- A Molecular Chameleon: Reversible pH- and Cation-Induced Control of the Optical Properties of Phthalocyanine-Based Complexes in the Visible and Near-Infrared Spectral Ranges
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A series of novel nonperipherally substituted tetra-15-crown-5-dibutoxyoxanthrenocyanines (H2, Mg, Zn), acting as chameleons with the unique properties of switchable absorption and emission in the near-infrared (NIR) spectral range have been synthesized and characterized by X-ray diffraction. The attachment of 15-crown-5-α-dibutoxyoxanthreno moieties to phthalocyanine is responsible for the high solubility of the resulting molecules and the red shift of the Q band to the NIR region and offers a unique possibility for postsynthetic modification of the optical properties of the molecules. Both aggregation of phthalocyanine and its participation in an acid-base equilibrium strongly alter their optical properties. For example, the absorption of complexes can be reversibly tuned from 686 up to 1028 nm because of the cation-induced formation of supramolecular dimers or subsequent protonation of meso-N atoms orf macrocycle, in contrast to peripherally substituted tetra-15-crown-5-phthalocyanines without oxanthrene moieties. The reversibility of these processes can be controlled by the addition of [2.2.2]cryptand or amines. All investigated compounds exhibit fluorescence with moderate quantum yield, which can also be switched between the ON and OFF states by the action of similar agents.
- Safonova, Evgeniya A.,Martynov, Alexander G.,Nefedov, Sergey E.,Kirakosyan, Gayane A.,Gorbunova, Yulia G.,Tsivadze, Aslan Yu.
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- Understanding the limitations of NIR-to-visible photon upconversion in phthalocyanine-sensitized rubrene systems
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Low-power near-infrared (NIR)-to-visible (vis) photon upconversion (UC) systems are in demand for biomedical, photovoltaic and photocatalytic applications; however, the practical utilization is still hampered by low UC efficiency. Aiming to identify effic
- ?inkeviciute, Ugne,Javorskis, Tomas,Jozeliunaite, Augustina,Jur?enas, Saulius,Kazlauskas, Karolis,Orentas, Edvinas,Radiunas, Edvinas,Rai?ys, Steponas
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p. 5525 - 5534
(2020/05/13)
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- The Development of Solid Spectral Filters for the Regulation of Plant Growth
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Phthalocyanine derivatives have been prepared and incorporated into polymer films for use as spectral filters for the modification of plant growth. The unusual absorption characteristics of phthalocyanines, notably the narrow absorption band in the visible region of the electromagnetic spectrum, allows the selective filtering of wavelengths necessary for excitation of either of the two isomeric phytochrome species. The resulting change in the photostationary state for the phytochrome is shown to have a marked effect on the growth characteristics of both chrysanthemums and antirrhinums. Chrysanthemums (short-day plants) grown under a far-red-absorbing film showed a reduction in height (≈14%) and internodal length compared to those grown under a red-absorbing film or a control with no absorption in the visible part of the spectrum; both leaf number and time to flowering were not affected by the presence of the spectral filter. For antirrhinums (long-day plants) both a reduction in height and a substantial increase in leaf area (70%) of the plants grown under the far-red-absorbing film were observed, although flowering was delayed. The potential of these filters as replacements for chemical plant growth regulators is discussed.
- Van Haeringen,West,Davis,Gilbert,Hadley,Pearson,Wheldon,Henbest
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p. 407 - 413
(2007/10/03)
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- Octa-alkoxy Phthalocyanine and Naphthalocyanine Derivatives: Dyes with Q-band Absorption in the Far Red or Near Infrared
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The lithium alkoxide-catalysed cyclic tetramerisation of various 3,6-dialkoxy-4,5-dichlorophthalonitriles, 1,4-dialkoxynaphthalene-2,3-dicarbonitriles and 3,6-dialkoxyphthalonitriles to give the corresponding metal-free octa-alkoxyoctachlorophthalocyanines, octa-alkoxynaphthalocyanines and octa-alkoxyphthalocyanines is described.An unexpected trans-alkoxylation reaction occurs during the cyclisation of the first two series of precursors.Metal-free phthalocyanines and naphthalocyanines have been converted into derivatives containing various metal ions.Compounds show Q-band absorption in the region 739-862 nm in toluene solution.The fluorescence spectra of selected examples are reported.The solubility of some of the compounds has been measured in a formulation of liquid crystal materials.
- Cook, Michael J.,Dunn, Adrian J.,Howe, Steven D.,Thomson, Andrew J.,Harrison, Kenneth J.
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p. 2453 - 2458
(2007/10/02)
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