@article { ISI:000263163200021,
	title = {Synthesis and self-organization properties of copolyurethanes based on perylenediimide and naphthalenediimide units},
	journal = {Journal of Polymer Science Part A-Polymer Chemistry},
	volume = {47},
	number = {4},
	year = {2009},
	month = {FEB},
	pages = {1224-1235},
	publisher = {JOHN WILEY \& SONS INC},
	address = {111 RIVER ST, HOBOKEN, NJ 07030 USA},
	abstract = {<p>A series of perylene and naphthalene diimide-containing random copolyurethanes with different ratios of perylene/naphthalene diimide content was synthesized and characterized. Copolymerization improved the solubility of these rigid aromatic diimides, and the copolymers were soluble in common organic solvents like chloroform, tetrahydrofuran, and so forth. The absorption spectra of perylene-based copolymers showed a red-shifted peak at a wavelength of 557 nm corresponding to J-type aggregates. For naphthalene copolymers, the quenching of fluorescence at higher naphthalene incorporation suggested the presence of aggregates because of the extensive pi-pi stacking of the aromatic core. FTIR spectroscopic analysis showed that the hydrogen bonding tendency of the polymer decreased with increase in perylene/naphthalene incorporation. The fluorescence spectra of the perylene polymers were exactly a mirror image of the absorption spectra. The fluorescence spectra of the naphthalene polymers at higher naphthalene incorporation showed a red-shifted excimer like emission peak, which was assigned as static excimers based on their excitation spectra. These polymers could exhibit two types of secondary interaction modes, namely, hydrogen bonding (via urethane linkage) and pi-stacking (via aromatic perylene or naphthalene units) thus highlighting the importance of polymer design in inducing self-organization at both low and high incorporation of the rigid bisimide moieties. (C) 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polyrn Chem 47: 1224-1235, 2009</p>},
	keywords = {fluorescence, hydrogen bonding, naphthalene diimide polymers, polyurethane copolymer, self-organization, structure-property relations},
	issn = {0887-624X},
	doi = {10.1002/pola.23233},
	author = {Jancy, B. and Asha, S. K.}
}
@article { ISI:000306215900061,
	title = {Structure engineering of naphthalene diimides for improved charge carrier mobility: self-assembly by hydrogen bonding, good or bad?},
	journal = {Journal of Materials Chemistry},
	volume = {22},
	number = {30},
	year = {2012},
	month = {MAY},
	pages = {15235-15246},
	publisher = {ROYAL SOC CHEMISTRY},
	type = {Article},
	address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND},
	abstract = {<p>Two families of naphthalene diimide (NDI) derivatives were compared and contrasted for the effect of self-assembly on charge carrier transport. One series of NDI derivatives had a terminal phenyl ring attached to a hexyl spacer substituted naphthalene core either through an ester or an amide linkage (NDI-E and NDI-A, respectively), while the other series had a 3,4,5-tridodecyloxy phenyl unit (NDI-E3, NDI-A3) instead of the terminal phenyl unit. Solution processed thin films of these molecules exhibited n-type charge transport characteristics in a bottom gate top contact organic field effect transistor (OFET) geometry. The amide derivatives showed evidence of self-organization with observation of red shifted aggregate emission in solution as well as solid state. Variable temperature FTIR studies in the solid state confirmed the existence of strong hydrogen bonding which could be broken only at very high temperature. However, contrary to expectations, the NDI ester derivatives showed better device efficiency with electron mobilities in the range 8.5 x 10(-3) to 2 x 10(-2) cm(2) V-1 s(-1) and on/off ratio similar to 10(4). The thin film crystallinity and morphology of NDI-E and NDI-A were examined through X-ray diffraction and atomic force microscopy (AFM). The correlation of crystallinity, hydrogen bonding and charge carrier mobility was studied using energy minimized structures from density functional theory (DFT). The higher electron mobility of ester linked NDI derivatives over the amide linked ones was attributed to the freedom in charge transport pathways offered by a three dimensional crystalline organization in the ester compared to the restricted directional hydrogen bonding interaction in the amide derivatives.</p>},
	issn = {0959-9428},
	doi = {10.1039/c2jm32554c},
	author = {Kolhe, Nagesh B. and Devi, R. Nandini and Senanayak, Satyaprasad P. and Jancy, B. and Narayan, K. S. and Asha, S. K.}
}
