149474-78-2Relevant articles and documents
Photoswitchable NIR-Emitting Gold Nanoparticles
Bonacchi, Sara,Cantelli, Andrea,Battistelli, Giulia,Guidetti, Gloria,Calvaresi, Matteo,Manzi, Jeannette,Gabrielli, Luca,Ramadori, Federico,Gambarin, Alessandro,Mancin, Fabrizio,Montalti, Marco
supporting information, p. 11064 - 11068 (2016/10/13)
Photo-switching of the NIR emission of gold nanoparticles (GNP) upon photo-isomerization of azobenzene ligands, bound to the surface, is demonstrated. Photophysical results confirm the occurrence of an excitation energy transfer process from the ligands to the GNP that produces sensitized NIR emission. Because of this process, the excitation efficiency of the gold core, upon excitation of the ligands, is much higher for the trans form than for the cis one, and t→c photo-isomerization causes a relevant decrease of the GNP NIR emission. As a consequence, photo-isomerization can be monitored by ratiometric detection of the NIR emission upon dual excitation. The photo-isomerization process was followed in real-time through the simultaneous detection of absorbance and luminescence changes using a dedicated setup. Surprisingly, the photo-isomerization rate of the ligands, bound to the GNP surface, was the same as measured for the chromophores in solution. This outcome demonstrated that excitation energy transfer to gold assists photo-isomerization, rather than competing with it. These results pave the road to the development of new, NIR-emitting, stimuli-responsive nanomaterials for theranostics.
Macroscopic photocontrol of ion-transporting pathways of a nanostructured imidazolium-based photoresponsive liquid crystal
Soberats, Bartolome,Uchida, Emi,Yoshio, Masafumi,Kagimoto, Junko,Ohno, Hiroyuki,Kato, Takashi
, p. 9552 - 9555 (2014/07/22)
The photocontrol of the macroscopic alignment of nanostructured 2D ion-transporting pathways is described. The uniplanar homogeneous alignment of the thermotropic smectic (Sm) liquid-crystalline (LC) phase has been successfully achieved via photoinduced reorientation of the azobenzene groups of the imidazolium-based LC material. The ionic layers of the Sm LC phase are macroscopically oriented perpendicular to the surface of the glass substrate. The oriented films show anisotropic ion conduction in the Sm phase. This is the first example of the macroscopic photoalignment of ion-conductive LC arrays. Reversible switching of homeotropic and homogeneous alignments has also been achieved for the LC material. These materials and the alignment methodology may be useful in the development of ion-based circuits and memory devices.
Non-symmetric liquid crystal dimer containing a carbohydrate-based moiety
Cook, Andrew G.,Wardell, James L.,Brooks, Nicholas J.,Seddon, John M.,Martinez-Felipe, Alfonso,Imrie, Corrie T.
, p. 78 - 83 (2012/11/07)
The synthesis and characterisation of a novel non-symmetric liquid crystal dimer, 1-[3-O-(d-glucopyranos-3-yl)]-8-[(4-methoxyazobenzene-4′-oxy)] octane is reported. This exhibits glassy behaviour and a highly interdigitated smectic A phase in which the aromatic and alkyl structural fragments overlap. Variable temperature infrared spectroscopy reveals that the strength and extent of hydrogen bonding within the system does not show a marked change at either the glass transition or at the smectic A-isotropic transition. This observation indicates that the smectic A-isotropic transition is driven by changes in the van der Waals interactions between the molecules while hydrogen bonded aggregates persist into the isotropic phase.
Effect of Structure of Photoresponsive Molecules on Photochemical Phase Transition of Liquid Crystals I. Synthesis and Thermotropic Properties of Photochromic Azobenzene Derivatives
Ikeda, T.,Miyamoto, T.,Kurihara, S.,Tsukada, M.,Tazuke, S.
, p. 357 - 371 (2007/10/02)
Seventeen azobenzene derivatives were synthesized and their thermotropic properties were examined.They are classified into three groups.In the first group, 4-cyanobiphenyl moieties are attached to both sides of azobenzene through various alkyl spacers: AB(nCB)2 where n = 3, 4, 5 and 6.In the second group, the 4-cyanobiphenyl moiety is attached to one side of the azobenzene, while the substituent of the other side was kept as OCH3:1ABnCB, where n = 3, 4, 5, 6 and 8.The third group is the azobenzene derivatives which possess alkoxy substituents at both para positions of azobenzene (nABm) or at various positions of the azobenzene phenyl rings (k,1ABn,m).The introduction of the 4-cyanobiphenyl group at the end(s) of the molecules is based on the attempt of highly efficient photochromic molecules to induce photochemical phase transition of liquid crystals by providing the photochromic trigger molecules with high affinity to the host liquid crystal.Both 1ABnCB and AB(nCB)2 exhibited the liquid crystalline phases, whereas among nABm and k,1ABn,m, only 1AB8 and 8AB8 showed the liquid crystalline phase.The 1ABnCB series exhibited a distinct odd-even variation in phase transition temperatures as well as enthalpy and entropy changes with the length of the flexible spacers, while the AB(nCB)2 series did not show clear odd-even variation except for the liquid crystal to isotropic phase transition temperatures.
