 2 [1,2-bis(4sulfonatophenyl)ethane] apohost (G 2 BSPE) was prepared according to a previously reported method. [15] Chlorosulfonic acid (4.43 mL, 7.88 g, 67.6 mmol) was added slowly via syringe to a chilled (-15°C) round-bottom flask containing anhydrous chloroform (20 mL) and 1,2-biphenylethane (4.66 mL, 5.00 g, 29.4 mmol), all under a nitrogen atmosphere. After 15 min, the chloroform and excess chlorosulfonic acid were decanted from the oily residue.…”

Guanidinium Binding Modulates Guest Exchange within an [M4L6] Capsule

“…[1] Here we demonstrate the use of guanidinium-sulfonate interactions [2] to close the faces of a metal-organic container molecule, [3] thus resulting in the modulation of guest exchange kinetics between bulk solution and the hosts cavity. Membrane transport proteins serve many purposes; ligand-gated ion channels, for example, open and close in response to the binding of specific ligand molecules, thereby regulating the flow of ions across membranes.…”