We report the control of molecular orientation in solid films through self-organization and inducedorientation processes. We synthesized water-soluble cationic 3,4,9,10-perylene diimide (1) and studied its self-organization in aqueous solution. By UV-vis spectroscopy, H-aggregates of 1 were observed forming in solutions with concentrations as low as 10 -7 M. At concentrations above approximately 0.1 M (7% w/w), these solutions were observed with polarized microscopy to form a chromonic N phase (a nematic lyotropic liquid crystalline phase) at room temperature. Upon induced alignment (by shearing) of the chromonic N phase on a glass substrate and removal of solvent, anisotropic solid films of the dichroic dye were produced. These films have dichroic ratio values that routinely exceed 25 and in some cases 30, making them excellent polarizers over the blue and green region. By use of a combination of polarized UV-vis and FT-IR spectroscopies, the orientation of the average molecular plane in these films was determined to be perpendicular to both the shearing direction and the substrate plane. Small-angle X-ray diffraction studies indicate that the molecules in the solid film possess a high degree of order.

Considerable research effort has recently been focused on the interplay between molecular architecture, molecular order, and macroscopic properties. 1 Many of these studies involve selfassembly or self-organization processes in which molecules associate spontaneously into ordered aggregates as a result of noncovalent interactions and/or entropic factors. In contrast to self-assembly that involves atom-specific interactions producing assemblies with definable structures, 2 self-organization involves less specific interactions generating aggregates with less definable structures such as cell membranes. 3 Many self-organized materials are liquid-crystalline; molecules in this intermediate phase are mobile as in liquids and yet show short-range orientational order as in crystals. 4 Tremendous success has been achieved in the

The chromonic liquid-crystalline properties of bis-(N,N-diethylaminoethyl)perylene-3,4,9,10-tetracarboxylic diimide dihydrochloride in an aqueous solution were investigated by polarized light microscopy and 2H NMR spectroscopy. Both techniques indicate a narrow I + N biphasic region and a broad N phase region at concentrations ranging from approximately 6.9 to approximately 30 wt % at room temperature. Optical microscopy indicates that a hexagonal M phase exists at higher concentrations. The variation of the I --> N + I and N + I --> N transition temperatures with concentration was studied by 2H NMR spectroscopy. Finally, the effects of temperature and concentration on the order parameter of the N phase were investigated by 2H NMR using a tetra-deuterated derivative. A value of 0.97 was obtained for the N phase at its upper concentration limit.

Within the broad scope of supramolecular chemistry, [1, 2] the construction of materials and devices through self-assembly and self-organization processes is becoming one of the premier frontiers. [3][4][5][6][7][8][9][10][11] In the last decade, there has been extensive research on the interplay between molecular architecture, molecular order, and macroscopic properties. [12] In this paper, we report the aggregation and liquid-crystalline properties of a novel ionic quaterrylenebis(dicarboximide) 1 in aqueous solution. More importantly, by exploiting the selforganizing properties of 1, unprecedented control of the molecular orientation of the quaterrylenebis(dicarboximide) in thin solid films was achieved, which produces a novel linear polarizer of light at long wavelengths.Nonionic quaterrylenebis(dicarboximide)s 2 a-c are known to absorb light at long wavelengths. In chlorinated organic solvents, the absorption maxima of 2 b and 2 c are at 764 nm and 781 nm, respectively. [13, 14] These thermally and photochemically stable dyes can potentially be used in optical applications in conjunction with commercially available GaAlAs lasers that emit at 780 nm. Near-infrared (NIR) absorbing and emitting dyes have potential use in hightechnology applications such as optical recording, thermally written displays, laser printers, laser filters, infrared photography, and fiber-optic communications. [15, 16] However, the solubility of 2 a-c in chlorinated solvents is only about 10 À2 m. [13, 14] The design and synthesis of more-soluble quaterrylenebis(dicarboximide) derivatives will allow greater convenience in the processing of such materials. In addition, because of the intrinsic anisotropy in the molecular optical properties of quaterrylenebis(dicarboximide)s, the development of techniques for controlling their orientation on a macroscopic scale in the solid state will lead to novel anisotropic materials and broaden their utility. For instance, NIR polarizers have applications as optical isolators that are used in conjunction with semiconductor lasers and fiber optics. [17] In the structural design of 1, we anticipated that the functionalization of the hydrophobic quaterrylenebis(dicarboximide) core with cationic pendant groups would impart amphiphilicity, which would render it soluble in aqueous solution. Aggregation of these molecules in an aqueous medium is expected because of p-stacking among the "plankshaped" aromatic molecules and the entropy-driven hydrophobic interactions. Furthermore, it was expected that the introduction of flexible alkyl chains would enhance the formation of lyotropic (solvent-dependent) liquid-crystalline phases by hindering regular close-packing of the molecules into a crystalline phase. Although liquid-crystalline phases are only of short-range structural regularity, induced alignment of the self-organized ensembles under an external force can increase the degree of orientational order over a substantially longer range in thin liquid films. [18] By preserving this longrange anisotropic...

Ionic perylenebis(dicarboximide)s 1-5 were synthesized. The aggregation and liquid-crystalline properties of these compounds in aqueous solutions were investigated. In the concentration range of approximately 5 x 10-7-5 x 10-4 M, the structures of the ammonium side chains and counterions did not have a significant effect on the electronic transition properties and H-aggregate formation of these compounds. However, the liquid-crystalline phase properties varied with the structure of the side chains and the counterions. Ionic perylenebis(dicarboximide)s 1, 3, and 5 with chloride ions formed nematic (N) phases from the isotropic (I) phase, while 2 and 4 with p-methylbenzenesulfonate ions formed chromonic ribbons from the I phase. Studies by polarized light microscopy and 2H NMR spectroscopy indicated that the N phase of 5 (with gem dimethyl groups) formed at higher concentrations than those observed for 1 and 3 at the same temperature. Furthermore, the N phase of 5 was less ordered compared to those of 1 and 3 at a similar concentration and temperature, presumably due to the bulkiness of the side chains of 5 that hindered the stacking and pi-interactions of the aromatic rings.