02411nas a2200181   4500008004100000022001400041245012600055210006900181260011000250300001400360490000600374520163300380100002102013700002802034700002302062700001702085856012702102       2014                        eng d  a2050-752600aStructure-property relationship in charge transporting behaviour of room temperature liquid crystalline perylenebisimides0 aStructureproperty relationship in charge transporting behaviour   aTHOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLANDbROYAL SOC CHEMISTRYcOCT  a9882-98910 v23 a<p>A homologous series of pentadecyl phenol functionalized perylenebisimide (PBI) terminated with trialkoxy gallate esters was synthesized, where the terminal alkyl chain length was varied from n = 4 to 12 (PBI-En). The thermotropic liquid crystalline (LC) characteristics of the molecules were analyzed using differential scanning calorimetry (DSC), polarized light microscopy (PLM) combined with variable temperature wide angle X-ray diffraction (WXRD) techniques. A clear odd-even oscillation was observed in the melting as well as isotropization enthalpies as a function of alkyl spacer length in the terminal gallate unit, with the even spacers exhibiting higher values. The higher members of the series with n &gt; 8 exhibited thermotropic liquid crystalline textures in the PLM, which remained stable until room temperature. The nature of the LC phase was identified to be columnar rectangular and columnar hexagonal based on detailed analysis of the WXRD pattern recorded in the LC phase. The WXRD pattern of the room temperature LC frozen samples indicated a nearly constant intra columnar stack distance of similar to 3.7 angstrom for all the members. The space-charge-limited current (SCLC) values of the LC frozen sample films were analyzed for dependence of the bulk mobility estimate on the nature of the LC phase. The columnar hexagonal phase exhibited a mobility value one order (10(-3) cm(2) V-1 s(-1)) higher than that of crystalline (10(-4) cm(2) V-1 s(-1)) and two orders higher than that of columnar rectangular phase (10(-5) cm(2) V-1 s(-1)), indicating a strong dependence of packing on bulk mobility.</p>1 aPrajitha, K., P.1 aChithiravel, Sundaresan1 aKrishnamoorthy, K.1 aAsha, S., K.  uhttps://library.ncl.res.in/content/structure-property-relationship-charge-transporting-behaviour-room-temperature-liquid-001887nas a2200145   4500008004100000245009100041210006900132260000800201300001400209490000700223520134800230100002101578700001701599856012501616       2016                        eng d00aSynthesis and structural characterization of twin liquid crystalline perylenebisimides0 aSynthesis and structural characterization of twin liquid crystal  cAUG  a8471-84780 v403 aA series of twin perylenebisimide (PBI) molecules were synthesized and characterized having the structure PBI-(methylene spacer)-n-PBI where the length of the central polymethylene spacer segment was varied from n = 1 to 12. The PBI unit was imidized with an ethyl hexyl branched alkyl segment at the terminal and pentadecyl phenol at the other end which was linked through the polymethylene spacer to form the twin molecules. The differential packing afforded by the odd and even spacer central methylene segments resulted in an odd-even oscillation of the melting transitions as well as their enthalpies with higher values observed for the even twins. The odd-even oscillation was quite prominent for the spacers up to n < 7 after which it tapered off. PBI-T1 and PBI-T3 exhibited tendencies to form smectic liquid crystalline (LC) phases while most of the higher membered twin molecules exhibited tendencies for high temperature nematic phases. The ability to control the crystalline or mesogenic nature of the PBI molecules, which constitute an important member of the n type rylenebisimide family that finds application as electron transporters in field effect transistors (FETs) and organic solar cells, is promising as it provides a handle to design systems whose bulk packing is pre-defined to suit the requirements of the application.1 aPrajitha, K., P.1 aAsha, S., K.  uhttps://library.ncl.res.in/content/synthesis-and-structural-characterization-twin-liquid-crystalline-perylenebisimides-002205nas a2200289   4500008004100000022001400041245008700055210006900142260000800211300001100219490000800230520126600238653001601504653001301520653003101533653001701564653003601581653003301617100002001650700002101670700002001691700002101711700001801732700001701750700003101767856011701798       2020                        eng d  a0927-775700aDual responsive cellulose microspheres with high solid-state fluorescence emission0 aDual responsive cellulose microspheres with high solidstate fluo  cAPR  a1245100 v5913 a<p>Materials that respond to multiple stimuli such as magnetic field and light are attractive for security and medical diagnostic applications. One of the major challenges in dual functional microspheres is that the presence of magnetic nanoparticles can quench fluorescence emission. Also, there is a probability of solid-state quenching due to the proximity of the fluorophore. We report here a facile approach to prepare cellulose microspheres with high solid-state fluorescence using 40 % tetrabutylammonium hydroxide (TBAH). The fluorescence quenching effect due to the presence of Fe3O4 nanoparticles and solid-state quenching due to aggregation of fluorophore was systematically investigated. Microspheres with the detectable magnetic response and fluorescence quantum yield as high as 0.57 (FMB 414) was obtained by optimizing the reaction conditions. Such a high quantum yield has not been reported before for dual stimuli-responsive fluorescent microspheres. The magnetic and fluorescent properties were found to be durable even after multiple washing cycles. These dual responsive cellulose microspheres can be added as security features to authenticate documents such as passports, degree certificates, currency notes, financial documents etc.</p>
10aFluorescent10aMagnetic10aMicrocrystalline cellulose10amicrospheres10aStimuli responsive microspheres10aTetrabutylammonium hydroxide1 aYadav, Prashant1 aPrajitha, K., P.1 aDhaware, Vinita1 aSubramani, Mohan1 aJoy, Pattayil1 aAsha, S., K.1 aShanmuganathan, Kadhiravan  uhttps://library.ncl.res.in/content/dual-responsive-cellulose-microspheres-high-solid-state-fluorescence-emission