02364nas a2200157   4500008004100000022001400041245008500055210006900140260007100209300001400280490000800294520174500302100002002047700001902067856012002086       2009                        eng d  a1520-610600aSupramolecular ring banded prototype liquid crystalline oligo(phenylenevinylene)0 aSupramolecular ring banded prototype liquid crystalline oligophe  a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcAPR  a5083-50910 v1133 a<p>We report a new ring banded supramolecular structure in thermotropic liquid crystalline oligo(phenylenevinylene) (OPV) via a melt crystallization process. A series of structurally different OPV molecules were synthesized using tricyclodecanemethanol (TCD) as a bulky pendant unit to trace ring banded morphology. Among all, an OPV molecule with rigid bis-TCD units in the central core and flexible dodecyl chains at the outer phenyl rings (BTCD-BDD-OPV) was found to show ring banded morphologies, which is a first of its kind in T-conjugated materials. BTCD-BDD-OPV experiences strong aromatic pi-pi interactions in both film and liquid crystalline (LC) frozen stage. The pi-induced aggregation leads to lamellar self-assembly of OPV-mesogens that subsequently undergo helical crystal growth, thereby producing dark and bright ring banded patterns. Variable temperature X-ray diffraction analysis revealed the existence of three peaks at 27.07, 13.97, and 8.90 angstrom corresponding to 001, 002, and 003 fundamental layers, respectively, thus confirming the lamellar self-assembly of OPV-mesogens. Electron microscopic (SEM and TEM) analysis of the LC frozen sample showed images confirming helical microcrystalline assembly and providing direct evidence for the self-organization mechanism. Detailed photophysical experiments such as excitation, emission, and timeresolved fluorescence decay studies indicated that BTCD-BDD-OPV has very strong pi-pi interaction in both film and LC frozen stage, which was found to be main driving force for the formation of supra-ring structure. Upon illumination with light, the OPV chromophores in the LC phase were excited and the color of the samples turned into luminescent green ring bands.</p>1 aAmrutha, S., R.1 aJayakannan, M.  uhttps://library.ncl.res.in/content/supramolecular-ring-banded-prototype-liquid-crystalline-oligophenylenevinylene-0