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Patterning of pH sensitive fluorescent bipyridazine derivatives.
Do, Jaekwon,Kim, Yuna,Attias, André,-Jean,Kreher, David,Kim, Eunkyoung American Scientific Publishers 2010 Journal of Nanoscience and Nanotechnology Vol.10 No.10
<P>A pH sensitive pipeprazine substituted bipyridazine fluorophore, DPP-BPDZ was explored as a pH sensor in solution and thin film state. Greenish highly fluorescent solution of the DPP-BPDZ with fluorescence quantum yield of 0.63 showed fluorescence decrease as the acetic acid concentration of the media was increased. The fluorescence quenching was correlated linearly with the content of acetic acid dose and attributed to the protonation at the terminal piperazine group. An acid sensitive film was fabricated using a transparent polymeric host (PMMA) and the DPP-BPDZ dye molecules as a guest. The resultant bright green fluorescent film (1.4 microm thick) showed exponential decrease of the fluorescence intensity as the pH of the dipping solution was decreased. In the range of pH below 4.5, the film sensitivity to pH was higher than the pH range over 4.5. A patternable film sensor was fabricated by introducing a photo acid generator (PAG) layer on the dye layer. Fluorescence patterns was formed on the film sensor through a photo-mask by relatively weak power of UV light (0.4 mW/cm2). Fluorescent line patterns having 10 microm line width were obtained with high fluorescence contrast between the patterns.</P>
Sosa-Vargas, Lydia,Kim, Eunkyoung,Attias, André,-Jean The Royal Society of Chemistry 2017 Materials horizons Vol.4 No.4
<▼1><P>Designing new molecular building blocks for functional supramolecular self-assembly at surfaces.</P></▼1><▼2><P>2D supramolecular self-assembly has emerged as a powerful tool in nanoscience for bottom-up fabrication of well-defined and long-range ordered two-dimensional (2D) molecular nanostructures at surfaces. Following an overview of the principles of this distinctive self-assembly process, this review focuses on recent strategies developed to go beyond surface nanopatterning and to provide functional surfaces. With an emphasis on the chemical engineering of the molecular building blocks constituting the adlayer, we show that besides supported nanoporous networks, a more promising approach lies in the upstanding 3D functional building blocks mounted on the substrate. We highlight the opportunities offered by graphene, a substrate for which non-covalent functionalization by supramolecular self-assembly represents a way to either control its electronic properties or provide a new functionality. Finally, future perspectives are addressed.</P></▼2>
Madathil, Pramod Kandoth,Heinrich, Benoî,t,Donnio, Bertrand,Mathevet, Fabrice,Fave, Jean-Louis,Guillon, Daniel,Attias, Andre-Jean,Lee, Changjin,Kim, Tae-Dong,Lee, Kwang-Sup American Scientific Publishers 2010 Journal of Nanoscience and Nanotechnology Vol.10 No.10
<P>We report here the synthesis and characterization of novel diethynylbenzene-based liquid crystalline semiconductor (P1) for organic thin-film transistors (OTFTs). Compound P1 was synthesized by the Sonogashira coupling reaction between 2-bromo-5-(4-hexylthiophen-2-yl)thieno[3,2-b]thiophene and 1,4-bis(dodecyloxy)-2,5-diethynylbenzene. Top contact OTFTs were fabricated by spin casting with 2 wt% solution of P1 in chloroform and their best performance, which exhibited a hole mobility of 4.5 x 10(-5) cm2/Vs, was showed after annealing of the films at liquid crystalline temperature. Time-of-flight (TOF) mobility measured at liquid crystalline phase was observed to be 1.5 x 10(-6) cm2/Vs for both positive and negative carriers. These results indicate that the liquid crystallinity helps to improve the molecular packing and enhance charge mobility for P1. These advantages can be applicable to design and construct solution-processable OTFT materials for electronic applications.</P>
Lee, Kwang Jin,Xiao, Yiming,Woo, Jae Heun,Kim, Eunsun,Kreher, David,Attias, André,-Jean,Mathevet, Fabrice,Ribierre, Jean-Charles,Wu, Jeong Weon,André,, Pascal Nature Publishing Group, a division of Macmillan P 2017 NATURE MATERIALS Vol.16 No.7
<P>Charge transfer (CT) is a fundamental and ubiquitous mechanism in biology, physics and chemistry. Here, we evidence that CT dynamics can be altered by multi-layered hyperbolic metamaterial (HMM) substrates. Taking triphenylene: perylene diimide dyad supramolecular self-assemblies as a model system, we reveal longer-lived CT states in the presence of HMM structures, with both charge separation and recombination characteristic times increased by factors of 2.4 and 1.7-that is, relative variations of 140 and 73%, respectively. To rationalize these experimental results in terms of driving force, we successfully introduce image dipole interactions in Marcus theory. The non-local effect herein demonstrated is directly linked to the number of metal-dielectric pairs, can be formalized in the dielectric permittivity, and is presented as a solid analogue to local solvent polarity effects. This model and extra PH3T:PC60BM results show the generality of this non-local phenomenon and that a wide range of kinetic tailoring opportunities can arise from substrate engineering. This work paves the way toward the design of artificial substrates to control CT dynamics of interest for applications in optoelectronics and chemistry.</P>
Yoon, Seong‐,Jun,Kim, Jong H.,Kim, Kil Suk,Chung, Jong Won,Heinrich, Benoî,t,Mathevet, Fabrice,Kim, Pyosang,Donnio, Bertrand,Attias, André,‐,Jean,Kim, Dongho,Park, Soo Young WILEY‐VCH Verlag 2012 Advanced Functional Materials Vol.22 No.1
<P><B>Abstract</B></P><P>A new dicyanodistyrylbenzene‐based phasmidic molecule, (2Z,2′Z)‐2,2′‐(1,4‐phenylene)bis(3‐(3,4,5‐tris(dodecyloxy)phenyl)acrylonitrile), GDCS, is reported, which forms a hexagonal columnar liquid crystal (LC) phase at room temperature (RT). GDCS molecules self‐assemble into supramolecular disks consisting of a pair of molecules in a side‐by‐side disposition assisted by secondary bonding interactions of the lateral polar cyano group, which, in turn, constitute the hexagonal columnar LC structure. GDCS shows very intense green/yellow fluorescence in liquid/solid crystalline states, respectively, in contrast to the total absence of fluorescence emission in the isotropic melt state according to the characteristic aggregation‐induced enhanced emission (AIEE) behavior. The AIEE and two‐color luminescence thermochromism of GDCS are attributed to the peculiar intra‐ and intermolecular interactions of dipolar cyanostilbene units. It was found that the intramolecular planarization and restricted molecular motion associated with a specific stacking situation in the liquid/solid crystalline phases are responsible for the AIEE phenomenon. The origin of the two‐color luminescence was elucidated to be due to the interdisk stacking alteration in a given column driven by the specific local dipole coupling between molecular disks. These stacking changes, in turn, resulted in the different degree of excited‐state dimeric coupling to give different emission colors. To understand the complicated photophysical properties of GDCS, temperature‐dependent steady‐state and time‐resolved PL measurements have been comprehensively carried out. Uniaxially aligned and highly fluorescent LC and crystalline microwires of GDCS are fabricated by using the micromolding in capillaries (MIMIC) method. Significantly enhanced electrical conductivity (0.8 × 10<SUP>−5</SUP> S•cm<SUP>−1</SUP>/3.9 × 10<SUP>−5</SUP> S•cm<SUP>−1</SUP>) of the aligned LC/crystal microwires were obtained over that of multi‐domain LC sample, because of the almost perfect shear alignment of the LC material achieved in the MIMIC mold.</P>